WO2003090923A1

WO2003090923A1 - Material for adsorbing ozone

Info

Publication number: WO2003090923A1
Application number: PCT/GB2003/001704
Authority: WO
Inventors: Chedly Tizaoui
Original assignee: University Of Bradford
Priority date: 2002-04-23
Filing date: 2003-04-22
Publication date: 2003-11-06
Also published as: GB0209232D0; AU2003229925A1

Abstract

A composition in the form of a particle comprising one or more adsorbents for adsorbing ozone in admixture with a binder, wherein the binder comprises less than or equal to 9 % by weight of aluminium cations based on the weight of the binder.

Description

MATERIAL FOR ADSORBING OZONE

The present invention relates to a composition and, in particular, but not exclusively, to a composition having a high affinity for ozone, a process for preparing the composition and its use for removing a contaminant from a fluid, such as water or air.

Contaminated fluids may be produced from a variety of sources. For example, contaminated air may be produced by the introduction and/or formation of various pollutants, for example oxides of nitrogen and sulphur, into ..the atmosphere. Suitably, such pollutants may be produced and discharged into the atmosphere as a consequence of household and industrial activities i.e. burning fuels such as coal and gasoline. The presence of such pollutants in the air typically presents undesirable environmental consequences, as they may contribute to acid rain , and smog. Suitably,* it is desirable to minimise the amount of pollutants in air, either by removing pollutants from the air or by discharging fewer pollutants into the atmosphere .

Various techniques are known for removing pollutants from air for example: flue gas desulphurisation (FGD) may be used for removing S0₂ from flue gases of power stations by contacting the gas with calcium carbonate; and selective catalytic reduction (SCR) may be used for controlling nitrogen oxides. However, such techniques typically involve complex equipment and may be expensive to install. Suitably, it is desirable to provide improved techniques for removing pollutants from or reducing the amount of pollutants in the atmosphere. Contaminated liquids, such as water, may be produced from a variety of sources, such as, groundwater containing waste deposits and direct effluents from household and industrial activities, for example pharmaceutical manufacturing plants. Typically, it is desirable to purify these aqueous effluents either before discharging them into the environment or before reusing the water.

Traditional processes for purifying water, particularly sewage treatment, involve physical processes, such as sedimentation and flotation, for removing pollutants from water. Chemical, biological processes, membrane filtration, ion exchange, enzymatic action, reverse osmosis and chemical oxidation reactions have also been employed.

Chemical oxidation techniques have been widely used for treating polluted water. Suitable chemical oxidising agents include chlorine, chlorine dioxide, hydrogen peroxide and/or hypochlorite which are capable of oxidising a wide range of pollutants such as halogenated hydrocarbons, including chlorine- and bromine-containing compounds, pesticides, insecticides, polycyclic aromatics', dyestuffs, cyanides, phenols, mercaptans, and microorganisms .

Suitably, the usefulness of chemical oxidising agents for water treatment is dependent, amongst other things, on the ability of the oxidising agent to oxidise pollutants to less harmful and less toxic products . Although chlorine and chlorine-containing compounds e.g. hypochlorite and chlorine dioxide, have been widely used for treating water, the utility of these compounds is limited to a certain degree as these oxidants may generate compounds having a higher toxicity than the original pollutants.

In an attempt to overcome the disadvantages associated with chlorine containing oxidants, alternative oxidising agents such as ozone have been investigated. Ozone (0₃) is a gas that is formed when oxygen is exposed to ultraviolet light. Ozone is a powerful oxidant, deodorizer and disinfectant, and it therefore represents an alternative reagent to traditional chlorine-containing oxidants ^■ for treating water. Ozone is capable of destroying bacteria and viruses, spores and cysts, while at the same time removing other pollutants by oxidation. Moreover, ozone, unlike chlorine-containing oxidants, may not produce undesirable by-products as it breaks down into diatomic oxygen. Ozone has been used to purify drinking water* and industrial wastewaters, for example for removing colour pollutants from wastewaters of the food and textile industry.

Suitably, processes for treating liquids, such as water, with ozone comprise generating an oxygen/ozone . or air/ozone gaseous mixture from oxygen in an ozone generator and then contacting water with the gaseous oxygen/ozone or air/ozone mixture. The gaseous oxygen/ozone or air/ozone mixture may be bubbled into a stream of water using injectors, porous diffusers, dispersing turbines or by use of a contact chamber which ozonates a proportion of the main stream of water. However, a major drawback associated with using gaseous ozone/oxygen or ozone/air mixtures is the problem of increasing the ozone concentration in the liquid, i.e. water, to a level that enables the reaction to proceed at an acceptable rate. Hence, the throughput and commercial viability of such processes may be reduced. Moreover, another problem associated with bubbling gaseous ozone/oxygen or ozone/air mixtures into a liquid, i.e. water, is that a foam may form on the water, particularly if the water contains a surfactant. Foam formation typically necessitates a further treatment step, thereby increasing the overall cost of the process.

It is believed that the difficulty of increasing the ozone concentration in a liquid, such as water, is at least in part, due to the, limitations of the ozone generator which typically produces dilute mixtures of ozone in oxygen or air. Consequently, the liquid is contacted with a gaseous ozone stream containing a low concentration of ozone gas.

In an attempt to rectify this difficulty, attention has focussed on contacting a liquid, i.e. water with gaseous streams having a higher concentration of ozone gas. One such method involves condensing a gaseous oxygen and ozone mixture at low temperature, and removing at least part of, suitably the majority of, unconverted oxygen from the mixture to produce a liquefied mixture containing a higher concentration of liquefied ozone. The unconverted oxygen may be recycled to the ozone generator. The concentrated liquefied ozone mixture may be vaporised and the resultant gas contacted with the water. Although, this method has gone some way to solve the problems of providing a higher concentration of ozone in a liquid (i.e. water), typically it is necessary to use expensive and specialist apparatus to produce and handle the concentrated liquid ozone mixture. Moreover, the method is potentially extremely hazardous, as the concentrated liquefied and gaseous ozone mixture may spontaneously explode and/or ignite.

An alternative procedure for increasing the concentration of ozone obtainable from a gaseous oxygen/ozone ^• or ozone/air mixture involves passing the gaseous mixture through a solvent that is immiscible with the liquid to be treated i.e. water. Suitable immiscible solvents with water include liquefied dichlorodifluoromethane or chlorotrifluoro-methane, which exhibit a higher selectivity for dissolution of ozone than oxygen, thereby producing a carrier solvent having a high concentration of ozone dissolved therein.

The ozone solvent mixture may be contacted with, the water directly and the carrier solvent then physically separated from the water' for re-use. Suitably, such a process involves an additional treatment step to remove the carrier solvent and may necessitate the use of specialist and expensive equipment, thereby detracting from the commercial viability of the process .

Alternatively, the carrier solvent may be vaporised to produce gaseous ozone and the gaseous ozone contacted with the water. However, the vaporisation method also suffers from similar drawbacks associated with producing and handling highly concentrated gaseous ozone, namely: it is necessary to use expensive and specialist apparatus, ' and the method is potentially hazardous, as the concentrated gaseous ozone may explode or ignite.

More recently, alternative procedures for increasing the concentration of ozone obtainable from a gaseous oxygen/ozone or ozone/air mixture have focused on passing the gaseous mixture over an adsorbent, such as silica gel or zeolite, which exhibits a higher selectivity for ozone adsorption than adsorption of oxygen. Suitably, ozone may be desorbed from the adsorbent by the application of reduced pressure. Although this may reduce the hazards associated with handling gaseous or solvent mixtures having a high concentration of ozone, a major drawback of such a process is associated with the capacity of _t the adsorbent to adsorb insufficient quantities of ozone'. Typically, silica gel and/or other types of adsorbents may exhibit a low adsorptive capacity for ozone at ambient temperatures and it may be necessary to employ temperatures approaching the cryogenic range to achieve satisfactory ozone loading. Consequently, the overall cost of the process may increase substantially because of the requirement for expensive refrigeration equipment. Moreover, the adsorbents may promote decomposition of ozone adsorbed thereon. Consequently, this may further significantly reduce the productivity and commercial viability of the process.

The present invention seeks to solve the aforementioned technical problems associated with handling and delivering ozone to a fluid. In particular, the present invention aims to solve the aforementioned problems of removing a contaminant/pollutant from a fluid. Suitably, the present invention aims to solve the aforementioned problems associated with producing a high concentration of ozone in a fluid, such as a gas or a liquid. Suitably, the present invention aims to solve problems associated with producing a high concentration of ozone in a solution, particularly an aqueous solution such as contaminated water. Furthermore, the present invention aims to solve the problems associated with producing a high concentration of ozone in a gas, particularly contaminated air. Even still further, the present invention aims to enhance contact of ozone with chemicals dissolved and/or suspended and/or dispersed in a fluid, such as a gas, water or other liquids .

According to a first aspect, the present invention provides a composition in the form of a particle comprising one or more adsorbents for adsorbing ozone in admixture with a binder, wherein the binder comprises less than or equal to 9% by weight of aluminium cations based on the weight of the binder. Such- a composition is ^' referred to herein as the composition of the present invention.

Suitably, the binder in the composition of the present invention comprises less than or equal to 9% by weight, preferably less than or equal to 8% by weight, more preferably less than or equal to 5% by weight, even more preferably less than or equal to 2% by weight, even more preferably less than or equal to 0.5% by weight, even more preferably less than or equal to 0.3% by weight, most preferably less than or equal to 0.1% by weight of aluminium cations. An especially preferred binder in the composition of the present invention does not include" any aluminium cations .

By the term "aluminium cations" we mean aluminium in a positive oxidation state. Compounds containing aluminium cations include oxides and hydroxides of aluminium, such as aluminium (III) oxide (Al₂0₃) . Suitably, the binder comprises less than or equal to 1.7% by weight, more preferably less than or equal to 1.5% by weight, even more preferably less than or equal to 1.3% by weight, even more preferably less than or equal to 1.0% by weight, even more preferably less than or equal to 0.7% by weight, even more preferably less than or equal to 0.5% by weight, even more preferably less than or equal to 0.2% by weight, even more preferably less than or equal to 0.1% by weight, most preferably less than or equal to 0.05% by weight aluminium (III) oxide based on the weight of the binder. An especially preferred binder includes substantially no aluminium (III) oxide.

Suitably, the concentration of aluminium cations in the binder and/or the composition of the present invention may be determined by techniques well known to those skilled in the art, for example atomic absorption spectrometry.

Suitably, the composition of the present invention , may exhibit a high adsorptive capacity for ozone at ambient temperatures, thereby negating the requirement for employing expensive refrigeration equipment. Suitably, the composition of the present invention may not promote decomposition of ozone adsorbed thereon. Consequently, near quantitative desorption of ozone may be realised from a composition of the present invention having ozone adsorbed thereon. Suitably, the inclusion of the binder may prevent the composition of the present invention from breaking down into smaller particles, particularly when the composition of the present invention is placed in contact with a fluid, such as a liquid (i.e. water) <pr a gas. Consequently, the composition of the present invention may be employed to deliver high concentrations of ozone to fluids, such as during a water purification process, without increasing resistance to fluid flow rates . Thus it may not be necessary to employ high pressures during such a process, thereby increasing the commercial and economic viability of these processes.

Moreover, the composition of the present invention may be used to produce high concentrations of ozone, particularly high localised concentrations, in a fluid such as in solutions, such as contaminated water, and/or enhance contact of ozone with a material, such as contaminant, located therein. Thus, the rate of reaction of a contaminant present in a fluid, such as water or air, with ozone may be increased by employing a composition of the present invention having ozone adsorbed thereon, thereby increasing the efficiency and commercial viability of a water purification process.

Suitably, the binder in the composition of the present invention comprises less than or equal to 9% by weight, preferably less than or equal to 8% by weight, more preferably less than or equal to 2% by weight, more preferably less than or equal to 0.5% by weight, more preferably less than or equal to 0.3% by weight, most preferably less than or equal to 0.1% by weight of metallic cations based on the weight of the binder. An especially preferred binder in the composition of the present invention does not include any metallic cations.

By the term "metallic cations" we mean compounds containing a metallic element in a positive oxidation state e.g. oxides and hydroxides of metals, such as metals of Groups I to III of the periodic table (i.e. sodium, zinc and aluminium) as well as other metals such as titanium. By the term "metallic cations" we do not include silicon in* an oxidised state.

Suitably, the concentration of metallic cations and other components (i.e. silicon) present in the binder and/or, the composition of the present invention may be determined, for example, by atomic absorption spectrometry.

Suitably, if the composition of the present invention and/or the binder of the composition of the present invention includes a low concentration of metallic cations, preferably a low concentration of aluminium cations within the above defined limits, more preferably no aluminium and/or metallic cations, then the stability of ozone adsorbed by the composition of the present invention may be increased compared to a comparable composition having a higher concentration of metallic cations, particularly aluminium cations outside the above defined limits. This may further permit easier and near quantitative desorption of ozone from the composition of the present invention compared to the adsorbent per se or the adsorbent bound with a binder having a higher concentration of metallic and/or aluminium cations outside these limits.

As described hereinafter, the particulate composition of the present invention may be prepared by adding the one or more adsorbent (s) , typically in powder form, to a solution/slurry of the binder, e.g. an aqueous silicon based solution. The particulate may subsequently be formed by evaporating a major proportion of, preferably the entire, solvent from the solution/slurry of the binder: Consequently, by the term "binder in the composition of the present invention" as used herein we mean the binder in the composition of the present invention when- in particulate form. Preferably, the binder binds two or more adsorbents in particulate form. However, the binder may fully or partially coat a single particulate. Such particulates are also embraced by the scope of the present invention.

Preferably, the binder in the composition of the present invention provides less than or equal to 20% by weight, more preferably less than or equal to 18% by weight, most preferably less than or equal to 15% by weight of the total weight of the composition of the present invention.

Preferably, the binder in the composition of the present invention provides greater than or equal to 5% by weight, more preferably greater than or equal to 7% by weight, most preferably greater than or equal to 10% by weight of the total weight of the composition of the present invention.

Preferably, the binder comprises a silicon-based binder, especially a binder that is essentially silicon-based.

By the term "silicon based binder" we mean a binder that includes silicon and/or silicon in a positive oxidation state e.g. oxides and hydroxides of silicon. Suitably, the binder binds the one or more adsorbents into a particle.

Preferably, the silicon based binder in the composition of the present invention includes greater than or equal to 90% by weight, more preferably greater than or equal to

92% by weight, more preferably greater than or equal to

98% by weight, more preferably greater than or equal to 99.5% by weight, more preferably greater than or equal to 99.7% by weight, most preferably greater than or equal to 99.9% by weight of silicon and/or silicon in a positive oxidation state.

Preferably, the binder is porous so that the adsorptive capacity of the one or more adsorbents is not substantially reduced by the inclusion of the binder. Preferably, the average pore size of the binder is less than or equal to 200 angstroms, more preferably less than or equal to 150 angstroms, most preferably less than or equal to 100 angstroms. The pore size may be measured using nitrogen adsorption techniques well known to those skilled in the art, for example using ASAP 2010 equipment obtainable from Micromeritics .

Most preferably, the binder is a silica sol gel.

Silica sol gels are transparent oxide glasses, typically having pore sizes within the ranges stated above, and are available from commercial suppliers such as CATAL Ltd. Sheffield Science Park, Cooper Bldgs., Arundel St., Sheffield SI 2NS. Alternatively, silica sol gels may be prepared by the polycondensation and hydrolysis of silica alkoxides, such as tetramethylorthσsilicate, by methods well known to those skilled in the art. Suitably, the gels have excellent adhesive properties.

Unexpectedly, the inclusion of a binder comprising a silicon-based material may promote increased adsorption of ozone by the one or more adsorbents, increased stability of ozone adsorbed on the adsorbents, and may permit near quantitative desorption of ozone from the adsorbents compared with employing a binder that does not include a silicon based material. Although only theory, it is believed a silicon-based binder may increase the relative number of available silicon sites for reversible binding with ozone by introducing further silicon sites for reversible coordination with ozone.

Suitably, the excellent adhesive properties of the binder, particularly silica sol gel, may prevent the composition of the present invention from disintegrating into fine particles during use, such as in a water treatment processes. Consequently, high pressures may not be required during such purification processes, thereby increasing the commercial viability of these processes.

Preferably, the one or more adsorbent (s) for adsorbing ozone is selected from silica gel and/or a zeolite. More preferably, the one or more adsorbent (s) comprises one or more zeolites. Most preferably, the one or more adsorbent (s) includes one or more zeolites only.

Preferably, the one or more adsorbents of the composition of the present invention provides greater than or equal to 80% by weight, more preferably greater than or equal to 82% by weight, most preferably greater than or equal to 85% by weight of the total weight of the composition of the present invention.

Preferably, the one or more adsorbents of the composition of the present invention provides less than or equal to 95% by weight, more preferably less than or equal to 93% by weight, most preferably less than or equal to 90% by weight of the total weight of the composition of the present invention.

^■ 5

By the term "one or more adsorbents of the composition of the present invention" as used herein we mean that adsorbent (s) in the composition of the present invention when in particulate form.

10

Silica gel is an amorphous form of silicon dioxide that includes a microporous structure of interlocking cavities producing a high surface area. Suitable silica gels are available from GeeJay Chemicals Ltd of 16 Gosforth Close,

15 Sandy, Bedfordshire, UK and sold under the trade names of nonindicating silica gel.

Preferably, when the one or more adsorbent (s) of the composition of the present invention include one or more

20 silica gels only, then the composition of the present invention comprises less than or equal to 0.8% by weight, more preferably less than or equal to 0.7% by weight, even more preferably less than or equal to 0.6% by weight, even more preferably less than or equal to 0.5% by weight, even 5 more preferably less than or equal to 0.4% by weight, even more preferably less than or equal to 0.3% by weight, even more preferably less than or equal to 0.2% by weight, even more preferably less than or equal to 0.1% by weight, most preferably less than or equal to 0.05% by weight' of 0 aluminium cations based on the total weight of the composition.. An especially preferred composition of the present invention does not include substantially any aluminium cations, when the one or more adsorbent (s) include one or more silica gels only.

Typically, zeolites are three-dimensional, microporous, crystalline solids having defined structures comprising aluminium, silicon and oxygen in their framework. The microporous^' structure permits the zeolite to accommodate other molecules and ions. Suitably, the silicon and aluminium are present as oxides namely, silicon (IV) and aluminium (III) oxide, respectively. The silicon and aluminium atoms are typically tetrahedrally coordinated with each other through shared oxygen atoms. The silicon

(IV) units are neutral as the charge on the silicon ion is neutralised by an electron from each of the shared tetrahedrally coordinated oxygen atoms. The aluminium

(III) units have a net negative charge as the' aluminium

(III) ion is coordinated to four oxygen atoms. The overall net negative charge of the zeolite is balanced by counter cations, such as sodium, ammonium and hydrogen, that are present during synthesis of the zeolite.

Zeolites and silica gels may be used to adsorb' a variety of molecules and compounds. It is believed adsorption and desorption of ozone is accomplished, amongst other things, by ozone penetrating the microporous structure and reversibly coordinating to the silicon.

Although only theory, it is believed that ozone forms a relatively weak coordination complex with a silicon ion compared to a metallic cation, particularly an aluminium cation, as the metallic cation is typically a stronger Lewis acid than the silicon ion. The stronger binding of the ozone molecule to a metallic cation, particularly an aluminium cation, may not only hinder desorption of ozone from an adsorbent but may also promote decomposition of the coordinated ozone molecule. The metallic cation may cause the shape of the coordinated ozone molecule" to distort, which may occur to such an extent that the ozone molecule dissociates to produce diatomic oxygen which is not bound to the adsorbent and a surface oxygen atom bound to the metallic cation. It is believed that the binder in the composition of the present invention may effectively reduce the relative number of metallic cations in 'the adsorbent which are available for coordination with ozone.. Suitably, the reduction in the relative number of available metallic cations in the adsorbent (s) may be due to an overall increase in the number of silicon sites, thereby promoting preferential reversible coordination of ozone to the silicon sites in the adsorbent (s) . 'The preferential reversible coordination of ozone to the silicon sites may thus increase the stability of the ozone adsorbed by the adsorbent (s) and may permit easier and near quantitative desorption of ozone from the adsorbent (s) .

It will be appreciated that when the one or more adsorbents comprise a zeolite, then the binder in the composition of the present invention may effectively reduce the relative number of aluminium cations in the zeolite (s), thereby increasing the number of silicon sites available for reversibly coordinating to ozone.

Suitably, increasing the mole ratio of silicon (IV) oxide to aluminium (III) oxide in the one or more zeolites in the composition of the present invention may permit increased adsorption of ozone by and/or increased desorption of ozone from the composition of the present invention.

Preferably, the mole ratio of silicon (IV) oxide to aluminium (III) oxide in the one or more zeolites

(Si0₂/Al₂0₃ mole ratio) in the composition of the present invention is greater than or equal to 30, more preferably greater than or equal to 60, more preferably greater than or equal to 100, more preferably greater than of equal to 150, more preferably greater than or equal to 225, most preferably greater than or equal to 275.

Suitably, when the one or more adsorbents includes a zeolite, we have found that if the counterion of the one or more zeolites is a hydrogen ion as opposed to an ammonium ion, then this may promote increased adsorption of ozone by and/or increased desorption of ozone from the composition of the present invention.

Thus, according to a preferred embodiment of the present invention wherein the one or more adsorbents include a zeolite (s), greater than or equal to 50% of the available counterions of the one or more zeolites are hydrogen ions, preferably greater than or equal to 70%, more preferably greater than or equal to 80%, more preferably greater than or equal to 90%, more preferably greater than or equal to 95%, more preferably greater than or equal to 98%, more preferably greater than or equal to 99%, most preferably greater than or equal to 99.5% of the available counterions of the one or more zeolites are hydrogen ions. In an especially preferred embodiment essentially all of the counterions of the one or more zeolites are hydrogen ions . It will be appreciated by those skilled in the art that when greater than or equal to 50% of the available cations of the one or more zeolites are hydrogen ions, then less than or equal to 50% of the available cations of the one or more zeolites are selected from other counter cations such as ammonium or sodium ions .

Suitably, increasing the surface area of the one or more adsorbent (s) in the composition of the present invention may permit increased adsorption of ozone by and/or increased desorption of ozone from the composition of the present invention.

Preferably, the surface area of the one or more adsorbents in the composition of the present invention is greater than or equal to 250 m/g, more preferably greater than or equal to 300 m²/g, more preferably greater than or equal to 350 m²/g, more preferably greater than or equal to 400 m²/g, more preferably greater than or equal to. 450 m²/g, most preferably greater than or equal to 500 tτi²/g. Suitably, the surface area may be determined using ASAP 2010 equipment obtainable from Micrometrics .

Suitably, increasing the adequate pore size of the one or more adsorbents in the composition of the present invention may permit increased adsorption of ozone by and/or increased desorption of ozone from the composition of the present invention.

Preferably, the average pore size of the one or more adsorbents in the composition of the present invention is greater than or equal to 2 angstroms (A) , more preferably greater than or equal to 5A, even more preferably greater than or equal to 20A. Preferably, the average pore size of the one or more adsorbents in the composition of the present invention is less than or equal to 100 ^' angstroms A, more preferably less than or equal to 75A, even more preferably less than or equal to 40A.

Suitably, the one or more adsorbents has a weight average particle size of greater than or equal to 1 μm, preferably greater than or equal to 5μm, more preferably greater than or equal to 7μm, even more preferably greater than or equal to 10 μm. Suitably, the one or more adsorbents has a weight average particle size of less than or equal to 100 μm, preferably less than or equal to 75 μm, more preferably less than or equal to 40 μm. The particle size of the one or more adsorbents may be measured by techniques well known to those skilled in the art such as electron microscopy.

Preferably, the composition of the present invention has a weight average particle size (mesh) in the range of 10 mm to 0.1 mm, more preferably greater than or equal to 2 mm and less than or equal to 4 mm. Typically, the particle size may be ^• determined by sieving the composition of the present invention.

Preferably, the average maximum dimension of the composition of the present invention is greater than or equal to 0.1 mm, more preferably greater than or equal to 0.5 mm, more preferably greater than or equal to 1 mm as determined by passing the composition through a set of sieves . Preferably, the average maximum dimension ' of the composition of the present invention is less than or equal^, to 10 mm, more preferably less than or equal to 8 mm, most preferably less than or equal to 5 mm as determined by passing the composition through a set of sieves.

The composition of the present invention may have a regular shape e.g. spherical, bead or rod-shaped.. Alternatively, the composition of the present invention may have an irregular shape. Preferably, the composition of the present invention is in the form of substantially spherical particles. Most preferably, the spherical particle has a cross-sectional diameter of about 2 mm.

Preferably, the amount of ozone desorbed from a composition of the present invention having ozone adsorbed thereon is greater than or equal to 50% by weight, more preferably greater than or equal to 60% by weight, more preferably greater than or equal to 70% by weight, more preferably greater than or equal to 80% by weight,, preferably greater than or equal to 90% by weight, preferably greater than or equal to 95% by weight, most preferably, greater than or equal to 97% by weight of the ozone adsorbed by the composition of the present invention.

We have found that the adsorptive capacity of the composition of the present invention is typically reduced much less when the composition of the present invention includes moisture compared to its capacity when it does not contain moisture i.e. it is essentially "dry". Typically, adsorption of ozone by an adsorbent, particularly a silica gel adsorbent, may be significantly reduced if the adsorbent contains a small quantity of moisture. Consequently, if such an adsorbent e.g. silica gel having ozone adsorbed thereon is used to deliver ozone to an aqueous solvent, such as in a water purification process to treat contaminated water, in order to permit re-use of the adsorbent after the ozone has completely desorbed therefrom, it is typically necessary to remove substantially all of the moisture from the adsorbent, for example by drying it in an oven or exposing it to dry air for prolonged periods of time, before exposing the adsorbent to an ozone gas mixture. In contrast, the regeneration of the composition of the present invention to permit further ozone adsorption following contact with an aqueous solvent typically requires reduced drying times, thereby increasing the commercial viability of the use of the composition of the present invention for delivering ozone to an aqueous solvent e.g. in a water treatment process.

Preferably, the composition of the present invention comprises less than or equal to 30% by weight water, more preferably less than or equal to 20% by weight water, most preferably less than or equal to 10% by weight water, even more preferably less than or equal to 5% by weight water, even more preferably less than or equal to 2% by weight water, even more preferably less than or equal to 1% by- weight, most preferably less than or equal to 0.5% by weight water.

Although the composition of the present invention may include water within the above defined limits, an especially preferred composition of the present invention is substantially anhydrous. Suitably, the composition of the present invention is capable of adsorbing greater than or equal to 0.1 mg, preferably greater than or equal to 0.5 mg, preferably greater than or equal to 1 mg, more preferably greater than or equal to 2 mg, more preferably greater than or equal to 3 mg, more preferably greater than or equal to 4 mg, most preferably greater than or equal to 5.5 mg, especially greater than or equal to 6 mg of ozone per gram of the composition of the present invention from a gaseous ozone stream having an ozone concentration of between 1 to 100 gm^"3 at room temperature and atmospheric pressure.

According to a second aspect, the present invention provides a process for manufacturing the composition of the present invention comprising contacting one or more adsorbents as defined herein with a binder as defined herein, and forming a particle from the composition.

Suitably, the one or more adsorbents and the binder are mixed together, preferably at room temperature. Preferably, the binder as defined herein is in the form of a solution or suspension. Most preferably, the solvent is an aqueous based solvent, such as an aqueous based organic solvent mixture.

A particularly preferred process for manufacturing a composition of the present invention, further includes the step of washing the particle with water and then drying the particle.

Unexpectedly, it has been found that if the composition of the present invention is initially washed with water, preferably washed with water and then dried within the aforementioned limits, prior to contact with ozone then the composition of the present invention may exhibit a higher capacity for ozone adsorption compared with a comparable composition that has not been washed and/or washed and then dried.

Suitably, the composition of the present invention is soaked in water at room temperature for greater than or equal to 1 minute, more preferably greater than or equal to 3 minutes, most preferably greater than or equal to 5 minutes .

Preferably, the composition of the present invention is dried so that it comprises a water content as defined hereinbefore. Suitably the composition of the present invention may be dried in a hot air oven (120°C) or dry air at room temperature and/or under vacuo.

According to a third aspect, the present invention provides a process for adsorbing ozone on a composition of the present invention, comprising providing a composition of the present invention as defined herein and contacting the composition with ozone gas.

Preferably, the process for adsorbing ozone on a composition of the present invention, further includes the step of washing the particulate composition with water, more preferably washing and then drying the composition, before contacting the composition with ozone gas.

It will be appreciated that the ozone gas may comprise an ozone/air or ozone/oxygen mixture . According to a fourth aspect, the present invention provides a use of the composition of the present invention for reducing the concentration of a material. Preferably, the material is suspended and/or dissolved and/or dispersed in a fluid, such as a liquid or gas. In a preferred aspect, the material as defined herein is suspended and/or dissolved and/or dispersed in a liquid such as an aqueous solution or aqueous solvent mixture . In a further alternative preferred aspect the material as defined herein is dispersed in a gas, such as air. Suitably, the material is a contaminant/impurity i.e. a material which is naturally not present in essentially pure fluid. Suitably, the material is capable of being oxidised by ozone.

According to a fifth aspect, the present invention provides a process for reducing the concentration of a material in a liquid, comprising adsorbing ozone on a composition of the present invention, and contacting a liquid including a material therein with the composition of the present invention having ozone adsorbed thereon.

Preferably, the process for reducing the concentration of a material in a liquid, i.e. a solvent further comprises the step of removing the composition of the present invention from the liquid after ozone has desorbed therefrom, contacting the composition with ozone gas, and then contacting the composition of the present invention having ozone adsorbed thereon with a liquid including a material . Preferably, the step of contacting the liquid including a material therein with the composition of the present invention having ozone adsorbed thereon, involves passing the liquid including a material therein over a bed of the composition of the present invention. Suitably, the liquid including a material therein may be passed continuously or passed in separate batches over the bed of the composition of the present invention.

Suitably, the liquid is passed over the bed of the composition of the present invention at a velocity of less than or equal to 200 x 10^"4ms^_1, preferably less than or equal to 168 x lO^ms^"1, more preferably less than or equal to 140 x 10^"4ms^-1, even more preferably less than or equal to 100 x 10^"4ms^-1, even more preferably less than or equal to 56 x 10^"4ms^-1, even more preferably less than or equal to 28 x 10^"4ms^"1, even more preferably less than or equal to 14 x 10^'ms^~1, most preferably less than or equal to 2 x

10^"4ms^"\

As mentioned previously, the inclusion of the binder may prevent the composition of the present invention from breaking down into smaller particles when in contact with the liquid. Consequently, the composition of the present invention may be employed to deliver high concentrations of ozone to a liquid without substantially increasing resistance to liquid flows.

Suitably, the material in the liquid may be dissolved and/or suspended and/or dispersed in the liquid. Preferably, the material is dissolved in the liquid. Preferably, the liquid comprises an aqueous solvent, such as water or an aqueous organic solvent mixture. It will be appreciated that when the liquid comprises an aqueous solvent, the process of this aspect of the invention embraces a method for reducing the concentration of a contaminant in water. Suitably, the material is oxidised to a less harmful material by ozone.

Suitably, when the liquid comprises an aqueous solvent, the step of removing the composition of the present invention from the aqueous solvent after ozone has desorbed therefrom, involves removing water from the composition of the present invention as defined herein (e.g. drying) so that it comprises a water content as defined herein.

Preferably, the material in the liquid is a contaminant/impurity which is essentially not present in the pure liquid. Preferably, in the case of a liquid, particular an aqueous solvent such as water, the material is selected from bacteria, viruses, spores, cysts and organic molecules such as dyes e.g. reactive azo dyes such as Drimarene Brilliant Red dye (DBR) or a combination or two or more of these impurities .

Preferably, the concentration of the material in the liquid is greater than or equal to 5 parts per million

(ppm) , more preferably greater than or equal to 10 ppm, even more preferably greater than or equal to 50 ppm, even more preferably greater than or equal to 100 ppm, most preferably greater than or equal to 150 ppm. Suitably, the concentration of material in the liquid may be as high as 50 mg/L, preferably less than or equal to 40 mg/L, more preferably less than or equal to 30 mg/L, most preferably less than or equal to 10 mg/L.

According to a sixth aspect, the present invention provides a process for reducing the concentration of a material in a carrier gas, comprising adsorbing ozone on a composition of the present invention, and contacting the carrier gas and material therein with the composition of the present invention having ozone adsorbed thereon.

Preferably, the process for reducing the concentration of a material in a carrier gas further comprises the step of removing the composition of the present invention from the carrier gas after ozone has desorbed therefrom, contacting the composition with ozone gas, and then contacting the composition of the present invention having ozone adsorbed thereon with carrier gas including a material .

Preferably, the step of contacting the carrier gas including a material therein with the composition of the present invention having ozone adsorbed thereon, involves passing the carrier gas including a material therein over a, bed of the composition of the present invention. Suitably, the carrier gas including a material therein may be passed continuously or passed in separate batches over the bed of the composition of the present invention.

Suitably, the material may be dissolved and/or suspended and/or dispersed in the carrier gas. Preferably, the material forms a homogeneous mixture with the carrier gas. Most preferably, the material as defined herein is a gas itself which is oxidised by ozone to form an oxidised gaseous product; the ozone is concomitantly reduced to oxygen. Suitably, the oxidised gaseous product is more soluble in a liquid, such as water, than the material itself. For example, if the material is nitrogen dioxide and/or nitrogen monoxide the ultimate oxidised gaseous product is N₂0₅ which dissolves in water, to form nitric acid. Thus according to a preferred aspect of the present invention, after the carrier gas and material contained therein is contacted with the composition of the present invention having ozone adsorbed thereon, the carrier , gas and material therein (i.e. in an essentially oxidised state) is passed through a liquid, for example water. Conveniently, this permits removal of the oxidised material from the carrier gas, thereby further purifying the gas .

Preferably, the carrier gas comprises air, most preferably the gas is essentially air. It will be appreciated that when the carrier gas comprises air, the process of this aspect of the invention embraces a method for reducing the concentration of a contaminant in air. Suitably, the contaminant is oxidised to a less harmful contaminant by ozone.

Preferably, the material in the gas is a contaminant/impurity which is essentially not present in the pure gas. Suitably, the impurity may be oxidised by ozone. Preferably, particularly where the gas is air, the material is an oxide of nitrogen and/or an oxide of sulfur, for example nitrogen monoxide, nitrogen dioxide, sulfur dioxide or sulfur trioxide. Alternatively, and/or additionally the material may be a volatile organic compound, such as chlorofluorocarbon. By volatile organic compound we mean essentially all of the organic compound is in the vapour state at room temperature and atmospheric pressure. Suitably, the material is a gas.

Preferably, the concentration of the material in the carrier gas is greater than or equal to 5 parts per million (ppm) , more preferably greater than or equal to 10 ppm, even more preferably greater than or equal to 50 ppm, even more preferably greater than or equal to 100 ppm, most preferably greater than or equal to 150 ppm. Suitably, the concentration of material in the gas may be as high as 1000 ppm, preferably less than or equal to 900 ppm, more preferably less than or equal to 800 ppm, most preferably less than or equal to 500 ppm.

Although only theory, it is believed that the composition of the present invention may not only permit delivery of a high concentration of ozone into the fluid but also may attract material present in the fluid thereby enhancing mass transfer and the chemical reaction rate by effectively bringing the material and ozone closer together.

According to a seventh aspect, the present invention provides the use of a composition of the present invention as defined herein having ozone adsorbed thereon for oxidising a material, particular a material as defined herein.

According to an eighth aspect, the present invention provides the use of a composition of the present invention as defined herein having ozone adsorbed thereon * for delivering ozone to a fluid, particularly an aqueous and/or organic solution or suspension and/or a gas. According to a ninth aspect, the present invention provides the use of the composition of the present invention for reducing the amount of and/or removing a contaminant (e.g. a material as defined above) from water.

According to a tenth aspect, the present invention provides the use ^• of the composition of the present invention for reducing the amount of and/or removing a contaminant (e.g. a material as defined above) from air.

According to an eleventh aspect, the present invention provides the use of the composition of the present invention for storing ozone.

It will be appreciated that features of the first, second, third, fourth, fifth, sixth, seventh, eight, ninth, tenth and eleventh aspects of the present invention, respectively, represent preferred features of the other aspects of the present invention.

The present invention will now be illustrated, by way of example only, with reference to the following drawings, in which: ^{• ■}

Figure 1 is a schematic illustration of apparatus' , for monitoring ozone adsorption by and ozone desorption from an adsorbent ;

Figure 2 is a schematic diagram of a pilot plant for treating contaminated water using a composition of the present invention; Figure 3 is a schematic diagram of a closed system for monitoring the effectiveness of either gaseous ozone or ozone loaded on an adsorbent for removing an impurity from water;

Figure 4 is a schematic diagram of apparatus for removing a contaminant from a carrier gas ;

Figure 5a is a plot of ozone adsorbed with respect to time at 26 °C for a glass column of length 30cm and internal diameter 15mm;

Figures 5b and 5c show the mass of ozone adsorbed (M_ads) by and the mass of ozone desorbed from (Ma_es) a glass column, respectively, with respect to specific concentration, of ozone in the ozone/oxygen gas mixture Cι_n at a column temperature of 19°C and 26°C respectively;

Figure 6a shows the mass of ozone adsorbed (M_ads) by (1) the zeolite powder per se; (2) the composition of the present invention which has been washed and dried prior to pellets of ozone adsorption; (3) the composition of the present invention which has been washed but not dried prior to ozone adsorption; and (4) the composition of the present invention which has not been washed or dried prior to ozone adsorption;

Figure 6b shows the mass of ozone desorbed (Md_es) from (1) the zeolite powder per se; (2) the composition of the present invention which has been washed and dried prior to pellets of ozone adsorption; (3) the composition of the present invention which has been washed but not dried prior to ozone adsorption; and (4) the composition of the present invention which has not been washed or dried prior to ozone adsorption;

Figure 6c is a bar graph of the results of Figures 5a and 5b;

Figure 7a shows the amount of ozone adsorbed (A_ads) by and the amount of ozone desorbed (Ades) from the composition* of the present invention with respect to varying moisture content;

Figure 7b compares the effect of moisture content on the amount of ozone adsorbed^' (A_ads) by the composition of the present invention and silica gel per se;

Figure 8a- is a comparative example showing ozone adsorption by a pelletised zeolite including, a binder containing aluminium compounds ;

Figure 8b is a plot of ozone adsorption by a composition of the present invention comprising zeolite and a silica sol gel binder;

Figure 8c is a plot of adsorption of ozone by ' and desorption of ozone from a composition of the present invention comprising a zeolite and a silica sol gel binder;

Figure 9 is a plot showing ozone adsorption by a zeolite having an ammonium or hydrogen counterion; Figure 10 shows ozone adsorption by and ozone desorption from a composition of the present invention (pelletised D915) and ozone loaded on silica gel; and

Figure 11 shows the variation of the final steady state concentration of Drimarene Brilliant Red (DMR) dye (C_df) compared to the initial concentration of the dye at time t=0 (C₀) due to oxidation by different concentrations of gaseous ozone, ozone loaded on silica gel or ozone loaded on a composition of the present invention (pelletised D915) .

1. Measuring Ozone Adsorption and Ozone Desorption

There is shown in Figure 1 apparatus (1) for monitoring ozone adsorption by and desorption of ozone from an adsorbent .

The apparatus (1) comprises a glass column (2) for receiving an adsorbent therein having an outlet (4) at its upper end and an inlet (6) at its lower end. The column

(2) includes a sintered glass support (8) for supporting a bed of adsorbent (7) . Typically, the column is 30cm in length and has a cross-sectional inner diameter of 15mm if the adsorbent is in pellet form. Typically, the column is

12cm in length and has a cross-sectional inner diameter of

125mm if the adsorbent is a powder.

The column's outlet (4) is in fluid communication with an inlet (9) of a first ozone gas analyser (10) , model BMT963 supplied by BMT Messtechnik GmbH of Argentinische Allee 32a, D-14163 Berlin Germany. The first ozone gas analyser (10) is connected via a serial interface (12) to- a computer (14) . The outlet (11) of the first ozone gas analyser (10) is connected to an ozone destruction means (16) via inlet (18) . The outlet (20) of the ozone destruction means (16) is vented to the atmosphere.

An outlet (22) of an ozone generator (24) is connected to the inlet (6) of the glass column (2) via a second ozone gas analyser (25) (not shown) which in turn is connected to the computer (14) . The inlet (26) of the ozone generator (24) is connected to a pressurised ^■ supply of oxygen (28) via flow meter (30) and throttle valve (32) ,. All connections between the various elements of the apparatus are gas tight and comprise PTFE tubes- or stainless steel pipes.

In use, oxygen flows from the pressurised oxygen supply

(28) to the ozone generator (24) . The oxygen flow rate is measured by the flow meter (30) and set to a specified flow rate, typically 500ml/min, by the throttle valve (32) . A gaseous stream of ozone and oxygen is generated by the ozone generator (24) and fed to the inlet (6) of glass column (2) via the second ozone gas analyser (25) . The gaseous ozone and oxygen mixture passes through the glass column (2) to the ozone destruction means • (16) via the first ozone gas analyser (10) . Ozone present in the gaseous ozone and oxygen mixture is destroyed by the destruction means (16) and the gaseous effluent discharged into the atmosphere. The ozone gas analysers (10, 25) in combination with the computer (14) measure, amongst other things, the ozone concentration in g/m³ exiting and entering the glass column (2) , respectively. Initially, ozone adsorption by and ozone desorption from the glass column (2) including the sintered glass support ^'(8) in the absence of any adsorbent is calculated to determine the adsorptive/desorptive capacity of the empty glass column (2) per se. Secondly, ozone adsorption by and ozone desorption from a known amount of adsorbent loaded in the glass column including the glass support is determined under identical conditions. The difference between the latter results and the initial results obtained using the glass column alone and making volume corrections, provides values of ozone adsorption by and ozone desorption from a known mass of adsorbent at specific parameters.

General Procedure for Ozone Adsorption

A dry gaseous oxygen/ozone stream at approximately atmospheric pressure containing a known concentration of ozone (Ci_n) , as measured by the second ozone analyser (25) , is passed through the column (2) . The concentration of ozone (C_out) in the gaseous stream exiting the column (2) is measured by the first ozone analyser (10), at various time periods (e.g. 1 second intervals). Measurements are continued until the concentration of ozone (Cout) in the gaseous stream exiting the column (2) is the same as the concentration of ozone (Cι_n) entering the column i.e. the column or the column plus adsorbent when present is saturated with adsorbed ozone. Typically the specific concentration of ozone (Ci_n) in the ozone/oxygen mixture entering the column is between 15 and

90 g/m³ at Normal Temperature and Pressure, (NTP corresponding to a temperature of 0°C and pressure of 1 bar) , the flow rate (Qo_2/o₃) of the gaseous ozone mixture is approximately 500 ml/min, and the temperature of the glass column is kept constant in the range of 19^CC to 26°C throughout the experiments .

The computer generates a graphical plot of the ratio of Cout/Cin against time for a specific gaseous ozone flow rate (Qo2_/o₃) a specific column temperature and a specific concentration of ozone (Cι_n) in the ozone/oxygen mixture entering the column. Integration of the computer¹ generated plot with respect to time in accordance with Equation 1 below provides the quantity of ozone adsorbed by the column or the column plus adsorbent when present (M_ads) at a specific flow rate (Qo_2/o₃) of the oxygen/ozone gaseous mixture, at a specific column temperature and a specific concentration of ozone (C*._n) in the ozone/oxygen mixture entering the column.

Equation 1.

M_ads }dt

The difference between ozone adsorbed by the column plus an adsorbent and ozone adsorbed by the column alone provides absolute values of ozone adsorption for a known amount of adsorbent.

General Procedure for Ozone Desorption

The gaseous oxygen/ozone stream is replaced by a stream of pure dry oxygen having a specific flow rate (Q₀₂) which is the same as the flow rate (Qo_2/o₃) of the oxygen/ozone stream employed for adsorption e.g. approximately 500 ml/min. The column is maintained at the same temperature employed for ozone adsorption. The concentration of ozone in the gaseous stream exiting the column (C_out) is measured by the first ozone gas analyser (10) at various time periods (e.g. 1 second intervals). Measurements are continued until the concentration of ozone in the gaseous stream exiting the column (C_out) is zero i.e. all the ozone has been desorbed from the column or the column plus adsorbent when present .

A graphical plot of the concentration of ozone in the gaseous stream exiting the column (C_out) with respect to time (t) at a specific oxygen flow rate (Qo₂) is generated by the computer (14) , to display ozone desorption from the column (2) . Integration of this plot with respect to time in accordance with Equation 2 provides the quantity of ozone desorbed from the column or the • column plus adsorbent when present (M_des) at a specific flow rate of oxygen (Qo) and a specific column temperature.

Equation 2.

The difference between ozone desorbed from the column plus an adsorbent and ozone desorbed from the column alone provides absolute values of ozone desorption for a known amount of adsorbent . 2. Removal of Materials from an Aqueous Solution

Initially, a composition of the present invention is contacted with a gaseous mixture of ozone and oxygen for sufficient time (T_x) until the composition is saturated with adsorbed ozone. Next, contaminated water including one of more impurities, such as Drimarene Brilliant Red dye (DBR) a reactive azo dye, is passed over a bed of the composition of the present invention loaded with ozone, so that the one or more impurities react with the adsorbed ozone. This stage is continued until a steady state is reached e.g. all the impurity (ies) has reacted with the ozone or the concentration of impurity (ies) remains constant, thereby indicating that all of the impurity (ies) has been removed from the water or all of the ozone has desorbed from and reacted with the impurity (ies) , respectively. Finally, the composition of the present invention is regenerated for further use by drying the composition either with dry hot air and/or under vacuo, and then contacting the dried composition with a further gaseous mixture of ozone and oxygen for sufficient time

(Ti) until the composition is saturated with adsorbed ozone. The regenerated composition may then be contacted with contaminated water.

Pilot Plant Apparatus

There is shown in Figure 2 a schematic diagram of a pilot plant (30) suitable for treating contaminated water using a composition of the present invention. ^"The pilot plant (30) includes a glass column (32) comprising four separate glass modules (34, 36, 38, 40) (each being 75cm. in height and having an internal diameter of 50mm) sealingly joined together in fluid communication. Each glass module includes a stainless steel mesh (42, 44, 46, 48) havirig a pore size of 0.5 mm extending across the cross-section of the module for supporting a bed of the composition of the present invention (50, 52, 54, 56).

In order to avoid problems associated with expansion by particle swelling or by virtue of fluid flow through "the bed of the composition of the present invention, each bed (50, 52, 54, 56) in each glass module (34, 36, 38, 40) is approximately 50cm in height. Thus, there is a dead space

(58, 60, 62, 64) of approximately 25 cm between the top of the bed in one glass module and the stainless steel mesh of an adjoining glass module. The glass column (32). is connected via a network of pipes, such as PTFE and stainless steel, and a series of valves to four units: an ozone generating unit (66) ; an ozone destruction unit (68) ; a water storage and collection unit (70) ; and a drying unit (72) .

The ozone generating unit (66) is similar to that illustrated in Figure 1 above and comprises an ozone generator (74) supplied by Invent Water Treatment Limited of Dell Road Shawclough Rochdale Lancashire the inlet of which (76) is connected to a controllable pressurised oxygen supply (78) via flow meter (80) and throttle valve

(82) by PTFE tubes. The outlet (86) of the ozone generator (74) is. connected to a gas distributor (88) by stainless steel pipes and PTFE tubes (90) .

The gas distributor (88) is connected to: an inlet (92) at the base of the column (32) by EPDM pipe (ozone resistant) (94) ; an outlet (97) at the top of column (32) by EPDM pipe (96) ; the ozone destruction module (68) by EPDM pipe (98) ; and an ozone monitoring station (100) by PTFE tubes' (102). The gas distributor comprises five valves (104, 106, 108, 110, 112), which are independently operable to direct selectively an ozone/oxygen gas stream from the ozone generator (74) or from the outlet (96) of column (32) to the inlet (92) at the base of column (32) and/or the ozone monitoring station (100) and/or the ozone destruction unit (68) .

The ozone destruction unit comprises a glass column (114) of length 40cm and inner diameter 25mm packed with a bed of alumina-based molecular sieve. The inlet' (116) of glass column (114) is connected by EPDM pipe (98) to the gas distributor (88) , whereas the outlet (118) of glass column (114) is connected by stainless steel pipe (120) to an injector (122) of a vacuum system (124) via valve (142) . The vacuum system comprises a storage vessel (126) containing an aqueous potassium iodide solution. The outlet (128) of storage vessel (126) is connected via pump

(127) to the injector (122) located at the inlet (130) of storage vessel (126) by copper pipes (131, 132) . Ozone which is not deactivated by the aluminium oxide in column

(114) is sprayed into a jet of aqueous potassium iodide in injector (122) where it is destroyed.

The ozone monitoring station (100) is similar to the one illustrated in Figure 1 and comprises an ozone gas analyser (134) linked to a computer (136) . The inlet (137) of the ozone gas analyser (134) is connected to the gas distributor (88) by PTFE tubes via a flow meter (138) . The outlet (140) of the ozone gas analyser (134) is connected to valve (142) by PTFE tubes (146) . Valve (142) is selectively operable to direct an ozone/oxygen gas, mixture either to the inlet (92) of column (32) via an EPDM tube (144) or to the injector (122) of the vacuum system (124) .

The water storage and collection module (70) comprises a polyethylene storage tank (146) of 340L capacity ^'for storing water containing impurities. The storage tank (146) is connected to a water distributor (148) via pump (150) and flow meter/flow regulator (152) by PVC flexible tubes (154, 156, 158) .,

The water distributor (148) is connected to: an irilet

(160) at the top of column (32) by PVC tubes (162) ; an outlet (164) at the bottom of column (32) by PVC tubes

(166) ; a water collection system (168) via PVC tubes

(170); and, to the drying module (72) by PVC tubes (172).

The water distributor comprises four valves (174, 176,

178, 180) which are independently operable to permit: water to be fed from storage tank (146) to (either the top or bottom of the column) the inlet (160) of column (32) ; water exiting from outlet (164) of column (32) to be fed to the water collection system (168) or to be recycled to the inlet (160) of column (32) ; and, dry air generated by the drying module (72) to' be passed over the packed beds

(50, 52, 54, 56) in column (32) .

The water collection system (168) comprises a plastic water collection tank (182) of 30L capacity for collecting treated water via the water distributor (148) which has passed through column (32) . The collection tank (182) preferably includes a variable speed stirrer (not shown) and activated carbon to remove oxidation by-products from the treated water. The collection tank also includes a drain (not shown) for removing treated water from the collection tank (182) . A UV/visible spectrόphotometer

(184) supplied by Hewlett Packard (model HP8451A) interfaced to a computer (186) is coupled to the feed .pipe

(170) of the water collection tank (182) to enable ,the purity of the treated water to be monitored.

The drying unit (72) is selectively coupled to the column (32) via the water distributor (148) by valve (188) . The drying unit comprises a heat-less dryer (190) model 3HA by

Pall Pneumatics Limited, an inlet (191) of which is fed by a compressed air line (192) having a pressure regulatof

(194) . The outlet (196) of the heat-less dryer (190) , which includes a humidity meter (197) is connected to a reservoir (198) for storing dry air via valve (200) by copper piping. The reservoir (198) is connected to the water distributor (148) by PVC tubes via valve (188) .

All connections in the system are fluid tight.

During operation of the water treatment pilot plant the following steps are followed.

Set Up

(a) Column (32) is charged with the composition of the present invention.

(b) Column (114) is charged with alumina-rich molecular sieve.

(c) Storage Vessel (126) is charged with aqueous potassium iodide at 2.5 g/L. (d) Storage Tank (146) is charged with water and an impurity e.g. an aqueous solution of a reactive azo dye DBR (50 mg/L) .

(e) All connections are checked to ensure fluid tight seals.

Ozone Adsorption

(a) Valves (104, 106, 108, 110) are closed and valve (112) is opened so that the ozone generator (74) is in-line with the ozone destruction module (68) and the ozone monitoring station (100) .

(b) Valve (142) is opened so that the ozone gas analyser (134) and column (114) packed with alumina-rich molecular sieve is in line with the injector (122) of the vacuum system (124) .

(c) Pump (127) of the vacuum system is run to circulate aqueous potassium iodide solution from storage vessel (126) to injector (122) and back to storage vessel (126) .

(d) Oxygen is fed to the ozone generator and the ozone generator operated to form an ozone/oxygen gas mixture .

(e) The flow rate of ozone/oxygen gas passing through the ozone gas analyser (134) is ^• adjusted to approximate IL/min.

(f) The ozone/oxygen gas mixture passes through the ozone gas analyser (134) , then through the column (114) packed with alumina-rich molecular sieve to destroy it, and finally to the injector (122) where what remains of it is destroyed by contact with potassium iodide. (f) Once the concentration of ozone in the ozone/oxygen gas mixture is constant with time valves (104 and 108) or valves (106 and 110) are opened and valve (112) is closed so that a gaseous ozone/oxygen mixture is circulated through column

(32) and vented to the ozone destruction module (68) .

(g) The ozone/oxygen gas mixture is passed through column (32) until the ozone concentration of the gas mixture entering the column (32) is equal to the ozone concentration of the gas mixture exiting the column (32) i.e. the composition of the present invention is saturated with adsorbed ozone. (h) Valves (104, 106, 108, 110) are closed, and valve

(112) is opened to isolate column (32) from the ozone generator and to pass the ozone/oxygen ,gas mixture from the ozone generator to the ozone destruction module (68) . (i) The ozone generator is stopped and oxygen is circulated through the ozone generator and destruction module (68) until all ozone has been flushed from the generator (74) . (j) The oxygen stream is stopped and valve (112) closed.

Water Treatment

(a) Open valves (176 and 178) or valves (174 and 180) of the water distributor to permit water containing DBR to flow from the storage tank (146) through column (32) to collection tank (182) . (b) Run UV/visible spectrophotometer (184) and computer (186) to monitor the concentration of DBR in the water exiting column (32) .

(c) Run pump (150) to feed water through the column (32) to the collection tank at a velocity fixed between 8 and 133 L/h.

(d) Run system until the concentration of dye in water exiting column (32) is constant i.e. all available ozone has desorbed from the composition of the present invention and has oxidised DBR.

(e) Stop pump (150) .

(f ) Remove treated water from collection tank (182)

(g) Load storage tank (146) with pure water and wash the composition of the present invention with pure water to remove contaminants which may have accumulated thereon.

Drying the composition of the present invention

(a) Open valve (188) .

(b) Operate the drying system to pass dry air through column (32) until air exiting column (32) has a humidity of less than or equal to 10%.

The system is regenerated and steps 2 to 4 above may be repeated.

The removal of pollutant (s) from contaminated water may be controlled by the following variable parameters.

The concentration of the pollutant in the water The quantity of ozone adsorbed by the composition of the present invention. • The amount of the composition of the invention used in the bed (e.g. the bed length and diameter)

• Temperature

• Particle size of the composition of the present invention.

• Flow rate of water passing over the composition of the present invention

• pH of the contaminated water

3. Water Treatment in a Closed System

There is shown in Figure 3 a closed system (219) for monitoring the effectiveness of either gaseous ozone or ozone loaded on an adsorbent for removing an impurity from water. The system comprises a glass column (220) of 24 mm diameter and 20 cm height having a glass sinter (not shown) for supporting an adsorbent. The outlet (224) of column (222) is connected by a PTFE tube (226) to an inlet (228) of storage vessel (230) for storing water containing an impurity. The outlet (232) of water storage vessel

(230) is connected by PTFE tubes (234, 236) to the inlet

(238) of glass column (222) via pump (240) . The glass column (222) further includes first and second sampling points (242, 244) connectable to a UV/visible spectrophotometer linked to a computer (not shown) for monitoring the level of impurity in the water.

In use, either a known concentration of gaseous ozone or an adsorbent having a known concentration of ozone adsorbed thereon is introduced into glass column (220) , which is then fitted into the closed system (219) . A fixed volume of an aqueous solution (2310 ml) containing an impurity, Drimarene Brilliant Red (DBR) dye (50 mg/L) , is introduced into storage vessel (230) . The pump (240) is activated and the aqueous DBR dye solution is circulated throughout the closed system. The DBR dye is oxidised by the ozone. The UV/visible spectrophotometer monitors the concentration of the DBR dye in the system over time and records the final steady state concentration of the dye following oxidation by the available ozone.

4. Removal of Nitrogen Dioxide from Nitrogen

There is shown in Figure 4 _ apparatus (250) for removing a contaminant (i.e. nitrogen dioxide) contained in a carrier gas (i.e. nitrogen). The apparatus (250) includes a glass column (252) , of internal diameter 19 mm and length 30 cm, having an inlet (254) and an outlet (256) . The glass column (252) includes an outer cooling jacket (258) having an inlet (260) for receiving water and an outlet (262) for discharging water from the jacket. The glass column (252) includes a glass sinter (not shown) having a pore size ^' of 0.5 mm extending across the interior of the column in the region of the outlet (256) . The glass sinter supports a bed of the composition of the invention (264) which fills substantially the whole of the interior of the glass column (252) .

The inlet (254) of the glass column (252) is connected to a gas mixer (266) which is operable to place the glass column (252) in fluid communication with an ozone generating unit (268) and/or a source of contaminant contained in a carrier gas (270) . The ozone generating unit (268) is similar to that illustrated in Figure 1 and comprises an ozone generator (272) supplied .by Invent Water Treatment Limited of Dell road, Shawclough,

Rochdale, Lancashire, UK, the inlet (274) of which is connected to a controllable pressurised oxygen supply

(276) via flow meter (278) and valve (280) . The outlet (282) of the ozone generator (272) is connected to the gas mixer (266) via an ozone gas analyser (284) . The source of contaminant contained in a carrier gas (270) comprises a controllable pressurised supply of 100 ppm nitrogen dioxide in nitrogen (286) . The nitrogen dioxide/nitrogen mixture is connected to the gas distributor (266) via flow meter (288)- and valve (290) .

The outlet (256) of the glass column (252) is connected to the inlet (292) of a scrubber (294) via valve (296) . The scrubber (294) comprises a glass column having a volume of approximately 250 ml. The scrubber (294) has an outlet (298) to allow gas to exit therefrom. The scrubber further includes a second inlet (300) connected via valve (302) to a water supply and a second outlet (304) connected to valve (306) . The second inlet (300) and second outlet (304) with valves (302,306) permit controlled addition of water to and removal of water from the scrubber (294) .

All connections in the apparatus (250) comprise fluid tight pipes, such as PTFE and stainless steel.

During operation of the apparatus (250) the following steps are followed:

Set Up

(a) Column (252) is charged with the composition of the present invention. (b) The scrubber (294) is charged with approximately 150 ml of water.

(c) The outlet (298) of the scrubber is connected to an ozone destruction unit similar to that as described in relation to Figure 2.

(d) All connections are checked to ensure fluid tight seals.

Ozone Adsorption

(a) Valve (296) and gas distributor (266) are opened so the glass column (252) is in-line with the scrubber (294) and the ozone generating unit (268) . (b) Oxygen is fed to the ozone generator- (272) and the ozone generator operated to form an oxygen/ozone gas mixture. The flow rate of oxygen/ozone gas mixture passing through the ozone analyser (284) is adjusted with valve (280) to approximately 1 litre/minute.

(c) The oxygen/ozone gas mixture passes through the glass column (252) ,- then through the scrubber (294) and finally via outlet (298) to the ozone destfuction unit (not shown) . The oxygen/ozone gas mixture is passed through the glass column (252) until the ozone concentration of the gas mixture entering the column is equal to the ozone concentration of the gas mixture exiting the column i.e. the composition of the present invention is saturated with adsorbed ozone.

(d) The gas distributor (266) is operated to isolate the ozone generating unit (268) from and. place the nitrogen dioxide/nitrogen gas mixture (286) inline with the glass column (252) .

(e) Nitrogen dioxide/nitrogen gas mixture is fed through the glass column. The flow rate of the gas mixture is adjusted with valve (290) _. to approximately lL/min.

(f) Nitrogen dioxide in the nitrogen dioxide/nitrogen gas mixture is oxidised by ozone adsorbed on , the composition of the present invention to form nitrogen pentoxide (N₂0₅) . The ozone is suitably reduced to oxygen. The gas mixture exiting the glass column (252) contains a lower concentration of nitrogen dioxide than the gas mixture entering the column. Suitably the gas mixture exiting _ι the column contains a nitrogen pentoxide/nitrogen/oxygen mixture .

(g) The nitrogen pentoxide/nitrogen/oxygen gas mixture (plus any unoxidised nitrogen dioxide) passes through the scrubber (294) . The nitrogen pentoxide dissolves in the water to form nitric acid and _r the remaining nitrogen/oxygen gas mixture passes through outlet (298) . (h) The concentration of nitric acid formed with time in the scrubber may be monitored by titrating a portion of the aqueous solution with sodium hydroxide (0.0022 mol/L) . (i) After approximately 10 minutes the nitric acid is drained from the scrubber by opening valve (306) .

After draining, valve (306) is closed and valve (302) opened to replenish the scrubber with fresh water. Example 1 - General preparation of a composition of ,the present invention including a silica sol binder

Zeolite powder 31 g is mixed slowly with 21 g of an aqueous solution of silica sol gel 20% by weight CT208 from CATAL Ltd. Sheffield Science Park at room temperature for approximately 15 min until the silica sol gel/zeolite mixture forms a thick paste. Pellets may be formed from the silica sol gel/zeolite mixture in one of two ways:

(a) The silica sol gel/zeolite mixture is fed directly to a rotating disc pelletiser made at the University of Bradford, and spherical pellets having an average mean diameter of about 2 mm are produced from the mixture.

(b) The silica sol gel/zeolite mixture is dried at 70 °C to 80 °C and the resultant solid is crushed using a knife to form pellets having a random size and shape about 10 mm average size.

The pellets are then calcined for 2 hours by heating the pellets in a flowing air furnace at approximately. 400 to 450 °C, and then cooled to ambient temperature in the presence of a dessicant and/or in vacuo. The dried pellets comprise approximately 90% by weight zeolite and 10% by weight binder.

Example 2 - Ozone adsorption by and desorption of ozone from a glass column

Ozone adsorption by and ozone desorption from a glass column of length 30cm and internal diameter of 15 mm and a glass sinter was determined using the apparatus of Figure 1 in accordance with the general procedures described hereinbefore and the following specific operating parameters :

Flow rate of ozone/oxygen gas (Qo_2/o₃) 495 ml/min

Ozone concentration in ozone/oxygen gas (Cι_n) 78..89 g/m³ at NTP.

Temperature of glass column 26°C and 19 °C

Flow rate of oxygen for ozone desorption (Q₀₂) 495 ml/min

A graphical plot of ozone adsorption with respect to time at 26°C is shown in Figure 5a. Figures 5b and 5c show the mass of ozone adsorbed (M_ads) and the mass of ozone desorbed (M_des) respectively, with respect to specific concentration of ozone in the ozone/oxygen gas mixture Cι_n at a column temperature of 19°C -and 26°C respectively.

Example 3 - Ozone adsorption by and desorption of ozone from pelletised zeolite CBV3024E and silica sol gel

A composition . of the present invention comprising spherical pellets having an average cross-sectional diameter of 2 mm and comprising zeolite CBV3024E (having a Si0₂/Al0₃ mole ratio of 32, a surface area of 428 m²/g, and an ammonium counterion supplied by ZEOLYST international, UK office: D6-Dukes Court, Duke-* Street, Woking, Surrey GU21 5BH) and silica sol gel binder were prepared in accordance with Example 1(a) above. A sample of the pellets after calcination treatment was washed thoroughly with distilled water for 1 hour and a portion of the washed pellets dried at 120 °C for 12 hours. Ozone adsorption by and ozone desorption from the following materials was determined using the apparatus of Figure 1 in accordance with the general procedures described hereinbefore and the operation procedures of Example 2 at room temperature about 21°C.

(a) Unwashed pellets of CBV3024E and silica sol gel.

(b) Washed pellets of CBV3024E but not dried comprising 26% by weight water. (c) Washed pellets of CBV3024E then dried comprising less than 1% by weight water, (d) Powder zeolite CBV3024E per se .

Figure 6a shows the mass of ozone adsorbed (M_{a s}) by the zeolite powder per se (referred to as powder) , the washed and dried pellets of CBV3024E (referred to as washed/dried) , the washed but undried pellets of CBV3024E having a moisture content of 26% by wt water (referred to as 26% H₂0) , and unwashed pellets of CBV3024E (referred to as unwashed) with respect to specific concentrations of ozone in the ozone/oxygen gas mixture (Cι_n) .

Figure 6b shows the mass of ozone desorbed (M_des) from the zeolite powder per se, the washed and dried pellets of CBV3024E, the washed but undried pellets of CBV3024E having a moisture content of 26% by wt water, and unwashed pellets of CBV3024E with respect to specific concentrations of ozone in the ozone/oxygen gas mixture

(Cin) •

Figure 6c is a bar graph of the results of Figures 6a and 6b. The results clearly demonstrate that the pellets of CBV3024E (i.e. the composition of the present invention) which have been washed in watef and dried exhibit a greater affinity for ozone adsorption and desorption of ozone therefrom than pellets which have not been- washed or pellets which have been washed but not dried. The washed and dried pellets of CBV3024E also exhibit a greater affinity for ozone adsorption and desorption of ozone therefrom than the powder zeolite CBV3024E per se, thereby demonstrating that the overall Si0₂/Al₂0₃ molar ratio is increased in the composition of the present invention.

Example 4 - Comparison of the effect of moisture content on ozone adsorption and desorption of ozone from a composition of the present invention and silica gel

A composition of the present .invention .comprising spherical pellets having an average cross-sectiόnal diameter of 2mm comprising zeolite CBV28014 (having a Si0₂/Al0₃ mole ratio of 276, a surface area of 383 m²/g, and an ammonium counterion obtainable from ZEOLYST international, UK office: D6-Dukes Court, Duke Street, Woking, Surrey GU21 5BH) were prepared in accordance with Example 1(a). Batches of the pellets were partially dried in an oven at 120 °C to varying degrees and the moisture content of the respective batches of pellets determined. The effect of moisture present in the pellets on the adsorptive and desorptive capacity of the pellets to ozone was determined using the apparatus of Figure 1 in accordance with the general procedures described hereinbefore and the operating procedures of Example 2 at room temperature 21°C. As a comparative experiment, the effect of moisture present in Gjay silica gel obtained from Geejay Chemicals Ltd. of 16 Gosforth Close Sandy Beds on the adsorptive capacity for ozone was also determined.

Figure 7a shows the amount of ozone adsorbed (A_ads) by ■pellets of CBV28014 and the amount of ozone desorbed (Aa_es) from CBV28014 with respect to various moisture contents. Figure 7b compares the effect of moisture content on the amount of ozone adsorbed (A_ads) by pellets of CBV28014 and silica gel.

The results as shown in Figure 7a demonstrate that ozone ^• adsorption by the composition of the present invention (pelletised CBV28014) remains approximately constant for pellets having a moisture content up to approximately 15% by weight water. Furthermore, the composition of .the present invention having a moisture content of 9% by weight water has the same capacity for ozone adsorption at the same ozone concentration in the gas phase used in loading as approximately anhydrous silica gel as shown in Figure 7b.

Example 5 - Effect of different binders on the stability of adsorbed ozone

A first batch of particles of the composition of the present invention (average cross-sectional diameter 2 mm) comprising 90% by weight zeolite HZSM5 having a Si0₂/Al₂0₃ ratio of 30, a surface area of 450 m²/g, and a hydrogen counterion (supplied by Catal Ltd of Sheffield Science Park, Cooper Bldgs . , Arundel St., Sheffield SI 2NS) and silica sol gel 10%wt was prepared as described in Example la. The particles were soaked in water for 3 days and then dried at 120 °C. Ozone adsorption by and desorption of ozone from the particles was determined using the apparatus of Figure 1 in accordance with the general operation procedures described hereinbefore.

A second batch of particles (average cross-sectional diameter 2 mm) comprising 90% by weight zeolite HZSM5 having a Si0₂/Al₂0₃ ratio of 30, a surface area of 450 m²/g, and a hydrogen counterion and a binder ' including aluminium cations (9% by weight betonite clay which includes 20% by weight A1₂0₃) were obtained from CATAL Ltd of Sheffield Science Park, Cooper Bldgs., Arundel St., Sheffield SI 2NS . The particles were soaked in water for three days and then dried at 120 °C. Ozone adsorption by the particles was determined using the apparatus of Figure 1 in accordance with the general operating procedures described hereinbefore.

The results indicate that ozone adsorption by the particles comprising a binder containing aluminium cations

(Figure 8a) is significantly inhibited compared to ozone adsorption by particles comprising a binder not including aluminium ions (Figure 8b) . This is indicative of adsorbed ozone decomposing on the particles having a binder containing aluminium cations.

The ability of the first batch of particles to adsorb ozone and the desorption of ozone therefrom is displayed in Figure 8c, which demonstrates near quantitative desorption of ozone. This is indicative of the stability of adsorbed ozone on the first batch of particles . Example 6 - Effect of countercation of the zeolite

Powder zeolite HZSM5 (supplied by Catal Ltd) having a Si0₂/Al₂0₃ ratio of 30, a surface area of 450 m²/g and a hydrogen cation was used. Ozone adsorption/desorption by the zeolite in hydrogen cation form was monitored using the apparatus of Figure 1 and using the general operating procedures as described hereinbefore.

Powder zeolite CBV3024E (supplied by Zeolyst) having a Si0₂/Al₂0₃ of 32, a surface area of 428 m²/g and an ammonium cation, was used. Ozone adsorption/desorption by the zeolite in ammonium cation form was monitored using the apparatus of Figure 1 and using the general operating procedures as described hereinbefore.

The results as illustrated in Figure 9 demonstrate that for zeolites having comparable Si0₂/Al₂0₃ molar ratios and surface areas, a zeolite having a hydrogen cation exhibits increased capacity for ozone adsorption compared to a zeolite having an ammonium cation.

Example 7 - Comparison of ozone adsorption by and desorption of ozone from a composition of the present invention and silica gel

A first batch of particles (average cross-sectional diameter 2 mm) comprising 90% by weight zeolite HZSM5 having a Si0₂/Al₂0₃ ratio of 30, a surface area of 450 m²/g, and a hydrogen counterion (supplied by CATAL Ltd of

Sheffield Science Park, Cooper Bldgs., Arundel St., Sheffield SI 2NS) and silica sol gel 10%wt was prepared as described in Example la. The particles were soaked in water for three days and then dried at 120 °C. Ozone adsorption by and desorption of ozone from the particles was determined using the apparatus of Figure 1 in accordance with the general operating procedures described hereinbefore.

A second batch of particles (average cross-sectional diameter 1.5 mm) comprising silica gel i.e. no silica sol binder having a surface area of 650 m²/g supplied by Geejay Chemicals Ltd. of 16 Gosforth Close, Sandy, Bedfordshire, UK. Ozone adsorption by and ozone desorption from the particles was determined using the apparatus of Figure 1 in accordance with the general operating procedures as described hereinbefore. -

The results as shown in Figure 10 demonstrate that the composition of the present invention . (pelletised HZSM5) exhibit a higher adsorptive capacity for ozone than palletised silica gel itself. Moreover, the composition of the present invention exhibits near quantitative desorption of ozone adsorbed thereon.

Example 8 - Removal of Drimarene Brilliant Red dye from Water

Particles having an average cross-sectional diameter 2mm comprising 90% by weight zeolite D915 (supplied by CATAL Ltd of Sheffield) and silica sol gel 10%wt were prepared as described in Example la. The particles were soaked in water for several hours and then dried at 120°C.

Batches of the particles were contacted with gaseous ozone/oxygen mixtures having different ozone concentrations (Ci_n) using the apparatus of Figure 1 and general procedure described hereinbefore. , Separate batches of particles having different amounts of ozone adsorbed thereon were loaded into the glass column (220) of the closed system (219) as depicted in Figure 3 and the removal of DBR dye from an aqueous solution monitored as described hereinbefore. The apparatus of Figure 3 was run as described hereinbefore for each batch of particles and the final steady state concentration of the dye 'was recorded.

Analagous experiments .were performed employing particles comprising nonindicating silica gel only i.e. no silica sol binder (average cross-section diameter of 1.5 mm) supplied by Geejay having different amounts of ozone adsorbed thereon, ,and by contacting . the DBR solution with known concentrations of a gaseous oxygen/ozone mixtures.

Figure 11 shows the variation of the final steady state concentration of the DBR dye (C_df) compared to the initial concentration of the dye at time t=0 (C_do) due- to oxidation by different concentration: of gaseous ozone; ozone loaded on silica gel; or ozone loaded on a composition of the present invention (pelletised D915) . The results as shown in Figure 11 clearly demonstrate that for ozone concentration in the range of 0 to 100 g/m³ NTP, a linear decrease of the dye concentration is found using ozone in the gas phase, whereas an exponential decrease in dye concentration is found using ozone loaded on an adsorbent. Moreover, the composition of the present invention (pelletised D915) is far superior at oxidising the pollutant DBR at a specific ozone concentration than either ozone adsorbed on silica gel itself or ozone in the gas phase.

Claims

1. A composition in the form of a particle comprising one or more adsorbents for adsorbing ozone in admixture with a binder, wherein the binder comprises less than or equal to 9% by weight of aluminium cations based on the weight of the binder.

2. A composition as claimed in claim 1 wherein the binder comprises less than or equal to 1.7% by weight of an oxide and/or hydroxide of aluminium, particularly Al₂0₃.

3. A composition as claimed in any one of claims 1 or 2 wherein the binder is a silicon based binder.

. A composition as claimed in any one of the preceding claims wherein the binder is a silica sol gel.

5. A composition as claimed in any one of the preceding claims wherein the binder in the composition contributes less than or equal to 20% by weight of the total weight of the composition^'.

6. A composition as claimed in any one of the preceding claims wherein the one or more adsorbents is selected from silica gel and a zeolite or combinations thereof.

7. A composition as claimed in any one of claims 1 to 5 wherein the one or more adsorbents comprises zeolite only.

8. A composition as claimed in claims 6 or 7 wherein said one or more zeolites comprise silicon (IV) oxide (Si0₂) and aluminium (III) oxide (Al₂0₃) , and the molar ratio of silicon (IV) oxide to aluminium (III) oxide is greater than or equal to 25.

A composition as claimed in any one of claims 6 to

8 wherein greater than or equal to 50% of , the available counterions of the one or more zeolites are hydrogen ions .

10. A composition as claimed in claim 6 wherein the one or mofe adsorbents comprises silica .gel only and the composition of the present invention comprises less than or equal to 0.9% by weight of aluminium cations based on the total weight of the composition of the present invention.

11. A composition as claimed in any one of ^• the preceding claims, wherein said one or more adsorbents includes a surface area greater than or equal to 250 m²/g.

12. A composition as claimed in any one of the preceding claims, wherein said one or more adsorbents includes a porous structure having a pore size of greater than or equal to 25A.

13. A composition as claimed in any one of the preceding claims, wherein the composition has an average particle size that is less than or equal to 10 mm.

14. A composition as claimed in any one of the preceding claims, wherein a maximum cross-sectional dimension of the composition is less than or equal to 10 mm.

15. A composition as claimed in any one of the preceding claims, wherein the composition is in the form of a spherical particle.

16. A composition as claimed in any one of the preceding claims wherein the composition comprises less than or equal to 30% by weight water.

17. A composition as claimed in any one of the preceding claims further including ozone.

18. A process for manufacturing a composition as claimed in any one of claims 1 to 17, comprising forming a mixture of one or more adsorbents and a binder, and forming a particle from the mixture.

19. A process as claimed in claim 18 further including the step of drying the particle, so that the particle comprises less than or equal to 15% by weight water.

20. A process as claimed in claim 18, further including the steps of contacting the particle with water and then drying the particle so that the particle comprises less than or equal to 15% by weight water.

21. A process as claimed in any one of claims 18 to' 20 further including the step of contacting the particle with ozone.

22. A process for reducing the concentration of a material in a fluid, comprising adsorbing ozone on a composition as defined in any one of claims 1 to

17 or prepared according to the process of claims

18 to 21, and contacting a fluid including a material therein with the composition having ozone adsorbed thereon to permit desorption of ozone from • the composition.

23. A process as claimed in claim 22 wherein the material is oxidisable in the presence of ozone.

24. A process as claimed in claim 22 or 23, wherein the fluid is a liquid, particular a liquid comprising an aqueous solvent .

25. A process as claimed in any one of claims 22 to 24 further including the steps of removing the composition from the fluid, drying the composition, contacting the dried composition with ozone and then contacting the composition having ozone adsorbed thereon with the fluid including the material therein.

26. A process as claimed in any one of claims 23 to 25 wherein the material includes a moiety selected from bacteria, viruses, spores, cysts and organic compounds such as dyes pesticides, phenol compounds, fungicides or a combination of two or more of these moieties.

27. A process as claimed in claim 22 or 23 wherein the fluid comprises a carrier gas, especially air.

28. A process as claimed in claim 27 wherein the material is a gas.

29. A process as claimed' in claim 28 wherein the material is selected from the group consisting of nitrogen oxide, nitrogen dioxide, sulfur dioxide, sulfur trioxide, a volatile organic compound, or combinations thereof.

30. A process as claimed in any one of claims 27 to 29 further including the step of contacting the carrier gas with an aqueous solution after the carrier gas has contacted the composition having ozone adsorbed thereon.

31. Use of a composition as defined in ' any one of claims 1 to 17 for reducing the concentration of a material.

32. Use of the composition as defined in any one of claims 1 to 17 for oxidising a material.

33. Use of the composition as defined in any one of claims 1 to 17 for delivering ozone to a fluid, particularly an aqueous solvent or a gas .

34. Use of a composition as defined in any one of claim 1 to 17 for generating ozone.

35. Use of a composition as defined in any one of claims 1 to 17 in the purification of water.

36. Use of a composition as defined in any one of claims 1 to 17 in the purification of a gas, particularly air.