RU2441700C2 - Water filters materials and water filters containing mixture of microcellular and mesopore carbon particles - Google Patents

Abstract

FIELD: water purification.

SUBSTANCE: method of removal of trihalomethanes, bacteria and viruses from potable water includes water infiltration. At this filter is filled with filter material. The filter consists of body, which has inlet and outlet holes. Filter material is made of the mixture of certain quantity of macroporous, mesoporous and microporous particles of activated carbon. At this at least some mesoporous particles of activated carbon shall be covered by cationic polymer, aluminosilicate powder material and binding agent.

EFFECT: effective purify water and remove bacteria, viruses, microorganisms and trihalomethanes.

1 dwg, 3 tbl, 1 dwg, 3 ex

Description

Technical field

The present invention relates to the field of water filter materials, water filters and processes for their use and, in particular, to the field of water filters containing microporous and mesoporous carbon particles.

State of the art

Water can contain a wide variety of contaminants, including, for example, particles, harmful chemicals and microbiological organisms such as bacteria, parasites, protozoa and viruses. There are various circumstances in which these contaminants must be removed before using water. For example, in many medical applications and in the manufacture of certain electronic components, extremely pure water is required. If we turn to a more familiar example, then the harmful impurities present in the water must be removed, reduced to a safe level or deactivated (sometimes called “neutralize”) so that the water becomes drinkable, that is, suitable for use. Despite modern water treatment, the general population is at risk, and in particular children and those with weakened immune systems are at significant risk.

In the United States and other developed countries, in a centralized manner, purified water usually contains one or more of the following impurities: suspended solids, bacteria, parasites, viruses, organic matter, heavy metals, and chlorine. Accidents and other malfunctions of water treatment systems sometimes lead to incomplete removal of bacteria and viruses. In other countries, exposure to contaminated water has deadly consequences, as in some of them population density is increasing, water sources are becoming scarcer and there are no water treatment plants. A common situation is when sources of drinking water are located in the immediate vicinity of human and animal waste, so microbiological pollution is a serious public health problem. It is estimated that six million people die each year from waterborne microbiological contamination, half of which are children under 5 years of age.

Other sources of contamination of drinking water supply systems are chemical contaminants such as chlorine, taste, smell, lead, arsenic, volatile organic compounds (VOCs) (VOC), trihalogenomethanes (THM) (THM), chromium, etc. For example, trihalogenomethanes (THMs), which are by-products that can form when residual chlorine from water treatment processes react with organic substances found in water, are found in many water sources around the world. These substances can occur naturally and can inadvertently form in water supply systems when organic compounds, such as industrial waste, are discharged into the water mass, which is then treated with chlorine. In the water treatment and filtration industries, THMs represent a wide class of compounds and are commonly referred to as “complete trihalogenomethanes” (PTHM) (TTNM). PTHM can be carcinogenic and may have a more direct effect on health, such as a rash or skin irritation. In addition, PTHM can and often does have a very negative effect on the taste of drinking water. Thus, it is highly desirable to remove PTGM from water.

Known methods and filters for removing from water PTGM and other organic compounds. But these methods and filters are different from the removal of small particles, such as bacteria and viruses, and are often incompatible with it. Thus, water consumers often need to have two or more filters, or one multi-stage filter, to satisfy all filtering requirements. Multistage filters and many filters often require more space and are more expensive than a single filter.

Therefore, there is a need for a single-stage filter that can remove various contaminants having different properties. In other words, a filter that can be made from a single material, even a material that is a mixture of various components, in a single-stage process, which leads to a single-stage filter having multiple removability. More specifically, there is a need for a single-stage filter that can simultaneously remove small particles such as viruses and bacteria, as well as organic compounds such as PTGM. These and other advantages are provided by the present invention.

SUMMARY OF THE INVENTION

A filter is provided for providing or purifying drinking water. The filter includes a housing having an inlet and outlet, and a filter material located inside the housing. The filter material is constituted by a plurality of microporous activated carbon particles, from about 25% by weight to about 75% by mass, and by a plurality of mesoporous activated carbon particles, from about 25% by mass to about 75% by mass. In one aspect of the present invention, microporous activated carbon filter particles, mesoporous activated carbon filter particles, or both are coated, at least partially or completely, with a cationic polymer. And in another aspect of the present invention, at least a portion of the microporous activated carbon filter particles, the mesoporous activated carbon filter particles, or both are coated with silver or silver-containing material.

Other materials can be added to the filter media of the present invention, such as activated carbon powders, activated carbon granules, activated carbon fibers, carbon nanotubes, activated carbon nanotubes, single-walled carbon nanotubes (OCHT) (SWNT), multi-walled carbon nanotubes ( MCHT) (MWNT), zeolites, activated alumina, magnesia, activated magnesia, diatomaceous earth, activated silica, hydrotalcites, organometallic materials (MOF), stack yannye particles or fibers, nanofibers from synthetic polymers, natural polymers nanofibers, polyethylene fibers, polypropylene fibers, ethylene maleic anhydride, sand, clay and mixtures thereof. These other materials, such as activated carbon particles, which were directly discussed above, may be coated, at least partially or completely, with a cationic polymer, silver, silver-containing material, or mixtures thereof.

In another aspect of the present invention, there is provided a kit comprising a filter for providing drinking water. The filter comprises a housing having an inlet and outlet openings, and a filter material located inside the housing, which form, at least in part, a plurality of microporous and mesoporous activated carbon filter particles, at least a portion of these particles being coated with cationic material. The kit additionally contains a filter packaging, and either the packaging or the filter housing contains information that the filter or filter material: reduces the number of bacteria; reduces the number of viruses; reduces the number of microorganisms, reduces PTHM, reduces the amount of chemicals or any combination of the above.

Brief Description of the Drawing

Although the description concludes with a claims that specifically emphasizes and clearly characterizes the invention, it is intended that the present invention be better understood from the following description in conjunction with the accompanying drawing, which is a side cross-sectional view of a radial flow filter made in accordance with the present invention.

Detailed Description of Preferred Embodiments

All cited documents, in the relevant part, are incorporated into this description by reference. The citation of any document should not be construed as recognition that this document is a prior art in relation to the present invention.

I. Definitions

As used herein, the terms “filters” and “filtration” refer to structures and mechanisms associated with the removal of microorganisms (and / or with the removal of other contaminants) mainly by adsorption and (or) to a lesser extent by size exclusion.

In this document, the terms "removal", "reduce", "reduction" and their derivatives refer to a partial reduction in the amount or concentration of contaminants.

As used herein, the phrase “filter material” refers to a combination of filter particles. The combination of filter particles forming the filter material can be either homogeneous or heterogeneous. The filter particles may have a uniform or non-uniform distribution in the filter material. In addition, the filter particles forming the filter material are not necessarily the same in shape and size and may have either an unbound or interlocking shape. For example, the filter material may contain microporous, mesoporous and basic particles of activated carbon in combination with activated carbon fibers, and these filter particles can either have an unbound shape or be partially or fully bonded with a polymeric binder or other means to form a coherent structure.

As used herein, the phrase “filter particle” refers to a single element or part that is used to form at least a portion of the filter material. For example, fiber, granule, bead, etc. are filter particles in this document. In addition, the filter particles can be of different sizes, from intangible filter particles (for example, very fine powder) to tangible filter particles.

In this document, the phrase "pore volume of the filter material" refers to the total volume of interparticle pores in the filter material having a size of more than 0.1 μm.

As used herein, the phrase “total volume of filter material” refers to the sum of the volume of interparticle pores and the volume occupied by filter particles.

As used herein, the terms “microorganism”, “microbial organism”, “microbiological organism” and “pathogen” are used interchangeably. These terms refer to various types of microorganisms that can be characterized as bacteria, viruses, parasites, protozoa and microbes.

In this document, the phrase "coefficient of removal of bacteria" (KUB) (BRI) for filter particles is defined as:

CUB = 100 × [1- (concentration in the bath of E. coli bacteria in equilibrium) / (control

concentration of E. coli bacteria], where “concentration in the bath of E. coli bacteria in equilibrium” refers to the concentration of bacteria in equilibrium in the bath, which contains a mass of filter particles having a total outer surface area of 1400 cm ² and an average Sauter diameter of less than 55 microns, as described in more detail below. Equilibrium is considered achieved when the concentration of E. coli, measured at two points in time with an interval of 2 hours, remains unchanged within half an order of magnitude. The phrase "control concentration of E. coli bacteria" refers to the concentration of E. coli bacteria in the control bath, it is approximately 3.7 × 10 CFU / L (CFU / L). The Sauter average diameter is the diameter of the particle at which the ratio of surface area to volume is equal to this ratio for the entire particle distribution. Note that the term “CFU / L” means “colony forming units per liter” and is the standard term used for counting E. coli bacteria. KUB is measured in the absence of the use of chemicals with a bactericidal effect. An equivalent method for describing the removal ability of filter particles uses the "logarithmic coefficient of bacteria removal" (LKUB), which is defined as:

LKUB = -log [1- (KUB / 100)].

LKUB is measured in units called log (where “log” means the logarithm). For example, filter particles in which the CUB is 99.99% have a BAC of 4 log. The measurement procedure used to determine these values can be found in international application No. PCT / US03 / 05416 of February 21, 2003, as well as in international application No. PCT / US03 / 05409, filed February 21, 2003, the contents of which are included in this document by reference.

In this document, the phrase "virus removal coefficient" (CCL) (VRI) for filter particles of a filter is defined as:

KUV = 100 × [1- (concentration of phage MS-2 in the bath in equilibrium) / (control concentration of phages MS-2)]

where "the concentration in the bath of phages MS-2 in equilibrium" refers to the concentration of phages that are in equilibrium in the bath, which contains a mass of filter particles having a total outer surface area of 1400 cm ² and an average Sauter diameter of less than 55 μm, as described in more detail said below. Equilibrium is considered achieved when the concentration of MS-2, measured at two points in time with an interval of 2 hours, remains unchanged within half an order of magnitude. The phrase “control concentration of phages of MS-2” refers to the concentration of phages of MS-2 in a control bath and is approximately 6.7 × 10 ⁷ PFU / L (PFU / L). Note that the term “PFU / L” means “plaque forming units per liter,” which is the standard term used in calculating MS-2. CWV is measured in the absence of chemicals with a virucidal effect. An equivalent way of describing the removal ability of filter particles uses the "logarithmic coefficient of virus removal" (LKUV), which is defined as:

LKUV = -log [1- (KUV / 100)].

LKUV is measured in units of “log” (where “log” is the logarithm). For example, filter particles in which the CLE is equal to 99.9% have a LCL equal to 3 log. The measuring procedures used to determine these values can be based on international application No. PCT / US03 / 05416 dated February 21, 2003, as well as on international application No. PCT / US03 / 05409, filed February 21, 2003, the contents of which are incorporated into this document by reference.

In this document, the phrase “logarithmic degree of removal of bacteria by the filter” (LSUB-F) (F-BLR) refers to the ability of the filter to remove bacteria after the first 2000 pore volumes of filter material flow through it. LSUB-F is defined and calculated as:

LSUB-F = -log [(output concentration of E. coli bacteria) / (input concentration of E. coli)]

where the "input concentration of E. coli bacteria" is set equal to approximately 1 × 10 ⁸ CFU / l for the entire measurement time, and the "output concentration of E. coli" is measured after 2000 pore volumes of filter material flow through the filter. LSUB-F is measured in units of “log” (where “log” is the logarithm). Note that if the output concentration is below the detection limit of the method used for measurements, then the output concentration for calculating LSUB-F is taken to be the detection limit. We also note that LSUB-F is measured in the absence of chemicals with a bactericidal effect. The measurement procedures used to determine these values can be found in international application No. PCT / US03 / 05416 of February 21, 2003, as well as in international application No. PCT / US03 / 05409, filed February 21, 2003, the contents of which are included in this document by reference.

In this document, the phrase “logarithmic degree of removal of viruses by filter” (LSUV-F) (F-VLR) refers to the ability of a filter to remove viruses after the passage of the first 2000 pore volumes of the space of the filter material. LSUV-F is defined and calculated as:

LSUV-F = -log [(output concentration MS-2) / (input concentration MS-2)],

where the “MS-2 outlet concentration” is set to about 1 × 10 ⁷ PFU / L throughout the measurement, and the “MS-2 outlet concentration” is measured after about 2000 pore volumes of filter material flow through the filters. LSUV-F is measured in units of “log” (where “log” is the logarithm). Note that if the output concentration is lower than the detection limit of the method used for measurements, then the output concentration for calculating the LSOC-F is taken to be the detection limit. We also note that LSUV-F is measured in the absence of chemicals with a virucidal effect. The measurement procedure used to determine these values can be based on international application No. PCT7US03 / 05416 dated February 21, 2003, as well as on international application No. PCT / US03 / 05409, filed February 21, 2003, the contents of which are incorporated herein by reference.

As used herein, the phrase “total external surface area” refers to the total geometric external surface area of one or more filter particles, as described in more detail below.

In this document, the phrase “specific external surface area” refers to the total external surface area per unit mass of filter particles, as described in more detail below.

As used herein, the term “micropore” refers to an intraparticle pore with a width or diameter of less than 2 nm (or, equivalently, 20Å).

As used herein, the term “mesopore” refers to an intraparticle pore with a width or diameter of 2 nm to 50 nm (or, equivalently, 20Å to 500Å).

As used herein, the term “macropore” refers to an intraparticle pore with a width or diameter greater than 50 nm (or, equivalently, 500 Å).

In this document, the phrase "total pore volume" and its derivatives refer to the volume of all intraparticle pores, that is, micropores, mesopores and macropores. The total pore volume is calculated by the volume of nitrogen adsorbed at a relative pressure of 0.9814 using the BET process (ASTM standard D 4820-99) known in the art.

In this document, the phrase “micropore volume” and its derivatives refer to the volume of all micropores. The micropore volume is calculated by the volume of nitrogen adsorbed at a relative pressure of 0.15 using the BET process (ASTM standard D 4820-99) known in the art.

In this document, the phrase “the sum of the volumes of mesopores and macropores” and its derivatives refer to the volume of all mesopores and macropores. The sum of the volumes of mesopores and macropores is equal to the difference between the total pore volume and the volume of micropores, or, equivalently, is calculated from the difference between the volumes of nitrogen adsorbed at relative pressures of 0.9814 and 0.15 using the BET process (ASTM D 4820- 99), known from the prior art.

As used herein, the phrase “pore size distribution in the mesopore range” refers to pore size distribution calculated by the Barrett, Joyner and Hallenda (BJH) process known in the art.

As used herein, the term “carbonization” and its derivatives refers to a process in which the content of non-carbon atoms in a carbon-containing substance is reduced.

As used herein, the term “activation” and derivatives thereof refers to a process in which a carbonated substance is made more porous.

As used herein, the term “activated carbon particles” or “filter particles of activated carbon” and derivatives thereof refers to carbon particles that have been subjected to an activation process.

As used herein, the phrase “zero charge point” refers to pH above which the total surface of carbon particles is negatively charged. The measurement procedure used to determine this value can be based on international application No. PCT / US03 / 05416 dated February 21, 2003, as well as on international application No. PCT / US03 / 05409, filed February 21, 2003, the contents of which are included to this document by reference.

As used herein, the term “basic” refers to filter particles whose zero charge point exceeds 7.

As used herein, the term “acidic” refers to filter particles whose zero charge point is less than 7.

As used herein, the phrase “mesoporous activated carbon filter particle” refers to an activated carbon filter particle in which the sum of the volumes of mesopores and macropores may exceed 0.12 ml / g.

As used herein, the phrase “microporous activated carbon filter particle” refers to an activated carbon filter particle in which the sum of the volumes of mesopores and macropores may be less than 0.12 ml / g.

In this document, the phrase “mesoporous and main activated carbon filter particle” refers to an activated carbon filter particle in which the sum of the volumes of mesopores and macropores can exceed 0.12 ml / g and the point of zero charge exceeds 7.

In this document, the phrase “mesoporous and basic filtering particle of activated carbon with reduced oxygen” refers to a filtering particle of activated carbon, in which the sum of the volumes of mesopores and macropores can exceed 0.12 ml / g, the point of zero charge exceeds 7, and the total mass fraction of oxygen is 1.5% or less.

As used herein, the phrase “mesoporous and acid activated carbon filter particle” refers to an activated carbon filter particle in which the sum of the volumes of mesopores and macropores can exceed 0.12 ml / g and a zero charge point of less than 7.

As used herein, the phrase “starting material” refers to a starting material containing mesopores and macropores or forming mesopores and macropores during carbonization and / or activation.

As used herein, the phrase “axial flow” refers to a flow passing through a flat surface perpendicular to that surface.

As used herein, the phrase “radial flow” generally refers to a flow passing through a substantially cylindrical or substantially conical surface perpendicular to these surfaces.

In this document, the phrase "front area" refers to the area of the filter material, initially exposed to incoming water. For example, in the case of axial flow filters, the front area is the cross-sectional area of the filter material at the fluid inlet, and in the case of a radial flow filter, the front area is the outer area of the filter material.

In this document, the phrase “filter depth” refers to the linear distance that the incoming water travels from the inlet to the outlet of the filter material. For example, in the case of axial flow filters, the depth of the filter is the thickness of the filter material, and in the case of a radial flow filter, the depth of the filter is half the difference between the outer and inner diameters of the filter material.

In this document, the words “average liquid residence time” and / or “average liquid contact time” refer to the average time during which the liquid contacts the filter particles inside the filter when it passes through the filter material and is calculated as the ratio of the pore volume of the filter material to the rate of fluid flow.

In this document, the phrases “filter porosity” and / or “porosity of the filter body” refer to the ratio of the pore volume of the filter material to the total volume of the filter material.

As used herein, the phrase “inlet” refers to a means through which liquid can enter a filter or filter material. For example, the inlet may be a structural element that is part of the filter or the front area of the filter material.

As used herein, the phrase “outlet” refers to a means through which a liquid can escape from a filter material or filter. For example, the outlet may be a structural member that is part of a filter or a cross-sectional area of a filter material at a fluid outlet.

As used herein, the term "flow properties of particles" and derivatives thereof refers to the pressure drop that these particles cause when water flows between them. For example, when comparing two types of particles having the same particle size and distribution, one of them has better flow properties than the other if it creates a lower pressure drop.

II. Microporous and Mesoporous Activated Carbon Filter Particles

The filter material of the present invention contains a mixture of microporous and mesoporous activated carbon particles. The mesoporous activated carbon material described herein has an excellent ability to remove small particles, such as bacteria and nanosized viruses, while microporous activated carbon particles have an excellent ability to remove chemicals, such as total trihalogenomethanes (PTGM). Mesoporous activated carbon particles also have much better flow properties compared to microporous activated carbon particles and, thus, mesoporous activated carbon particles cause a lower pressure drop compared to microporous activated carbon particles. In one embodiment, the filter material comprises a plurality of microporous activated carbon particles in an amount of from about 25% by weight to about 75% by weight, and a plurality of mesoporous activated carbon particles in an amount of from about 25% by weight to about 75% by weight. As described in more detail below, the activated carbon filter particles are preferably coated at least partially or completely with a cationic polymer and, more preferably, the mesoporous activated carbon particles are coated at least partially with a cationic polymer.

Filter particles can have various shapes and sizes. For example, the filter particles may be in a simple form, such as powder, granules, fibers and granules. The filter particles can take the form of a sphere, polyhedron, cylinder, as well as other symmetric, asymmetric or irregular shapes. In addition, filter particles can also form complex shapes, such as canvases, sieves, nets, nonwovens, woven materials, and knitted blocks, which may or may not be formed from the simple shapes described above.

Similarly to the shape, the particle size may be different, and the particle size in one filter does not have to be the same. In fact, it may be desirable to have filter particles of different sizes in one filter. In general, the size of the filter particles may be between about 0.1 μm and about 10 mm, preferably between about 0.2 μm and about 5 mm, more preferably between about 0.4 μm and about 1 mm, and most preferably between about 1 μm and approximately 500 microns. For spherical and cylindrical particles (e.g. fibers, grains, etc.), the above dimensions refer to the diameter of the filter particles. For filter particles having substantially different shapes, the dimensions described above refer to the largest dimension (e.g., length, width or height).

Microporous Activated Carbon Particles

In a preferred embodiment of the present invention, a plurality of microporous activated carbon particles are present in a concentration of from about 30% by weight to about 55% by weight, and more preferably from about 30% by weight to about 50% by weight. Typical examples of microporous activated carbon are coconut activated carbon, activated carbon based on bituminous coal, activated carbon physically activated, wood based, activated carbon physically activated, based on pitch, etc. Preferred microporous activated carbon particles are coconut activated carbon particles.

Mesoporous Activated Carbon Particles

The microporous carbon particles of the present invention have good chemical removal properties, such as PTHM. But mesoporous carbon filter particles adsorb more microorganisms compared to microporous activated carbon filter particles. In addition, it was unexpectedly found that the mesoporous and basic filter particles of activated carbon adsorb a greater number of microorganisms in comparison with that adsorb mesoporous and acid filter particles of activated carbon. In addition, it was unexpectedly found that the mesoporous and basic filter particles of activated carbon with reduced oxygen adsorb a larger number of microorganisms compared with the adsorb mesoporous and basic filter particles of activated carbon, in which the total mass fraction of oxygen is not reduced.

Although the applicants do not wish to be bound by any theory, according to their hypothesis, taking into account porosity, a large number of mesopores and (or) macropores provide more convenient adsorption centers (openings or inlets of mesopores / macropores) for pathogens, their fimbriae, and surface polymers (e.g. proteins, lipopolysaccharides, oligosaccharides and polysaccharides) that make up the outer membranes, capsids and shells of pathogens, since their typical size is similar to the size of the entrances of mesopores and macropores. In addition, mesoporosity and macroporosity may correlate with one or more surface properties of the coal, such as surface roughness.

In addition, the applicants, not wishing to be bound by theory, suggest that the surfaces of the main activated carbon contain those types of functional groups that are necessary to attract more microorganisms than those attracted by an acidic carbon surface. This increased adsorption to the main carbon surfaces may perhaps be attributed to the fact that the main carbon surfaces attract usually negatively charged microorganisms and functional groups on their surface. Applicants further suggest that base carbon, when placed in water, is capable of forming disinfectants through a molecular oxygen reduction reaction. Although the end product of the reduction is hydroxide, applicants believe that intermediate reactive oxygen products are formed, such as peroxide, hydroperoxide, and / or hydroxyl radicals, and they can be long enough to diffuse from carbon into the bulk solution.

In addition, applicants believe that carbon becomes more basic as the mass fraction of technical oxygen decreases. The low mass fraction of technical oxygen can lead to improved adsorption of bacteria / viruses, since this will result in: (1) less carboxylic acids and, therefore, a less negative surface that repels bacteria / viruses; and (2) a less hydrated surface, so that water is more easily displaced by bacteria / viruses when they try to adhere to the surface (i.e. bacteria / viruses require less energy to displace other instances that already occupy surface locations). This last reason (i.e., a less hydrated surface) is also related to the idea that the ideal surface, discussed below, should be somewhat hydrophobic (i.e., the substitution of oxygen at the boundary carbon atoms should be sufficient so that the surface is moistened, but not too much so that it did not become excessively hydrophilic).

Mesoporous filter particles can be the product of any starting material that contains mesopores and macropores or creates mesopores and macropores in the process of carbonization and (or) activation. For example, in particular, the mesoporous filter particles may be wood-based activated carbon particles, coal-based activated carbon particles, peat-based activated carbon particles, pitch-based activated carbon particles, tar-based activated carbon particles, particle-based activated carbon particles fine coal, other particles of activated carbon based on lignocellulose and mixtures thereof.

Activated carbon may exhibit acidic, neutral, or basic properties. Acidic properties are associated with oxygen-containing functional properties or functional groups, such as, in particular, phenols, carboxyls, lactones, hydroquinones, anhydrides and ketones. The main properties to date have been associated with functional groups such as pyrons, chromones, ethers, carbonyls, and also π-electrons of the basal plane. The acidity or basicity of activated carbon particles is determined by the “zero charge point” method (Newcombe, G., et al., Colloids and Surfaces A: Physicochemical and Engineering aspects, 78, 65-71 (1993)), the essence of which is incorporated herein by links. The method is described below in section VII. The zero charge point of the mesoporous filter particles of the present invention can be between 1 and 14, preferably greater than about 4, preferably greater than about 6, preferably greater than about 7, preferably greater than about 8, more preferably greater than about 9, and most preferably between 9 and 12.

The zero point of activated carbon has an inverse correlation with the mass fraction of technical oxygen. The mesoporous activated carbon particles of the present invention may have a mass fraction of industrial oxygen of less than about 5%, preferably less than about 2.5%, preferably less than about 2.3%, preferably less than about 2%, more preferably less than about 1.2% and most preferably less than about 1% and / or more than about 0.1%, preferably more than about 0.2%, preferably more than about 0.25% and most preferably more than about 0.3%. In addition, the zero point of activated carbon particles correlates with the redox potential (ORP) of the water containing the particles, since the zero point is a measure of the ability of carbon to reduce oxygen (at least for basic carbon). The filter particles of the present invention may have an ORP of less than about 570 mV, preferably less than about 465 mV, preferably less than about 400 mV, preferably less than about 360 mV, preferably less than about 325 mV, and most preferably between about 290 mV and about 175 mV.

Particle activation

The electrical resistance of filter particles or filter material from activated carbon is one of the most important properties, since it relates to their ability to form filter blocks. For example, a resistive heating method can be used to form filter blocks, in which the filter material is heated by passing an electric current between the 2 ends of the filter material. Electrical resistance is measured by forming filter blocks and measuring the electrical resistance between the two ends of the block by applying 2 electrodes from a voltmeter to them.

Filter particles can be obtained by treating the starting material as described below. The conditions under which the treatment is carried out may include the composition of the gaseous medium, pressure, temperature and (or) time. The gaseous media of the present invention may be reducing or inert. When the filter particles are heated in a reducing gas medium, steam or inert gas medium, a filter material with a reduced functional group of surface oxygen is obtained. Examples of suitable reducing gas media may include hydrogen, nitrogen, dissociated ammonia, carbon monoxide and / or mixtures. Examples of a suitable inert gaseous medium may include argon, helium and / or mixtures thereof.

The processing temperature in the case when the activated carbon particles do not contain noble metal catalysts (e.g. platinum, gold, palladium) can be between about 600 ° C and about 1200 ° C, preferably between about 700 ° C and about 1100 ° C. more preferably between about 800 ° C and about 1050 ° C, and most preferably between about 900 ° C and about 1000 ° C. If the activated carbon particles contain noble metal catalysts, the processing temperature may be between about 100 ° C and about 800 ° C, preferably between about 200 ° C and about 700 ° C, more preferably between about 300 ° C and about 600 ° C. and most preferably between about 350 ° C and about 550 ° C.

The processing time may be between about 2 minutes and about 10 hours, preferably between about 5 minutes and about 8 hours, more preferably between about 10 minutes and about 7 hours, and most preferably between about 20 minutes and about 6 hours. The gas flow rate can be between about 0.25 standard l / h · g (i.e. standard liters per hour per gram of carbon; 0.009 standard feet / h · g) and about 60 standard l / h · g (2.1 standard feet / h · g), preferably between about 0.5 standard l / h · g (0.018 standard feet / h · g) and about 30 standard l / h · g (1.06 standard feet / h · g), more preferably between about 1.0 standard l / h · g (0.035 standard feet / h · g) and about 20 standard l / h · g (0.7 standard feet / h · g), and most preferably between about 5 standard l / h G (0.18 standard GOVERNMENTAL ft / hr · g) and about 10 standard L / h.g (0.35 standard ft / h.g). During the treatment time, the pressure can be maintained greater than atmospheric, equal to atmospheric or less than atmospheric. It should be borne in mind that other processes can be used to obtain the mesoporous main filter material from activated carbon with reduced oxygen. In addition, to obtain a filter material, such a processing of the starting material described above can be repeated many times depending on the starting material.

The source material can be purchased on the market or can be manufactured by methods known from the prior art, for example, described in articles: Jagtoyen, M., and F. Derbyshire, Carbon, 36 (7-8), 1085-1097 (1998), and Evans et al., Carbon, 37, 269-274 (1999), and Ryoo et al., J.Phys. Chem. B, 103 (37), 7743-7746 (1999), the contents of which are incorporated herein by reference. Typical chemicals used for activation / carbonization include phosphoric acid, zinc chloride, ammonium phosphate, etc., which can be used in combination with the methods described in the two journals cited above.

Particle size and volume porosity

The specific surface area according to Brunauer, Emmett and Teller (BET) and the pore size distribution according to Barrett, Joyner and Halend (BJH) can be used to characterize the pore structure for both microporous and mesoporous activated carbon particles. The BET specific surface area of the mesoporous and basic activated carbon filter particles may preferably be between about 500 m ² / g and about 3000 m ² / g, preferably between about 600 m ² / g and about 2800 m ² / g, more preferably between about 800 m ² / g and about 2500 m ² / g, and most preferably between about 1000 m ² / g and about 2000 m ² / g.

The total pore volume of the mesoporous and basic particles of activated carbon is measured in the process of nitrogen adsorption by BET and is calculated as the volume of nitrogen adsorbed at a relative pressure of P / P ₀ 0.9814. More specifically, the total pore volume, as is known from the prior art, is calculated by multiplying the “volume of absorbed nitrogen in ml / g (under normal conditions)” at a relative pressure of 0.9814 by a conversion factor of 0.00156, which converts the volume of nitrogen under normal conditions (at normal temperature and pressure) to the liquid. The total pore volume of the mesoporous activated carbon filter particles may be greater than about 0.4 ml / g, or more than about 0.7 ml / g, or more than about 1.3 ml / g, or more than about 2 ml / g, and (or ) less than about 3 ml / g, or less than about 2.6 ml / g, or less than about 2 ml / g, or less than about 1.5 ml / g.

The sum of the volumes of mesopores and macropores is measured in the process of nitrogen adsorption by BET and is calculated as the difference between the total pore volume and the volume of nitrogen adsorbed at P / P ₀ 0.15. The sum of the volumes of mesopores and macropores of the activated carbon filter particles may be more than about 0.12 ml / g, or more than about 0.2 ml / g, or more than about 0.4 ml / g, or more than about 0.6 ml / g, or more than about 0.75 ml / g, and / or less than about 2.2 ml / g, or less than about 2 ml / g, or less than about 1.5 ml / g, or less than about 1.2 ml / g or less than about 1 ml / g.

The pore size distribution by BJH can be measured using the Barrett, Joyner and Hallenda (BJH) process, which is described in J. Amer. Chem. Soc, 73, 373-80 (1951) and in Gregg and Sing, ADSORBTION, SURFACE AREA, AND POROSITY, 2-nd edition, Academic Press, New York (1982), the contents of which are incorporated herein by reference. In one embodiment, the pore volume of the mesoporous activated carbon particles may be at least about 0.01 ml / g for any pore diameter between about 4 nm and about 6 nm. In an alternative embodiment, the pore volume of the mesoporous activated carbon particles may be between about 0.01 ml / g and about 0.04 ml / g for any pore diameter between about 4 nm and about 6 nm. In yet another embodiment, the pore volume of the mesoporous activated carbon particles may be at least about 0.03 ml / g for pore diameters between about 4 nm and about 6 nm, or between about 0.03 ml / g and about 0.06 ml / g In a preferred embodiment, the pore volume of the mesoporous activated carbon particles may be between about 0.015 ml / g and about 0.06 ml / g for pore diameters between about 4 nm and about 6 nm.

The ratio of the sum of the volumes of mesopores and micropores to the total pore volume of the mesoporous activated carbon particles may be greater than about 0.3, preferably greater than about 0.4, preferably greater than about 0.6, and most preferably between about 0.7 and about 1.

, где

- средний диаметр по Заутеру, который представляет собой диаметр частицы, у которой отношение «поверхности к объему» равно этому отношению для всего распределения частиц. Известный из уровня техники процесс для измерения среднего диаметра по Заутеру - это лазерная дифракция, например, при помощи оборудования Malvern (Malvern Instruments Ltd., Malvern, Великобритания). Удельная внешняя поверхность фильтрующих частиц, либо микропористых, либо мезопористых, может быть между примерно 10 см²/г и примерно 100000 см²/г, предпочтительно между примерно 50 см²/г и примерно 50000 см²/г, более предпочтительно между примерно 100 см²/г и примерно 10000 см²/г, и наиболее предпочтительно между примерно 500 см²/г и примерно 7000 см²/г.The total external surface area is calculated by multiplying the specific external surface area by the mass of filter particles and depends on the size of the filter particles. For example, the specific external surface area of monodisperse fibers (i.e., having the same diameter) is calculated as the ratio of the fiber area (in this case, 2 cross-sectional areas at the ends of the fibers are neglected) to the weight of the fibers. Thus, the specific external surface area of the fibers is: 4 / Dρ, where D is the fiber diameter and ρ is the fiber density. For monodisperse spherical particles, similar calculations give the following formula for the specific external surface area: 6 / Dρ, where D is the particle diameter and ρ is the particle density. For polydisperse fibers, spherical particles, or irregularly shaped particles, the specific surface area of the external surface is calculated using the same corresponding formulas above with the replacement of D by

where

- Sauter average diameter, which is the diameter of a particle for which the “surface to volume” ratio is equal to this ratio for the entire particle distribution. A prior art process for measuring Sauter average diameter is laser diffraction, for example using Malvern equipment (Malvern Instruments Ltd., Malvern, UK). The specific outer surface of the filter particles, either microporous or mesoporous, may be between about 10 cm ² / g and about 100,000 cm ² / g, preferably between about 50 cm ² / g and about 50,000 cm ² / g, more preferably between about 100 cm ² / g and about 10,000 cm ² / g, and most preferably between about 500 cm ² / g and about 7000 cm ² / g.

In one preferred embodiment of the present invention, the filter particles comprise mesoporous activated carbon particles, which are wood-based activated carbon particles. These particles have a specific BET surface area of between about 1000 m ² / g and about 2000 m ² / g, a total pore volume between about 0.8 ml / g and about 2 ml / g, and a sum of mesopore and macropore volumes between about 0, 4 ml / g and approximately 1.5 ml / g.

In another preferred embodiment of the present invention, the filter particles comprise mesoporous and basic activated carbon particles, which are wood based activated carbon particles. These particles have a specific BET surface area between about 1000 m ² / g and about 2000 m ² / g, a total pore volume between about 0.8 ml / g and about 2 ml / g, and a sum of mesopore and micropore volumes between about 0, 4 ml / g and approximately 1.5 ml / g.

Removal rates

The size of the KUB of mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles when measured in accordance with the measurement procedure described herein may be more than about 99%, preferably more than about 99.9%, more preferably more than about 99.99%, and most preferably more than about 99.999%. The equivalent LKUB value of mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles can be more than about 2 log, more preferably more than about 3 log, more preferably more than about 4 log and most preferably more than about 5 log. The magnitude of the ECC of mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles when measured in accordance with the measurement procedure described herein may be more than about 90%, preferably more than about 95%, more preferably more than about 99%, and most preferably more than about 99.9%. The equivalent LHEC of the mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles may be more than about 1 log, preferably more than about 1.3 log, more preferably more than about 2 log, and most preferably more than about 3 log .

The LSUB-F value for the filters of the present invention containing mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles, when measured in accordance with the measurement procedure set forth herein, may be more than about 2 log, preferably more about 3 log, more preferably more than about 4 log, and most preferably more than about 6 log. The LCL-F value for the filters of the present invention containing mesoporous, or mesoporous and basic, or mesoporous, basic and oxygen-reduced activated carbon particles, when measured in accordance with the measurement procedure set forth herein, may be more than 1 log, preferably more than approximately 2 log, more preferably more than about 3 log, and most preferably more than about 4 log.

In another preferred embodiment of the present invention, the filter particles comprise mesoporous and basic reduced oxygen activated carbon particles that were initially acidic and became basic with reduced oxygen during processing in dissociated ammonia. These particles are wood-based activated carbon particles. The processing temperature is between about 925 ° C. and about 1000 ° C., the ammonia consumption is between about 1 standard l / h · g and about 20 standard l / h · g, and the processing time is between about 10 minutes and about 7 hours. These particles have a specific BET surface area between about 800 m ² / g and about 2500 m ² / g, a total pore volume between about 0.7 ml / g and about 2.5 ml / g, and a sum of the volumes of mesopores and macropores between about 0.21 ml / g; and about 1.7 ml / g. A non-limiting example of acid activated carbon, which is converted to basic reduced oxygen activated carbon, is given below.

In yet another preferred embodiment of the present invention, the filter particles comprise mesoporous, basic reduced oxygen activated carbon particles that were originally mesoporous and basic and that were treated in an inert (i.e. helium) gas environment. These particles are wood based activated carbon particles. The processing temperature is between about 800 ° C. and about 1000 ° C., the helium flow rate is between about 1 standard l / h · g and about 20 standard l / h · g, and the processing time is between about 10 minutes and about 7 hours. These particles have a specific BET surface area of between about 800 m ² / g and about 2500 m ² / g, the total pore volume is between about 0.7 ml / g and about 2.5 ml / g, and the sum of the mesopore volumes and Macropore is between about 0.21 ml / g and about 1.7 ml / g. A non-limiting example of a basic activated carbon converted to a basic reduced oxygen activated carbon is given below.

The oxygen reduction fraction (OEC) is measured using a redox electrode, model 96-78-00 from Orion Research, Inc. (Beverly, Mass.), And in accordance with ASTM D 1498-93. The procedure consists in obtaining a suspension of about 0.2 g of carbon in 80 ml of tap water and reading the readings at the ends of the electrode (in mV) after about 5 minutes of gentle stirring.

III. Silver and silver-containing materials

It is known that the presence of metals in active carbon can significantly increase the efficiency and selectivity of the action of active carbon when used for filtering purposes. In particular, the presence of silver can improve the removal of microorganisms in carbon-based water filters. Even more specifically, the addition of silver can increase both the coefficient of removal of bacteria (KUB), and the coefficient of removal of viruses (KVV).

However, it will be understood by those skilled in the art that coating materials and other filter additives, in addition to filter particles, add to the cost of the filter. In addition, coating materials can transfer from particles to drinking water, which could potentially lead to adverse effects. Thus, although the coating materials and other additives described herein provide certain advantages, it is highly desirable to obtain the same benefits without any additives to the activated carbon particles of the present invention.

Thus, in one preferred aspect, the present invention is directed to a filter for providing drinking water. The filter includes a housing having an inlet and outlet openings, and a filter material located inside the housing, which is formed, at least in part, from a plurality of activated carbon filter particles and particles selected from the group consisting of microporous or mesoporous activated carbon filter particles, completely coated with silver or silver-containing material, microporous or mesoporous activated carbon filter particles, partially coated with silver or silver-containing material, silver particles and mixtures of the above.

More specifically, the filter material of the present invention may include, but is not limited to, an admixture of silver to the microporous and mesoporous activated carbon filter particles, microporous or mesoporous activated carbon filter particles coated partially or completely with silver and / or silver-containing material; microporous or mesoporous activated carbon filter particles coated partially or completely with silver or silver-containing material; or an admixture of microporous activated carbon particles, mesoporous activated carbon filter particles, microporous or mesoporous activated carbon filter particles coated partially or completely with silver and / or silver-containing material. Preferably, the mass fraction of silver or silver-containing material relative to the microporous and mesoporous activated carbon filter particles is from about 1: 10000 to about 1: 1, where the mass of silver or silver-containing material is respectively taken as a unit, with a BET surface area of at least 800 m ² / g and a density of at least 0.1 g / ml.

Known methods for adding silver to a carbon-based matrix, and any of these methods are suitable for obtaining the filter material of the present invention. See, for example, U.S. Patent Nos. 4,482,641 and 4,045.553, issued respectively to Wennerberg on November 13, 1984 and Mitsumori et al. August 30, 1977. See also Dimitry, US Pat. The Dimitry method consists of mixing an aqueous solution of a lignin salt with an aqueous solution of a transition metal salt to precipitate the transition metal and lignin as a metal lignate. The transition metal must be able to form a chemical bond with lignin and at the same time precipitate with lignin from the solution in the form of a metal lignate. Dimitry discloses that the time required to complete the deposition is less than one hour, and that usually 30 minutes is sufficient for this purpose. According to Dimitry, the precipitated wet metal lignate can then be suitably dried in a spray dryer. The precipitate is then carbonized at a temperature between 371 ° C and 983 ° C and finally activated at a temperature between 760 ° C and 1065 ° C. According to Dimitry, although drying the precipitated metal lignate is not essential to obtain an activated carbon product, drying is necessary to obtain a large surface area of the final product. Patents Dimitry, Mitsumori et al. and Wennerberg are fully incorporated herein by reference.

One method for producing a substantially uniform dispersion of silver or silver-containing material on a porous carbon matrix, without implying a limitation of the present invention, comprises the steps of: forming a uniform cocrystallite starting material for silver or silver-containing material, or the aforementioned carbon starting material; form a homogeneous powdery mixture of cocrystallite and organic solids containing alkali metal hydroxide; pyrolyzing the powder mixture in an inert gas atmosphere at a temperature in the range of from about 400 ° C. to about 980 ° C. to form a carbon matrix having silver or silver-containing material substantially uniformly dispersed therein; and separating unreacted inorganic material and inorganic reaction products other than dispersed silver or silver-containing material from a matrix of porous carbon.

For the formation of co-crystallite in the method of the present invention, any of a variety of known techniques that allow uniform co-crystallization, namely, the simultaneous crystallization of the carbon starting material and the starting material for silver or silver-containing material and the formation of a substantially uniform co-crystallite from them, can be used. The homogeneity of the co-crystalline mixture is essential for the final formation of a uniform dispersion of silver or silver-containing material on activated carbon with a large surface area. A preferred method for forming a homogeneous co-crystallite from a carbon starting material and starting material for silver or silver-containing material according to the method of the present invention involves the formation of a stable solution of both starting materials in an appropriate solvent and spray-drying the solution to dryness. With this technique, solvent removal should be performed fast enough to ensure the fastest, simultaneous and uniform co-crystallization of both starting materials from the solution. Spray drying provides the required rapid evaporation, which provides fast, simultaneous and uniform co-crystallization and the formation of a homogeneous co-crystallite of both starting materials. In a spray drying system that is suitable for performing the spray drying step upon receipt of the filter material of the present invention, a solution of a carbon starting material and a starting material for silver and silver-containing material is introduced into the drying chamber through a nozzle. Hot inert gas, such as nitrogen, is introduced into the drying chamber through a line located around the nozzle, and helps to spray the solution introduced into the drying chamber through the nozzle, accelerates the sprayed droplets of the solution and increases their temperature and thereby contributes to essentially instantaneous evaporation of the solvent from them , which leads to the formation of a homogeneous co-crystalline powder. Air is introduced into the drying chamber to displace the co-crystalline powder and nitrogen down in the drying chamber, and the mass of the co-crystalline powder falls to the bottom of the drying chamber, where it accumulates and is subsequently removed for use in subsequent steps of the method of the present invention. Gas passes from the drying chamber and then enters the cyclone system, where the co-crystalline powder captured by the gas stream is separated from the gas and passes downward through the storage line. The mass fraction of the dispersed metal or metal-containing material with respect to the active carbon matrix in the composition of the present invention is preferably from 1: 10000 to 1: 1, where the mass of metal or metal-containing material is respectively taken as a unit.

IV. Cationic coating materials

The isoelectric point of carbon is usually below 6, since there is usually an excess of acid functional groups on its surface. Therefore, carbon often has a negative surface charge at a pH above 6 and, therefore, is anionic at a pH of drinking water, which usually lies between 6 and 9. In some cases, it is desirable that the carbon have a positive surface charge. It was found that the surface charge of carbon can be inverted by adsorbing some cationic polymers to its surface. More specifically, it is desirable to cover at least a portion of the microporous or mesoporous activated carbon filter particles of the existing filter material with one or more cationic polymers listed below. It is even more desirable to cover at least a portion of the microporous or mesoporous activated carbon filter particles of the existing filter material with one or more cationic polymers listed below and silver or silver-containing material.

However, it will be understood by those skilled in the art that coating materials and other filter additives, in addition to directly filter particles, add to the cost of the filter. In addition, coating materials can enter particles from drinking water, potentially leading to adverse effects. Thus, although the coating materials and other additives described herein provide certain advantages, it is highly desirable to obtain the same benefits without any additives to the activated carbon particles of the present invention.

The polymers used must contain amine or quaternary nitrogen or a mixture of both, and can be prepared by chain polymerization or step polymerization with the appropriate monomers. If desired, these monomers can be copolymerized with other monomers. In addition, the polymer may be a synthesized or naturally occurring biopolymer. If any of these polymers, regardless of the source, does not contain amine or quaternary nitrogen, these functional groups can be added by an appropriate grafting chemical reaction. When the polymer lacks quaternary nitrogen, but it contains amine nitrogen, the amine functional group must be sufficiently basic to attach a proton in water and make the polymer cationic enough to overcome the anionic charge introduced by carbon. If the nitrogen is not basic enough, polymers containing amine nitrogen can be quaternized by reaction with methyl chloride, dimethyl sulfate, and other conventional alkylating agents. As used herein, the phrase “cationic coating material” means a cationic polymer used to coat filter particles.

Examples of cationic polymers suitable for use in the present invention that are prepared by chain polymerization include, but are not limited to, polyvinylamine, poly (N-methylvinylamine), polyallylamine, polyallyldimethylamine, polydiallylmethylamine, polydiallyldimethylammonium chloride, polyvinylpyridinium pyridine chloride , poly (4-vinylpyridine), polyvinylimidazole, poly (4-aminomethylstyrene), poly (4-aminostirol), polyvinyl (acrylamide-sodimethylaminopropylacrylamide) and polyvinyl (acrylamide-sodimethylaminoethylmethacrylate).

Examples of cationic polymers suitable for use in the present invention that are prepared by step polymerization include, but are not limited to, polyethyleneimine, polylysine, DAB-Am and PAMAM dendrimers (or hyperbranched polymers containing an amine or quaternary nitrogen functional group), polyaminoamides, polyhexamethylene biguanide , polydimethylamine-epichlorohydrin and any of a variety of polyaminosiloxanes that can be constructed from monomers such as aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltri toksisilan chloride, N-trimethoxysilylpropyl-N, N, N-trimethylammonium chloride and bis (trimethoxysilylpropyl) amine.

Examples of cationic polymers suitable for use in the present invention that are biopolymers include chitosan and starch, the latter being inoculated with reagents such as diethylaminoethyl chloride.

Examples of cationic polymers suitable for use in the present invention that contain amine nitrogen but which are made more basic by quaternization include alkylation of polyethyleneimine with methyl chloride and alkylation of polyaminoamides with epichlorohydrin.

Other categories of cationic polymers suitable for use in the present invention are generally coagulants and flocculants. As well as cationic polyacrylamide with cationic monomers dimethylaminoethylacrylatemethyl chloride (AETAC), dimethylaminoethylmethacrylamethyl chloride (METAC), acrylamidopropyltrimethylammonium chloride (APTAC), methacrylamidopropyltrimethylammonium chloride (MAD) DIAMETA DIAMETA, MADMALDIAMETA, DIAMETA, and MADMALDIAMETA dimethylMDiMalmDiLa Finally, in this case, ionenes and silanes can also be used.

Preferred cationic polymers for use in the present invention include polyaminoamides, polyethyleneimine, polyvinylamine, polydiallyldimethylammonium chloride, polydimethylamine-epichlorohydrin, polyhexamethylene biguanide, poly [2- (2-ethoxy) ethoxyethyl guanidine chloride].

The cationic polymers of the present invention can be attached to the carbon surface by physical sorption or chemical crosslinking. Physical sorption can be accomplished by spraying a polymer solution onto a carbon surface or adding a polymer solution to a suspension of carbon in water. This application method is applicable to all polymers of the present invention. Chemical crosslinking is generally applicable only to those polymers that are capable of undergoing crosslinking reactions. This excludes, for example, a diallyldimethylammonium chloride homopolymer and any other polymer that does not have a reactive functional group. If the reactive polymer was thermoset (for example, polyaminoamide grafted with epichlorohydrin), it could simply be added to the carbon surface by one of the two above methods and by heating. If the reactive polymer is not thermoset, then a suitable crosslinking molecule must be introduced into the polymer solution before being applied to the carbon surface. In the polymers of the present invention (which all contain reactive nucleophilic functional groups), the crosslinking molecules must be electrophilic and may include citric acid, ethylene glycol diglycidyl ether, 3-glycidoxypropyltriethoxysilane and the like. During the crosslinking reaction, the polymer can form covalent bonds with carbon, but this is not a requirement of the present invention. Preferably, the mass fraction of the cationic coating material with respect to the activated carbon filter particles is from 1: 10000 to 1: 1.

V. Filters of the present invention

The following describes an example of a filter made in accordance with the present invention, with reference to the drawing. The filter 20 comprises a cylinder-shaped housing 22 having an inlet 24 and an outlet 26 openings. The housing 22 may have a different shape, size and layout depending on the intended use and the required characteristics of the filter 20, known from the prior art. For example, the filter 20 may be an axial flow filter in which the inlet 24 and the outlet 26 are arranged so that liquid flows along the axis of the housing 22. Alternatively, the filter 20 may be a radial flow filter in which the inlet 24 and the outlet 26 are arranged so that a fluid (for example, either liquid, gas, or a mixture thereof) flows along the radius of the housing 22. In both axial and radial flow configurations, the filter 20 may preferably be configured to a face area of at least about 0.5 square inches (3.2 cm), more preferably at least about 3 square inches (19.4 cm ² ), and most preferably at least about 5 square inches (32.2 cm ² ), and preferably a filter depth of at least about 0.125 inches (0.32 cm), at least about 0.25 inches (0.64 cm), more preferably at least about 0.5 inches (1.27 cm), and most preferably at least about 1.5 inches (3.81 cm). For radial flow filters, the filter length may be at least 0.25 inches (0.64 cm), more preferably at least about 0.5 inches (1.27 cm), and most preferably at least about 1.5 inches (3.81 cm). In addition, the filter 20 may include axial flow segments and radial flow segments.

Within the scope of the present invention, the housing may also be made as part of another design. Although the filters of the present invention are particularly suitable for use with water, it is understood that other fluids (e.g., air, gas, and mixtures of air and liquids) can be used. Thus, the filter 20 is a universal filter for liquid or gas. The size, shape, distance, relative position and position of the inlet 24 and the outlet 26 can be selected, as is known from the prior art, to ensure the flow rate and the intended use of the filter 20. Preferably, the filter 20 is adapted to be used for domestic and commercial production of drinking water. including, in particular, as common-house filters, filters for refrigeration units, devices for producing drinking water (for example, in travel devices, such as bottles water filters), filters installed on a water tap, filters installed under a sink, filters for medical devices, industrial filters, air filters, etc. Examples of constructions of filters, devices for drinking water, household appliances and other devices for filtering water, come to be used with the present invention, are disclosed in US patent No. 5.527.451, 5.536.394, 5.709.794, 5.882.507, 6.103.114, 4.969.996, 5.431.813, 6.214.224, 5.957.034, 6.145.670, 6.120.685 and 6.241.899, the essence of which is incorporated herein by reference. When used to produce drinking water, filter 20 may preferably be configured to provide a flow rate of less than about 8 l / min, or less than about 6 l / min, or between about 2 l / min and about 4 l / min, and the filter may contain less than about 2 kg of filter material, or less than about 1 kg of filter material, or less than about 0.5 kg of filter material. In addition, when used to produce drinking water, the filter 20 may preferably be configured to provide an average liquid residence time of at least about 1 s, preferably at least about 3 s, preferably at least about 5 s, more preferably at least at least about 10 seconds, and most preferably at least about 15 seconds. In addition, when used to produce drinking water, the filter 20 may preferably be configured to provide a pore volume of the filter material of at least about 0.4 cm ³ , preferably at least about 4 cm ³ , more preferably at least about 14 cm ³ and most preferably at least about 25 cm ³ .

The filter 20 also contains filter material 28, which can be used in combination with other filter systems, including reverse osmosis systems, ultraviolet light irradiation systems, ion exchange systems, electrolyzed water systems, and other water treatment systems known to those skilled in the art.

The filter 20 also contains filter material, the filter material containing one or more filter particles (e.g. fibers, granules, etc.). In addition to the microporous particles of the filter materials of the present invention, one or more filter particles can be mesoporous, more preferably mesoporous and basic, and most preferably mesoporous, basic and with reduced oxygen, and possess the previously discussed characteristics. Microporous filter media 28; mesoporous; or mesoporous and basic; or mesoporous, basic and with reduced oxygen activated carbon can be coated either partially or completely with silver, a silver-containing material, any of the above cationic polymer coating materials, or a combination of the above. Microporous filter media 28; mesoporous; or mesoporous and basic; or mesoporous, basic and reduced oxygen activated carbon can be combined with other materials selected from the group consisting of powdered activated carbon, activated carbon granules, activated carbon fibers, carbon nanotubes, single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) zeolites, activated aluminum oxide, magnesium oxide, activated magnesium oxide, diatomaceous earth, silver particles, activated silicon dioxide, hydrotalcites, ste materials, materials with an organometallic base (MOF), glass particles or fibers, nanofibers from synthetic polymers, nanofibers from natural polymers, polyethylene fibers, polypropylene fibers, fibers from a copolymer of ethylene and maleic anhydride, clay sand and mixtures thereof.

These other materials may be coated either partially or completely with silver, a silver-containing material, any of the above cationic coating materials, or combinations thereof. Examples of filter materials and combinations of filter materials with which microporous and mesoporous and basic activated carbon can be combined are disclosed in US Pat. 628.632, which is incorporated herein by reference. As discussed above, the filter material can be obtained either in an unbound or in an interconnected form (for example, partially or fully bonded polymeric binder or other means for the formation of a holistic structure).

The filter material can be used for various applications (for example, used as a pre-filter or post-filter) by changing the size, shape, complexation, charge, porosity, surface structure, functional groups, etc. filter particles, as discussed above. The filter media may also be mixed with the other materials described above in order to adapt it for a specific application. Regardless of whether the filter material is mixed with other materials or not, it can be used in the form of an unbound layer, in the form of a block (including as a coextruded block described in US Pat. No. 5,679,248, incorporated herein by reference) and in the form of mixtures thereof. Preferred methods that can be used with the filter material include the formation of a block filter made of a ceramic-carbon mixture (in this case, bonds are formed by firing the ceramic), the use of powder between nonwoven materials, as described in US patent No. 6.077.588, which is incorporated herein by reference, applying the pre-baking strength method described in US Pat. No. 5,928,588, which is incorporated herein by reference, activating a binder resin that forms a block, or using using the method of resistive heating described in PCT application No. WO 98/43796, which is incorporated herein by reference.

VI. Filter Examples

EXAMPLE 1

Filter containing microporous and mesoporous activated carbon particles

About 5.5 g of microporous coconut charcoal supplied by Barnebey Sutcliffe is mixed with 13.0 g of Nuchar® RGC mesoporous and basic powdered activated carbon (D _{V, 0.5} is approximately 45 μm) from MeadWestvaco Corp., Covington , Virginia, which is then mixed with about 7 g of Microthene® Low Density Polyethylene (LDPE) Binder FN510-00 from Equistar Chemicals, Inc. of Cincinnati, Ohio, and about 2 g of Alusil® 70 aluminosilicate powder from Selecto, Inc., Norcross, GA. Before mixing, the mesoporous activated carbon particles are coated with polydiallyldimethylammonium chloride (polyDADMAC) and the coating is dried. The mixed powders are then poured into a round aluminum mold with an inner diameter of about 3 inches (about 7.62 cm) and a depth of about 0.5 inches (about 1.27 cm). The mold is closed and placed in a heated press, at the working table of which a temperature of about 204 ° C is maintained for 1 hour. Then the mold is allowed to cool to room temperature, it is opened and the axial flow filter is removed. Filter characteristics: front area - approximately 45.6 cm ² ; filter depth - about 1.27 cm; the total volume of the filter is approximately 58 ml; the porosity of the filter (for pores greater than about 0.1 microns) is about 0.43; and the pore volume of the filter material (for pores greater than about 0.1 μm) is about 25 ml (as measured by mercury porosimetry). The filter is placed in a Teflon® housing, described below in the description of the measurement procedures. When the volumetric flow rate is about 200 ml / min, the pressure drop for this filter is about 17 pounds per square inch (about 1.2 bar, 0.12 MPa) for about the first 2000 pore volumes of the filter.

EXAMPLE 2

Filter containing microporous and mesoporous activated carbon particles

Approximately 13.0 g of microporous coconut charcoal supplied by Barnebey Sutcliffe is mixed with 13.0 g of mesoporous base powdered activated carbon (D _V0.5 is approximately 92 μm), mixed with 7 g of binder FN510-00 made of low polyethylene Microthene® Density (LDPE) from Equistar Chemicals, Inc. of Cincinnati, Ohio; and about 2 g of Alusil® 70 Aluminosilicate Powder from Selecto, Inc. of Norcross, GA. Before mixing, the mesoporous activated carbon particles are coated with polydiallyldimethylammonium chloride (polyDADMAC) and the coating is dried. The mixed powders are then poured into a round aluminum mold with an inner diameter of about 3 inches (about 7.62 cm) and a depth of about 0.5 inches (about 1.27 cm) ) The mold is closed and placed in a heated press, at the working table of which the temperature is maintained at about 204 ° C for 1 hour. Then the mold is allowed to cool to room temperature, it is opened and the axial flow filter is removed. Filter characteristics: front area - approximately 45.6 cm ² ; filter depth - about 1.27 cm; the total volume of the filter is approximately 58 ml; the porosity of the filter (for pores greater than about 0.1 microns) is about 0.44; and the pore volume of the filter material (for pores greater than about 0.1 μm) is about 25.5 ml (as measured by mercury porosimetry). The filter is placed in a Teflon® housing, described below in the description of the measurement procedures. When the volumetric flow rate is about 200 ml / min, the pressure drop for this filter is about 17 pounds per square inch (about 1.2 bar, about 0.12 MPa) for about the first 2000 filter pore volumes.

EXAMPLE 3

Removal of PTHM, viruses and bacteria for filters containing microporous and mesoporous activated carbon particles

Filters made in accordance with the above Examples 1 and 2, and filters made by similar methods, but using other mixtures of microporous and mesoporous activated carbon particles, are tested for the ability to remove PTGM, bacteriophages MS-2 and bacteria Raoultella terrigena (R.t.). The filters were wrapped in a single layer of uncharged nylon having holes of 0.65 μm (BLA 065, supplied by Cuno, Inc., Meriden, Connecticut). A filter containing only mesoporous activated carbon and a filter containing only microporous activated carbon were also tested. The results of such a test are shown below in Table 3. It will be understood by those skilled in the art of manufacturing water filters that the conditions for such a test depend on the volume of the filter, the type of flow (for example, axial, radial, or other) and the type of coal used. One such protocol is presented in the 1987 Guidelines for Testing Microbiological Water Purifiers issued by the US Environmental Protection Agency. The Protocol establishes minimum requirements for the characteristics of drinking water treatment systems, which are designed to reduce the number of pollutants affecting health in public and private water sources. The bacteriophage MS-2 (or simply the phage MS-2) is usually used as a typical microorganism to verify the removal of viruses, since its size and shape (namely, about 26 nm, the icosahedral shape) are similar to many viruses. Thus, the ability of a filter to remove the bacteriophage MS-2 characterizes the ability to remove other viruses. Similarly, the ability of a filter to remove PGTM characterizes its overall ability to remove chemicals from liquids.

In the table, mesoporous activated carbon particles are various types of RGC carbon supplied by MeadWestvaco Co. Companies UCRF Coal (nPSD) is Nuchar® RGC activated carbon that has been treated to remove some large and small particles to produce multiple particles with a narrow particle size distribution (UCRF). Microporous charcoal is coconut based charcoal supplied by Barnebey Sutcliffe. Chloroform (which is a replacement for PTGM, proposed by the ANSI 53-2002 standard), bacteria R.t, and bacteriophages MS-2 are introduced into the filters and the removal efficiency is measured at various points in time, some of which are given below.

PTHM effectiveness is measured by breakthrough, or by how many gallons of contaminated water passes through the filter before PTHM is detected at the outlet. As can be seen from the table, for filters containing 0-20% microporous activated carbon particles, an average of 70 gallons of water passes through the filters before PTHM is detected. But when the microporous particles of activated carbon are 30%, the amount of water passing through the filter before the detection of PTHM in one test more than doubled, amounting to 160 gallons, and for other filters it was 100 gallons or more. These results, especially a sharp increase in the degree of removal of PTGM with a microporous activated carbon content of about 25%, are surprising and unexpected for those skilled in the art.

The degree of removal of R.t. and MS-2 is measured by the logarithmic degree of removal described above. As you can see, the logarithmic degree of removal for R.t. is approximately 7 log for all filters from day 1 to day 16, except for a filter containing 100% microporous activated carbon particles. For this filter, delete R.t. fell from about 6 logs on 1 day to about 3.7 to 5 days, to about 2.3 to 9 days, to about 1.3 logs on day 16. Similarly, the logarithmic removal rate for MS-2 was approximately 4-5 log for all filters from day 1 to day 16, except for a filter containing 100% microporous activated carbon particles. For this filter, the MS-2 removal rate was initially 1 log and remained at that level throughout the test. Although a relatively low degree of removal of MS-2 and R.t. in the case of a filter of 100% microporous activated carbon, it should not surprise those skilled in the art, but it is surprising and unexpected that filters containing more than 50% microporous carbon particles retain an excellent ability to remove these viruses and bacteria. In other words, it is truly surprising and unexpected that a mixture of microporous and mesoporous activated carbon particles in certain proportions can preserve the properties of each type of particle.

TABLE R.t. Microporous carbon content PTGM Pressure drop at 2 l / min Volumetric flow rate 1 day 5 day 9 day 16 day % of total carbon gal psi inch l / m log log log log 100% rfdr RGC coated with pDAD-MAC 0 80 24 ~ 2 7 6.6 6.8 6.6 100% RGC-55 coated with pDADMAC 0 60 56 ~ 2 7 6.7 6.8 7 80% RGC-coated RGC twenty 70 ~ 28 ~ 2 7.3 6.6 7.3 7 pDAD-MAC 70% rfdr RGC coated with pDAD-MAC thirty 160 34 2 7.2 7.1 6.9 7.3 35% 80X325 RGC + 35% RGC-55, both coated with pDADMAC thirty one hundred 37 ~ 2 7.3 6.6 7.3 7 50% rfdr RGC coated with pDAD-MAC fifty 110 thirty 2.2 7.1 6.9 6.2 7 50% rfdr RGC coated with pDAD-MAC fifty 110 32 2.2 7.1 7.2 6.8 7 0% RGC RGC coated with pDADMAC * one hundred 150 26 2.1 6.6 3,7 2,3 1,5 Ms-2 Microporous carbon content PTGM Pressure drop at 2 l / min Volumetric flow rate 1 day 5 day 9 day 16 day % of total carbon gal psi inch l / m log log log log 100% rfdr RGC coated with pDAD-MAC 0 80 24 ~ 2 5 5 4.8 4.6 100% RGC-55 coated with pDADMAC 0 60 56 ~ 2 4.7 4.8 4.1 5.1 80% RGC RFID coated with pDADMAC twenty 70 ~ 28 ~ 2 5.1 4.9 5 4.7 70% RGC RFID coated with pDADMAC thirty 160 34 2 four 4.6 4.6 4.7 35% 80X325 RGC + 35% RGC-55, both coated with pDADMAC thirty one hundred 37 ~ 2 5.1 4.9 5 4.7 50% RGC RFID coated with pDAD-MAC fifty 110 thirty 2.2 4.9 4,5 <4 4.6 50% RGC RFID coated with pDAD-MAC fifty 110 32 2.2 4.6 4.6 4.1 5.7 0% RGC RGC coated with pDAD-MAC * one hundred 150 26 2.1 one 1,1 1,2 1,2 * In this test, a nylon wrapper on the filter was not applied.

VII. Kits

The present invention may further include information that will inform the consumer, using words and / or images, that using the carbon filter particles and / or filter material of the present invention will provide benefits that include the removal of microorganisms, and this information may include statement about superiority over other filtering products. In a highly desirable embodiment, the information may include a message that the use of the invention provides reduced levels of microorganisms having nanoscale sizes. Accordingly, it is very important to use the packaging in conjunction with information that will inform the consumer, in words or images, that using the invention provides the benefits discussed herein, such as drinkable or more potable water. For the purpose of informing the consumer, the information may include, for example, advertisements in all conventional media, as well as messages and pictograms on the packaging or on the filter itself. More specifically, either the package or the filter housing may contain information that the filter or filter media provides: reduction in bacteria; reduction in the number of viruses; reduction in the number of microorganisms; removal of bacteria; virus removal; removal of microorganisms; destruction of bacteria; the destruction of viruses; destruction of microorganisms, removal of PHTM, reduction of the number of PTHM, or any combination of the above.

The embodiments described herein have been selected and described in order to best illustrate the principles of the invention and its practical application so as to enable a person skilled in the art to use the invention in various embodiments and in various modifications that are most suitable for the particular intended application. All such modifications and alterations do not fall outside the scope of the invention defined by the attached claims, interpreted with the degree of breadth to which it is entitled from the point of view of justice, legality and impartiality.

Claims (1)

1. A method for removing trihalogenomethanes, bacteria and viruses from drinking water, comprising the steps of:
provide a filter containing:
(a) a housing having an inlet and outlet; and
(b) a filter material inside the specified housing, and the specified filter material contains:
(i) a plurality of filter particles containing microporous activated carbon particles, from about 25% to about 75% by weight, the sum of the volumes of mesopores and macropores of said filter particles not exceeding 0.12 ml / g, and the mesopore is related to the intraparticle pore with a diameter of 2 nm to 50 nm, and the macropore refers to an intraparticle pore with a diameter of more than 50 nm,
(ii) a plurality of filter particles containing mesoporous activated carbon particles, from about 25% to about 75% by weight, wherein:
A. the sum of the volumes of mesopores and macropores of these mesoporous filter particles is from about 0.2 ml / g to about 2 ml / g, the mesopore refers to the intraparticle pore with a diameter of 2 nm to 50 nm, and the macropore refers to the intraparticle pore with a diameter of more than 50 nm;
B. the total pore volume of said mesoporous filter particles is greater than about 0.4 ml / g and less than about 3 ml / g, and
C. the ratio of the sum of the volumes of mesopores and macropores to the total pore volume of said filter particles is greater than about 0.3, and
(iii) a cationic polymer supported on at least a portion of a plurality of filter particles containing mesoporous activated carbon particles and microporous activated carbon particles,
(iv) aluminosilicate powder and
(v) a binder for binding a plurality of filter particles containing mesoporous activated carbon particles and microporous activated carbon particles; and
drinking water is passed through the inlet and through the filter material so that the filter material removes trihalomethanes by passing up to and more than 95 gallons of water through the filter material and remove bacteria and viruses from drinking water, while the filter is characterized by LKUB-F (logarithmic removal coefficient bacteria filter) (F-VLR) greater than about 2 log, and LKUV-F (logarithmic virus removal rate by filter) (F-VLR) greater than about 1 log.

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