FR2975915A1 - Use of a composite material for remediation of contaminated water, potable water, swimming pool water or thermal springs or spring water or river by microorganisms - Google Patents

Abstract

Use of a composite material for the remediation of contaminated water by micro-organisms, is claimed, where the material comprises: (I) at least one type of alumina as a porous support (80-99.8 wt.%); (II) at least one assistant material (0.1-10 wt.%) deposited on the support (I) and comprising titanium oxide, compounds containing phosphate anion, molybdenum trioxide, silicon dioxide, boron trioxide, chromate ions or dichromate ions; and (III) at least one active phase (10-40 wt.%) deposited on the layer of assistant material (II). Use of a composite material for the remediation of contaminated water by micro-organisms, is claimed, where the material comprises: (I) at least one type of alumina as a porous support (80-99.8 wt.%), which has a surface area of at least 250 m 2>/g and a porosity of at least 0.65 m 3>/kg; (II) at least one assistant material (0.1-10 wt.%) deposited on the support (I) and comprising titanium oxide, compounds containing phosphate anion, molybdenum trioxide, silicon dioxide, boron trioxide, chromate ions or dichromate ions; and (III) at least one active phase (10-40 wt.%) deposited on the layer of assistant material (II), and the active phase comprises one or more oxides, or water-insoluble salts, transition metals comprising cations of silver, nickel, copper, cobalt, iron or manganese.

Description

Composite mineral materials with germicidal capabilities

The subject of the present invention is the use of a composite material for the purification of waters contaminated by microorganisms, said material comprising (1) at least one porous support, alumina; (II) at least one assistant material selected from the group consisting of: titanium oxide TiO 2, phosphate compounds comprising anions PO43-, MoO3, SiO2, 8203, a compound containing chromate ions CrO42, a compound containing ions bichromate Cr2072-; and (III) at least one active phase comprising one or more oxides, or water-insoluble salts, transition metals comprising cations selected from the group consisting of: Ag +, Ni2 +, cu2 +, co2 +, co3 +, Fe3 +, Mn4 + .

BACKGROUND The contact of humans (or animals) with water in various circumstances presents a risk of transmitting diseases related to pathogenic microorganisms, including bacteria.

This general problem concerns not only drinking water systems, but also any other situation in which human beings will come into contact with potentially contaminated water. For example, it is known that large volumes of water frequented by the public, such as swimming pools and hot springs, pose a high risk of microbial contamination and that it is therefore necessary to treat the waters concerned effectively and efficiently. continuous, in particular by means of pumps which circulate the liquid by making it undergo a germicidal treatment before joining the general volume of water. Even in countries with large drinking water systems, water treatment booster devices can be found in rural areas, hikers, and so on. needing to consume spring water, river etc. encountered in geographically isolated areas.

Various types of processes are known for water purification in various contexts. Some processes are of a purely physical nature, for example the maintenance of water at high temperature (not always effective against all bacteria), or treatment with germicidal radiation (UV-C irradiation with a wavelength around 250 nm, irradiation with γ rays). Filtration systems, reverse osmosis filtration, or adsorption devices whose operation is based on physical effects may also include the addition of chemical reagents. In the category of chemical treatments, the use of halogens is naturally well known, for example iodine-based tablets, the use of chlorine (which is very well known in the bathing water field), as well as bromine treatment. The use of other chemical agents with high oxidation capacity, such as ozone, has also been described. Mention may also be made, as chemical reagents commonly used for water sterilization, sodium dichloroisocyanurate (NaDCC), or arent-based materials.

Problems to be solved In most cases, the existing processes for sanitizing water contaminated by microorganisms are dangerous (radiation risks), technically sophisticated (ozonation), or likely to deteriorate the quality of the water to be treated (treatment with halogenated products ). These treatments produce residues that are harmful to the environment or that are difficult to degrade. Moreover, their cost, either of implementation or of operation is high. The purpose of the present invention is to propose an alternative solution that is secure and technically simple, the application of which minimizes the risks associated with the risks of irradiation and does not lead to the deterioration of the quality of the water to be sanitized, in particular by the release of products. chemical.

SUMMARY OF THE INVENTION It has been surprisingly found, and this is the basis of the present invention, that the use of a composite material comprising three distinct parts, (1) a porous support (alumina), (H) an assistant material (TiO2, PO43, MoO3, SiO2, B203, CrO42-, Cr2022-), and (III) an active phase comprising one or more oxides, or water insoluble salts, transition metals comprising cations selected from the group consisting of Ag +, Ni2 +, cu2 +, co2 +, co '+, Fe3 + and / or Mn4 +, effectively inactivates microorganisms in contaminated waters. The present invention thus relates in particular to the use of a composite material for the purification of waters contaminated with microorganisms, said material comprising the following components (1), (II) and (III): (1) ) at least one type of alumina as a porous support, said porous support having a specific surface area of at least 250 mm 2 / g and a porosity of at least 0.65 μm (II) at less an assistant material deposited on the support (I) and selected from the group consisting of: TiO 2 titanium oxide,> phosphate compounds comprising PO anions; , MoO, Si B203,

compounds containing chromate ions CrO42-, compounds containing bichromate ions Cr, (III) at least one active phase deposited on the layer of assistant material (II), said active phase comprising one or more oxides, or insoluble salts in the water, transition metals comprising cations selected from the group consisting of: Ag +, NI2 +, cu2 +, co2if, co ', Fe3 +, Mn4 +; in which the porous support (s) forming part (I) constitutes (s) from 80 to 99.8% by weight relative to the total mass of said composite material, the material (s) assistant (s) forming the part (II) is (are) from 0.1 to 10% by weight relative to the total mass of said composite material, and the (or) phase (s) active (s) forming part (III) constitutes (s) from 10 to 40% by weight relative to the mass of the (or) auxiliary material (s) forming part (II) of said composite material. According to an advantageous embodiment of the present invention, the assistant material (s) forming part (II) constitutes (s) from 5.0 to 7.0% by weight relative to the mass. total of said composite material.

In a process according to the present invention, the contaminated water is brought into contact with this composite material defined above and then the water is treated and removed from the material. The use of these composite materials according to the invention for the decontamination of water containing microorganisms, can find application in various contexts of water purification. According to one nonlimiting example, the method according to the present invention can be used for the treatment of bathing water, recycled by means of a pump and subject to a sterilization stage before being reintroduced into the swimming pool from which it is derived. .

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows a test installation for evaluating the germicidal capacities of composite material within the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION In the materials used in the present invention, the essential role assigned to the support (I) is to optimally expose the assistant material (II) and the active phase (III) to the medium to be treated. this is why the carrier (I) must have a specific surface area and a large pore volume. The specific surface area in the context of the present invention will be as measured by physical adsorption (physisorption) with an inert gas, the details of the method being well known to those skilled in the field of porous solid materials (adsorbents, catalysts). The porosity within the scope of the present invention will be as measured by the equally well known method of mercury intrusion. Without wishing to be limited by a particular theoretical interpretation, it is considered that the combination of the phases (II) and (III) contributes to the inactivation of the microorganisms by electron transfer from the medium, either by simple removal of the electrons from microorganisms or by local production of free radicals (hydroxyl radicals, for example) with a biocidal effect. The probable role of the active phase (III) is considered to consist of the initial trapping of electrons from the reducing sources, and in particular of the microorganisms in the medium to be cleaned up, whereas the role of the assistant material ( II) would provide temporary retention but longer duration of trapped electrons, so that the active phase (III) can fully discharge and resume its

function of the initial trapping of electrons from the microorganisms to be inactivated. It has been found, as will be demonstrated later with some embodiments, that certain particular (II) assisting materials (TiO 2, PO 2 MoO, S 2 O 2, B 2 O 3, CrC 4 2 Cr, 0), and some specific active phases (III) represented by oxides, or water insoluble salts, transition metals comprising cations selected from the group consisting of Ag '', Ni2 +, Cu2 +, c02 ÷, Fe3 + and / or Mn4 +, allow to achieve an effective inactivation of microorganisms. Without this having to limit the scope of the invention, it is believed that a certain balance between the affinities of the material layers for electrons (due to the properties of the relevant metal ions exposed at the surface) is probably necessary for the proper functioning of tandem of layers (II) and (III).

Regarding the methods for preparing the composite materials of the invention, for the support (I), any activated alumina fulfilling the specific surface and porosity criteria can be used. Such products are commercially available. In the context of the present invention, the amount of assistant material (H), from 0.1 to 10% by weight relative to the total mass of said composite material, preferably from 5 to 7%, is such that one considers that it is in principle able to cover homogeneously exposed surface of the support (I). On the other hand, for the active phase (III), a quantity used, at least 10 and at most 40% by weight relative to the mass of the assistant material (s) forming the part (II) of said material composite, is such that it will form islands on the surface of the homogeneous layer of assistant material (11), thus covering it in a non-homogeneous manner. Without wishing to be bound by one possible theoretical interpretation of the invention, the fact that the active phase

is not sufficient to completely cover the layer of assistant material (II), may be necessary to allow the discharge of electrons trapped transiently to the outside environment. The assistant material (II) may be deposited on the support layer (I) by means known to those skilled in the art. For example, the PO43- phosphate ions as assistant material (II) may be deposited on a support (I) consisting of alumina by impregnation with solutions of ortho-phosphoric acid H3PO4, followed by the appropriate heat treatment of the support. impregnated. The deposition of boron oxide B203 can also be carried out by the impregnation method from solutions of boric acid H3803, followed by thermal conditioning. The deposition of titanium dioxide (TiO2) as assistant material (II) can be achieved both by impregnation, in accordance with the reference recommendations in the field [Aronson B.J., Blanford C.F., Stein A., Chem.

Mater., 9 (12), 2842-2851 (1997)], that using other techniques, especially by the chemical vapor phase (commonly called CVD, Cern / cal Vapor Deposition) with various volatile precursors ( titanium chloride, titanium isopropoxide, etc.), by the sol-gel technique, or possibly by the physical vapor phase (commonly called PVD, Physlcal Vapor Deposition) .The deposition of the chemical components constituting the active phase ( III) is preferably carried out also by the impregnation technique from solutions because none of the materials being precursors of the active components (III) is volatile If the active phase (III) is formed in the chemical form of oxide, the support to be impregnated is generally subjected to an appropriate thermal conditioning (drying at 110 ° -120 ° C., calcination at 250-550 ° C.) If the active phase (III) consists of an insoluble salt deposit in water, some phosphates, sulphides and chlorides can In this case, the solid support which already contains the components (I) and (II) is impregnated, in solution, with one or more substances comprising at least one cation selected from the list consisting of: A g +, N12 + , cu2 +, co2 +, Co ', Fei + and / or mn4t Containing, after the impregnation, the cationic forms chosen, the support may then be treated with a mineral acid allowing the formation of insoluble deposits (for example, orthoacidic acid). phosphoric, sulfuric, hydrochloric, etc.). The choice of the acid to be applied is dictated, on a case by case basis, by the properties of the salt to be deposited. It should be noted that the deposition of the active phase (III) in the form of oxide, except the obvious technological facilities, allows the best fixation of the component (III) on the support surface, whereas the salt deposition is, in general, less stable. Among the specific oxides that can be deposited on the surface comprising the Ag +, Ni2 +, cu2 +, co2 +, co3 +, Fe3 + and / or Mn 'cations, and without this list being exhaustive, mention may be made of Ag2O, NiO, CuO, CO3O4. , Fe2O3, MnO2. In the context of the present invention, it is conceivable to use a single assistant material (II) selected from the group consisting of: TiO2, PO43, M003, S102, B2O3, CrO42-, Cr2022, or a combination of two or several of these assistant subjects. Similarly, a single component or a combination of active phase components (III) selected from the oxides, or water insoluble salts, transition metals whose cations constitute the group Ag +, M2 +, cu2 +, c02 +, Co3 +, Fe3 + and / or Mn4 + may be used. The size of the particles of the composite material is not critical in the context of the present invention. Nevertheless, in order to promote contact with the water to be treated, particles of average diameter less than or equal to 1 cm will advantageously be used. The water treatment process according to the present invention is carried out in the presence or absence of light, no activation by light being necessary to cause the inactivation of microorganisms. The process of the present invention can therefore be carried out in closed enclosures excluding light. The water treatment process according to the present invention can also be carried out in the presence or absence of oxygen (01). According to a preferred embodiment, the invention will be implemented on water containing a normal amount of oxygen (dissolved) resulting from the contact of the water to be treated with air.

10 Examples

Preparation of Test Samples The test samples were made from pure activated alumina as a physical carrier (I) with a large surface area (250-270 m 2 / g) and significant pore (0.68 m3 / kg). The samples were divided into two series: A - with an assistant material based on phosphate anion PO43-, which is attributed a very high electron attraction capacity, and B - with titanium dioxide , TiO 2, as assistant material, which is assigned a moderately strong electron attracting capacity. The active phases (III) consisted of certain oxides of d-elements (NiO, CuO, FeOOi, MnO;). Type A assistant materials were deposited on aluminum supports by the impregnation technique using orthophosphoric acid H 2 PO 3 in aqueous solution (concentration of 35-40% by weight). Type B assistants were deposited by the CVD technique using titanium chloride TiCl; as a precursor. The deposition of the active phases was carried out from the metal salt solutions, with the appropriate thermal conditioning of the

impregnated substrates. The contents of assistant materials (PO43-, TiO2) of the prepared samples were set at the level of 5 - 7% by mass total composite material, the content of active phases (NiO, CuO, C Fe O, MnO) - at the level of 2% by mass of the composite material.

In view of peculiarities of the conditions of deposition of titanium oxides on the porous supports by the impregnation technique, the recommendations [Aronson B.J., Blanford C.F., Stein A., Chem. Mater., 9 (12), 2842-2851 (1997) have been taken into account. Table 1 summarizes the list of composite samples developed to be tested for their germicidal capabilities:

Table 1. List of Composite Samples Developed for Testing No. Chemical Composition Abbreviation 1 y-Al 2 O 3 / PO 43 -AP 2 y-Al 2 O 3 / PO 4 '/ N 2 AP-Ni 3 y-Al 2 O 3 / PO 4 O / CO 3 O 4 AP-Co 4 Al 2 O 3 / PO 43 - / Fe 2 O 3 AP-Fe 5 γ-Al 2 O 3 / PO 4 O-CuO AP-Cu 6 γ-Al 2 O 3 / PO 4 / MnO 2 AP-Mn 7 γ-Al 2 O 3 O 2 A-Ti 8 y Al 2 O 3, O / NiO A-T- Ni 9 O -Al 0 O7Co A-T -Co 10 AI, O / TiO i / Fe, O, A-T Fe 11, Al O7TiO / CuO A-Ti-Cu 12; i-Al Oz / TiO. / MnO , A-TI-Mn Preparation of test bacterial cultures The activity tests were carried out with the bacterium Escherichia colt transformed by pUC 18 to make it resistant to ampicillin (AMP) and thus make it possible to differentiate possible contaminations (supplier INRA, France). The mother cultures were prepared from E. coli by dilution 1/1000 (10 μl of stationary culture in 10 ml of liquid LB medium, supplier Fluka, France). The bacterial culture was brought into the stationary phase by incubation at 37 ° C and then diluted in 5 liters of water for testing.

Test protocol Two containers A and B of 5 liters each were connected by a Heidolph Pumpdrive 5201 SP Quick water pump (supplier - Acros Organics, France). The transfer of the test solutions between the containers A and B was carried out through a layer consisting of samples 1 - 12 (see Table 1) placed in a cylindrical glass reactor. Two continuously functioning pH meters ensured the permanent control of the acidity of the aqueous media in the A and B containers. Two magnetic stirrers were applied for the homogenization of the test solutions (see Figure 1 in the appendix). Sample collection of the liquid medium (5 ml) upstream and downstream of the active layer consisting of composite products 1 - 12 (see Table 1) was carried out every 15 minutes for one hour.

25 μl aliquots of each sample taken were plated in Petri dishes containing the nutrient gel. The seeded petri dishes were then incubated (16 h, 37 ° C), and the colonies counted.

The operating parameters of the test facility are listed in Table 2.

Table 2 Operating parameters of the test facility Parameter Measurement Value Bed mass of the composite product to be tested g 50 Average concentration of the test solutions CFU / ml Time of contact of the liquid medium to be treated s 25 with the active bed Test duration min 60 Interval between consecutive samples min 15 Volumes taken live upstream and in ml 5 downstream of the active bed Volumes transferred to Petri dishes PI 25 for incubation Temperature of the liquid medium to be treated ° C 20 Test results 10 The results of the test samples 1 - 12 (see Table 1) are shown in Table 3. The controls are samples (1) and (7), where only the support phase (I) and your assistant phase (II) are present . Efficiency is indicated as a percentage, indicating the decrease in the number of bacterial colonies observed between samples before and after passage through the active layer. The corrected efficiency is the difference between the total effectiveness of a composite and that of the control sample (where the contaminated water is not in contact with any composite material). It therefore represents the efficiency gain due to the active phase (In), itself, as well as to interaction between the active phase (III) and the assistant material (II).

Table 3. Germicidal efficacy of the tested samples 1O It should be noted that the control samples (1) and (7), which contain an assistant material (II), but do not include an active phase (III) and are therefore not materials Three-layer composites according to the teaching of the present invention exhibit limited antibacterial activity. Sample and its No. according to Table 1 Treatment Efficacy Corrected Efficacy% AI-P (1) 12 AI-Ti (7) 11 AI-P-Ni (2) 34 22 AI-P-Co (3) 60 48 AI -P-Fe (4) 53 Al-P-Cu (5) 48 36 Al-P-Mn (6) 50 38 Al-Ti-Ni (8) Al-Ti-Co (9) 28 16 Al In addition, aging tests (of durability of action over time) have been carried out in the course of time. achieved by leaving the active beds in contact with bacterial solutions for 14 days (Table 4). For the 14-day test, a new bacterial culture was prepared under conditions similar to those of the baseline test.

Table 4. Efficacy of the products after prolonged contact with the bacterial culture Sample and Efficacy Sound efficiency No. according to the correction corrected in table 2 time = Oj time = 14j AI-P-Cu (5) 36 39 AI-P-Mn (5) 6) 38 16 Al-Ti-Cu (11) 8 8 Al-Ti-Mn (12) 15 0

Claims (6)

REVENDICATIONS1. Use of a composite material for the purification of waters contaminated by microorganisms, said material comprising the following components (I), (II) and (III): (I) at least one type of alumina as porous support, redit porous support having a surface area of at least 250 m2 / g and a porosity of at least 0.65 m3 / kg; (II) at least one assistant material deposited on the support (I) and selected from the group consisting of: titanium oxide TiO2, phosphate compounds comprising anions PO43, MoO3, 902, B203, compounds containing chromate ions CrO42-, compounds containing dichromate ions Cr2022-; (III) at least one active phase deposited on the assistant material layer (II), said active phase comprising one or more oxides, or water insoluble salts, transition metals comprising cations selected from the group consisting of: Ag +, Ni2 +, ce *, co2 +, co3 +, Fe3 +, Mn4 +; in which the porous support (s) forming part (I) constitutes (s) from 80 to 99.8% by weight relative to the total mass of said composite material, the material (s) assistant (s) forming the part (II) is (are) from 0.1 to 10% by weight relative to the total mass of said composite material, and the (or) phase (s) active (s) forming part (III) constitutes (s) from 10 to 40% by weight relative to the mass of the (or) assistant material (s) forming part (II) of said composite material. 2. The use as claimed in claim 1, wherein the assistant material (s) forming part (II) is (are) from 5.0 to 7.0% by weight relative to the mass. total of said composite material. 3. Use according to claim 1 or 2, wherein the composite material is contained in a cartridge, column or other enclosure provided with an inlet of the water to be treated and an outlet of the treated water. 4. Use according to any one of the preceding claims, wherein the contacting of the water contaminated by microorganisms with the composite material is protected from light. 5. Use according to claim 3 or 4, wherein the treatment of the contaminated water is carried out by letting the water come into contact with the composite material contained in a cartridge, column or other enclosure by means of a pump. 6. Use according to any one of the preceding claims, for the purification of drinking water, swimming pool water or thermal springs, or spring water or river.