OA11208A - Product for the bactericidal treatment of fluids - Google Patents

Abstract

The invention concerns a product for the bactericidal treatment of fluids, characterised in that it consists almost exclusively of a porous support with inner and outer specific surface determined according to needs, for instance activated carbon and of a metal, for instance silver, covering said specific surface in a thin layer substantially uniform over the whole specific surface, said metal being bound to the porous support by strong bonds such as covalent bonds. The product is obtainable in a cold plasma reactor.

Description

01 1 2C8

Produced for the bactericidal treatment of fluids.

Bactericidal water treatment products consisting of activated carbon impregnated with silver in the form of salts obtained by immersion of charbondans in a solution of silver nitrates are known.

Such a product has disadvantages: release of nitrates and salting out of money. Indeed, impré-gnation does not allow to obtain a sufficient hooking between money and carbon and the release is inevitable. The use of this product in the field of potable water is therefore limited by the fact that the concentration of dissolved silver is limited to 0.01 ppm.

In the laboratory, it is known to metallize charcoal with silver metal, hot, in a cavity where a very high vacuum is performed. In this room, the silver is evaporated to be able to penetrate the coal. This process allows a good diffusion of ar-gent in the pores of the coal but the bad hook-chage of the money with the carbon entails a relargage of dissolved money. The internal structure of activated charcoal is completely upset and presents important pollution. This product obtained is more friable and gets water passing through. This application does not allow to obtain a stable product and the manufacture of this product is very difficult because the vacuum is long to obtain, so not industrializable. 2 011208

The object of the present invention is to provide a product with bactericidal and bacteriostatic properties after much greater treatment than the knownproducts and practically free of any pollution. The bactericidal power depends on the useful surface of the product, which must have a very high Active over-face usable.

The product for the bactericidal treatment according to the invention is characterized in that it consists pra-tically exclusively on the one hand, a po-reux support of specific external and internal specific surface determined according to requirements and, on the other hand, a metal covering said specific surface thickness of substantially uniform thickness on any specific surface, this metal being bonded to the po-reux support by strong bonds covalent-type links.

Since the metal is very strongly bonded to the porous body, it is unlikely to detach and may be present as a very thin film of the order of 5 to 10 Å. The product is very pure.

The porous support may be inorganic or organic, in particular synthetic. It can be constituted for example of activated charcoal, pumice stone, rock, resinsynthetic, etc.

The product has a remanence, that is to say a preservation po-de, inhibiting any ul-ture contamination of the treated fluid. 3 011208

The metal may be for example silver pure metal, or copper, nickel or any other metal having the desired effects.

Such a product is obtained by injecting the metal, in particular silver, in atomic form into a porous body, for example activated charcoal powder immersed in a plasma.

Two examples of obtaining a product according to the inven-tion, consisting of activated carbon and silver, will be described below.

Example 1

The activated carbon, in powder form, was treated in a capacitive capacitance (13.56 MHz) radiofrequency discharge in a reactor. The configuration was chosen so as to obtain a high self-biasing voltage across the space charge sheath.

The gas used in the reactor is argon, a de-bit of seem corresponding to a pressure of 1 Pa and the electric power RF coupled to the gas is 400 W.This coupling is carried out through an adapter box As the space charge sheath has a width of about 1.5 cm, the intensity of the electric field in the sheath is 5.3101 Vm-1. The density of the plasma under these conditions is estimated at 10'10 cm-3. 011208

The activated carbon powders are immersed in the plasma where they are therefore subjected to a continuous bombardment of ions. This bombardment has the effect of heating the coal within the plasma itself. The flux of ions reaching the surface of the coal powders is estimated at 7.3 1012 ions. The silver is injected atomically into the gas phase. Plasma has the effect of creating anchor sites for silver atoms. This anchoring thus results in strong C-Ag atomic bonds of the type of covalent bonds. Thus, the aggregates of ar-gent observed by scanning electron microscope are firmly bound to the coal support and can not be "salted out".

The physico-chemical analyzes carried out on the coal powders thus treated show a proportion of silver of 57% of the external surface of the coal. As for the proportion of silver diffusing in the volume of the carbon, through the pores of the powders, it can be modulated by acting on the physical parameters of the discharge. In addition, the fluorescence X analyzes reveal a very negligible level of pollution, which is non-zero compared to that of powders treated by chemical impregnation processes. This result is due to the fact that the coal powders are subjected to a gaseous environment control, in the example considered ungaz inert, serving only vector for metallization. As a result, all pollution is reduced to a minimum. 5 011208

It should also be noted that this process is in-built: it does not require post-treatment, for example thermal. The powders are treated once only for a definite period of time, for example 20 minutes.

Example II

Argon is injected through the reactor base and pom-page from the top of the reactor. Activated charcoal, virgin from calcined coconut, and pure silver N6 (that is to say having a purity equal to 99.9999%) are placed in powder form in a rotary drum allowing these powders to bathe in a plasma remote from the pumping valve. An electric field of high intensity is created in the reactor to ensure levitation of the powders in the plasma. Under these conditions, the plasma density is about 10 "cm -1 and the electron and ionic temperatures are 3 eV, respectively. and 0.03eV.

The activated carbon granules are immersed in the plasma and, consequently, subjected to continuous bombardment of silver ions. This bombardment has the effect of raising the temperature of the coal to about 900 ° C.

The working parameters are as follows: Argon flow: approx. 9 SCCM (cm "3 per minute) 011208

Working pressure: 2 Pa

Plasma excitation power: 100 W 5 Self-biasing voltage: 1.2.105 Vm'1

Deposit time: 25 minutes

Thickness deposited: 5 to 10 A. The deposited thickness is therefore nanometric. It responds to an internal density of Ag greater than 4 corres

Claims (7)

Claims. 1. Product for the bactericidal treatment of fluids, consisting of a porous support coated with a metal, characterized in that the metal covers the specific inner and outer surfaces of the porous body in a layer of substantially uniform thickness on any specific surface, c that is to say, also say the internal surface of the pores, the metal being bonded to the porous support by strong bonds of the covalent bond type. 2. Product according to claim 1, characterized in that the metal is silver pure metal (Ag °), copper or nickel. 3. Product according to claim 1 or 2, characterized in that the porous support is made of activated carbon. 4. Product according to one of claims 1 to 3, characterized in that it has a remanence inhibiting any subsequent contamination of the treated fluid. 5. Process for obtaining the product according to one of Claims 1 to 4 consisting in depositing a thin metal coating on a porous support by the treatment of the porous support in a cold plasma reactor by immersing the porous body in an inert gas plasma. , characterized in that the metal is injected formeatomically in the gaseous plasma by subjecting the porous carrier to an electric field greater than 104 Vm -1. 011208 6. A process according to claim 5, characterized in that the porous carrier is treated in a reactor having a space charge sheath of a width equal to about 1.5 cm. 7. Process according to claim 5, characterized in that the inert gas is argon.