RU2288179C1 - Method of disinfecting water with hydrogen peroxide in presence of heterogeneous catalyst - Google Patents

Abstract

FIELD: water treatment processes.

SUBSTANCE: invention relates to methods for disinfection of water with hydrogen peroxide in presence of heterogeneous catalyst and can be used to control microorganisms in drinking and reuse water supply systems as well as when treating water for manufacture of drinks and food products and when maintaining purity of fish farming-destination reservoirs. Disinfection process with hydrogen peroxide is, in particular, conducted in presence of carbon steel in the form of grid, cuttings, wire fragments, rings, or particles, which is preliminarily treated for 1-2 h according to one of the following techniques: firing at 500-550°C, contacting with concentrated nitric acid at 10-15°C, and simulated rusting in wet air atmosphere at 29-40°C. In a specific case, pretreated carbon steel particles 1-5 mm in size are mixed with binder (cement powder or clay) in weight proportion 1:2, supplemented by water to pasty state, partially dried, and molded into pellet-shaped or granulated catalyst.

EFFECT: simplified and reduced in price catalyst preparation procedure.

2 cl, 1 tbl, 9 ex

Description

The invention relates to methods of disinfecting water with hydrogen peroxide in the presence of a heterogeneous catalyst and can be used to destroy unwanted microorganisms in drinking and recycled water supply systems, when preparing water in the technologies for preparing drinks and food products, and also to maintain proper chemical and microbiological quality in fishery reservoirs destination.

It is known that hydrogen peroxide is widely used in water treatment practice as an active and environmentally friendly oxidizing agent, which not only does not impair the quality of the water treated by it, but even saturates it with oxygen - the product of its own decomposition by the reaction: 2Н ₂ О ₂ → 2Н ₂ О + О ₂ ↑ (Selyukov A.V., Skurlatov Yu.I., Kozlov Yu.P. The use of hydrogen peroxide in wastewater treatment technology. Water supply and san. Technique, 1999, No. 12, p.25-27).

It is also known that hydrogen peroxide has bactericidal properties, but less than that of ozone and chlorine. Therefore, in order to increase the bactericidal activity of hydrogen peroxide, it is combined with ions of certain metals (homogeneous catalysts) or particles of some water-insoluble compounds (heterogeneous catalysts). A list of some suitable catalysts is given in the monograph: W. Schamb, C. Weatherfield, R. Ventvers. Hydrogen peroxide. M .: Publishing house of foreign countries. literature, 1958). Among the former, for example, iron, copper, and silver ions are noted; among the latter, manganese dioxide, iron oxide, etc.

Thus, a known method of disinfecting water by the combined action of hydrogen peroxide and 0.05-1.0 mg / l of copper ions. In this case, copper ions is a homogeneous catalyst for the decomposition of hydrogen peroxide (Savluk I.P. et al. Antimicrobial properties of copper. Chemistry and technology of water, 1986, v. 8, No. 6, pp. 65-67). Copper ions are obtained by electrolysis, which is an energy-consuming process, or by chemical dissolution of copper-containing salts. Meanwhile, given the large volumes of the above categories of water, respectively, large quantities of catalysts are required. It is also obvious that for the manufacture of catalysts it is desirable to use affordable and relatively inexpensive materials.

A known method of disinfection of drinking water, including its treatment with hydrogen peroxide and a heterogeneous catalyst. In this case, a heterogeneous catalyst is obtained by mixing powdered granules of hopcalite with particles of finely divided metallic silver, then adding water to obtain a paste, drying it and molding it in the form of tablets. These tablets are introduced into water in an amount of 0.1-1 mg / l (RU 2213705, 2003). This method is the closest analogue of the proposed invention. This method has a number of disadvantages. As you know, hopcalite is a catalyst based on manganese dioxide, copper oxide and, in part, silver, used in the form of granules, mainly in the oxidation of carbon monoxide CO. To obtain a heterogeneous catalyst according to RU 2213705, it is necessary to grind hopcalite and introduce expensive, finely divided metallic silver into it, which is not always an economically viable measure.

The objective of the invention was to simplify and cheapen the technology for the preparation of a heterogeneous catalyst, which contributes to a significant increase in the bactericidal activity of hydrogen peroxide when used together in the process of water disinfection.

The problem is solved in that the method of disinfecting water with hydrogen peroxide in the presence of a heterogeneous catalyst differs from the closest analogue in that carbon steel in the form of a mesh, shavings, pieces of wire, rings or particles, which is preliminarily within 1-2 hours, is used as a catalyst treated in accordance with one of the methods: calcination at 500-550 ° C, contacting with concentrated nitric acid at a temperature of 10-15 ° C, artificial rusting in an atmosphere of moist air At a temperature of 20-40 ° C.

In the particular case, pre-treated particles of carbon steel 1-5 mm in size are mixed with a binder, for example cement powder or clay, in a mass ratio of 1: 2, respectively, water is added to a paste-like state, dried and the catalyst is formed into tablets or granules.

The starting material for the preparation of the catalyst is ordinary, widely available carbon steel, for example, Art. 3. As you know, carbon steel contains iron (97-99.5%), carbon (<2.14%), as well as deoxidizing elements - Mn, Si, Al, is a solid solution of carbon in iron, including iron carbide and these deoxidizing elements. To obtain a catalyst, steel (in the form of rings, wire segments, shavings, nets, particles of various sizes) is subjected to preliminary treatment in an aqueous and air medium (artificial rusting), or in an air medium (calcination), or in a solution of a strong oxidizing agent - concentrated nitric acid. In this case, an water-insoluble oxide film containing iron with a variable valency (oxidation state) is formed on the surface of the alloy, and the alloy itself under the film surface remains sufficiently hard and plastic.

A feature of the proposed technical solution is that the heterogeneous catalyst essentially contains a chemical composition comprising iron of variable valency (or with a different oxidation state: Fe ⁰ , Fe ²⁺ and Fe ³⁺ , which corresponds, respectively, to free iron , iron oxide (II) FeO and iron oxide (III) Fe ₂ O ₃ ), as well as C, Fe ₃ C, Mn, Si and Al. We found that the combination of the proposed complex catalyst with hydrogen peroxide in water accelerates the process of its decomposition, the intermediate stage of which is the formation of OH radicals that are overactive in the bactericidal and oxidative ratio. The latter are the "killers" of bacteria, if any, are present in the water. Subsequently, OH radicals spontaneously turn into water molecules.

Being present together in a mixed type catalyst, such as pre-treated carbon steel, iron in various oxidation states and other ingredients contribute not to additively deeper decomposition of H ₂ O ₂ molecules, and therefore to the appearance of a larger number of OH bactericidal radicals and the destruction of a greater number of microorganisms. An additional positive aspect of the use of the recommended catalyst is the acceleration of the process of releasing water from residual amounts of hydrogen peroxide, which is important in the sanitary and environmental respect.

Mixing the treated particles with a binder allows the catalyst to be formed in a convenient form - in the form of cylinders, tablets or granules, which are conveniently stored until use, while their activity remains almost unchanged during storage.

Namely, the above set of essential features of the proposed invention provides the intended technical result.

The combined treatment of water with hydrogen peroxide and the proposed catalyst an order of magnitude or more (compared to using only hydrogen peroxide or only steel) increases the depth of water disinfection.

The following are examples of the implementation of the proposed method.

Example 1

Natural water (20 ° C) contained 10 ⁴ specimens of E. coli (E. coli) microorganisms in 1 liter. Hydrogen peroxide was introduced into it at the rate of 0.8 g / l. After 1 hour (with constant stirring) in water, the number of surviving microorganisms was determined, as well as the concentration of hydrogen peroxide. The test results are presented in the table.

Example 2

Temperature, water contamination - according to example 1. Hydrogen peroxide was not introduced. Difference: a heterogeneous catalyst was introduced into the reactor, consisting of pieces of steel wire (steel St.3) with sizes of 1-2 mm. Previously, the wire was degreased and dried. The contact time of the catalyst layer with disinfected water was 1 hour. The test results are presented in the table.

Example 3

Temperature, water contamination and the content of hydrogen peroxide in it - according to example 1. The catalyst was introduced into the reactor, its characteristics and test conditions according to example 2. The test results are presented in the table.

Example 4

The temperature, water contamination and the content of hydrogen peroxide in it, according to Example 1. A catalyst in the form of rings from St. 3 (outer diameter 30 mm, inner diameter 10 mm, thickness 2 mm) was preliminarily calcined at 500-550 ° C for 1 hours. The test results are presented in the table.

Example 5

The temperature, water contamination and the content of hydrogen peroxide in it — according to Example 1. The catalyst — steel wire shavings — was previously in contact with concentrated nitric acid at a temperature of 12 ° C for 1 hour. Next, the catalyst was washed with distilled water, dried at room temperature, and then loaded into the reactor. The test conditions are similar to example 2. The test results are presented in the table.

Example 6

Temperature, water infestation and the content of hydrogen peroxide in it, according to Example 1. The catalyst is a steel wire mesh (Art. 3), it was pre-immersed in water and kept moist in an atmosphere of moist air at a temperature of 40 ° C for 1 hour until evenly coated with rust. Rust contains iron in oxidation states +2 and +3. After that, the grid was placed in the reactor. The contact time of the catalyst with water containing hydrogen peroxide was 1 hour. The test results are presented in the table.

Example 7

The temperature, water contamination and the content of hydrogen peroxide in it according to example 1. As a catalyst, particles of carbon steel St.3 1-2 mm in size were used, which were in contact with humid atmospheric air for 2 hours at a temperature of 20 ° C (for artificial rust) and placed in a reactor in an amount of 2 mg / L. Contaminated water was introduced into the reactor, into which 0.8 g / L of hydrogen peroxide was introduced. The contact time of water with the catalyst (with constant stirring) is 1 hour. The test results are presented in the table.

Example 8

The temperature, water contamination and the content of hydrogen peroxide in it are according to Example 1. Previously, Part 3 particles prepared according to Example 7 were mixed with cement powder in a mass ratio of 1: 2, respectively. Then the mixture was moistened and, after solidification and crushing, a catalyst fraction with a particle size of 2-5 mm was loaded into the reactor. Test conditions - according to example 2. The experimental results are presented in the table.

Example 9

The temperature, water contamination and the content of hydrogen peroxide in it are according to Example 1. Previously, Part 3 particles prepared according to Example 7 were mixed with clay powder of the Chasov-Yarsky deposit in a mass ratio of 1: 2, respectively. Then the mixture was moistened, molded in the form of cylinders, then dried at a temperature of 110-115 ° C for 1 hour, crushed and a catalyst fraction with particle sizes of 1-3 mm was loaded into the reactor. The test conditions are similar to example 2. The experimental results are presented in the table.

As follows from the table data, the recommended catalysts provide a sharp increase in the bactericidal activity of hydrogen peroxide, the number of microorganisms in treated water is reduced by an order of magnitude or more; at the same time, the content of residual peroxide in water decreases.

METHOD FOR DISINFECTING WATER WITH HYDROGEN PEROXIDE IN THE PRESENCE OF A HETEROGENEOUS CATALYST
Table Example Bactericidal drug Content in water after 1 hour * microorganisms, individuals / l residual hydrogen peroxide, g / l one Hydrogen peroxide (0.8 g / l) 1100 0.6 2 Steel 3.1-2 mm (pieces of wire St3) 7 · 10 ³ - 3 H ₂ O ₂ (0.8 g / l) + pieces of wire (St3) 400 0.15 four H ₂ O ₂ . (0.8 g / l) + rings from Art. 3, calcined (Art. 3) 220 0,07 5 H ₂ O ₂ (0.8 g / l), shavings from Art. ₃ , treated with NHO ₃ 190 0.05 6 H ₂ O ₂ (0.8 g / l) + mesh from Art. 3, artificially rusted 110 0.04 7 H ₂ O ₂ (0.8 g / l) + particles with rust 70 0.01 8 Н ₂ O ₂ (0.8 g / l) + particles with rust mixed with cement (1: 2) 74 0.02 9 H ₂ O ₂ (0.8 g / l) + particles with rust mixed with clay (1: 2) 80 0.02 ^* The initial number of microorganisms 10 ⁴ individuals / l

Claims (2)

1. The method of disinfecting water with hydrogen peroxide in the presence of a heterogeneous catalyst, characterized in that the catalyst is carbon steel in the form of a mesh, shavings, pieces of wire, rings or particles, which is pre-treated for 1-2 hours in accordance with one of the methods : calcination at 500-550 ° C, contacting with concentrated nitric acid at a temperature of 10-15 ° C, artificial rusting in an atmosphere of moist air at a temperature of 20-40 ° C. 2. The method according to claim 1, characterized in that the pre-treated particles of carbon steel 1-5 mm in size are mixed with a binder, for example cement powder or clay, in a mass ratio of 1: 2, respectively, water is added to a paste-like state, dried and the catalyst is molded in the form of tablets or granules.