RU2528381C1 - Method of producing liquid agent for water treatment - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method includes electrolysis of aqueous sodium chloride solution in an electrolysis cell with unseparated cathode and anode spaces and is characterised by that electrolysis is carried out using an anode made of aluminium or aluminium alloys.

EFFECT: use of the disclosed method broadens functional capabilities of the obtained agent.

2 cl, 2 ex

Description

The invention relates to the field of electrochemistry, and in particular to electrochemical methods for producing liquid means for water purification.

Known electrochemical methods for producing products intended for the purification of water from pollution by electrolysis of aqueous solutions of alkali metal chlorides.

So, there are known methods for producing an aqueous solution of sodium hypochlorite, widely used for disinfecting water, which is carried out by electrolysis of an aqueous solution of sodium chloride in an electrolytic cell with undivided cathodic and anode spaces.

In these methods, anodes made from materials not subject to anodic dissolution are used. In practice, composite anodes are most often used, consisting of a titanium base onto which an active layer is deposited, in particular ruthenium dioxide (OPT anodes).

A known method of obtaining a liquid agent for water purification - a solution of sodium hypochlorite [RU 2153540], selected as the closest analogue.

This method involves the electrolysis of an aqueous solution of sodium chloride in an electrolytic cell with undivided cathode and anode spaces, in which an OPT anode is used. In this case, the method under consideration provides measures to reduce the anodic dissolution of the material of the specified electrode, such as changing the polarity of the current on the electrodes during electrolysis and introducing an additive in the electrolyte solution that inhibits the destruction of the active electrode coating.

The product obtained by this method has the property of disinfecting water, but does not have the ability to coagulate contaminants present in the water.

The objective of the invention is to expand the functionality obtained by the present method means for water purification.

The essence of the invention lies in the fact that in the method for producing a liquid means for water purification, comprising electrolysis of an aqueous solution of sodium chloride in an electrolyzer with undivided cathode and anode spaces, according to the invention, the electrolysis is carried out using an anode made of aluminum or aluminum alloys.

In the particular case of the invention, electrolysis is carried out using a cathode made of aluminum or aluminum alloys.

The fundamental difference of the claimed invention is that when carrying out the electrolysis of an aqueous solution of sodium chloride in an electrolyzer with undivided cathode and anode spaces, an anode made of aluminum or its alloys is used.

In this case, cathodes made, in particular, of steel, titanium, graphite, OPT cathodes, which are traditionally used in the electrolysis of an aqueous solution of sodium chloride in an electrolyzer with undivided anode and cathode spaces, can be used.

As a result of electrolysis, a liquid product is obtained, which, as shown by experimental studies, has the ability to coagulate contaminants present in water, such as fats, oils, oil products, and also has a disinfecting effect against microbial contaminants of water.

The specified coagulating effect is due to the presence in the resulting liquid agent of compounds formed during the anodic dissolution of aluminum during the electrolysis of an aqueous solution of sodium chloride, such as aluminum hydroxide and aluminum oxychlorides of different basicities, which are good coagulants. The disinfecting properties of the resulting product are imparted to it by oxygen-containing chlorine compounds, in particular sodium hypochlorite.

The concentration of sodium chloride in the electrolyte in the inventive method can lie within wide limits, while the maximum concentration corresponds to the value of the limiting solubility of sodium chloride in water. In practice, an aqueous solution of sodium chloride with a concentration of 5-150 g / l is predominantly used.

Thus, the technical result achieved by the implementation of the claimed invention is the expansion of the functionality obtained by the present method means for purifying water.

An advantage of the proposed method is also that its implementation requires relatively low currents and voltages, which ensures the efficiency of the method.

In the case when the electrolysis is carried out using a cathode made of aluminum or aluminum alloys, it is possible to carry out the operation of reversing the current on the electrodes, which allows to increase the uniformity of electrode wear and increase the life of the electrodes as sources of aluminum ions.

The method is as follows.

To obtain the target product, the electrolysis of an aqueous solution of sodium chloride is carried out in an electrolyzer with undivided anodic and cathodic spaces. An anode made of aluminum or its alloys is used, and an ORT cathode, a cathode made of steel, titanium, graphite or aluminum of its alloys are used as a cathode.

The electrolysis is carried out in a batch cell or in a continuous flow cell.

As an electrolyte in practice, an aqueous solution of sodium chloride with a concentration of 5-150 g / l is used.

The electrolysis process is carried out at a current value of 5-10 A and a voltage value of 3-5 V.

As a result of electrolysis, a liquid agent is obtained, which is an aqueous solution containing a mixture of aluminum compounds formed as a result of electrochemical reactions, such as aluminum hydroxide, aluminum oxychlorides of different basicities, oxygen-containing chlorine compounds, such as sodium hypochlorite, as well as residues of unreacted sodium chloride.

The specified tool has a coagulating and disinfecting effect and can be used to purify drinking and waste water.

As studies have shown, the tool obtained by the present method retains its cleansing properties for several days.

To enhance the disinfecting and coagulating effect of the liquid agent, an additive of sodium hypochlorite can be introduced into the initial electrolyte or an additive of sodium hypochlorite can be introduced into the solution obtained after electrolysis. The dose of added hypochlorite is selected depending on the degree of contamination of the treated water and in practice is a value that ensures the total sodium hypochlorite content in the liquid is from 0.1 to 15 mg / l.

The inventive method can be carried out using a compact electrolysis installation, located in the area of work on water treatment.

In the inventive method, sodium chloride dissolved in purified water can be used as an electrolyte. In this case, the formation of funds obtained by the claimed method, water is purified during the electrolysis process.

If a cathode made of aluminum or its alloys is used in the claimed method, the current can be reversed on the electrodes during electrolysis with a periodicity of 15 minutes to 24 hours.

The possibility of implementing the method is shown in examples of specific performance.

Example 1

Conducted electrolysis of an aqueous solution of sodium chloride with a concentration of 20 g / L. The process was carried out in a continuous flow electrolyzer with undivided anodic and cathodic spaces.

Plates having linear dimensions of 10 × 10 cm made of aluminum were used as the anode and cathode. The electrolysis process was carried out at a current of 3 A and at a voltage of 5 V for 48 hours.

During electrolysis, current was reversed at the electrodes with a frequency of 1 hour.

Using the liquid product obtained as a result of electrolysis, wastewater was purified from oil products. The tool was used in an amount of 10 g per 100 l of purified water. As a result of purification, the oil content in water is up to 0.01 mg / l.

Example 2

Conducted electrolysis of an aqueous solution of sodium chloride with a concentration of 30 g / L. The process was carried out in a continuous flow electrolyzer with undivided anodic and cathodic spaces.

Plates having linear dimensions of 10 × 10 cm made of aluminum were used as the anode and cathode. The electrolysis process was carried out at a current of 2A and at a voltage of 3V for 48 hours.

During electrolysis, current was reversed at the electrodes with a frequency of 1 hour.

After the end of electrolysis, sodium hypochlorite was added to the liquid product obtained as a result of electrolysis in an amount ensuring its concentration in the agent of 1 mg / L.

Using the liquid product obtained as a result of electrolysis, the wastewater was purified from mechanical and microbial contaminants. The tool was used in an amount of 10 g per 100 l of purified water. As a result of purification, water was obtained with acceptable indicators for turbidity and the degree of microbial contamination.

Claims (2)

1. A method of obtaining a liquid means for water purification, comprising electrolysis of an aqueous solution of sodium chloride in an electrolytic cell with undivided cathode and anode spaces, characterized in that the electrolysis is carried out using an anode made of aluminum or aluminum alloys. 2. The method according to claim 1, characterized in that the electrolysis is carried out using a cathode made of aluminum or aluminum alloys.