«Mahalliy xomashyolar va ikkilamchi resurslar asosida innovatsion texnologiyalar»

48 
TREATMENT OF INDUSTRIAL WASTEWATERS FROM IONS 
HEAVY METALS BY ELECTROCHEMICAL METHOD 
D. A. Mukhammadievа., D. A. Khadjibaev., F.I.Erkabaev 
Uzbekistan, Tashkent, Institute of General and inorganic chemistry of the 
Academy of Sciences of Uzbekistan 
Treatment of industrial wastewaters by the reagent method is the most 
effective. But these methods also have a number of significant disadvantages: they 
are characterized by high rates of reagent consumption, are accompanied by the 
formation of large amounts of sludge precipitations and require significant material 
costs for measures to protect process equipment from corrosion as they are carried 
out in a highly acidic environment. Methods of electrochemical treatment of 
chromate-containing wastewater and solutions, in turn, are divided into cathode 
reduction, electrodialysis and electrocoagulation. At the same time, it should be noted 
that cathode efficiency is very low (16-17%) during the electrochemical reduction of 
chromium ions, therefore the recommended method for wastewater treatment is 
advantageously carried out in remote areas formation of wastewater up to 50 m
3
/h, 
where it is difficult to regularly deliver chemical reagents. During the recovery 
process, most of the electricity is spent on undesirable processes such as ion 
polarization, deposition of some impurities in the solution, and electrolyte resistance. 
It was found that the rate of electrochemical dissolution of anodes increases with 
increasing current density and with pH changes in the direction of increasing acidity. 
Absolute values of the anode dissolution rate range from 1 to 10 mg/min.dm
2
. 
Experiments were conducted to study the effect of polyatomic alcohols on the 
reduction of chromium ions as described. The results of studies to determine the 
effect of various polyatomic alcohols, such as glycerol, xylitol, sorbitol on the 
reduction of chromium (VI) ions showed that of the above polyatomic alcohols, 
glycerol is the best additive for increasing the degree of purification during the 
electrochemical reduction of hexavalent chromium ions.
The aim of this study is to increase the cathode efficiency during electrolysis of 
waste solutions in the presence of polyatomic alcohols and to determine the optimal 
process conditions. 
The object of research were used chromate-containing wastewater from the 
chrome plating galvanic cell and polyatomic alcohols. A photocolorimetric method 
was used to determine the content of chromium ions in solutions. 
We performed electrolysis under the following conditions to increase the 
cathode efficiency and establish optimal conditions for the electrochemical reduction 
of hexavalent chromium in a standard electrolyte: the volume of the electrolyte is 200 
ml, the concentration of hexavalent chromium ions is 0.1 g/l, the cathode is graphite, 
and the time is 1.5 hours.

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49 
The concentration of chromium (VI) and chromium(III) ions before and after 
electrolysis was determined using photocolorimeter KFK-3. To determine the optimal 
conditions for the electrochemical reduction of hexavalent chromium were performed 
the experiments at different cathode current densities (Tab.1). 
Тable 1 
Effect of current density on cathode efficiency V
solution
= 200 мл, С
Cr
= 0,1 г/л, 
cathode – graphite, τ=1.5 hours 
№ 
Current density, А/dм
2 
Efficiency of cathode, % 
1 
0 
0 
2 
2 
0,3 
3 
4 
0,8 
4 
6 
2,4 
5 
7 
6.2 
6 
8 
14.1 
7 
10 
17.3 
8