Interaction of certain inorganic and organic compounds with activated carbon and the effect of such interaction on open circuit potential of activated carbon were studied. Open

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Electrochemical methods of redox potential measurements of aqueous solutions and biological media with a platinum electrode were analyzed. Probable reasons of the irreproducibility of open circuit potential measurements were considered. We suggested that accumulation of mixed oxides on the surface of platinum after each measurement may lead to potential shifts of the platinum electrode and therefore to a systematic error in redox potential measurements. Preliminary electrochemical treatment of platinum electrodes by cyclic impulses of externally applied potential was developed from the above considerations. The proposed method of measurement was tested in aqueous solutions of inorganic salts, blood, plasma and blood serum. Time dependencies of platinum electrode potential in the presence of inorganic salts and biological liquids were analyzed. We suggested defining the redox potentials of the tested solutions as potential of the platinum electrode after 10 - 30 min.

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The effect of various surfactants on the physicochemical parameters (particle size and zeta poten tial) of the disperse phase of copper, nickel, and zinc hydroxides at concentrations of cationic, anionic, and nonionic surfactants of 2, 10, 50, and 100 mg/L at pH of 9.5-10.5 was studied. The efficiency of their elec troflotation extraction into a flotation froth was determined in a laboratory electroflotation module with anti wear oxide electrodes with efficiency of higher than 95% (initial concentration 50 mg/L, in the form of flo tation sludge, processing time no more than 30 min, current density 0.2 A/L).

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An analysis of electrochemical degradation of organic compounds, in particular EDTA is presented. The influence of the nature of the anode and the nature of the oxidizing agent on the degradation of organic compounds is showed. Anode materials are classified based on their oxidizing power in an acidic environment. It is shown that direct oxidation of EDTA effectively occurs on the anodes Ti/PbO2 and Ti/SnO2. In the presence of NaCl EDTA is effectively oxidized on the anodes Ti/RuO2-TiO2 by the formation of hypochlorite. Examples of destruction of EDTA under the influence of ultraviolet radiation are given. Degradation products (nitro acetic acid, amino diacetic acid) form CO2, H2O, NO3-ions at full decomposition. It is noted that the neutralization of wastewater containing copper and EDTA is carried out in two stages: destruction of EDTA and the extraction of copper hydroxide. The extraction of copper ions from the system H2O-Cu2+-EDTA-electrolyte with different ratios of metal-ligand is investigated. The effect of EDTA concentration on the flotation process for extracting copper hydroxide is analyzed. The kinetics of flotation of copper extraction in the presence of two complexing agents - NH3 and EDTA is considered. The presented results allow to assess the degree of extraction of copper from solution copper-EDTA at different coal sorbents and resins. It is shown that the use of anion exchange resin Purolite A500 and anion exchange resin AB-17-8 is effective when the copper concentration is 25 mg/l. It is established that the sorption process is slow: stationary values are set for several hours. The degree of extraction of EDTA reaches 30-40%. When the ratio of copper-EDTA 1:1.0-1.5 it is possible to reach flotation copper extraction up to 80%. Under additional sorption treatment the extraction degree reaches to 99%. It is shown that the use of highly dispersed carbon materials (coal powders) allows extracting ligands from wastewater, increasing the efficiency of copper hydroxides electroflotation.