The dissertation is devoted to the development of reliable and effective methods for extracting and concentrating heavy metal solutions.
Ion exchange is one of the methods that is successfully used in the industry for the removal of heavy metals, including copper ions.
It was found that the use of strong acidic cation exchanger KU-2-8 and weakly acid cationite DOWEX MAС-3 provides both water softening and copper ion extraction at its initial concentrations of 30 and 1 mg/dm3. The degree of copper extraction for ion exchangers in 6 dm3 of water was 99,6 – 100,0 %. Regeneration of ion exchangers was carried out with solutions of hydrochloric acid, the degree of desorption was 100 %.
It was established that the capacity of ion exchangers on copper ions decreases with decreasing of its concentration in the initial solution. The capacity of the DOWEX MAС-3 cationite at a copper concentration of 2 mg/dm3 reaches 30 mg-eq/dm3, and at 1 mg/dm3 – 17 mg-eq/dm3.
The conditions of effective sorption of copper and lead ions from dilute solutions was estimated. Satisfactory results on the concentration of strongly diluted solutions of copper ions can be obtained at a concentration of copper ions up to 1 μkg/dm3. At the same time, the concentration of copper ions in regenerative solutions increases to 1 – 20 mg/dm3, that is 3 – 4 orders. It has been found that weakly acidic cation exchangers should be used when concentrating lead from insoluble solutions using sorption and desorption steps. Strongly acidic cation exchangers are better to use when removing lead ions from water during cleaning.
The effectiveness of using mixed filters in the removal of zinc, cadmium, nickel and copper ions has been investigated. For the experiment, cation exchanger KU-2-8 in acid form and an anion exchange agent AB-17-8 in the basic form were used, ion exchanger volume was 50 – 70 cm3. It was shown that copper can be removed from solutions at concentrations up to 0.1 μkg/dm3, whereas zinc, cadmium and nickel ions were completely removed at initial concentrations of 0.1 – 0.2 mg/dm3.
In the study of processes for the pretreatment of solutions from zinc, cadmium and nickel by ion exchange, it was important to determine the concentrations of ion leakage under different conditions. Thus, when zinc solution is filtered at a concentration of 0.985 mkg/dm3, the ion exchange rate of zinc ions increases by 13 to 90 μg/dm3 via ion exchanger KU-2-8. It was shown that in the DOWEX MAС-3 cationite the cadmium concentration from tap water was reduced to 0.6 – 3.4 μkg/dm3.
It is shown that the degree of extraction of zinc, cadmium and nickel ions depends on the shape of the ion exchanger.
Processes of baromembrane purification and concentration of heavy metals from dilute solutions were studied.
It was established that the performance of the OPMN-N nanofiltration membrane depends on the working pressure and practically does not depend on the degree of selection of the permate and the concentration of the salt of the metal.
It was investigated that the use of phosphonate complexones is not universal for heavy metals. So, when extracting cadmium ions, the most effective was the use of OEDFK. Сomplete removal of zinc and cadmium ions in the processes of nanofiltration cleaning of solutions was achieved only with the use of OEDFK, and nickel ions - with the use of NTMFK.
It has been established that for effective removal of zinc, cadmium and nickel from natural water, it is necessary to presoften water and remove hydrocarbons, chlorides and sulfates. It was shown that copper ions present in tap water are completely removed.
The technological schemes of deep water purification from heavy metal ions were proposed, allowing to receive purified water and concentrates, which increase the accuracy of the metals analysis.
