G.V. Kucherik, Yu.A. Omelchuk
Federal State Educational Institution of Higher Education «Sevastopol State University»,
Russian Federation, Sevastopol, Universitetskaya St., 33
Processes of ion-exchange cleaning are impossible without efficient regeneration of ionites. It is known that regeneration of anionites with alkali is much more effective than with soda. However, taking into account high capacity of the anionite as for chloride and sulfate in the carbonate form, the goal was to conduct studies on the regeneration of anionite in chloride, sulfate and mixed chloride-sulfate forms with both alkaline solutions and soda solutions.
In this paper, the influence of the concentration of reagents, the filtration rate and the specific consumption of alkali and soda solutions on the efficiency of the recovery of the capacity of anionite was studied.
4, 6 and 10% solutions of NaOH, as well as 5, 10, 15, 20% solutions of Na2CO3 were used to regenerate the anionite. For this purpose the solutions of alkali or soda were passed through the ionite in volume of 20 cm3 in Cl– and SO42- forms at a filtration rate of 0.42-1.06 m/h.
In the case of regeneration of anionite in Cl– form, samples of 20 cm3 were taken with NaOH solution, while regenerating with Na2CO3 solutions – 40 cm3 each. The content of desorbed chlorides and alkalinity were determined in the selected samples.
Under desorption of chlorides with alkali (4, 6, 10%) in all cases, complete regeneration of the ionite was achieved. Analysis of the data obtained suggests that it is not advisable to increase concentration of alkali during the regeneration of ionites from chlorides. It is possible to substantially increase the regeneration efficiency of the anionite AB-17-8 in the Cl– form by regulating flow rate of the regeneration solution.
The efficiency of regeneration of ionite in the Cl– form and the concentration of Na2CO3 is not very important. In general, it is almost the same as when using alkali. However, in this case, the consumption of solutions and their concentrations is significantly higher than when using NaOH.
Sufficiently well it is desorbed when using alkali and soda sulfates. The desorption efficiency increases with increasing NaOH concentration.
Regeneration processes are also successfully carried out both with solutions of NaOH and Na2CO3 anionite in a mixed chloride-sulfate form.
From the results presented in the work it is clear that the anionite AB-17-8 is regenerated fairly efficiently with solutions of NaOH and Na2CO3, while the productivity of the process depends little on the concentration of the reagent, but depends more on the rate of filtration and the specific consumption of its solution. The minimum concentrations used were sufficient to restore the capacity of the ionite. The authors showed that with a large expenditure of regeneration solutions, it is possible to achieve a complete restoration of the exchange capacity of the ionite.
Keywords: anionite, desorption, regeneration, regenerating solutions, regeneration rate, sulfates, chlorides.
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