Підвищення виходу активного хлору з хлормістких концентратів вдосконаленням процесів електродіалізу

This study investigates processes related to processing sodium chloride solutions at a concentration of 3.5–120 g/dm3 by electrodialysis to solve the task of utilizing chlorine-containing concentrates of membrane water desalination to obtain active chlorine. When electrolyzing the solutions, open and sealed two-chamber electrolyzers with an anion exchange membrane MA-41 were used. Solutions with NaCl were placed in the anode chamber, and the cathode chamber was filled with NaOH solutions (200–1000 mg-equiv./dm3). The electrolysis processes were carried out at an anode current density of 1.67–12.5 A/dm2. With an increase in the anode current density and chloride concentration in the solution, the intensity of chloride oxidation increases. During the anodic oxidation of chlorides, hypochlorites and chlorides are formed along with the formation of chlorine in the presence of hydroxides. This confirms the ratio of the amounts of active chlorine and oxidized chlorides. Prolonging the electrolysis time in an open electrolyzer does not contribute to an increase in the concentrations of oxidized chlorine in the anolyte because of its significant degassing. At low initial chloride concentrations (60 mg-equiv./dm3) and at low anodic current density (J = 0.83 A/dm2, 1.67 A/dm2), the yield of sodium hypochlorite reached 100.0–87.0%, respectively. At a current density of 4.17 A/dm2 and the same NaCl concentration, the yield of sodium hypochlorite decreased to 51.2%. The concentration of active chlorine in the solutions did not exceed 80–90 mg-equiv./dm3. When using a sealed two-chamber electrolyzer, the bulk of the active chlorine was concentrated in the anolyte. To capture active chlorine vapors, gases from the anode zone were passed through a NaOH solution in the absorber. The concentrations of active chlorine in the anolytes reached 1240–1920 mg-equiv./dm3. The degree of degassing of active chlorine did not exceed 11–17%