SONOLYSIS OF CHLORO-ORGANICS IN BLEACH PLANT E-1 EFFLUENTS

Degradation of chloro-organics in bleach plant E-1 effluents by ultras ound sonication was investigated to evaluate the effects of ultrasonic treatment on the dechlorination. On sonolysis, ca. 65mol% of 4-chloro phenol (1) at concentration of 1.0 x 10(-4)M in aqueous solution was d ecomposed and 35mol% of chlorine in the substrate was released as chlo ride ions (Cl-) after 80min at room temperature under atmospheric pres sure. By contrast, under the same reaction conditions, only ca. 1.1 mo l% and 3 mol % of 1 were decomposed at the concentrations of 1.0 x 10( -3)M and 1.0 x 10(-2)M with the release of ca. 5 and 1mol% of Cl-, res pectively. Although the kinetics for the disappearance of 1 fits a fir st-order law, the rate constant decreases with increasing initial conc entration of the substrate. This suggests that the disappearance rate of 1 does not followed the first order law and the reaction mechanism involved is rather complex. When hydrogen peroxide was added to the so lution in the molar ratio of substrate to hydrogen peroxide 1 : 10, bo th the rates of degradation and dechlorination were not affected. Howe ver, an addition of a smaller amount of hydrogen peroxide to the solut ion resulted in a decrease in the rate of the degradation. In the pres ence of hydrogen peroxide, the kinetics for the decomposition of I als o follows the same pattern for that without hydrogen peroxide. On sono lysis, polychlorinated oxylignins (PCOLs) isolated from E-1 effluent r eleased chloride ions. The high relative mass PCOL released larger amo unts of chloride ions than the low relative mass PCOL. The sonolysis b rought about a very small decrease in the relative mass of PCOLs, and no significant degradation of PCOLs except for release of chloride ion s. This result suggests that an acoustic cavitation by ultrasonic trea tment plays a important role in cleavage of C-Cl bonds, but not C-C bo nds.