SORPTION OF HIGH-MOLECULAR-WEIGHT CHLOROLIGNIN ON SEDIMENT

Sorption characteristics of organic compounds determine largely their fate in the aquatic environment. In this study, sorption of chlorolign in on sediments was studied in the laboratory. Chlorolignin is a major by-product of pulp bleaching with chlorine chemicals. The sediments w ere from the Baltic Sea and from Southern Lake Saimaa, Finland. The in fluence of bleaching process, pH and molecular weight on the sorption was determined in addition to studies for sorption kinetics and isothe rms. The results show that the sorption of chlorolignin on sediment is a two phase process in which the fast phase takes about 6 h. Equilibr ium was reached in most cases in 50 h which was the longest time studi ed. High molecular weight compounds sorbed most, especially at low pH. Only a part of the sorbed material desorbed when the sediment was sha ken with clean water. Much higher sorption coefficients were determine d for fresh water sediment than for Baltic Sea sediment.