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FATE OF DYES IN AQUATIC SYSTEMS. PART 3: THE ROLE OF SUSPENDEDSEDIMENTS IN ADSORPTION AND REACTION OF ACID AND DIRECT DYES
Citation:
Baughman, G. FATE OF DYES IN AQUATIC SYSTEMS. PART 3: THE ROLE OF SUSPENDEDSEDIMENTS IN ADSORPTION AND REACTION OF ACID AND DIRECT DYES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/419, 1995.
Description:
The behavior of nine acid and five direct dyes was examined in suspensions of lake and river sediments. even of the dyes demonstrated variable kinetics of loss from water. n most cases, there was an initial drop in water concentration due to sorption. ransformation kinetics of CI Acid Reds 4, 18, and 88 were first order in dye concentration and apparently first order in sediment concentration. I Acid Reds 4 and 18 also exhibited an initial lag period. ransformation and sorption of CI Acid Red 114 and CI Acid Red 151 could not be studied because of precipitation. I Acid Yellow 151, DO 1 and CI Acid Blue 92 were lost from solution by pathways that were not first order. f these, CI Acid Blue 92 was transformed at a rate that was too fast to measure reliably, but CI Acid Yellow 151 and DO 1 were very stable in the suspensions. roducts of azo group reduction were found for CI Acid Reds I and 4 and CI Direct Red 24. he results suggest that many acid and direct dyes will be stable in aquatic systems for long periods of time unless other transformation pathways (e.g., photochemical) are rate determining. ruendlich adsorption isotherms were measured for 12 of the dyes with both sediments. ecause of competitive transformation and sorption, isotherms were measured on boiled sediments after equilibration for 24 h. The data show that the dyes are not strongly sorbed and that the extent of sorption to boiled sediment is within a factor of two to three of that with natural sediment.