Studies of benzidine-based dyes in sediment-water systems

The sorption and degradation of several benzidine-based dyes were studied in sedimentwater systems. Studies in resaturated sediment demonstrated that sorption was strongly dependent on pH and the nature and concentration of the inorganic salt in solution. Degradation of the dyes in anaerobic pond sediment followed pseudo-first-order kinetics with half-lives ranging from 2 to 16 d. Product studies indicated that the amount of recovered benzidine accounted for only 2 to 5% of lost Direct Red 28. Studies in pH-amended pond sediment demonstrated that degradation is inhibited when the dyes are strongly sorbed to the sediment.