Factors affecting sorption of pentachlorophenol to suspended microbial biomass

Sorption and desorption of pentachlorophenol (PCP) to microbial biomass was studied in a series of laboratory experiments. Equilibrium conditions for sorption and desorption were established within 5 min after a step change in concentrations. Linear sorption isotherms were observed at up to 80 mu g/l of dissolved PCP at pH 6, and up to 160 mu g/l at pH 8. Linear sorption coefficients were primarily influenced by pH, although ionic strength (owing to pH-buffering) and the concentration of dissolved organic matter also had an impact. The influence of these factors was quantified by a simple mathematical model, which included separate sorption coefficients for the neutral and dissociated fraction of PCP.