Adsorption isotherms and kinetics for the removal of triclosan and methyl triclosan from wastewater using inactivated dried sludge

Abstract

Biosorption equilibrium and kinetics of TCS and MTCS sorption to inactivated dried sludge were studied in a batch system with respect to pH, temperature and sludge concentration. Linear and Freundlich isotherms were able to describe the adsorption system well. Sorption capacity increased from 4.80 to 7.36μg/g and 6.28 to 7.76μg/g for TCS and MTCS, respectively with an increase in temperature from 15 to 35°C. As pH decreased from 11.0 to 5.0, the sorption capacity of TCS and MTCS enhanced from 4.36 to 7.92μg/g and 5.52 to 7.52μg/g, respectively. The distribution coefficient for MTCS was higher than that for TCS due to hydrophobicity. The calculated Kf and 1/n implied that the adsorption process was physiosorption and exothermic in nature involving weak forces such as Van der Waal’s interactions. In the kinetic study, adsorption of TCS and MTCS to dried sludge predominantly followed a pseudo-second order kinetic over the range of applied initial concentrations based on regression coefficients and the relative error for the calculated equilibrium sorption capacity. IR analysis of sludge showed the presence of various polar groups that could highly affect the sorption of organic pollutants.