Cyclodextrin-Epichlorohydrin synthesis and its application in organic pollutants removal from compost leachate: Isotherm and kinetic study

Composting is an age old practice for the biological conversion of organic waste to humus like substance which can enhance physical, chemical and biological soil properties; but the major problem is producing leachate during the process that contain remarkable amounts of pollutants. In this study, cyclodextrin-epichlorohydrin was synthesized to reduce chemical oxygen demand (COD) of composting leachate. The copolymer was synthesized by polymerization of β-CD as a free radical initiator, in the presence of epichlorohydrin as a crosslinking agent. The structure of the copolymer was characterized by FTIR. Adsorption experiments illustrated that maximum adsorption capacity of the copolymer was in optimum condition as pH=3, contact time of 60 min and adsorbent dosage of 0.15gr/50ml. Pseudo-first order, pseudo-second order and intra-particle diffusion models were applied to study the mechanism of adsorption; data fitted well with pseudo-second order model with a correlation coefficient of 0.9968. Equilibrium isotherm was analyzed using the Langmuir and the Freundlich isotherms. It was obtained that the Freundlich isotherm described the adsorption process well with maximum adsorption efficiency of 10976.91 mg/g.