Effective removal of Bisphenol A from plastic waste leachates by microbial polymer impregnated with activated carbon

The extracellular polymer from a well-characterized environmental isolate of Klebsiella terrigena was impregnated with granular activated carbon (GAC) and evaluated for the removal of Bisphenol A (BPA) from plastic waste leachates. Adsorbent, BPA concentration, contact time, temperature and pH were optimized to obtain the maximum removal. Characterization of the adsorbents was carried out by FTIR and BET. The adsorption capacity was determined using Langmuir, Freundlich and Temkin isotherms; the maximum adsorption capacity (q(e)) of BPA by biopolymer-impregnated granular activated carbon (BIGAC) obtained by Freundlich and Temkin isotherms was 241 mg/g and 257 mg/g, respectively, with a correlation factor (R-2) of 0.9391 and 0.8085, respectively, at 30 degrees C. The kinetics and isotherm data could be well fitted in a pseudo-second-order kinetic model. Notable removal of BPA was observed by BIGAC in plastic waste leachates obtained directly from source. To obtain information on reusability of BIGAC, regeneration was attempted for granular activated carbon; however, significant (p > 0.05) efficiency of adsorption was lowered after the third instance. The results of this study suggest that BIGAC can effectively remove BPA with the possibility of reusing GAC at least twice. The method may prove to be valuable in cleanup processes for BPA from leachates.