Adsorptive removal of pentachlorophenol from water using agricultural and industrial wastes

The removal of pentachlorophenol (PCP) from aqueous solution using low-cost biosorbents including sunflower seed hulls, hazelnut shells, pine sawdust and milk thistle seeds was investigated. The effect of experimental parameters such as contact time, initial biosorbent dose, solution pH and ionic strength was evaluated. The adsorption kinetics was investigated according to the pseudo-first order, pseudo-second order and intra-particle diffusion kinetic models. The pseudo-second order model best described the adsorption process. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Sips isotherm models using non-linear regression method. The best results were achieved with the Freundlich model. The values of the Freundlich adsorption parameter (K-F) were 0.127, 0.168, 0.214 and 0.296 (mg/g)(L/mg)(1/n) for the sunflower seed hulls, milk thistle seeds, hazelnut shells and pine sawdust, respectively. The results showed that the agricultural and industrial wastes may be used as effective adsorbents without any treatment or any other modification for removal of PCP from the aqueous medium.