Removal of 2,4-dichlorophenoxy acetic acid from aqueous solutions by using activated carbon derived from olive-waste cake

Abstract

In this study, activated carbon was prepared from olive-waste cake by chemical activation using zinc chloride and subsequently it was utilized for the removal of 2,4-dichlorophenoxy acetic acid (2,4D) from aqueous solution. The surface characterization of both raw material and activated carbon was undertaken byusing FTIR spectroscopy and scanning electron microscopy (SEM) technique. The surface area and micropore volume of chemically modified activated carbon were 1418 m(2) g(-1) and 0.197 cm(3) g(-1), respectively at 800 degrees C and at an impregnation (ZnCl2: olive-waste cake) ratio of 3: 1. The adsorption experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated monolayer adsorption capacity was 129.87 mg g(-1) at 298 K. The adsorption process attains equilibrium within 300 min and adsorption free energy is 0.707 kJ mol(-1). The adsorption kinetics of 2,4-dichlorophenoxy acetic acid (2,4-D) obeys the pseudo-second-order kinetic model. The thermodynamic parameters such as.G,.H and.S were calculated to estimate the nature of adsorption and these parameters indicate a feasible, spontaneous and exothermic adsorption. According to these results, prepared activated carbon could be used as a low-cost and very effective adsorbent for the adsorption of 2,4-D from aqueous solutions.