Adsorptive Separation of Heavy Metals onto Xanthated Apple Waste From Aqueous Solution

Abstract

Biosorption is potentially an attractive technology for the treatment of wastewater retaining heavy metals in aqueous solution. This study investigated the feasibility of chemically modified apple waste as a novel type of biosorbent for lead, cadmium, zinc and Iron removal from aqueous medium. Xanthated apple waste as a biosorbent was prepared by simple chemical reaction with carbon disulphide under alkaline condition. The maximum exchangeable cations of the H V +

-form xanthated apple waste (XAWgel) were as high as 2.52 mol/kg. The effect of pH, sorption kinetics, effect of

competitive

ion and isotherm were studied by batch method. The significant effect of pH was in the range of 3 to 6. Time dependency experiments for the metal ions uptake showed the biosorption rate was fast initially for 2h, followed by slow attainment of equilibrium. Sorption isotherm test showed that equilibrium sorption data were better represented by Langmuir model than the Freundlich model, and the maximum adsorption capacity of Pb(II), Cd(II), Zn(II) and Fe(III) were found to be 250, 192.30, 123.45 and 62.89 mg/g respectively. The pseudo first-order, pseudo second-order, and secondorder

models were used to analyze the kinetic data. The good correlation coefficient was obtained for pseudo second-order kinetic model. XAW-gel was found to be more efficient than the conventionally used adsorbent activated carbon and other most of the biosorbent. Based on the result, a judicious choice of modification strategy for raw apple waste precursors can produce adsorbent with active xanthated surface functional groups and appears to be a promising biosorbent for removal of heavy metals from aqueous water.