Non-conventional low-cost adsorbent from <i style="">Euphorbia antiquorum L</i> for the removal of Direct Blue 53 from its aqueous solution

Abstract

This paper reports the adsorption potential of activated carbon prepared from <i style="">Euphorbia antiquorum L</i> wood by H₃PO₄ impregnation in batch mode experiments. The effects of various process controlling parameters such as solution pH, adsorbate concentration and temperature are analyzed. Maximum of 58.40 mg/g of dye adsorbed at a pH of 2.0 and the adsorption decreases with increase in pH. Various kinetic and isotherm models are employed to analyze the feasibility and mechanism of adsorption. The prepared adsorbent removed 145.45 mg/g of dye at an initial dye concentration of 100 mg/L and the kinetics obeys pseudo second order. Freundlich isotherm fits exceptionally well with good <i style="">r</i>² value. Thermodynamic parameters like <img src='/image/spc_char/delta.gif' border=0><i style="">G</i>°, <img src='/image/spc_char/delta.gif' border=0><i style="">H</i>° and <img src='/image/spc_char/delta.gif' border=0><i style="">S</i>° are evaluated. The positive enthalpy proves that the adsorption process is endothermic in nature. Experiments are also performed for recovery of dye loaded carbon through regeneration as a function of pH, the maximum desorption occurs at a pH of 10 is only 19.29%. The prepared sorbent can be conveniently employed for the colour removal as its adsorptive capacity is comparable with commercial adsorbents.