Removal of Cr (VI) from Aqueous Solution by Adsorption Using Cooked Tea Dust

Abstract

Chromium is considered one of the 14 most noxious heavy metals. In the present investigation, an attempt was made to remove chromium (VI) from aqueous solution using decolorized Cooked Tea Dust (CTD) by adsorption technique. Batch mode adsorptive removal was carried out at varying pH (2 -11), agitation time (5 - 60 min), particle size (125 - 750 μm) and adsorbent dosage (50 - 500 mg/50ml). The optimum pH for Cr (VI) adsorption on CTD was found to be 2.0. Adsorption equilibrium was obtained in 45, 50, 40, 45 and 45 min for the initial Cr (VI) concentrations of 25, 50, 75, 100 and 125 mg/l respectively. Results conformed to both Langmuir and Freundlich adsorption models for adsorption equilibrium of Cr (VI) onto CTD. The adsorption followed the pseudo second-order kinetics. The Langmuir adsorption capacity was found to be 30.39 mg/g while Freundlich constants Kf and n were 7.524 and 2.673, respectively. Desorption studies indicated 82.28% removal of the hexavalent chromium from the adsorbent.