Removal of Hexavalent Chromium from Aqueous Solution by Adsorption on Treated Cole Straw

Abstract

In this paper, cole straw was thermochemically modified with citric acid as biosorbent and characterized by FTIR spectra and CHN analysis.The adsorption properties of modified cole straw for Cr(VI) were determined.At room temperature, the removal efficiency of 0.2 g modified cole straw under 10 h vibration time for Cr(VI) solution with condition of 100 mL, 10 mg/L and pH 2 can be up to 100 %.The adsorption data were fitted well by Langmuir isotherm, adsorption capacity was found to be 28.2 mg/g of adsorbent at Cr(VI) concentration in the effluent being 5 mg/L, ∆G = -0.57kJ/mol.The negative value of ∆G indicates the feasibility and spontaneous nature of adsorption.The presence of Cr(III) proved that the adsorption of Cr(VI) coexists with the redox process in acidic condition.The modified cole straw is a potential biosorbent which could be used in treatment of chromium contaminated wastewater.