STUDY ON ADSORPTION CAPACITY OF Cr(VI) ON CARBON DERIVED FROM LOTUS STALKS

Abstract

This paper focus on the adsorption of Cr(VI) in aqueous solution on carbon derived from lotus stalks. The experiments were conducted using the following parameters: absorbent mass is 0.05g; the volume solution is 25mL; shaking speed is 200 rounds/minute; equilibrium time is 30 minutes at room temperature (25±1⁰C); pH is 1.0 – 2.0.In the temperature range of 303 - 323K, the values of ΔG^o < 0; ΔH^o = -63.48 kJ/mol implicates that the process is self-inflicted and exothermic. Maximum adsorption capacity is calculated by the Langmuir isothermal model. Maximum adsorption capacity was found as 76.92 mg/g at 25⁰C. The result indicates that, the adsorption of Cr(VI) on the carbon lotus followed Lagergren's second-order apparent kinetic model. Moving capacity corresponds to the flow rate of 1.0; 1.5 and 2.0 ml/min of 13.36; 17.76 and 25.88 mg/g, respectively. Mixture of HCl (1 - 2M) and H₂O₂ 0.1% solution was used to recover Cr (VI) with high effective elution. Using the carbon derived from lotus stalks to adsorb the wastewater containing Cr (VI) by static adsorption method for good results.