Abstract
Four low cost materials such as Lagenaria siceraria peel, Bauxite, Used aquaguard carbon and sand are chosen basing on a preliminary screening method for Cr(VI) removal. Simple modification procedures are followed to improve uptake capacities without affecting the cost of the final products. Effect of different parameters such as contact time, pH, temperature, adsorbate/adsorbent concentrations on Cr(VI) adsorption by modified adsorbents are studied. Lower pH and low temperature favor the adsorption reactions. Linear and non linear forms of Freundlich and Langmuir isotherm equations are fitted to the adsorption data. Nonlinear form of the equations fit better compared to linear forms. Data is also fitted to Lagergren’s, Ho & Mc-Kay, Morris Weber, Dubinin Radushkevich (D.R.) and Temkin equations. Kinetic interpretations show intraparticle diffusion process is the rate limiting step and adsorption is physiosorption in nature. Thermally treated bauxite (TTB) is taken to be the best adsorbent and the adsorbed Cr(VI) can be desorbed well with NaHCO3. The same adsorbent can be reused successfully for three adsorption–desorption cycles and can be effectively used for the treatment of real contaminated water.
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