Preparation and Characterization of Cassia-4 Hydroxy-Benzoic Acid Resin for Removal of Cr+6 From Contaminated Water

Abstract

The current research emphasizes on removal of Cr+6 from the contaminated water by the preparation of natural resin using cassia gum powder and testing its feasibility to reduce Cr+6in contaminated water. The effects of various process parameters including pH of the solution, amount of resin, initial Cr+6 concentration, contact time etc., on removal efficiency of Cr+6 from the water stream has been studied. The study demonstrates that the prepared natural CHBA resin has potential to remediate Cr+6 from the drinking water. It is observed that using 1g/ml resin 99.26% Cr+6 could be removed from initial concentration 3 ppm at pH 6.8 within 25 min. Experimental data obtained were allowed to fit to various models such as pseudo first order model, pseudo second order, intra particle diffusion, Elovich model. Results indicate that the process of adsorption on Cr+6 was followed by second order kinetic model with R2 value 0.989.Similarly other models of adsorption isotherms such as Langmuir, Freundlich, Temkin were also applied to the data and constants of isotherms were calculated. Cr+6 adsorption on the prepared resin shows good agreement to Freundlich adsorption isotherm model with the regression coefficient of 0.989. Thermodynamics parameter studied that the Positive values of change in enthalpy shows that there is a presence of an energy barrier during the process of adsorption and the process of adsorption follows process of endothermic reaction. The positive values in the change of entropy (∆S) shows good binding capacity of Cr+6 ions for the resin surface and it also increases the uncertainty of the solid solution interaction during the process of adsorption.
RSM experiments were also conducted which showed that the ideal conditions required for Cr+6 adsorption were as per the following: amount of resin as (0.43 g), at pH (6.13) as well as Initial Concentration of (4.53 mg/L) with the value of maximum adsorption is 95.05%. The following results were obtained from the box-behenkn design RSM method with a desirability of 0.989. The Column performances were also evaluated by varying the amount of resin inside the column bed, influent rate of flow with Cr+6 concentrations. Furthermore it was seen that with the expansion in height or depth of the bed, at lower flow rates and at low Cr+6concentration the column performance was good or proved to be better.