Optimization of Affective Parameter on Cadmium Removal From an Aqueous Solution by Citrullus colocynthis Powdered Fruits by Response Surface

Cadmium is a toxic metal that occurs naturally in the environment and is considered as a pollutant emanating from industrial and agricultural sources. Biosorption is a very simple and cheap technique for removal of metal pollutants from aqueous samples. In this study, removal of cadmium from aqueous solutions using C. colocynthis fruit powder was studied. The effect of three parameters such as pH, initial concentration of cadmium and adsorbent dosage were optimized. For investigation of these parameters and exemption of optimal conditions the Box-Behnken design (BBD) was used. The best results for percentage extraction of cadmium by C. colocynthis with BBD design was obtained at pH = 4.5, initial cadmium concentration of 31.22 and adsorbent dosage of 3.75 g/L. Analysis of variance (ANOVA) and R2 = 0.98 showed that the model was able to predict the removal of cadmium by C. colocynthis fruit powder. Results of this research imply that the adsorption of cadmium was enhanced, by increasing the cadmium concentration and contact time. Based on the ANOVA results, the models report high R2 value of 99% for cadmium removal, which is very high and advocates a high correlation between the observed values and the predicted values.