APPLICATION OF RESPONSE SURFACE METHODOLOGY FOR OPTIMIZATION OF CADMIUM ADSORPTION IN AN AQUEOUS SOLUTION BY ACTIVATED CARBON PREPARED FROM Bauhinia Purpurea LEAVES

Abstract

An empirical model was developed and validated applying ANOVA analysis incorporating interaction effects of all parameters and optimized using response surface methodology (RSM) for the adsorption of cadmium onto activated carbon prepared from Bauhinia Purpurea leaves.These analyses were performed by means of Fisher's F-test, Student t-test and Probability 'P' (< 0.05). For the effect of process parameters, the square (F = 806.731 and P = 0.000061) and linear (F = 8035.63 and P = 0.000035) terms are having a significant effect than interactive (F = 101.578 and P = 1.829998) terms on % removal of cadmium. The process variables of X1 and X4 showed the greatest significant positive effect and the other variables of X2 and X3 are having an insignificant effect on the cadmium adsorption process. All the squared terms, X1, X2, X3 and X4 shows a significant negative influence on the adsorption of cadmium. The interaction effect between process variables of X1X3 (P = 0.000808, t = 4.5669), X2X3 (P = 0.000018, t = 7.1926), were found to be statistically significant and having a positive effect, whereas the combinations of X1X2 (t =1.0919, P =0.298219), X1X4 (P = 0.185458, t = -1.4125), X2X4 (P = 0.832451, t = -0.2166), X3X4 (P= 0.513044, t = -0.6759) are having an insignificant and a negative effect on the % removal of cadmium. The optimal values from RSM for cadmium was pH (X1) = 6.45, Ci (X2) = 3.54 mg/L, w (X3) = 0.14 g, T(X4) = 313.56K and maximum removal efficiency is 87.63%.