Response Surface Optimization for Removal of Cadmium from Aqueous Solution by Waste Agricultural Biosorbent Psidium guvajava L. Leaf Powder

Response surface methodology (RSM) was applied to study the combined effects of the various parameters namely, pH, biosorbent dosage, cadmium concentration and temperature, and to optimize the process conditions for the maximum removal of cadmium using Psidium guvajava L. leaf powder. In order to obtain the mutual interactions between the variables and to optimize these variables, a 2⁴ full factorial central composite design using RSM was employed. The analysis of variance (ANOVA) of the quadratic model demonstrates that the model was highly significant. The model was statistically tested and verified by experimentation. A maximum cadmium removal of 93.2% was obtained under the following optimum conditions: aqueous cadmium concentration 40.15 mg/L, adsorbent dosage 0.5 g/50 mL solution, pH 5.0, and temperature (35°C). The value of desirability factor obtained was 1.