Remediation of cadmium contaminated water by Populus nigraSawdust as a low-cost biosorbent: Process optimization by using response surface methodology

In this study, the removal of Cd(II) from aqueous solutions have been carried out using Populusnigra saw dust as low-cost, readily available biosorbent. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and contact time were studied at room temperature to optimize the conditions for maximum adsorption. The central composite design was carried out with aqueous solution of cadmium with various concentrations ranging from 5-25 mgl-1. The range of variation for the other variables including pH, sawdust dosage and contact time are 2-10, 5-50 gl-1, and 5-105 minutes, respectively. A good agreement between predictive model for cadmium removal by sawdust and experimental results was observed (R2= 0.9283 and RMSE=2.93%). The maximum removal of 96.25% was achieved at cadmium concentration 38.75 mgl-1, pH of 6.5, saw dust dosage of 10 gl-1 and contact time of 80 min as the optimal conditions. The highly efficient and the rapid uptake of Cd(II) by low cost saw dust indicated that it could be an excellent alternative for the removal of cadmium by sorption process from contaminated aqueous solutions.