Study on regeneration of Ni-bentonite with response surface methodology

This paper assesses the potential of ultrasonic desorption of toxic heavy metal Ni(II) from bentonite. Response surface methodology (RSM) was used to optimize the response variable desorption percentage of Ni(II) adsorbed on bentonite by varying the amount of adsorbent, connect time, pH and ultrasound time. The results showed that in the range studied, pH and ultrasound time were the most significant variables affecting Ni (II) desorption from bentonite. Based on statistical analysis, the Ni (II) desorption model proved to be highly significant with very low p-values (<;0.0001) and the optimal control parameters were determined as follows: solid/liquid ratio (0.5 g/mL), connect time (6 h), pH (3.37) and ultrasound time (30 min). The experimental value of desorption percentage (59.4%) for regeneration of bentonite under the optimum conditions was in good agreement with the predicted value (64.5%).