Optimization of process variables for a biosorption of nickel(II) using response surface method

The biosorption of nickel(II) was studied by using crab shell particles of diameter (dp=0.012 mm) under
different initial concentrations of nickel(II) in solution (0.01-5.0 g/l), temperature (20-40 oC), pH (2-6.5), and biosorbent
dosages (0.5-10 g/l). The maximum removal of nickel(II) occurred at pH 6.5 and temperature 40 oC for a biosorbent
dosage of 6 g/l. The results were modeled by response surface methodology (RSM), which determines the maximum
biosorption of nickel(II) as a function of the above four independent variables, and the optimum values for the
efficient biosorption of nickel(II) were obtained. The RSM studies were carried out using Box-Behnken design and
the analysis of variance confirms the adequacy of the quadratic model with coefficient of correlation R2 to be 0.9999.
The quadratic model fitted the data well with Prob>F to be <0.0001, indicating the applicability of the present proposed
model.