Pod of pigeon pea (
Cajanus cajan
), a celluloserich
agricultural residue, was investigated for its nickel
binding efficiency. The influence of key physicochemical
parameters such as contact time, initial metal ion concentration,
adsorbent dosage and pH on nickel (II) removal
was studied. The equilibrium time was found to be 45 min.
The optimum Ni (II) removal was obtained at an initial
metal ion concentration of 80 mg/l, pH of 9.0 and an
adsorbent dose of 400 mg/100 ml. A search for optimal
combination of key variables was studied by response
surface methodology for maximum removal of nickel. The
experiment encompassing 17 runs was established with the
aid of Box–Behnken design. Owing to the reasonable
agreement between predicted and adjusted
R2 value
(0.9714), the corresponding quadratic model gives the most
appropriate relationship between the variables and
response. The optimal point obtained was located in the
valid region and the optimum adsorption parameters were
predicted as an initial Ni (II) concentration of 60 mg/l, pH
value of 9.0 and contact time of 75 min. Under these
adsorption conditions, a maximum removal of 96.54 % of
initial metal concentration was demonstrated.
