Fig. 12, describes the rate of removal of Pb+2 ion as very fast
with its disappearance from the solution sharply in the first
20 min. After 2hours, Pb+2 ion residual concentration was
about 3.57 and 27.9 ppm by NiOppt and NiOorg catalysts,
respectively indicating that NiOorg catalyst acquire relatively
large surface area (Table 1) and strong adsorption capacity
than NiOppt catalyst [30] (Fig. 13).