Similar results have been reported
for other types of biosorbents (King et al., 2008; Yan and
Viraraghavan, 2003). Biosorption at pH above 5.0 was not
carried out to avoid zinc ions precipitation. Therefore, the
optimum initial pH value for zinc(II) biosorption was obtained
at 5.0 and used for all other biosorption experiments
in this study.