biosorption of cr(vi) ions onto walnut flowers: application of isotherm models

Biosorption of cr(vi) ions onto walnut flowers (wf) is studied in a batch system in relation to the physical parameters. the efficiency approaches 100% with 5 g wf/l at ph~1.5  for a cr(vi) concentration of 100 mg/l in less than 1 h. the experimental data are analyzed using two-parameter models (langmuir, freundlich, and temkin), and three-parameter models (redlich–peterson, sips, and toth). in order to determine the best isotherm, two error analysis methods are used to evaluate the correlation coefficient and chi-square test. the error analysis demonstrates that the three-parameter models better describe the cr(vi) biosorption data. the sips equation provides the best fitting. the possible interaction between the cr(vi) and the biosorbent surface was evaluated by ft-ir analyses. overall, the proposed biosorbent material was successfully used for the removal of a cr(vi) from contaminated solutions.