Characterization of chemically modified biosorbents from rice bran for biosorption of Ni(II)

The current study explains the effect of chemical pretreatments on rice bran (RB) for the removal of Ni(II) from aqueous solution. Among the pretreated RB biomasses, NaRB, HARB, CaRB and SARB showed much improvement in adsorption capacity. The kinetic data was analyzed in term of pseudo first-order and pseudo second-order expressions. The Langmuir and Freundlich isotherm models were applied to the equilibrium data and defined very well the Langmuir isotherm model. The maximum biosorption capacity of NaRB, HARB, CaRB and SARB for Ni(II) was found to be 153.6, 149.4, 144.0 and 140.0 mg/g, respectively. The results from the sequential adsorption-desorption cycles showed that it was possible to reuse the biosorbent. Among the desorbents studied, HNO3 with desorption efficiencies equal to 68.2 and 67.4%, for NaRB and HARB, respectively, at the end of three cycles, was found to be the best desorbent.