Selective Biosorption of Zirconium and Hafnium from Acidic Aqueous Solutions by Rice Bran,Wheat Bran and Platanus Orientalis Tree Leaves

Abstract

The Zr(IV) and Hf(IV) biosorption characteristics of rice bran, wheat bran and Platanus orientalis tree leaves were examined as a function of initial pH, contact time, temperature, and initial metal ions concentration. Adsorption equilibriums were achieved in about 1, 5 and 40 min for rice bran, wheat bran, and leaves respectively. The biosorption behavior of leaves was significantly affected by solution pH whereas rice bran and wheat bran adsorption efficiencies were slightly affected by solution pH. The Freundlich and Langmuir adsorption equations, which are commonly used to describe sorption equilibrium for metals removal by biomasses, were use to represent the experimental and equilibrium data fitted well to the Langmuir isotherm model. The negative Gibbs free energy values obtained in this study with rice bran wheat bran and Platanus orientalis tree leaves confirmed the feasibility of the process and the spontaneous nature of sorption. In the optimum conditions, the adsorption efficiencies of other metal ions such as Fe³⁺, Cu²⁺, Pb²⁺, Hg²⁺, La³⁺, Ce³⁺ were significantly lower than Zr(IV) and Hf(IV) ions and these biomasses are excellent sorbents for the selective uptake of proposed ions from acidic aqueous solutions.