Biosorption of cadmium and zinc from aqueous solution by rice bran

The study evaluated the sorption of Cd(II) or Zn(II) ions from aqueous solution by a new biosorbent, rice bran. The rate and extent of accumulation were affected by chemical treatment of rice bran, pH, contact time and initial metal ions concentration. When each metal ions initial concentration was 100 mg/L, pH 6.0, contact time 30 min, NaCl 0.1 mol/L treated rice bran 1 g/L, the removal efficiency of Cd(II) and Zn(II) attainted the maximum 98.25% and 94.21%, respectively. The equilibrium was established in less than 30 min and good correlation coefficients were obtained when the pseudo-second-order kinetic model of this process was assumed. The equilibrium process was described well by the Langmuir isotherm model with maximum sorption capacities of 233.7 and 190.1 mg/g for Cd(II) and Zn(II) on rice bran, respectively. Rice bran was found to be an efficient biosorbent of metal ions from the effluent of electroplating industry.