Biosorption of Cadmium from Aqueous Solution Using Mulberry Wood Sawdust: Equilibrium and Kinetic Studies

In the present study sawdust, an inexpensive material, obtained from mulberry wood has been studied after treatment with hydrochloric acid as biosorbent for cadmium removal using batch experiments. The effect of different parameters on biosorption process, such as contact time with shaking and without shaking, pH of the solution, and initial concentration of Cd(II) ions were studied. The biosorption of Cd(II) ions was found to be pH dependent and maximum biosorption was achieved at pH 6 after 30 min shaking. The maximum biosorption capacity of CTSD obtained from Langmuir isotherm was 403.73 (mg g(-1)) for Cd(II) ions. The Langmuir isotherm showed monolayer biosorption process of Cd(II) ions on the surface of CTSD. The empirical constants of Freundlich isotherm K-F and n obtained for Cd(II) ions were 0.334 (L g(-1)) and 4.83 respectively. The data shows that the pseudo-second-order model (r(2)=0.9887) was the best choice among the kinetic models studied for description of biosorption of Cd(II) ions on CTSD. The effect of interfering ions [Na(I), K(I), Mg(II), and Ca(II)] were also studied. For desorption of retained Cd(II) ions, various eluents were investigated and HCl (1.5 mol L-1) was found to be the most effective among them.