Biosorption of Cu2+ from Aqueous Solutions Using NaOH-Modified Fir Sawdust

Fir sawdust, a low-cost residual agricultural material, was used as adsorbent for the removal of Cu2+from aqueous solutions. Factors affecting the adsorption behavior of Cu2+, such as pH, initial metal concentration, contact time and temperature, have been carried out. The Cu2+ removal was pH-dependent, reaching a maximum at pH 5. The adsorption capacity of the fir sawdust from Langmuir adsorption isotherm was 38.6 mg/g at 25°C. The adsorption process followed pseudo-second-order kinetics. The equilibrium data fitted very well to the Freundlich isotherm. The negative ΔGo values at various temperatures confirm that the adsorption processes are spontaneous.