Adsorption of Cu2+ from Aqueous Solution by Walnut Shell

Walnut shell was used as adsorbent to remove Cu2+ metal ions from the simulated aqueous solution. The influence of factors, namely: particle size, initial pH, oscillation intensity, adsorbent dosage and adsorption time were investigated through single factor experiments.The results show that, the adsorption capacity reached the peak for Cu2+ in 25°C when the initial pH was 5, particle size was 1.25~1.6mm, adsorbent dosage was2.5g, oscillation speed reached 200r/min, and the adsorption time was 360min, all above leads the removal rate of Cu2+reached 75.7%, and the adsorption capacity of Cu2+ 0.702 mg/g. The pseudo-second-order model was fitted to describe the adsorption of Cu2+ , it was shown that adsorption rate for the metal ions in proportion to the square of the concentration.The equilibrium concentration of adsorption fitted well with Langmuir isotherm equation, the process of adsorption was single molecular layer adsorption.