Nickel pollution abatement from landfill leachate using biomaterials

Abstract

Batch experiments were conducted to assess the removal of Ni(II) from aqueous solutions and landfill leachates using low cost adsorbents eggplant peel (EGP), sweet potato peel (SWP) and banana peel (BNP). Preliminary studies were carried out to optimize biosorbent mass, pH, Ni(II) concentration, temperature and contact time for Ni(II) removal. The optimized conditions were then applied to landfill leachates using the selected low cost adsorbents. Ni(II) removal efficiency for each biosorbent was investigated for each parameter. Results indicated that biosorbents masses, pH, initial concentration as well as solution temperature were important factors influencing Ni(II) removal from aqueous solutions. Percentage Ni(II) removal was 66±0.30, 38±3.97 and 33±1.20 using EGP, SWP and BNP, respectively. Ni(II) removal efficiency increased significantly (P ≤ 0.05) with increasing biosorbent mass, pH and Ni(II) initial concentration while it decreased significantly (P ≤ 0.05) with increasing temperature. Although Ni(II) removal efficiency varied significantly with time and the biosorbents no significant (P 0.05) difference was observed between the time interval whether the experiment was conducted in batch or semi batch mode. Results of FTIR studies indicated that several binding and chelating functional groups such as carboxyl, carbonyl and hydroxyl groups on the biomaterials surfaces could be responsible for Ni(II) biosorption. The optimum biosorbent mass for EGP and SWP was 0.4 g and for BNP was 0.05 g. The values for initial concentration, pH, temperature and contact time were 100 mg/L, 5, 22oC and 2 hours, respectively. Ni(II) removal efficiencies using EGP, SWP and BNP were 66, 38 and 33%, respectively. Taking into account the result and optimum condition obtained on Ni(II) removal efficiency from aqueous solution using EGP, SWP and BNP, the Ni(II) removal efficiency using these biosorbents from landfill leachate was investigated. It was found to be significantly (P ≤ 0.05) lower than what was found from aqueous solution.