Comparative Study On Pb²⁺ Adsorption By Biomass Adsorbents

Adsorption is a highly effective way to treat wastewater containing Pb2+, moreover, developing a low-cost adsorbent is a hot research topic in the recent years. In the paper, active carbon modified by small molecules organic acids was studied to improve the properties, and the adsorption of peanut shell and rice bran to Pb2+was also studied. The purpose provides the basis for treating wastewater containing Pb2+. The main results were as follows:The adsorption properties of modified and unmodified active carbon to Pb2+were investigated. The results showed that:active carbon modified by0.1mol/L oxalic acid, tartaric acid, citric acid and DDTC can significantly improve the adsorption rate of Pb2+and the active carbon modified by oxalic acid saturated adsorption capacity to Pb2+increased by1.6times. The maximum adsorption amount of Pb2+by the active carbon modified by oxalic acid reached to54mg/g. The adsorption rate of Pb2+over active carbon modified by oxalic acid increased with the increasing temperature. To provide Pb2+is not precipitated, the adsorption rate of Pb+over the active carbon modified by oxalic acid increases with the increasing pH, the adsorption of Pb2+by active carbon modified by oxalic acid was saturated after2h, The best adsorbent dosage was1g/L, the optimum pH for adsorption was5.0.The treatment effect of modified and unmodified active carbon to Pb2+was studied using dynamic column adsorption. The effects of craftwork parameter including modification, flow rate were investigated. The results showed that when the pH was5, the adsorption of Pb2+with500ml50mg/L concentration by active carbon modified by oxalic acid was better than active carbon (no modified). The poor regeneration property was observed for active carbon (no modified) dynamic column adsorption with0.1mol/L HCl as desorption solution. However, active carbon modified by oxalic acid after regenerated by0.1mol/L HCl still exhibited a good adsorption of Pb2+under the same conditions.Peanut shell and rice bran were applied to treat wastewater containing Pb2+, and the influence of pH, adsorbent dose, temperature and concentrations were investigated. The results showed that:under the same conditions, peanut shell and rice bran was better than active carbon on Pb2+adsorption. At25℃and pH5.0,0.1g/L adsorbent dosage, the removal of Pb2+by peanut shell reached to78%, but the removal of Pb2+by active carbon was only29%. In addition, it was found that the adsorption capacity of Pb2+by peanut shell and rice bran after microwaving carbon decreased markedly.