香蕉皮对汞的吸附特征研究

Study on Adsorption Characteristics of Mercury by Banana Peel

以香蕉皮作为吸附剂，探究其用量与粒径、pH、吸附时间、温度和汞的初始浓度等因素对汞吸附效果的影响。结果发现，随香蕉皮吸附剂用量的增加与粒径的减小、pH的增大、汞的初始浓度的降低和反应温度的升高，溶液中汞的去除率均呈逐渐增高的趋势；在吸附剂用量 ≥ 0.075 g、粒径 ≥ 60目、pH ≥ 5、汞的初始浓度 ≤ 200 mg/L和室温 ≥ 23℃条件下，吸附时间 ≥ 20 min时，汞去除率 〉 90%。Langmuir、Freundlich和Temkin等温吸附模型对吸附过程均具有较高的拟合度；符合伪二级动力学模型；吸附反应是自发进行的，且为吸热过程；吸附过程较为复杂，颗粒内的扩散不是唯一控制吸附反应过程的因素或步骤。香蕉皮对汞的吸附具有吸附剂用量少，在较宽的pH范围和温度条件下对不同浓度汞均具有较高去除率的优点，可广泛应用于含汞废水的处理，发展潜力较好。

Banana peel was selected as sorbent to identify its mercury sorption ability under various conditions, such as dosage, particle size, pH, sorption time, reaction temperature and the initial mercury concentration. The results indicated that the mercury removal efficiency increased with increased dosage, smaller particle size, higher pH, higher reaction temperature, and lower mercury initial concentration. The mercury removal efficiencies were found to be more than 90% when dosage ≥ 0.075 g, particle size ≥ 60 mesh, pH ≥ 5, initial mercury concentration ≤ 200 mg/L, and temperature ≥ 23℃. Sorption models of Langmuir, Freundlich and Temkin are all adequate to fit the sorption process. The sorption reaction, a spontaneous endothermic reaction, is consistent with the pseudo-second order kinetic model. The sorption process was complex controlled by more influence factors other than the intra-particle diffusion. Banana peel showed an excellent development potential in removing mercury from wastewater because of the high removal rate as well as the low dosage, wide suitable ranges of pH and temperature for the sorption reaction.