Adsorption Characteristics of Arsenite and Arsenate on Hydrous Ceric Oxide
- 海洋环境－已发表论文 
以开发新型高效除砷吸附材料为目的 ,在室温 (2 5℃ ) ,初始浓度 0 .0 5～ 2 5 0mg/L ,pH4～ 11条件下 ,对稀土材料氢氧化铈 (HCO)进行了吸附除砷的性能评价 .实验结果表明 ,在实验条件下 ,HCO对亚砷酸和砷酸阴离子都显示了良好的吸附效果 ,其吸附等温线能很好地用Langmuir方程进行描述 .对于低浓度 (0 0 5～ 10mg/L)的砷溶液 ,HCO在所选 pH条件下对亚砷酸和砷酸阴离子的吸附率可达 10 0 % .对于高浓度的砷溶液 ,偏酸性 (pH 4 )条件有利于砷酸阴离子 ,而中性 /微碱性 (pH 7,8)条件最有利于亚砷酸阴离子的吸附 .HCO对 2种形态的砷阴离子的吸附效应在较宽 pH范围内同溶液的离子强度基本无关 ,常见阴离子 (Cl-,NO-3 ,SO2 -4)的存在对砷的吸附也未显示出干扰效应 .从实验结果推测 ,HCO吸附亚砷酸和砷酸阴离子的主要反应机理应属于专性吸附Seeking to develop novel adsorbents for arsenic removal from polluted water, adsorption isotherms of arsenite and arsenate in aqueous solutions at room temperature (25℃) onto hydrous ceric oxide (HCO), CeO 2·xH 2O, were studied over the arsenic concentration range 0.05～250 mg/L and the pH range 4～11. The HCO adsorbent proved to be effective to remove both arsenite and arsenate from water. These isotherms fit well in the Langmuir model of adsorption. At the lower concentration range of 0.05～10 mg/L As, adsorption of both arsenic anions was virtually independent of pH and up to 100% removal can be achieved. At higher concentrations, a pH of 4 is optimum for arsenate adsorption, whereas adsorption of arsenite goes through a maximum at approximately pH 7 to 8. Both adsorption processes were little influenced by changing ionic strength in a wide pH range. The presence of common anions such as Cl -, NO - 3, and SO 2- 4 had no interference in the removal processes. The principal adsorption mechanism is presumed that arsenite and arsenate are specifically adsorbed onto HCO surfaces.