材料期刊网

研究了纳米TiO_2吸附剂对Mo(Ⅵ)、Re(Ⅶ)的吸附行为,考察了溶液pH、吸附时间、温度等因素对吸附的影响. 结果表明,纳米TiO_2对Mo(Ⅵ)的吸附在pH值为1～8条件下,吸附率超过99%,2 mL 0.05 mol/L NaOH溶液可将吸附的Mo(Ⅵ)完全洗脱,解吸率可达97%. pH值在1～10范围内,纳米TiO_2几乎不吸附Re(Ⅶ),从而达到Mo(Ⅵ)、Re(Ⅶ)分离. 在275～323 K范围内,纳米TiO_2对Mo(Ⅵ)的最大吸附容量从11.51 mg/g增至14.19 mg/g,吸附过程符合Langmuir等温式. 纳米TiO_2分离钼后,溶液剩余的铼,用活性碳吸附,pH值在1～10范围内,Re(Ⅶ)的吸附率可达99%,用浓氨水进行洗脱,洗脱率可达96%;吸附过程可用准二级反应动力学模型描述,是以化学吸附为控制步骤的吸附过程;吸附等温线与Freundlich模型有较好的拟合.

A novel sorbent, nano-TiO_2 was employed for the removal of molybdenum and rhenium from aqueous solution in batch equilibrium experiments in order to investigate their adsorption properties. The removal percentage of molybdenum by the sorbent is closed to 99% in a pH range of 1 ～8. The elution rate of molybdenum with 2 mL of 0. 05 mol/L NaOH is closed to 97%. As rhenium is hardly adsorbed onto nano-TiO_2, molybdenum and rhenium can be separated. The adsorption capacities and removal percentage of Mo( Ⅵ) onto nano-TiO_2 were evaluated as a function of the solution concentration and temperature. Results have been analyzed by means of the Langmuir, Freundlich adsorption isotherms. Adsorption isothermal data could be well interpreted by the Langmuir model. Saturated adsorption capacity increases from 11. 51mg/g to 14. 19 mg/g in a temperature range of 275 ～323 K. The removal percentage of Re ( Ⅶ) by the actived carbon is closed to 99% in a pH range of 1 ～ 10. The results showed that the elution rate of Re (Ⅶ) with strong ammonia is 96%. Adsorption isothermal data could be well interpreted by the Freundlich model. The kinetic experimental data of Re( Ⅶ) are properly correlated with the second-order kinetic model.