改性纳米SiO_2/PVA复合纤维的制备及重金属离子吸附性能

Removal of heavy metal ions from aqueous solution using amidoxime-functionlized SiO_2/PVA composite nanofibers prepared by sol-gel electrospinning

通过静电纺丝技术制备酰肟化功能改性的纳米SiO_2/聚乙烯醇(SiO_2/PVA)复合纤维膜。采用SEM、FTIR、DSC和TGA进行表征分析;考察了在水溶液中随pH值和接触时间的变化纤维膜对金属离子吸附效果的影响。研究表明,在pH=6的条件下,纳米纤维对金属离子的吸附最佳,对Cu2+、Ni 2+金属离子的最大吸附量分别为143.7mg/g和125.1mg/g,平衡吸附时间为240min。在纤维膜吸附的前50min内,SiO_2/PVA纤维膜对Cu2+和Ni 2+金属离子的吸附量为126.8mg/g和109.8mg/g,吸附率分别为90.18%和89.92%。通过吸附等温线和吸附方程考察SiO_2/PVA纤维对Cu2+和Ni 2+金属离子的吸附行为。结果显示,复合纤维对两种金属离子的吸附满足拟二级动力学方程,热力学分析表明,吸附过程符合Langmuir单层吸附。使用酸处理纤维膜进行再生吸附试验,发现循环4次试验后,吸附效率达到53%,结果说明复合纤维膜可作为可再生金属离子吸附材料。

Amidoxime-functionalized SiO2/polyvinyl alcohol（SiO2/PVA） nanofiber adsorbent was prepared by electrospinning technique. The composite SiO2/PVA nanofibers was analyzed by SEM, FTIR, DSC and TGA. The nanofiber adsorbent was also evaluated for mental ions adsorption capacity. The results indicate that the highest ad- sorption occurs at pH=6 and the adsorption capacity can be 143.7 mg/g and 125.1 mg/g for Cu^2＋ and Ni^2＋ , respectively. The composite SiO2/PVA nanofibers can remove almost 90% aforementioned ions from aqueous solu- tions within 50 min. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order kinetic mod- el, the kinetic process is found to fit the pseudo-second-order equation and the adsorption isotherm data fit well the Langmuir isothermal model. Furthermore, HNO3 is found to be effective in regenerating the adsorbent and 53% of the metal ions are removal from the aqueous even in the fourth regeneration/reuse cycle, which imply that the nano- fibers can be suitable for water treatment as adsorbent.