Removal of heavy metal ions from aqueous solution using amidoxime-functionlized SiO2/PVA composite nanofibers prepared by sol-gel electrospinning
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摘要: 通过静电纺丝技术制备酰肟化功能改性的纳米SiO2/聚乙烯醇（SiO2/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+、Ni2+金属离子的最大吸附量分别为143.7 mg/g和125.1 mg/g，平衡吸附时间为240 min。在纤维膜吸附的前50 min内，SiO2/PVA纤维膜对Cu2+和Ni2+金属离子的吸附量为126.8 mg/g和109.8 mg/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SiO2/PVA纤维对Cu2+和Ni2+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。Abstract: 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 adsorption occurs at pH=6 and the adsorption capacity can be 143.7 mg/g and 125.1 mg/g for Cu2+ and Ni2+, respectively. The composite SiO2/PVA nanofibers can remove almost 90% aforementioned ions from aqueous solutions within 50 min. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order kinetic model, 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 nanofibers can be suitable for water treatment as adsorbent.
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Keywords:
- electrospinning /
- amidoxime-functionlized /
- nano fibers /
- adsorbent /
- heavy metal ion
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