纤维素纳米纤维水凝胶的构筑与吸附性能研究

Synthesis,characterization and adsorption property of cellulose nanofiber-based hydrogels

现代化工农业生产和食品加工过程中产生的大量废水,给生态环境带来了严重负面影响。废水色度是水质污染的一个重要指标,因此寻求有色废水的高效处理技术是目前的研究热点之一。笔者试图构建环境友好型纤维基纳米材料吸附剂,并就其结构、吸附机制与性能以及实际应用的安全性进行分析与评价。基于静电纺丝-原位水解-水溶液聚合简易多步法,以纳米纤维中纤维素分子为反应对象、过硫酸铵(APS)为反应引发剂、丙烯酸(AA)和丙烯酰胺(AM)为反应单体、N,N-亚甲基双丙烯酰胺(MBA)为反应交联剂,成功研制了具有三维网络多孔结构的互穿纤维素纳米纤维水凝胶(CNF-HGs)。通过扫描电子显微镜(SEM)、傅里叶红外光谱仪(FTIR)、热重分析仪(TGA)进行表征及亚甲基蓝(MB)溶液吸附性能测试与吸附动力学研究,从CNF-HGs的微观形貌、分子结构以及热稳定性能方面揭示了其良好的吸附能力与作用机理。细胞毒性试验进一步验证了其良好的细胞相容性和低毒性,有助于降低水处理中二次污染的可能性。研究结果可为纤维基生物吸附剂在有色污水吸附乃至其他废水处理与防治的应用中提供理论依据。

The presence of water pollution poses a major concern for public health. Large amounts of waste water generated from industries,agriculture and food processing processes have caused the negative effects on the environment. The chromaticity of wastewater is an important index of water pollution. Therefore,colored waste has been considered as one of the major sources of water pollution,which is a hot research topic to seek an efficient way for the colored wastewater treatment. Several technologies,such as physical,chemical,biological methods or various combinations of them have been employed to clear the colored water. Nevertheless,these methods are proved to be either high cost or low efficiency,some even generating secondary pollution. Considerable attention has presently been devoted to developing nanoscale biomass materials as adsorbents for wastewater treatment. But,the correlation between structural feature of adsorbents and removal capability still remains to be further elucidated. In this paper,an environment-friendly cellulose-based adsorbent was prepared and its structure,adsorption mechanism and properties as well as safety in practical application were evaluated. Based on the united technology of electrospinning-in situ hydrolysis-aqueous solution polymerization,a three-dimensional porous cellulose nanofibers-based hydrogels( CNF-HGs) with pore structure and functional groups were successfully developed by grafting acrylic acid( AA) and acrylamide( AM) onto cellulose backbone chains in the nanofibers( cellulose as response object,ammonium persulfate( APS) as initiator,AA and AM as reaction monomers,and N,N-methylene double acrylamide( MBA) as crosslinking agent reaction). The microscopic morphology,molecular structure,and thermal stability of CNF-HGs were characterized by the scanning electron microscope( SEM),Fourier infrared spectrometer( FT-IR),and thermogravimetric analyzer( TGA). On account of the methylene blue( MB) solution adsorption test,the obtained CNF-HGs showed good adsorption performance because porous structure facilitated MB diffusion and provided more active sites to strengthen the attraction between functional groups( e.g.,carbonyl and amino groups) and MB molecules. The cytotoxicity experiment also further verified that CNF-HGs had good cellular compatibility and low toxicity,which may reduce the possibility of secondary pollution in water treatment. This work is important because it provides not only a facile approach to synthesis adsorbent for pollutant removal,but also interesting information concerning the adsorption performance influenced by pore structure and surface functional groups.Results from this work may provide a promising cellulose-based bioadsorbent that can be used as an emerging material in large-scale wastewater treatment.