壳聚糖-SiO_(2)气凝胶/纤维素/聚丙烯复合水刺材料的制备及其吸附染料性能

Preparation of chitosan-SiO_(2)aerogel/cellulose/polypropylene composite spunlaced nonwovens and adsorption dye performance

为制备用于有机染料废水处理的生物质材料,以纤维素纤维/聚丙烯(CF/PP)为基材,经氧化后与以壳聚糖(CS)和硅酸四乙酯(TEOS)为原料制备的CS-SiO_(2)混合溶液进行反应,再通过冷冻干燥得到CS-SiO_(2)气凝胶/氧化纤维素(OCF)/PP复合水刺非织造材料。对复合材料的形貌、结构和其对有机染料吸附性能进行测试与表征,结果表明:相较于CF/PP水刺非织造材料,CS-SiO_(2)气凝胶/OCF/PP复合水刺非织造材料表面出现明显的微孔结构,在OCF/PP水刺非织造材料表面出现了归属于CS和SiO_(2)的红外特征峰;当TEOS体积分数为25%时,制得的样品在30℃、pH值为7的条件下对亚甲基蓝(MB)的吸附效率可达99.63%,经5次重复使用后,其对MB的吸附效率仍保持在80.59%左右;相比于CF/PP水刺非织造材料,CS-SiO_(2)气凝胶/OCF/PP复合水刺非织造材料的拉伸强度和断裂伸长率略有下降。

Objective The cellulose fiber(CF)spunlaced nonwovens have the advantages of wide availability,low cost,excellent mechanical properties,and large specific surface area.However,as adsorption materials,cellulose and its derivatives have limited potential for intramolecular chain interactions and hydrogen bonding with organic dyes.In order to expand the application of cellulose-based spunlaced materials in the treatment of organic dye wastewater,CF/polypropylene(PP)spunlaced nonwovens with the mass ratio of 9∶1 was used as substrate material and oxidated.Then chitosan(CS)-silicon dioxide(SiO_(2))aerogel was prepared by sol-gel method and loaded on the surface of the oxidated CF(OCF)/PP spunlaced nonwovens to prepare CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens.Method After oxidation,the OCF/PP spunlaced nonwoven fabric was used as the substrate and reacted with a mixed solution of CS and tetraethyl orthosilicate(TEOS)with different volume fractions via the sol-gel method,and then CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwoven fabric was obtained by freeze drying.The optimal volume fraction of TEOS in the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwoven material was determined based on the studies of the morphology,structure,and organic dye adsorption performance of the composite spunlaced nonwovens.Additionally,the mechanical properties of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwoven material were investigated.Results When the volume fraction of TEOS increased to 25%,the pores on the surface of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwoven became smaller and more densely distributed compared to the CF/PP spunlaced nonwovens material,and many micropores generated on the pore walls,providing more adsorption sites for organic dyes.FT-IR characteristic peaks belonging to CS and SiO_(2) appeared on the surface of the OCF/PP spunlaced nonwovens.Compared to the OCF/PP spunlaced nonwovens,the diffraction peaks at 2θ of 14.39°and 17.22°in the XRD pattern of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5^(#))were significantly weakened,indicating a reduction in the crystallinity of the reconstituted polysaccharide structure.The CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5#)exhibited higher adsorption efficiency for cationic dyes than those of anionic dyes.The adsorption efficiency of CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens for MB increased when the volume fractions of TEOS increased.When the volume fraction of TEOS was 25%,the adsorption temperature was 30℃,and the pH of adsorption solution was 7,the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens exhibited the highest adsorption MB efficiency,reaching 99.63%.Compared with the pseudo-first-order adsorption model,the pseudo-second-order adsorption model showed better agreement with the experimental results,indicating that the main adsorption MB mechanism of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5^(#))was chemical adsorption.The adsorption thermodynamic analysis indicated that the adsorption MB of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5#)was a spontaneous process.After five cycles,the adsorption MB efficiency of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5#)remained around 80.59%.Compared to the CF/PP spunlaced nonwovens,the tensile strength and elongation at break of the CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens(5#)showed a slight decrease.Conclusion The CS-SiO_(2) aerogel/OCF/PP composite spunlaced nonwovens exhibited the highest adsorption performance(99.63%)when the volume fraction of TEOS was 25%,the adsorption temperature was 30℃,and pH was 7.The composite nonwovens demonstrated good stability and reusability.The findings of this study would be useful for expanding the application of the CF/PP spunlaced nonwovens in the water treatment industry.