【摘要】 纤维素、壳聚糖等天然多糖形成的水凝胶力学性能较弱,在应用中受到限制。该文利用香蕉纤维素-壳聚糖为第一层刚性网络,以聚丙烯酰胺为第二层柔性网络,通过"一锅法"制备了香蕉纤维素-壳聚糖/聚丙烯酰胺(cellulosechitosan/polyacrylamide, Ce-Cs/PAAM)双网络水凝胶,并采用傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)、扫描电子显微镜(scanning electron microscope,SEM)、X射线衍射(X-ray diffractometer,XRD)等对双网络水凝胶结构进行了表征,并分析其力学性能、溶胀性能和吸附性能。结果表明,Ce-Cs/PAAM水凝胶是一种三维多孔、双网络状结构,具有优良的机械强度和韧性,在90%的压缩应变下,其最大压缩应力可以达到60 MPa;水中的溶胀度为9.56 mg/mg,在pH值为12的溶液中溶胀度为15.34 mg/mg;Ce-Cs/PAAM双网络水凝胶吸附Cu2+试验结果表明,在Cu2+的初始浓度为350 mg/L、pH值为5.5、吸附时间为90 min时,最大吸附量为312.4 mg/g。该文制备的CeCs/PAAM双网络水凝胶方法简单、力学性能、吸附性能优良,在重金属离子吸附领域具有一定的应用前景。更多还原

【Abstract】 Hydrogel can significantly expand in water and maintain their original structures and properties. Hydrogels have a promising application in enrichment and separation of low concentration heavy metal ions, because of the large adsorption capacity, fast adsorption speed, easy analysis, rich source and being environmentally friendly. However, the traditional hydrogel adsorbents prepared from chitosan, cellulose and other natural polysaccharides have poor mechanical properties, so it is necessary to synthesize a hydrogel adsorbent having good mechanical properties, which restricte their application in heavy metal adsorption. In this work, cellulose-chitosan/polyacrylamide(Ce-Cs/PAAM) double network hydrogel was prepared by a one-pot method. 0.5 g of banana fiber cellulose and 0.5 g of chitosan were dispersed in 20 mL of 0.1 mol/L acetic acid(the precursor solution for the first network) and stirred at 60 ℃ for 5 h. The chitosan could be dissolved quickly while the banana fiber cellulose was partially dissolved. Then 4.26 g of acrylamide(the precursor solution for the second network) and 3 mL of epichlorohydrin(crosslinking agent) were added into the solution by magnetic stirring at 25 ℃ for 1 h. After that, 0.02 g of N,N-methylene diacrylamide(crosslinking agent), 0.02 g of potassium persulfate(initiator), and 0.2 g of α-ketoglutaric acid(light initiator) were added to the mixed solution and stirred for 15 min.The first and second network were polymerized and crosslinked simultaneously. The obtained solution was placed at 25 ℃ for 24 hours. The two polymer networks generated upon UV-curing for 6 hours to further polymerized the second layer of networked(polyacrylamide) under the action of light initiator, followed by washing in deionized water twice a day for 7 days to produce a white opaque gel. Cellulose-chitosan(CeCs) and polyacrylamide(PAAM) hydrogel were prepared as control. The structure of the three types of hydrogels were characterized by Fourier transform infrared spectroscopy(FTIR), scanning electron microscope(SEM) and X-Ray Diffractometer(XRD). The changes of functional group composition, surface structure, crystallization degree, mechanical properties, swelling properties and adsorption properties of samples were investigated. The results showed that the Ce-Cs/PAAM hydrogel was a three-dimensional porous and double network structure with excellent mechanical strength and toughness. Under the compressive strain of 90%, the maximum compressive stress was reached to 60 MPa. The swelling ratio in water was 9.56 mg/mg, and the swelling ratio in alkaline solution(pH 12) reached to 15.34 mg/mg. The maximum adsorption capacity of Cu2+ ions on Ce-Cs/PAAM hydrogel was 312.4 mg/g(Qe) under the concentration of C0 at 350 mg/L,pH at 5.5 and adsorption time for 90 min. Compared with polyacrylic acid/humus double network hydrogel(151.00 mg/g),the adsorption capacity of sample for Cu2+ ions was increased significantly. Therefore, the results indicated that Ce-Cs/PAAM double network hydrogel may be a promising Cu2+ ions adsorbent.更多还原