【作者】 王芳；

【导师】 李凭力； 徐义明；

【作者基本信息】 天津大学 ， 化学工程， 2018， 硕士

【摘要】 本文以亲水性氧化石墨烯(GO)为添加剂,采用热致相分离法制备得到具有高拉伸强度、高水通量和良好抗污染性能的iPP/GO共混膜。论文研究了制膜过程中喷丝头温度,空气隙距离,水浴温度对膜形貌结构,拉伸强度,压密性,孔径分布,孔隙率以及水通量的影响规律。研究结果表明:iPP/GO中空纤维膜均呈现出较好的双连续结构,孔隙率变化较小。随着喷丝头温度升高,拉伸强度,压密性和水通量均随之先增大后减小;随着空气隙距离和水浴温度的增大,拉伸强度减小,平均孔径、水通量和压密性均呈上升趋势;在优化的制膜条件下,改变GO的添加量,并采用了SEM,FTIR,XPS,接触角以及水通量等方式进行了表面形貌以及性能的一系列表征测试。研究发现随着GO添加量的增加,膜的接触角从125°降到52.33°,降低了58.14%,呈现了较好的亲水性;FTIR测试表明,改性后的膜表面出现了亲水的羟基和羧基基团;XPS的测试结果表明,改性后的iPP/GO膜中出现了氧元素,并呈上升趋势,进一步证实了GO与聚丙烯实现了较均一的混合状态。与此同时,iPP/GO共混膜的各项性能均随之先升高后降低。当GO含量为0.3%时,膜性能最好,孔隙率为67.67%,水通量达到1345 L/(m~2.h),平均孔径达0.4722μm。本文分别对牛血清蛋白溶液、奶粉溶液和乳化油溶液进行了过滤,并分析了膜的抗污染性能。结果表明,GO改性膜通量的衰减速率均小于纯聚丙烯膜,其中添加量为0.3%时,共混膜的衰减率最小,清洗之后的水通量恢复率最高。在过滤乳化油过程中,改性膜的截留率稍有下降,最低为89.2%;纯聚丙烯膜的稳定通量为22.44 L/(m~2.h),而0.3%共混膜则达301.53 L/(m~2.h);对污染膜采用不同的清洗方法,其中SDS的清洗效果最佳,未改性膜的通量恢复率为67.07%,而0.3%共混膜为93.99%,并发现提高清洗溶液的温度有利于提高iPP/GO膜的通量恢复。更多还原

【Abstract】 In this paper,an iPP/GO blend membrane was prepared by thermal phase separation method using grapheme oxide(GO)as modifier with high tensile strength,high water flux and good anti-pollution performanceWe mainly investigated the influence of spinneret temperature,air gap distance,water bath temperature on membrane structure,tensile strength,compaction,pore size distribution,porosity and water flux.The results show that the polypropylene hollow fiber membrane exhibits a good bi-continuous structure,and the porosity is basically unchanged.As the spinneret temperature increases,the tensile strength,compacting and water flux increase firstly and then decrease.The tensile strength decreases,and the average pore diameter,water flux and compactness are on the rise with the increase of air gap distance and water bath temperature.In the optimized operating condition,SEM,FTIR,XPS,contact angle and water flux were used in the detailed characterization with GO addition changing.The study found that with the addition of GO,the contact angle of polypropylene film decreased from 125°to 52.33°and decreased by 58.14%.The FTIR test shows that hydrophilic hydroxyl group and carboxyl group are present on the modified membrane surface.The test results of XPS show that oxygen elements appeared in the modified polypropylene membrane and exhibits a rising trend,which further confirms that GO successfully mixes into polypropylene membrane.At the same time,the performance of the polypropylene blend membrane was increased and then decreased.When the GO content was 0.3%,the membrane performance was the best,the porosity was 67.67%,and the water flux reaches 1345 L/(m~2.h),with an average pore diameter of 0.4722μm.The antifouling properties were analyzed by the filtration of bovine serum protein solution,milk powder solution and emulsified oil solution.The results show that the attenuation rate of GO modified film flux is less than that of pure polypropylene film,and the attenuation rate of the blend film is the minimum when the amount of the GO addition is 0.3%,and the water flux recovery rate is the highest after cleaning.In the process of emulsified oil filtration,the retention rate of modified film decreased slightly to 89.2%.The stable flux of pure polypropylene film was 22.44 L/(m~2.h),while the 0.3%blend film was 301.53 L/(m~2.h).Different cleaning methods were adopted to cleanpolluted membrane,and SDS achieved the best cleaning effect.Unmodified membrane flux recovery rate was just 67.07%,and 0.3%GO addition blend membrane is 93.99%.Moreover,it shows that raising the temperature of the cleaning solution can improve the flux recovery of polypropylene membrane.更多还原