聚酰胺复合纳滤膜表面接枝硅烷偶联剂及其性能研究

发布时间：2018-06-24 23:01

本文选题：纳滤膜 + 表面接枝　；参考：《浙江理工大学》2017年硕士论文

【摘要】：纳滤膜具有高效率、低能耗等优点,被广泛用于地表水有机物、地下水硬度、部分溶解性盐的去除和染料分离浓缩等领域,但膜污染则是目前制约纳滤膜规模化应用的关键因素。因而,提高纳滤膜的抗污染性能对于纳滤膜技术的发展具有重要意义。本课题选用3-氨基丙基三乙氧基硅烷(APTES)作为改性材料,利用初生态聚酰胺复合纳滤膜表面的残留酰氯基团与APTES之间的反应,对聚哌嗪酰胺纳滤膜进行表面接枝改性,研究表面改性对复合膜表面性质、分离性能及抗污染性能的影响规律。采用ATR-FTIR、XPS、FE-SEM、AFM、接触角和Zeta电位等手段对复合膜表面性质和形貌结构进行表征。采用错流分离装置系统地研究了复合膜的切割分子量及膜对不同无机盐和有机染料的分离性能。以腐殖酸(HA)、阳离子表面活性剂(DTAB)和牛血清蛋白(BSA)作为特征污染物,考察复合膜的抗污染性能。结论如下:(1)ATR-FTIR和XPS结果表明,初生态复合膜表面未反应的酰氯基团和APTES发生了酰胺化或酯化反应,利用表面二次反应技术可以成功地将APTES接枝到复合膜的表面;分离层孔径由0.88 nm变为0.84 nm,复合膜表面变得更加的致密,复合膜的切割分子量由290 Da降至260 Da。改性使粗糙度略微上升,均在20 nm以下,表面改性并未对其表面粗糙度造成很大的影响。静态接触角测试表明,复合膜接触角由58°下降至46°,复合膜的亲水性有所增加。Zeta测试显示复合膜表面的电负性下降,且接枝的浓度越大,电负性下降的越多。(2)APTES的浓度及反应时间影响改性膜的表面性质和分离性能。增加APTES浓度和延长反应时间可增强接枝效果,但酰胺化反应或酯化反应与酰氯的水解反应为竞争关系,继续增大反应浓度或延长反应时间改性效果变化不大。为了得到综合分离性能最优的复合膜,最终确定APTES改性浓度为0.4 wt%,反应时间为4 min,在此条件下,根据XPS分析可知,初生态膜表面的残留酰氯基团发生酰胺化、酯化和水解反应的比例为13.2%、17.6%和69.2%。(3)聚酰胺复合纳滤膜表面接枝APTES以后,在25℃、0.5 MPa的操作条件下,复合膜的水通量由67.9 LMH上升至73.3 LMH,脱盐率由97.83%下降至96.08%,二者之间存在着Trade-off效应;复合纳滤膜对无机盐的截留顺序为Na2SO4MgSO4NaClMgCl2,符合一般荷负电纳滤膜对无机盐的截留规律;染料分离试验发现,复合膜对染料的截留顺序为:结晶紫㧐玫瑰红B㧐甲酚红㧐亚甲基蓝㧐中性红,改性膜对染料的脱除率、通量皆优于原膜;染料的分离提纯实验表明,经过10 h的染料提纯试验,料液中的盐含量分别降至起始浓度的5.53%和0.62%,提纯时间缩短,提纯通量较原膜高出7.0%。(4)聚酰胺复合纳滤膜表面接枝APTES可提高复合膜的抗污染性能。对于DTAB、HA和BSA水溶液,改性膜的通量下降速率明显低于原膜,原膜与改性膜过滤DTAB溶液的平衡通量下降率分别为39.6%和29.7%、过滤HA溶液的平衡通量下降率分别为28.0%和25.8%、过滤BSA溶液的平衡通量下降率分别为33.7%和26.8%。经过原位清洗以后,改性膜的通量恢复率高于原膜,DTAB污染膜的通量恢复率由原始膜的90.6%提高到改性膜的96.0%、HA污染膜的通量恢复率由原始膜的88.0%提高到改性膜的93.0%、BSA污染膜的通量恢复率由原始膜的82.5%提高到改性膜的91.3%。
[Abstract]:Nanofiltration membrane has many advantages, such as high efficiency, low energy consumption and so on. It is widely used in the fields of surface water organic matter, groundwater hardness, removal of partial dissolved salt and dye separation and concentration, but membrane pollution is the key factor restricting the large-scale application of nanofiltration membrane. Therefore, the improvement of the anti pollution performance of nanofiltration membrane has been developed for nanofiltration membrane technology. It is important to use 3- amino propyl triethoxy silane (APTES) as a modified material. The surface grafting of polypiazine amide nanofiltration membrane was modified by the reaction between the residual acyl chloride group and APTES on the surface of the membrane surface of the first ecological polyamide composite nanofiltration membrane. The surface properties, separation properties and pollution resistance of the surface modification on the composite membrane were studied. The surface properties and morphology of the composite films were characterized by means of ATR-FTIR, XPS, FE-SEM, AFM, contact angle and Zeta potential. The cutting molecular weight of the composite membrane and the separation performance of the membrane to different inorganic salts and organic dyes were systematically studied. Humic acid (HA) and cationic surfactant (D) were used. TAB) and bovine serum protein (BSA) as the characteristic pollutants to investigate the anti pollution properties of the composite membrane. Conclusions as follows: (1) the results of ATR-FTIR and XPS showed that the acyl chloride group and APTES of the surface of the first ecological composite membrane were amidation or esterification, and the surface of the composite membrane could be successfully grafted on the surface of the composite membrane by using the surface two reaction techniques. The pore size of the separation layer changed from 0.88 nm to 0.84 nm, and the surface of the composite membrane became more compact. The cutting molecular weight of the composite membrane was reduced from 290 Da to 260 Da., and the roughness slightly increased, all of which were below 20 nm. The surface modification did not greatly influence the surface roughness. The static contact angle test showed that the contact angle of the composite film decreased from 58 to 46. The hydrophilicity of the composite film increased by.Zeta test. The electronegativity of the surface of the composite membrane decreased, and the greater the concentration of the graft, the more electronegativity decreased. (2) the concentration and reaction time of APTES influence the surface properties and separation properties of the modified membrane. Increasing the APTES concentration and prolonging the reaction time can enhance the graft effect, but the acylation reaction or ester The reaction was competitive with the hydrolysis reaction of acyl chloride, and the effect of the reaction time was not changed. In order to obtain the composite membrane with the best comprehensive separation performance, the APTES modified concentration was determined to be 0.4 wt% and the reaction time was 4 min. Under this condition, the residual acylation of the surface of the first ecological membrane could be found. After the chlorination of the chlorine group, the proportion of the esterification and hydrolysis reaction is 13.2%, 17.6% and 69.2%. (3) polyamide composite nanofiltration membrane graft APTES. Under the conditions of 25 C and 0.5 MPa, the water flux of the composite film rises from 67.9 LMH to 73.3 LMH, the desalination rate decreases from 97.83% to 96.08%, and there is a Trade-off effect between the two. The retention order of the membrane to inorganic salts is Na2SO4MgSO4NaClMgCl2, which conforms to the rule of the retention of inorganic salts in the general negative electric nanofiltration membrane. The dye separation test found that the retention order of the dyes by the composite membrane is crystal violet, rose red B, cresol red, methylene blue, neutral red, and the flux of the modified membrane is superior to the original film; the separation and extraction of the dye The pure experiment showed that after 10 h dye purification test, the salt content in the liquid was reduced to 5.53% and 0.62% of the initial concentration, the purification time was shortened, and the surface grafting APTES of 7.0%. (4) polyamide composite nanofiltration membrane higher than the original membrane could improve the anti pollution performance of the composite membrane. For DTAB, HA and BSA aqueous solutions, the flux decline rate of the modified membrane was reduced. The rate of balance flux of the original film and modified membrane filtration DTAB solution was 39.6% and 29.7%, respectively, and the balance flux decreased by 28% and 25.8% in the filtered HA solution, respectively, and the decrease rate of the equilibrium flux of the filtered BSA solution was 33.7% and 26.8%. after the in-situ cleaning, and the flux recovery rate of the modified membrane was higher than that of the original film and DTAB. The flux recovery rate of the dyed membrane is increased from 90.6% of the original film to 96% of the modified membrane. The flux recovery rate of the HA fouling film is increased from 88% of the original film to 93% of the modified membrane. The flux recovery rate of the BSA fouling film is increased from 82.5% of the original film to the 91.3%. of the modified membrane.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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