基于水凝胶中间层的聚酰胺复合纳滤膜制备及对PPCPs的去除

【作者】 孙敏；

【导师】 赵斌；

【作者基本信息】 天津工业大学 ， 环境科学与工程， 2023， 硕士

【摘要】 饮用水源中药品和个人护理品（Pharmaceutical and Personal Care Products,PPCPs）的检测日益增多,对人体健康构成严重威胁。聚酰胺（PA）纳滤（NF）膜对水中PPCPs的去除具有很大潜力,但是由于疏水亲合力强,对小分子的中性疏水PPCPs去除效果不理想。近年来,水凝胶由于其亲水性以及无毒性被广泛应用在膜改性中,但是水凝胶的引入对于膜的通量会有所损失。金属有机骨架（Metal-Organic Frameworks,MOFs）具备多孔结构和可调节的拓扑结构,被广泛应用在提高纳滤膜性能中,尤其是对水通量的提升尤为明显。本研究将海藻酸钙（Calcium Alginate,CaAlg）水凝胶和UiO-66-NH₂金属有机骨架两者结合,制备出了既有高通量又有较高的PPCPs去除率的复合纳滤膜。具体研究内容如下:（1）通过在界面聚合反应前将CaAlg水凝胶溶液过滤在亲水改性聚丙烯腈（HPAN）基膜上,制备了CaAlg/PA复合纳滤膜。CaAlg水凝胶中间层提升了膜表面的亲水性,降低疏水亲和力,提升了PPCPs的去除率。并且CaAlg水凝胶中间层促使膜表面形成管状条纹结构,增加了渗透面积,提升了水通量。优化后的CaAlg/PA复合纳滤膜CA-0.7膜,CaCl₂溶液的添加量为0.7 mL。CaAlg/PA复合纳滤膜的纯水通量随着CaCl₂溶液添加量的增加而逐渐增大（CA-0.9除外）,其中CA-0.7膜的纯水通量达到17 L·m^-2·h^-1·bar^-1,与薄膜复合膜（TFC）相比提高了40%。亲水性增强的PA层降低了对PPCPs的吸附,降低了PPCPs扩散的驱动力。CaAlg/PA复合纳滤膜对PPCPs的去除率也随着CaCl₂溶液的添加量的增加而增大,其中CA-0.7膜对对羟基苯甲酸甲酯（Methylparaben,MP）、对羟基苯甲酸丙酯（Propylparaben,PP）、双酚A（Bisphenol A,BPA）和对羟基苯甲酸苄酯（Benzylparaben,BP）的去除率分别为45%、53%、74%和87%,水/BP的选择性是TFC的3.7倍。结果表明,引入亲水性CaAlg水凝胶中间层是提高PPCPs去除率的有效策略。（2）为了进一步提高CaAlg/PA复合纳滤膜的通量,在界面聚合中的水相溶液中引入UiO-66-NH₂纳米颗粒,制备了UiO-66-NH₂/CaAlg/PA复合纳滤膜。UiO-66-NH₂聚集体自身所具备的孔道以及与膜表面形成的界面间隙提供了更多水通道,有效的提升了膜的水渗透率。优化后的UiO-66-NH₂/CaAlg/PA复合纳滤膜UIO-9膜,UiO-66-NH₂纳米颗粒的沉积量为9 mL。UiO-66-NH₂/CaAlg/PA复合纳滤膜的纯水通量随着UiO-66-NH₂纳米颗粒沉积量的增加而增大,其中UIO-9膜的纯水通量达到23 L·m^-2·h^-1·bar^-1,与TFC相比提高了83%,对Na₂SO₄的截留率为92%。并且UiO-66-NH₂纳米颗粒的引入没有明显影响纳滤膜本身的理化性质,仍然保持了良好的PPCPs去除率。结果表明,引入亲水MOFs是提高纳滤膜水通量的有效策略。更多还原

【Abstract】 The increasing detection of pharmaceutical and personal care products（PPCPs）in drinking water sources poses a serious threat to human health.Polyamide（PA）nanofiltration（NF）membrane has great potential to remove PPCPs from water,but the removal of neutral and hydrophobic PPCPs is not ideal because of its strong hydrophobic affinity.In recent years,hydrogels have been widely used in membrane modification because of their hydrophilicity and nontoxicity,but the introduction of hydrogels will lose the flux of membrane.Metal-organic frameworks（MOFs）are widely used to improve the performance of nanofiltration membranes,especially to enhance the water flux.In this study,calcium alginate（CaAlg）hydrogel and UiO-66-NH₂ metal-organic framework were combined to prepare composite nanofiltration membranes with high flux and high PPCPs removal rate.The specific research contents are as follows:（1）CaAlg/PA membranes were prepared by filtrating the CaAlg hydrogel solution onto hydrophilic modified polyacrylonitrile（HPAN）substrates before interfacial polymerization reaction.The intermediate layer of CaAlg hydrogel increased the hydrophilicity of the membrane surface,decreased the hydrophobic affinity and increased the rejection of PPCPs.Furthermore,the CaAlg hydrogel interlayer promotes the formation of a tubular stripe structure on the membrane surface,increases the permeation area and increases the water flux.The optimized CaAlg/PA composite nanofiltration membrane CA-0.7,CaCl₂ solution addition was 0.7 mL.The pure water flux of CaAlg/PA composite nanofiltration membrane increased with the increase of CaCl₂solution addition（except CA-0.9）,and the pure water flux of CA-0.7 membrane reached 17 L·m^-2·h^-1·bar^-1,compared with TFC film,it was improved by 40%.The enhanced hydrophilicity of PA layer decreased the adsorption of PPCPs and the driving force of PPCPs diffusion.The removal rate of PPCPs by CaAlg/PA composite nanofiltration membrane also increased with the increase of CaCl₂ solution（except CA-0.9）,the removal rates of methylparaben（MP）,propylparaben（PP）,bisphenol A（BPA）and benzylparaben（BP）by CA-0.7 membrane were 45%,53%,74%and 87%,respectively,the selectivity of water/BP was 3.7 times that of TFC.The results show that the introduction of hydrophilic CaAlg hydrogel intermediate is an effective strategy to improve the removal rate of PPCPs.（2）In order to improve the flux of CaAlg/PA composite nanofiltration membrane,UiO-66-NH₂ nanoparticles were introduced into the aqueous solution of interfacial polymerization,UiO-66-NH₂/CaAlg/PA composite nanofiltration membrane was prepared.The pores of the UiO-66-NH₂aggregates provide more water channels,ease the hydrophobic affinity,and effectively enhance the water permeability of the membrane.The optimized UiO-66-NH₂/CaAlg/PA composite nanofiltration membrane UIO-9 membrane,UiO-66-NH₂ nanoparticles deposition amount was 9mL.The pure water flux of UiO-66-NH₂/CaAlg/PA composite nanofiltration membrane increased with the increase of the deposition of UiO-66-NH₂nanoparticles（except UIO-12）,and the pure water flux of UIO-9 membrane reached 23L·m^-2·h^-1·bar^-1,which was 83%higher than that of TFC,and the retention rate of Na₂SO₄ was 92%.Moreover,the introduction of UiO-66-NH₂ nanoparticles did not affect the physical and chemical properties of the nanofiltration membrane,and still maintained good PPCPs removal rates（MP,PP,BP,BPA removal rates were 44%,52%,72%and 87%,respectively）.The results show that the introduction of hydrophilic MOFs is an effective strategy to increase the water flux of nanofiltration membranes.更多还原