乙二胺层层共价交联制备氧化石墨烯膜及其对微量有机物的去除机制

The toxic organic micro-pollutants in wastewater could lead to water quality risks during water reuse, limiting the safe uses of reclaimed water. Nanofiltration is an effective method for the removal of organic micro-pollutants in water. The disadvantages of the conventional polyamide composite membranes make the development of new membrane materials very necessary. Graphene oxide membranes have potential advantages of high water flux, strong antifouling capability and strong resistance to chlorine, having a promising application. This proposal will take ethylenediamine (ED) as interlayer covalent crosslinks and fabricate graphene oxide membranes by the layer-by-layer assembly, in order to overcome the structural instability of non-covalent crosslinking membranes and achieve the removal of organic micro-pollutants in wastewater.. In this research, we will study the fabrication processes of polyacrylonitrile (PAN) membrane and graphene oxide to regulate their performances, establish a fabrication method of ED-assisted layer-by-layer assembly including activation, first layer attachment and accumulation, and investigate the influence of PAN membrane, graphene oxide and fabrication conditions on the performance of graphene oxide membrane. Then, we will evaluate the removal of organic micro-pollutants by graphene oxide membranes, and analyze their removal mechanisms. The objective of this research is to promote the application of graphene oxide membranes in advanced wastewater treatment, and it will provide theoretical foundation and technical support for guaranteeing the safety of reclaimed water.

污水中的微量有毒有机物可导致污水再生利用中的水质风险，限制了再生水安全利用。纳滤膜分离技术是去除水中微量有机物的有效方法，但传统聚酰胺复合膜的缺点使得新型膜材料的开发十分必要。氧化石墨烯膜具有水通量高、抗污染强、耐氯性强等潜在优势，应用前景良好。本项目拟以乙二胺作为层间共价交联物，采用层层组装法制备氧化石墨烯膜，以克服非共价交联氧化石墨烯膜结构不稳定的问题，同时达到去除污水中微量有毒有机物的目的。. 本项目将研究聚丙烯腈基膜与氧化石墨烯的制备过程以调控二者材料特性，建立以“活化+首层交联+逐层累积”为主线的乙二胺共价交联层层组装制备法，考察聚丙烯腈基膜与氧化石墨烯特性以及制备工艺条件对共价交联氧化石墨烯膜性能的影响，评价氧化石墨烯膜对污水中微量有毒有机物的去除效果并解析其去除机制，为推进氧化石墨烯膜在污水深度处理中的应用、保障再生水水质安全提供理论依据和技术支持。

纳滤技术是去除水中微量有机污染物的有效方法，传统聚酰胺复合膜的缺点使得新型膜材料的开发十分必要。氧化石墨烯（GO）膜近年来在水处理领域受到广泛关注，但其在水中的稳定性是制约其应用的重要因素。本项目提出以乙二胺作为层间共价交联物，采用层层组装法制备氧化石墨烯膜，实现其对污水中微量有毒有机物的高效去除。. 研究首先成功地采用层层组装法制备了共价交联GO膜。通过XPS和FTIR表征分析，证明GO膜中成功引入了层间交联物乙二胺。通过XRD技术测定GO膜层间距，结合浸泡实验结果，表明交联膜比非交联膜的GO层更加稳定，更适合于水环境中的应用。. 研究进一步对GO膜的分离性能进行了优化。研究表明，使用更小尺寸的GO材料制备的GO膜，其水通量和无机盐截留率会更大；通过真空干燥减少GO膜微孔中残留的水分子，可以提高膜对无机盐的截留率；层间交联物可有效提高GO膜在过滤过程中的稳定性，同时还可提高GO膜对无机盐和小分子有机物的截留率。. GO膜对水中无机盐的去除率约为20%~40%，其中对一价阳离子的去除效果好于二价阳离子。GO膜对水中包括PPCPs在内的各类有机物的去除率一般可达80%以上。大分子有机物的去除机理主要为位阻作用，去除率较高且比较稳定。小分子有机物的去除机理包括位阻作用和静电作用，去除效果与其在水中的带电性有关。. 研究还发现，水中的无机阳离子可对GO膜的出水通量和分离性能产生影响。Na+可增大GO膜的层间距，导致GO膜通量升高、截留率下降；但与其他阳离子共存时，Na+的影响会减弱或消失。K+、Mg2+等对GO膜的影响不明显。而Ca2+可降低GO膜通量，提高其对有机物的去除率。在pH6~9的范围内，pH对GO膜分离性能的影响不明显。