State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
Tsinghua University, Beijing, 100084, China.
Chemosphere. 2019 Dec;237:124544. doi: 10.1016/j.chemosphere.2019.124544. Epub 2019 Aug 12.
This study evaluated the effects of co-existing cations (Na or Ca) on the lamellar structure of cross-linked graphene oxide (GO) layers and GO modified membrane performance in terms of their fouling behaviours and retention for single-model organic matter, namely, bull serum albumin (BSA), sodium alginate (SA), humic acid (HA) and tannic acid (TA). In the absence of co-existing cations, the GO layers mitigated membrane fouling for large molecules (SA, BSA, and HA) but led to severer pore blocking for small molecules (TA) compared with pristine membrane. Na and Ca altered the performance impacts of the GO modified membrane due to different interactions with the cross-linked GO layers. Low concentrations of Na (<0.4 mM) enlarged interlayer spacing of the GO layers and caused a decrease in flux after physical cleaning, but the GO layers maintained the uniform lamellar structure. High concentrations of Na (>0.4 mM) promoted the aggregation of cross-linked GO layers through charge shielding and reduced the uniformity of lamellar structure, which weakened the antifouling performance for large molecules and promoted the passage of small molecules through the membrane. However, Ca complexed with GO sheets and reinforced the uniform lamellar structure of the GO layers, leading to a better antifouling performance for the filtration of large molecules than the pristine membrane but aggravated TA fouling.
本研究评估了共存阳离子（Na 或 Ca）对交联氧化石墨烯（GO）层的层状结构以及 GO 改性膜在污染行为和对单模型有机物（即牛血清白蛋白（BSA）、海藻酸钠（SA）、腐殖酸（HA）和单宁酸（TA））保留方面的性能的影响。在不存在共存阳离子的情况下，与原始膜相比，GO 层减轻了对大分子（SA、BSA 和 HA）的膜污染，但导致对小分子（TA）的孔堵塞更严重。由于与交联 GO 层的不同相互作用，Na 和 Ca 改变了 GO 改性膜的性能影响。低浓度的 Na（<0.4 mM）扩大了 GO 层的层间距，并在物理清洗后导致通量下降，但 GO 层保持了均匀的层状结构。高浓度的 Na（>0.4 mM）通过电荷屏蔽促进了交联 GO 层的聚集，并降低了层状结构的均匀性，这削弱了对大分子的抗污染性能，并促进了小分子通过膜的传递。然而，Ca 与 GO 片层络合并增强了 GO 层的均匀层状结构，导致过滤大分子时的抗污染性能优于原始膜，但加剧了 TA 的污染。
