Effects of caustic cleaning on pore size of nanofiltration membranes and their rejection of trace organic chemicals
Effects of caustic cleaning on pore size of nanofiltration membranes and their rejection of trace organic chemicals
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DOI：
10.1016/j.memsci.2013.07.013
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发表时间：
2013-11
影响因子：
9.5
通讯作者：
Alexander Simon;J. McDonald;Stuart J. Khan;W. Price;L. Nghiem
中科院分区：
文献类型：
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作者：
Alexander Simon;J. McDonald;Stuart J. Khan;W. Price;L. Nghiem
本研究的目的是评估苛性碱清洗对两种纳滤（NF）膜（即NF 270和NF 90）对三组痕量有机化学品（TrOC）（即中性亲水性，中性疏水性和带负电荷）的截留率的影响。通过将原始膜样品暴露于商业苛性碱清洁制剂以及含有分析级添加剂（如十二烷基硫酸钠或乙二胺四乙酸）的氢氧化钠溶液来模拟化学清洁。基于孔传输模型确定暴露于市售苛性碱清洁制剂之前和之后的膜平均孔径。结果表明，碱洗可使膜孔径增大，渗透率增加，电导率截留率降低。苛性碱清洗对孔径和溶质截留率的影响是膜活性表层和清洗制剂化学性质的函数。碱清洗导致NF 270膜的孔径略有增加，并导致渗透率和盐通过率显著增加。相比之下，对NF 90膜的影响可忽略不计。碱洗对TrOC截留率的影响取决于每个TrOC的物理特性，包括它们的分子大小、电荷和疏水性。NF 270膜对中性和疏水TrOC的截留率在暴露于苛性碱清洁制剂后显著降低。然而，由于带负电荷的TrOC的排斥主要由静电相互作用控制，因此它们的排斥不受苛性碱清洗的显著影响。
The aim of this study was to assess the impact of caustic cleaning on the rejection of three groups of trace organic chemical (TrOC) (i.e. neutral hydrophilic, neutral hydrophobic and negatively charged) by two nanofiltration (NF) membranes—namely NF270 and NF90. Chemical cleaning was simulated by exposing virgin membrane samples to commercial caustic cleaning formulations as well as sodium hydroxide solutions containing analytical grade additives such as sodium dodecyl sulphate or ethylenediaminetetraacetic acid. The membrane average pore size before and after exposure to a commercially available caustic cleaning formulation was determined based on the pore transport model. The results show that caustic chemical cleaning could cause an increase in the membrane pore size, leading to an increase in permeability and decrease in rejection of conductivity. The impact of caustic cleaning on the pore size and solute rejection was a function of the membrane active skin layer and the chemistry of the cleaning formulation. Caustic cleaning led to a small increase in pore size of the NF270 membrane and resulted in a notable increase in the permeability and salt passage. By contrast, the impact on the NF90 membrane was negligible. The influence of caustic cleaning on TrOC rejection was dependent on physical characteristics of each TrOC including their molecular size, charge, and hydrophobicity. The rejection of neutral and hydrophobic TrOC by the NF270 membrane decreased significantly after exposure to caustic cleaning formulation. However, because the rejection of negatively charged TrOC is governed mostly by electrostatic interaction, their rejection was not significantly affected by caustic cleaning.