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A systematic study on triazine retention by fouled with humic substances NF/ULPRO membranes

机译：对腐殖质NF / ULPRO膜污染的三嗪截留的系统研究

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Naturally occurring organic compounds tend to form complexes with divalent cations and micro-pollutants, and to foul membrane surfaces; both phenomena have a significant effect on pollutant rejection. Previous study results show the significant influence of triazine herbicides complexation, with dissolved humic substances, on their rejection by NF/ULPRO membranes. The net effect of fouled membranes, on triazine retention, is systematically investigated herewith by comparing the performance of three types of clean and fouled membranes and relating them to changes observed in membrane surface characteristics. Two typical triazines (atrazine and prometryn) and three well characterized humic substances (HS) are employed. The results show that humic substances deposited on the membrane surfaces cause considerable changes of their characteristics, including the contact angle and salt retention, which affect water permeability and triazine retention. Specifically, a strong correlation is identified between the hydrophobicity/ hydrophilicity of dissolved HS and the resistance to flow of the fouling layer, which affects the retention of the smaller-size triazines. This trend is related to the condition of organic layers on the membrane. Generally, relatively loose fouling layers on the membranes are associated with reduced triazine retention. However, rather dense fouling layers formed by complexes of HS with calcium exhibit significant flux decline and an improved sieving effect on triazines. Moreover, tight and hydrophobic membranes display significant changes of triazine retention when fouled by HS of increased hydrophobicity. On the contrary, porous and hydrophilic membranes display significant changes of triazine retention only when fouled by HS of reduced hydrophobicity. The new results highlight the heed for good knowledge of the properties characterizing the organic matter present in natural waters, before their treatment process is designed.
机译：天然存在的有机化合物往往会与二价阳离子和微污染物形成络合物，并污染膜表面。两种现象都对污染物的排阻产生重大影响。先前的研究结果表明，三嗪类除草剂与溶解的腐殖质络合对它们被NF / ULPRO膜排斥的影响很大。通过比较三种类型的清洁膜和污损膜的性能，并将它们与膜表面特性的变化联系起来，系统地研究了膜污染对三嗪保留的净影响。使用了两种典型的三嗪（阿特拉津和脯氨酰胺）和三种表征良好的腐殖质（HS）。结果表明，沉积在膜表面的腐殖质会引起其特性的显着变化，包括接触角和盐分保留，从而影响透水性和三嗪的保留。具体而言，在溶解的HS的疏水性/亲水性与结垢层的流动阻力之间存在强相关性，这影响了较小尺寸的三嗪的保留。这种趋势与膜上有机层的状况有关。通常，膜上较疏松的污垢层与减少的三嗪保留有关。然而，由HS与钙的复合物形成的相当致密的污垢层表现出明显的通量下降和对三嗪的改善的筛分效果。此外，当被疏水性增加的HS污染时，紧密且疏水的膜显示出三嗪保留的显着变化。相反，只有当疏水性降低的HS污染了多孔和亲水膜时，三嗪的保留率才会发生显着变化。新的结果凸显了在设计自然水处理工艺之前对天然水中有机物特性的充分了解的注意。

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