Rejection mechanisms of plastic additives and natural hormones in drinking water treated by nanofiltration

Abstract

Rejection mechanism of nanofiltration (NF) membrane for organic solutes (including alkyl phenol, bisphenol A, phthalate acid esters, phosphoric acid esters, other plastic additives, and natural hormones like 17β estradiol, etc) was examined. The experiments indicated almost complete removal of these solutes by the tight NF membranes, while the rejection obtained by the loose membranes was dependent on solute species. Compounds with flat-shaped structure like 2-H-benzothiazol and dimethyl phthalate were more permeable than other target solutes within the same molecular size range. Of the four methods of size determination used, there was no significant difference in the accuracy of prediction of rejection from the solute sizes. The size configurations of molecules have been identified to greatly influence the permeation or retention, yet the size parameter was thought to be incomplete as a single parameter in describing rejection of organic solutes. The logarithm of octanol-water partitioning coefficients of solutes appears not to be an effective parameter in modelling rejections as its contribution was only slight or minor. We obtained better correlations with structural configuration of molecules (by molecular width and length) and polarity of the molecules.

Adsorption characteristics of bisphenol-A in aqueous solutions onto hydrophobic zeolite

“…The main partition properties of the hydrophobic compound are [19] log K ow , 3.32; Henry's Law constant, 1 × 10 −10 atm m 3 mol −1 (calculated from water solubility and vapor pressure at 25 • C); water solubility, 120 mg L −1 (at 25 • C). The molecular modeling of the tetrahedral adsorbate has been established from the following information [20,21]: largest distance (between the hydroxyl groups of the two aromatic rings), 0.94 or 11.19 nm; height, 0.53 nm; width (benzenic ring), 0.43 or 3.25 nm. A hydrophobic zeolite, which was originally from Degussa AG (Frankfurt, Germany) and commercially named Wessalith DAY, was employed as the adsorbent in this work.…”

Ultrathin Graphene Nanofiltration Membrane for Water Purification

“…Among all the possible solutions for the water resources crisis, low cost and high efficient nanofiltration might be the most promising one. Nanofiltration technology is now widely used in drinking water and waste water treatments due to its low energy cost and simple operational process, in which the properties of nanofiltration membranes (NFMs) are of vital importance 1–3. Generally, most of polymeric NFMs have advantages of flexibility, simple preparation process, and relatively low cost, but also face some problems, such as poor chemical resistance, limited lifetime, and membrane fouling 4.…”

Influence of membrane, solute and solution properties on the retention of phenolic compounds in aqueous solution by nanofiltration membranes

“…Many reports have been recently published describing the most important factors that affect the organic retention by nanofiltration and reverse osmosis membranes, such as membrane characteristics, physico-chemical properties of the solutes, solution chemistry and operational conditions [4][5][6][7][8]. However, the full understanding of the mechanism responsible for the rejection of phenolic compounds in particular remains unclear.…”