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A new approach to the facile preparation of high-performance composite membrane for solvent resistant nanofiltration is presented herein. Within the composite membrane, hydrophilic polyethyleneimine (PEI) and hydrophobic hydroxyl terminated trifluoride polydimethylsiloxane (PDMS) are cross-linked as skin layer, whereas polyacrylonitrile (PAN) ultrafilitration membrane serves as support layer. The microstructure and physicochemical properties of the membrane are extensively investigated. It is found that PEI chains and PDMS chains are covalently cross-linked via trimesoyl chloride through interfacial polymerization, generating hydrophilic–hydrophobic hybrid network. The cross-linking inhibits the chain mobility of PEI, affording the composite membrane enhanced thermal and mechanical stabilities relative to the membrane without PDMS. Combining the advantages of both hydrophilic and hydrophobic materials endows the composite membrane with excellent solvent resistance properties and nanofiltration performances in both polar solvents and nonpolar solvents, such as isopropanol, butanone, ethyl acetate, and n-heptane. Particularly, the composite membrane achieves permeate fluxes of 37.8, 3.5, 5.4, and 4.7 L m−2 h−1 for these four solvents, respectively, along with the area swellings below 3.2%. After being equilibrated in these solvents, the composite membrane exhibits good structural stability with molecular weight cut-off of 600. The operation stability of the composite membrane is also explored.

Refinery effluent-derived humic substances (HS) are important for developing refinery effluent reclamation techniques and studying the environmental chemistry of wastewater effluents. In this study, dissolved organic matter (DOM) from refinery effluent was concentrated using a portable reverse osmosis (RO) system. HS were isolated from RO retentates with XAD-8 resin. A variety of approaches such as specific UV absorbance at 254nm (SUV(254)), elemental analysis, size exclusion chromatography (SEC), solid-state cross polarization magic angle spinning (13)C nuclear magnetic resonance spectrometry ((13)C CPMAS NMR), Fourier transform infrared spectrometry (FTIR), and electrospray ionization/ion trap/mass spectrometry (ESI/ion trap/MS) were employed for characterization of HS. The portable RO system exhibited high yield and recovery of DOM for concentrating refinery effluent. The concentration of dissolved organic carbon (DOC) in the refinery effluent was 9.9mg/l, in which humic acids (HA) and fulvic acids (FA) accounted for 2.3% and 34.6%, respectively. Elemental and SUV(254) analyses indicated relative high amounts of aliphatic structures and low amounts of aromatic structures in refinery effluent-derived HS. Refinery effluent-derived HS displayed lower molecular weight than natural HS. The number-average molecular weight (M(n)) and the weight-average molecular weight (M(w)) of HA were 1069 and 2934, and those of FA were 679 and 1212 by SEC, respectively. By ESI/ion trap/MS, the M(n) and the M(w) of FA were 330 and 383. Four kinds of carbon structures (aliphatic, aromatic, heteroaliphatic, and carboxylic carbons) were found in refinery effluent-derived HS by (13)C NMR analysis. The quantitative results support the interpretation that these HS are rich in aliphatic carbons and poor in aromatic carbons. Proteinaceous materials were identified by FTIR analysis in refinery effluent-derived HS.