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Membrane technology in wastewater treatment enhanced by functional nanomaterials

Zhang, Yuqing, Wei, Song, Hu, Yanhua, Sun, Shichen
Journal of cleaner production 2018 v.197 pp. 339-348
aluminum oxide, chemical oxygen demand, coatings, hydrolysis, hydrophilicity, maximum residue limits, nanoparticles, oils, phosphorylation, polymers, porosity, tensile strength, titanium dioxide, ultrafiltration, wastewater, wastewater treatment, water yield
Ultrafiltration polymer membranes are facing great challenges in broader applications, for their inherent limitations especially poor hydrophilicity, anti-fouling and anti-compaction properties. In order to improve and enhance the integrated properties of the membrane, YxFeyZr1-x-yO2 coated TiO2 solid superacid (SYFZr-Tis) functional nanomaterial was synthesized via hydrolysis, calcination and sulfation, and phosphorylated ZrxSi1-xO2/Al2O3 (PZSA) was prepared through co-hydrolysis, silanization and phosphorylation, followed by coating of Al2O3. The functional nanomaterials show positive effects on membrane performances. The SYFZr-Tis nanoparticles can form micro reaction locations (MRLs) in the membrane when doping into polyvinylidene fluoride (PVDF) to prepare SYFZr-Tis/PVDF hybrid membranes, which show a tensile strength of 3.57 MPa, water contact angle of 29.1° and porosity of 73.58%. Moreover, the hybrid membrane shows a favorable oil retention ratio of 90.63% and a stable permeate flux of 345 L m−2 h−1 under operating pressure of 0.15 MPa (59.93% and 183 L m−2 h−1 for PVDF pristine membrane). In addition, the PZSA functional nanomaterials were employed as a functional layer to form PZSA self-assembled membrane on porous supports. Research shows that the self-assembled membrane performs oil and COD retention ratios of 86.84% and 85.23% respectively and a water yield of 526.32 L m−2 h−1 when treating oily wastewater (under operating pressure of 0.15 MPa). Furthermore, compared with the hybrid membrane, the PZSA self-assembled membrane performs recyclable character, which lowers membrane costs. Therefore, functional nanomaterials effectively enhance the development of membrane technology, and they are expected to achieve potential applications in wastewater treatment.