Heng Shi

Novel hydrophilic PVDF ultrafiltration membranes based on a ZrO 2 –multiwalled carbon nanotube hybrid for oil/water separation

A novel hydrophilic PVDF composite membrane based on ZrO2–multiwalled carbon nanotubes (MWCNTs) hybrid was prepared by a simple phase-inversion method. ZrO2 nanoparticles were firstly loaded on the surface of MWCNTs via hydrothermal route, which was characterized by Fourier-transform infrared, X-ray diffraction, thermogravimetric analyzer, scanning electron microscopy (SEM), and transmission electron microscopy. It was found that the ZrO2–MWCNTs hybrid formed network structures within the PVDF matrix, avoiding the aggregation of nanofillers. Then, the effects of ZrO2–MWCNTs hybrid on the performances of ultimate PVDF membrane were systematically investigated. The microstructure and surface morphology of novel membranes were observed by SEM and atomic force microscopy. The results indicated that ZrO2 were dispersed homogeneously on the surface of MWCNTs. The as-prepared membrane exhibited enhanced pure water flux and a lower contact angle than those of pure PVDF membrane. Furthermore, the as-prepared membranes processed also improved separation efficiency against oil/water emulsions and achieved better rejection ratio and good durable antifouling performance. In general, ZrO2–MWCNTs/PVDF membrane may provide a potential application against complex oil/water systems.

Facile fabrication of a robust superwetting three-dimensional (3D) nickel foam for oil/water separation

Abstract A superwetting three-dimensional (3D) nickel foam was prepared by a facile electrodeposition process. Wettability, surface morphology, and chemical composition were characterized with contact angle test, scanning electron microscopy, Fourier transform infrared spectra, and X-ray photoelectron spectroscopy, respectively. According to the results, the as-prepared 3D nickel foam presented robust superhydrophobicity and superoleophilicity with good mechanical and chemical stability simultaneously. Furthermore, with the superwetting behavior, the nickel foam showed excellent oil/water separation capability with both high efficiency and lasting recyclability. Besides, the simple, low cost, and environmentally friendly fabrication process endows a scale-up of 3D nickel foam for oil/water separation and pollution disposal of leakage of organic solvents.

Enhancing the photocatalytic and antibacterial property of polyvinylidene fluoride membrane by blending Ag–TiO2 nanocomposites

A novel polyvinylidene fluoride (PVDF) ultrafiltration membrane with photocatalytic and antibacterial properties was prepared by phase inversion. The in situ formed silver (Ag) nanoparticles were immobilized with titanium dioxide (TiO2) nanoparticles. And the modified PVDF membranes were fabricated by adding Ag–TiO2 into the casting solution. Results showed that the surface contamination of membrane can be degraded effectively by photocatalysis method. Compared with the pristine membrane, the hydrophilicity of modified membrane was improved. Besides, the modified membrane had an excellent antibacterial property. Therefore, the novel Ag–TiO2–PVDF membrane has a very promising application perspective.

Preparation of a novel anti-fouling β-cyclodextrin–PVDF membrane

As part of this work, polyvinylidene fluoride (PVDF) membranes were prepared via a phase inversion method. A novel β-cyclodextrin (β-CD)–PVDF membrane was prepared via an interfacial reaction, using Trimesoyl Chloride (TMC) and β-CD as cross-linking and modification agents, respectively. The membranes were modified by a simple dip-coating method. The results of comparison between the modified and unmodified membranes by attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) methods confirmed successful grafting of β-CD on the membrane surfaces. The morphology of the membrane was investigated by scanning electron microscopy (SEM) and atomic-force microscopy (AFM). The roughness of PVDF membranes increased after their surfaces were grafted with β-CD. It was also found that β-CD–PVDF membranes had higher permeate flux and hydrophilicity than those of the pristine PVDF membranes. Furthermore, in protein fouling experiments, bovine serum albumin (BSA) was used as a protein model solution. Modified membranes exhibited a higher flux recovery ratio. The experiment showed that the anti-fouling performance of β-CD–PVDF membranes was more effective in reducing the irreversible membrane fouling. The results of this study hold promise for useful applications of β-CD–PVDF membranes in membrane separation areas.