pH-Sensitive Membranes with Smart Cleaning Capability for Efficient Emulsion Separation and Pollutant Removal

Abstract

Since anionic dyes and surfactants abundantly exist in oily wastewater, both the separation of oil/water mixture and removal of low-molecular-weight pollutants are important to realize the advanced purification of water. By grafting poly(2-dimethylaminoethyl methacrylate) (pDMAEMA) onto polyethylene (PP) membrane via ultraviolet (UV)-initiated polymerization, the obtained PP-g-pDMAEMA membrane presented positively in water and negatively in an alkaline buffer (pH 9.0), respectively. Due to the switchable surface charge, the membrane had high emulsion separation efficiency and flux recovery ratio (approximately 100%). Besides, the dye (reactive black 5, RB-5) adsorption capacity reached 140 mg/m2 in water, and approximately 90% RB-5 could be released in pH 9.0. The anionic surfactant (sodium dodecyl benzene sulfonate, SDBS) was also reversely interpreted and released by the membrane via manipulating the ambient pH. The membrane constructed in this study is supposed to realize emulsion separation with smart cleaning capability, as well as the removal of dyes and surfactants, which could be utilized for multifunctional water purification.

Preparation of Hydrophobic PET Track-Etched Membranes for Separation of Oil–Water Emulsion

“…Lin and coauthors [8] prepared fluorinated SiO 2 -sprayed PVDF membrane with CA of 171.8 • for water-petroleum ether emulsion separation with high flux of 2379 L/m 2 h and efficiency of 99.94%. Emulsions with higher viscosity oil are less studied, separation of such emulsions with membranes leads to lower fluxes, for instance, Zhang et al [9] tested polyethylene (PP) membrane with grafted poly(2-dimethylaminoethyl methacrylate) in diesel/water separation with fluxes of 20-60 L/m 2 h. Flux for gasoline/water is around 500 L/m 2 h, olive oil/water is around 200 L/m 2 h and sesame oil/water is around 100 L/m 2 h for PS@Fe 3 O 4 membranes [7] with separation efficiency of 96-92%. Now, track-etched membranes (TeMs) have a record narrow pore size distribution, which can have a positive effect on the selective properties of separation, leading to its improvement.…”

Multiple strategies to control the hydrophilic–hydrophobic balance of P(DMA-co-DMAEMA-co-QDMAEMA) coatings

“…Cao et al 29 prepared PDMAEMA hydrogel modified stainless steel meshes (SSM), which penetrated water and oil in order by changing the temperature or pH. Researchers have also modified PDMAEMA on the surface of other substrates, for example cellulose nanofiber aerogels, 30 cotton fabrics, 31 polyethylene films, 32 magnetic nanoparticles, 33 etc. , to prepare responsive oil/water separation materials.…”

Light Response and Switching Behavior of Graphene Oxide Membranes Modified with Azobenzene Compounds

“…The variation of the membrane characteristics under external stimuli as attracted progressive attention during the past few years [1][2][3][4]. The interest in it is especially exciting due to the possibility of the precise tuning of the membrane separation performance without process termination occurring or by altering the process conditions.…”