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

Jiaming Zhang,Huiling Zhang,Wei Wei,Yunfei Wang,Xiansheng Zhang,Jindan Wu,Guoqiang Cai

doi:10.3390/membranes11030193

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.

Highlights

With the development of industrial society, the discharge of a large amount of oily wastewater has caused serious problems to the environment [1,2]
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
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

Summary

Introduction

With the development of industrial society, the discharge of a large amount of oily wastewater has caused serious problems to the environment [1,2]. The oil/water separation technology has received great attention in the past decades. Membrane separation is an efficient way for oily wastewater treatment and has already shown a good application prospect [3]. A superhydrophilic and underwater superoleophobic poly(vinylidene fluoride) (PVDF) membrane prepared by salt-induced phase inversion can effectively separate both surfactant-free and surfactant-stabilized oil/water mixtures driven by gravity [4]. The membrane with specific physicochemical properties is proven to be effective in emulsion separation, poor antifouling performance still limits their widespread application [5]. The contaminated membranes abandoned may cause secondary pollution since they are difficult to degrade in nature [6]

Methods

Results

Conclusion