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

Area of Science:

• Materials Science
• Environmental Science
• Polymer Chemistry

Background:

• Oily wastewater contains anionic dyes and surfactants, necessitating simultaneous oil/water separation and pollutant removal for advanced water purification.
• Effective treatment strategies are crucial for managing industrial effluents containing both emulsions and dissolved contaminants.

Purpose of the Study:

• To develop a multifunctional membrane capable of separating oil/water emulsions and adsorbing/desorbing anionic dyes and surfactants.
• To investigate the impact of switchable surface charge on membrane performance for water purification applications.

Main Methods:

• Grafting poly(2-dimethylaminoethyl methacrylate) (pDMAEMA) onto polyethylene (PP) membranes using ultraviolet (UV)-initiated polymerization.
• Characterizing the membrane's surface charge switchability with varying pH.
• Evaluating the membrane's performance in oil/water emulsion separation, dye adsorption/release, and surfactant adsorption/release.

Main Results:

• The modified PP-g-pDMAEMA membrane exhibited switchable surface charges, enabling high oil/water emulsion separation efficiency and flux recovery (approx. 100%).
• The membrane demonstrated significant adsorption capacity for anionic dye (Reactive Black 5, RB-5) at 140 mg/m², with efficient release (approx. 90%) at pH 9.0.
• Anionic surfactant (sodium dodecyl benzene sulfonate, SDBS) adsorption and release were also achieved by manipulating ambient pH.

Conclusions:

• The developed PP-g-pDMAEMA membrane offers a promising solution for multifunctional water purification, combining emulsion separation with smart cleaning and contaminant removal.
• This pH-responsive membrane technology facilitates efficient separation and recovery of pollutants, contributing to sustainable water treatment strategies.