Integrated multifunctional photothermal membrane for oil/water emulsion separation, dye effluent removal, and solar water purification

Abstract

Polyelectrolyte complexes (PECs) have received considerable attention in resource recovery from wastewater and enhanced separation technologies because they are multicomponent polymeric materials with unique wettability properties. From this perspective, we focused on new opportunities to develop photothermally effective PECs to separate oil/water emulsion and purify dye-contaminated wastewater. The PEC was also utilized for solar steam generation. Chondroitin sulfate (CS), a weak anionic polyelectrolyte material, was treated with a cationic copolymer of poly (acrylamide-co-diallyldimethylammonium chloride) (PAAm-DADMAc). This material is used as a membrane by modifying cellulose acetate filter paper. The formation of PECs was confirmed using various analytical techniques, and a cauliflower-like assembled microparticle morphology was achieved. The surfaces of the fabricated PEC self-assembled microparticles exhibited good emulsion separation efficiency (99.4%) and emulsion permeation flux of 2316 L m−2 h−1 bar−1 after eight filtration cycles. The versatile functional groups were recognized for their superhydrophilicity and underwater superoleophobic nature (approximately 150° of contact angle) for low-and high-viscosity oils. The abundance of functional groups in the PECs treated anionic Congo red dye, cationic methylene blue dye, and textile dyeing industrial effluent with 99% separation efficiency. In addition, PEC-modified membrane materials were successfully utilized as an effective solar steam generation to purify 3.5% NaCl contaminated water under 1 kW m−2. The evaporation rate was retained with 2.31 kg m−2 h−1 for five cycles. Overall, the proposed CS/PAAm-DADMAc/GO-modified membranes can offer a new route to treat oil-in-water emulsions and remove dye from wastewater at an industrial level along with solar desalination. Thus, the proposed materials will provide essential insights into scientific and practical accessibility for developing multifunctional membrane materials for wastewater treatment.