Super alkali-resistant PVDF membranes modified by coating and grafting with self-healing ability operate efficiently in the treatment of dye/water under pHs

• Published in: Journal of water process engineering 2024-12, Vol.68, p.106466, Article 106466
• Main Authors: Xia, Yun-Hao, Gui, Ying-Ying, Zhou, Jia-Hua, Chen, Gui-E, Xu, Zhen-Liang
• Format: Article
• Language: English
• Subjects: Alkali resistance; Alkaline textile wastewater; Membrane modification; Self-healing; Self-polymerization
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2024.106466

Poly (vinylidene fluoride) (PVDF) membranes are often corroded, leading to structural defects in the treatment of alkaline textile wastewater, greatly reducing separation efficiency. Herein, PVDF membranes were surface-modified through coating and self-assembly methods. Novel adhesives (ad-LNPs) were prepared by heat-releasing endo-crosslinked 2,2-Bis (4-glycidyloxyphenyl) propane (BADE) in lignin (LNP). ad-LNPs coatings provided stable adhesion properties to the PVDF membrane surface and exhibited pH-switchable surface charge with excellent alkali resistance. Subsequently, benzene amine monomers and water-soluble 2-acrylamide-2-methyl-1-propanesulfonic acid (AMPS) are introduced to form a polymer network (AMPS-PANI) layer through self-assembly. The results showed that the membrane permeability and selectivity reached the optimal equilibrium point when the aniline monomers self-polymerization time was 40 min (temperature: 5–10 °C). High dye retention (MB:99.8 %, RhB:99.5 %, CR:98 %, MO:96.2 %) at high purity water flux (172 L·m−2·h−1). Meanwhile, clever utilization of AMPS swelling behavior imparts the modified membrane with physical self-healing properties, as evidenced by scanning electron microscope (SEM) images showing the filling effect of the repaired membrane. Additionally, the construction of a hydrophilic interface increases the contamination resistance (FRR) of the modified membrane to 97 %. In conclusion, the prepared membrane (M4) not only effectively separates dyes/salts but also exhibits excellent alkali resistance and physical self-healing functionality, demonstrating significant potential for practical treatment of alkaline textile wastewater. [Display omitted] •Permeability and selectivity can achieve an optimal balance point.•SA@ad/AMPS-PANI separation membranes were successfully prepared.•Interface self-assembly operation is straightforward; manual transfer is not required.•Biomass lignin is an abundant and environmentally friendly resource.