Supramolecular-Based Regenerable Coating Layer of a Thin-Film Composite Nanofiltration Membrane for Simultaneously Enhanced Desalination and Antifouling Properties

Abstract

A high-performance nanofiltration (NF) membrane with simultaneously improved desalination and antifouling properties while maintaining regeneration ability is highly desirable in water treatment. Surface modification is an effective approach to enhance the performance of NF membranes. In the present study, a multifunctional thin-film composite NF membrane (Fe–TFC) was fabricated via coating a regenerable ferric ion–tannic acid (FeIII–TA) layer on the nascent polyamide membrane surface. The Fe–TFC membrane exhibited enhanced hydrophilicity, smaller pore size, and lower negative charge compared with the control membrane. The salt rejections and selectivity of divalent to monovalent ions were greatly improved with only a slight decrease in water permeability due to the presence of the coating layer. Meanwhile, dynamic fouling tests with humic acid demonstrated that the Fe–TFC membrane possessed an enhanced antifouling property and excellent flux recovery rate. After coating, the normalized water flux and flux recovery of the Fe–TFC membrane increased from 0.02 to 0.26 and 32.1 to 76.4% at the end of five cycles of fouling tests, respectively. In addition, the resultant membrane exhibited excellent durability and stability under harsh conditions for ∼10 days. Interestingly, the fouled coating layer can be easily removed by HCl cleaning and regenerated through an in situ strategy. Consequently, the regenerated membranes presented stable antifouling properties and desalination performance after several times of regeneration. It was demonstrated that the unique feature of FeIII–TA networks enables the coating layer to act as a protective layer for the underlying polyamide membrane, leading to the high performance of the composite membrane. This study provides a new insight for surface functionalization and easy regeneration of the TFC nanofiltration membrane in water treatment technology.

Enhanced Water Permeability and Antifouling Property of Coffee-Ring-Textured Polyamide Membranes by In Situ Incorporation of a Zwitterionic Metal–Organic Framework

“…As observed in Figure a, the characteristic peaks of R 4 N + and SO 3 – were observed at 957 and 1039 cm –1 , respectively. Characteristics peaks of polyamide were also present at 1662 cm –1 (N–CO amide stretching vibration) and 3400 cm –1 (O–H/N–H stretching vibration) Figure b presents the elements of the PZ@ZIF-8-TFN membrane detected by XPS, including carbon (C), nitrogen (N), oxygen (O), zinc (Zn), and sulfur (S).…”

“…Characteristics peaks of polyamide were also present at 1662 cm −1 (N−CO amide stretching vibration) and 3400 cm −1 (O−H/N−H stretching vibration). 46 Figure 6b presents the elements of the PZ@ZIF-8-TFN membrane detected by XPS, including carbon (C), nitrogen (N), oxygen (O), zinc (Zn), and sulfur (S). Compared with TFC and ZIF-8 TFN membranes (Table S1), the new signal (sulfur) assigned to the presence of zwitterionic DMAPS further demonstrated the existence of zwitterionic PZ@ZIF-8 on the membrane surface.…”

MXene Nanosheet Templated Nanofiltration Membranes toward Ultrahigh Water Transport

“…The TFC 0 membrane presented a dense polyamide film with a nodule-like structure (Figure a), which was typical for nanofiltration fabricated via PIP and TMC . In comparison, the TFC n (Figure S10) and TFC n O (Figure b) membranes exhibited a stripe-like structure, implying that oxidization was independent of surface morphology.…”

Toward Enhancing Desalination and Heavy Metal Removal of TFC Nanofiltration Membranes: A Cost-Effective Interface Temperature-Regulated Interfacial Polymerization

“…16 Consequently, a much thinner separation layer is achieved compared to that of the symmetrically structured NF membranes fabricated by the phase inversion method. 17 Benefiting from the special formation mechanisms of the IP-based TFC NF membranes, the accurate control of the transfer rate of the PIP monomers into the organic solutions is assumed to be an efficient method to regulate the generation of a PA film with tailored structure and performance. 18 To date, various approaches have been adopted to control the diffusion rate of the PIP monomers, thus tailoring the performance of the TFC NF membranes.…”

“…This phenomenon is also called the “self-sealing” effect of the IP reaction process . Consequently, a much thinner separation layer is achieved compared to that of the symmetrically structured NF membranes fabricated by the phase inversion method . Benefiting from the special formation mechanisms of the IP-based TFC NF membranes, the accurate control of the transfer rate of the PIP monomers into the organic solutions is assumed to be an efficient method to regulate the generation of a PA film with tailored structure and performance …”