A gelatin-zirconium phosphate nanoparticles composite interlayer for enhancing compaction resistance and antifouling performance of TFC NF membrane

From a practical point of view, the thin-film composite (TFC) nanofiltration (NF) membrane should not only have superior separation performance but also excellent compaction resistance and antifouling properties. Generally, polyamide (PA) separation layers of the TFC NF membrane prepared on the support with hydrophilic interlayer are crumpled, which may be detrimental to the compaction resistance and antifouling properties of TFC NF membranes. A flexible polymer-rigid nanoparticles composite interlayer was constructed on the pristine polysulfone (PSF) support in this work to design a TFC NF membrane with compaction resistance, antifouling, and excellent separation performance. Morphology and crosslinking degree of PA separation layers were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the composite interlayer can not only regulate the distribution and diffusion of piperazine (PIP) but also act as a template to induce the generation and growth of PA during the interfacial polymerization (IP) process, leading to the formation of the PA separation layer with a small nodular structure. The compaction resistance, antifouling properties, and separation performance of the TFC membrane were also investigated by nanoindentation, fouling experiment, and filtration test, respectively. The TFC NF membrane with the composite interlayer showed greatly improved mechanical properties with its hardness and elastic modulus approximately 1.5 and 1.6 times that of the reference, respectively. Furthermore, the flux recovery of the TFC NF membrane with the composite interlayer (93.8 %) was higher than that of the control (87.2 %), indicating that the TFC NF membrane with the composite interlayer had better antifouling properties. In addition, the obtained TFC NF membrane with the composite interlayer showed a water flux approximately twice as high as that of the reference with satisfactory rejection. This advancement will contribute to the development of more efficient and stable TFC NF membranes for industrial wastewater treatment.