Regulation of Nanomaterials on the Preparation of Nanofiltration Membranes and Its Research Progress in the Water Treatment Field: A Review.

Nanofiltration (NF) membranes, a key branch of membrane separation technology, exhibit broad application potential in water treatment owing to their unique ability to precisely retain small-molecule solutes and further offer a feasible technical approach to overcoming the difficulties involved in complex water purification. Nevertheless, the existing NF membranes still have scope for enhancement in terms of core performance metrics. In detail, their membrane flux fails to meet the high-load and high-efficiency demands of industrial water treatment processes, their separation selectivity toward pollutants requires further enhancement, and they lack adequate antifouling performance during prolonged operation. These problems have limited the large-scale industrial application of NF membranes to some degree. Nanomaterials demonstrate distinct advantages in optimizing the performance of NF membranes, primarily attributed to their ultrahigh specific surface area, ample active adsorption sites, and superior pore size distribution controllability. As a result, they have become ideal and extensively studied materials in the research of NF membrane modification. This paper presents a comprehensive review of the application status and research advances of nanomaterials in NF membrane technology, with particular emphasis on typical preparation methods such as surface grafting, interfacial polymerization, and blending. It further clarifies the intrinsic separation mechanisms governing nanomaterial-based composite NF membranes, including the charge effect, sieving effect, and dielectric effect. Existing research findings consistently show that these composite NF membranes exhibit excellent performance achieve outstanding performance in dye wastewater treatment, heavy metal wastewater purification, and seawater desalination processes; they remarkably improve water permeability, antifouling capability, and separation efficiency, thus manifesting extensive prospects for practical application. This paper provides innovative insights for high performance of NF membranes and plays a pivotal role in facilitating the advancement of water treatment technology toward more efficient and sustainable practices.