Improving the performance of polymer-based membranes for water treatment in terms of permeability and selectivity can be achieved through various strategies. These strategies focus on optimizing the membrane's structure, composition, and surface properties to enhance water flux and solute rejection. Here are some approaches to consider:1. Selection of suitable polymer materials: Choose polymers with high hydrophilicity, chemical stability, and mechanical strength. Examples include polyethersulfone PES , polyvinylidene fluoride PVDF , and polyamide PA . These materials can improve water permeability and reduce fouling.2. Blending and copolymerization: Mixing two or more polymers or creating copolymers can result in membranes with improved properties. This approach can enhance the hydrophilicity, mechanical strength, and thermal stability of the membrane, leading to better permeability and selectivity.3. Nanocomposite membranes: Incorporating inorganic nanoparticles, such as zeolites, metal-organic frameworks MOFs , or carbon nanotubes CNTs , into the polymer matrix can improve the membrane's performance. These nanoparticles can enhance the membrane's mechanical strength, hydrophilicity, and selectivity.4. Thin-film composite TFC membranes: Develop a thin, selective layer on top of a porous support layer. The thin layer provides high selectivity, while the support layer offers mechanical strength and high permeability. TFC membranes are widely used in reverse osmosis RO and nanofiltration NF processes.5. Surface modification: Modify the membrane surface by grafting hydrophilic functional groups, coating with hydrophilic polymers, or creating a zwitterionic surface. These modifications can reduce fouling, improve water permeability, and enhance solute rejection.6. Membrane fabrication techniques: Optimize the phase inversion, electrospinning, or interfacial polymerization processes to control the membrane's pore size, porosity, and surface properties. Proper control of these parameters can lead to improved permeability and selectivity.7. Post-treatment: Subject the membranes to post-treatment processes such as heat treatment, solvent extraction, or chemical crosslinking. These treatments can improve the membrane's hydrophilicity, mechanical strength, and chemical stability, leading to better performance.8. Membrane cleaning and fouling control: Implement effective cleaning strategies and antifouling agents to maintain the membrane's performance over time. Regular cleaning and the use of antifouling agents can help prevent fouling and maintain high permeability and selectivity.By employing these strategies, the performance of polymer-based membranes for water treatment can be significantly improved in terms of permeability and selectivity, leading to more efficient and effective water purification processes.