Changing the chemical composition of a polymer-based membrane can significantly impact its water treatment efficiency. The efficiency of a membrane in water treatment is determined by factors such as permeability, selectivity, fouling resistance, and mechanical stability. By altering the chemical composition, these properties can be affected in the following ways:1. Permeability: The rate at which water can pass through the membrane is crucial for efficient water treatment. Changing the chemical composition can either increase or decrease the permeability, depending on the specific modifications made. For example, introducing more hydrophilic groups into the polymer structure can enhance water transport, leading to higher permeability.2. Selectivity: The ability of the membrane to separate contaminants from water is essential for effective water treatment. Altering the chemical composition can improve or worsen the membrane's selectivity. For instance, increasing the size of the pores or introducing functional groups that can selectively interact with specific contaminants can enhance the membrane's ability to remove unwanted substances.3. Fouling resistance: Membrane fouling occurs when contaminants accumulate on the membrane surface, leading to a decrease in performance. Changing the chemical composition can improve the fouling resistance of the membrane. For example, incorporating hydrophilic or anti-fouling groups into the polymer structure can reduce the adhesion of contaminants to the membrane surface.4. Mechanical stability: The membrane's mechanical properties, such as tensile strength and elasticity, can also be affected by changes in the chemical composition. A mechanically stable membrane is essential for long-term operation in water treatment applications. By modifying the polymer structure, it is possible to enhance the membrane's mechanical stability, making it more resistant to wear and tear.In summary, altering the chemical composition of a polymer-based membrane can have both positive and negative effects on its water treatment efficiency. The specific outcome will depend on the nature of the modifications made and their impact on the membrane's permeability, selectivity, fouling resistance, and mechanical stability.