Nanofiltration Composite Membrane Resists Swelling

The patent applies composite materials by combining polymer nanofiltration membrane with inorganic nanoparticles (such as metal oxides, carbon materials, or clay nanoparticles) to create a composite membrane structure. The inorganic nanoparticles serve as a skeleton that prevents polymer chain expansion and swelling, while the polymer matrix maintains separation efficiency. This composite structure resolves the contradiction by providing both high separation efficiency and dimensional stability without membrane swelling.

The patent utilizes porous materials by incorporating nanoparticles with controlled pore structures into the membrane matrix. These porous nanoparticles provide a stable skeletal framework that prevents membrane swelling while maintaining selective permeability. The porous structure allows the membrane to achieve high separation efficiency through pore size selection while the nanoparticle framework prevents polymer chain expansion, thus resolving the swelling issue.

The patent replaces chemical oxidation methods with physical separation mechanisms. Instead of using chemical oxidants that require high pH and cause secondary pollution, the invention uses a physical nanofiltration membrane with pore size selection and surface charge properties to directly separate heavy metal complex ions from wastewater. This substitution eliminates the need for chemical oxidation, avoiding both high pH requirements and secondary pollution while maintaining effective heavy metal removal.

The patent extracts the harmful chemical oxidation process and replaces it with a physical separation mechanism. By using nanofiltration membrane with specific pore sizes and surface properties, the system directly extracts and separates heavy metal complex ions from the wastewater stream without requiring chemical oxidation. This extraction approach eliminates the harmful byproducts and pH requirements associated with advanced oxidation methods.