Nanofiltration desalination equipment is a device used for separating salt and aqueous solutions, typically consisting of two parts: a high-pressure pump and a nanofiltration membrane. High pressure pumps are used to pressurize aqueous solutions and pass them through nanofiltration membranes, which are semi permeable membranes that allow water molecules to pass through but prevent salt molecules from passing through.
Nanofiltration membrane is a thin layer composite membrane that can dialyze 90% of NaCl while retaining 99% of sucrose. Obviously, this type of membrane cannot be called a reverse osmosis membrane (as it cannot retain inorganic salts), nor does it belong to the category of ultrafiltration membranes (as it cannot dialyze low molecular weight organic matter). Due to the fact that the molecules with a rejection rate greater than 95% during the permeation process are approximately 1 nanometer, this membrane is named Nanofiltration. The production of nanofiltration membranes began in the 1990s, and their application scope has become increasingly widespread. Nanofiltration membranes can trap divalent ions while allowing monovalent salts to pass through, with a molecular weight cutoff of approximately 80-1000. The surface of nanofiltration membrane is composed of polyelectrolytes, which have electrostatic interactions with ions. Due to these characteristics, it is widely used for the removal of small molecule substances and salts from liquid materials to achieve material purification.
The nanofiltration membrane has been successfully applied to:
1. Desalination and concentration of dyes, replacing salt precipitation and acid precipitation;
2. Extraction and concentration of bioactive ingredients;
3. Wastewater treatment and recycling;
4. Low temperature concentration and ash removal of antibiotic drugs;
5. Softening of water quality, separation and purification of organic acids and amino acids
6. Concentration of dilute sugar solution and purification of oligosaccharides;
7. Recovering acid and alkali from waste acid and alkali, and treating and recovering wet metallurgical wastewater.