Diffusion dialysis (DD) is a membrane separation technology driven by a concentration difference. It uses selective ion-exchange membranes to transfer solute ions such as acid radicals and hydroxide ions from the high-concentration side to the low-concentration side, enabling resource recovery from waste acid and waste alkali.
Classification
- Diffusion dialysis anion-exchange membrane: provides acid permeability and salt retention, and can be used for separation and purification of acid from salts, and acid from organic matter.
- Diffusion dialysis cation-exchange membrane: provides alkali permeability and salt retention, and can be used for separation and purification of alkali from salts, and alkali from organic matter.
Recovery principle
- Waste acid recovery: free acid radicals and hydrogen ions diffuse through the anion-exchange membrane to the clean water side to form regenerated acid, while heavy metals, salts, and impurities are retained.
- Waste alkali recovery: effective components such as hydroxide ions and sodium ions diffuse through the cation-exchange membrane for recovery, while impurities and macromolecular pollutants are retained.
Core advantages
- Driven only by a concentration difference, with no power required and low operating energy consumption.
- Waste acid and waste alkali can be recovered, and the regenerated liquid can be reused in production processes.
- Operates at normal temperature and pressure, with no phase change, a simple process, and limited secondary pollution.
- The membrane module is corrosion-resistant and fouling-resistant, with relatively simple maintenance.
Application Fields
- Waste acid recovery from pickling in metallurgical industries such as steel, copper, and aluminum processing.
- Waste acid and alkali recovery from surface treatment processes such as electroplating, passivation, and polishing.
- Treatment of chemical waste acids and alkalis from titanium dioxide, phosphate fertilizer, fine chemicals, and other industries.
- Resource recovery from acid and alkali waste liquids in new energy production such as lithium batteries and photovoltaics.
- Reduction and resource recovery disposal of industrial hazardous waste acid and alkali liquids.
Illustrative materials
