Integrated equipment for electrodialysis recovery of acid and alkali

Integrated equipment for electrodialysis recovery of acid and alkalifeature

① Can simultaneously dilute, concentrate, separate, and purify electrolyte aqueous solutions;

② Can be used for the purification of non electrolytes such as sucrose to remove electrolytes;

③ In principle, an electrodialysis device is an electrolytic cell with a diaphragm that can utilize the high redox efficiency on the electrodes.

The electrodialysis recovery acid-base device can directly convert organic acid salts into organic acids using a bipolar membrane electrodialysis device based on the characteristics of low ionization and dissociation degree of organic acids. Such as gluconic acid, lactic acid, citric acid, amino acids, tartaric acid, acetic acid IDA、 Wait. Reaction equation: RNa+H2O=RH+NaOH. The bipolar membrane process has no wastewater discharge, and the by-product NaOH can also be recycled for fermentation. Traditional method: RNa undergoes hydrogen cation exchange tree to obtain RH, but resin regeneration requires a large amount of acid and alkali, resulting in a large amount of saline organic wastewater. Preparation and recovery of organic acids by electrodialysis

Integrated equipment for electrodialysis recovery of acid and alkaliPrecautions for use

(1) Calcium sulfate precipitation is difficult to remove, so the concentration ratio used should not exceed the value determined by the ion product of calcium sulfate in the concentrated water. When exceeding this value, the concentration ratio should be reduced or masking agents such as sodium hexametaphosphate should be added.

(2) The circulation of concentrated water for scale precipitation greatly increases the ion mass fraction of the concentrated water, thereby increasing the possibility of carbonate scale precipitation. To prevent this precipitation, acid is usually added to the concentrated water system to dissolve the precipitate. In China, hydrochloric acid is generally added to maintain the pH value of the concentrated water between 3.0 and 4.0. If the pH value is less than 3, the current efficiency will be significantly reduced. In foreign countries, sulfuric acid is often added to the concentrated water circulation system to maintain the pH value of the concentrated water between 4 and 6.

(3) The key to the concentrated water circulation process is to correctly control the concentration ratio, which is the ratio of concentrated water concentration to raw water concentration. As the concentration of concentrated water increases, the concentration difference between concentrated water and fresh water increases, resulting in a decrease in the selective permeability of the electrodialysis equipment membrane, an increase in salt counter diffusion and water electroosmosis, a decrease in current efficiency, a decrease in desalination rate, and even precipitation. There are many factors that affect the concentration ratio, such as the salt content of the raw water, the ion composition of the water, pH value, and the performance of the ion exchange membrane. The concentration ratio of raw water with high salt content, hardness, and alkalinity should be controlled lower. For different raw water qualities and membranes, it should be determined through experiments.