Integrated equipment for acid production and alkaline wastewater treatment using bipolar membrane electrodialysis

NegotiableUpdate on 04/07

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Overview

The bipolar membrane electrodialysis method was first used for desalination of seawater to produce drinking water and industrial water, concentration of seawater to produce salt, and combination with other unit technologies to produce high-purity water. Later, it was also widely used in wastewater treatment. wu

Product Details

　　Bipolar membrane electrodialysisThe preparation of acid and alkali bipolar membranes is a new type of ion exchange composite membrane, which is usually composed of a cation exchange layer and an anion exchange layer. Membrane materials with different charge densities, thicknesses, and properties can be used to make bipolar membranes with different properties and applications under different composite conditions. The basic principle of these applications is the dissociation of water molecules at the interface layer of the bipolar membrane under reverse pressure (also known as bipolar membrane hydrolysis), which decomposes water into hydrogen ions and hydroxide ions.

Bipolar membrane electrodialysis is developed based on the principles of water dissociation and ordinary electrodialysis mentioned above. It is composed of a bipolar membrane replacing some of the negative and positive membranes of ordinary electrodialysis or adding a bipolar membrane between the negative and positive membranes of ordinary electrodialysis.

The basic application is to prepare corresponding acids (HX) and bases (MOH) from salt solution (MX). The feed solution enters the three chamber electrodialysis membrane stack, and under the action of a direct current electric field, salt anions (X -) enter the acid chamber through the anion exchange membrane and dissociate with hydrogen ions from the bipolar membrane to generate acids (HX); And the salt cation (M+) enters the base chamber through the cation exchange membrane, where it dissociates with the hydroxide ions of the bipolar membrane to form a base (MOH).

　　Bipolar membrane electrodialysisThe preparation of acid and alkali electrodialysis method was first used for desalination of seawater to produce drinking water and industrial water, concentration of seawater to produce salt, and combination with other unit technologies to produce high-purity water. Later, it was also widely used in wastewater treatment.

In wastewater treatment, there are two types of electrodialysis operations based on process characteristics: one is the ordinary electrodialysis process composed of alternating positive and negative membranes, mainly used to separate pollutant ions from wastewater, or to separate pollutant ions from non electrolyte pollutants in wastewater and treat them using other methods;

Another type is the special electrodialysis cell separation process composed of composite membrane and cation membrane, which utilizes the polarization reaction in the composite membrane and the electrode reaction in the electrode chamber to generate H+ions and OH - ions, and produces acids and bases from wastewater.

双极膜电渗析

The commonly used electrodialysis method in wastewater treatment practice includes:

1) Process alkaline papermaking wastewater, recover alkali from concentrated solution, and recover lignin from dilute solution.

2) Separate and concentrate metal ions from wastewater containing metal ions, and then further treat or recycle the concentrated solution.

3) Separate radioactive elements from radioactive wastewater.

4) Produce sulfuric acid and sodium hydroxide from sodium sulfate waste liquid.

5) Preparation of sulfuric acid and deposition of heavy metal ions from acid pickling wastewater.

6) Electrodialysis is suitable for treating electroplating wastewater and waste liquids containing metal ions such as Cu2+, Zn2+, Cr (IV), Ni2+, etc. Among them, the most widely used method is to recover nickel from nickel plating waste liquid. Many factory practices have shown that this method can achieve closed-loop circulation.