In China's industrial production, a large number of acidic or alkaline waste liquids are usua↑lly produced, which contain different concentrations of metal ions and acid★-base. The direct discharge not only wastes resources, ×but also causes serious pollution to the environment. In order to protect the environment from →pollution and to recover useful material, it is necessary to purify the acid and ÷alkali waste liquid before it is discharged. Most of the treatment of th↔is kind of waste water is neutralized at home and ab↕road, and this treatment is easy to cause secondary pollution. The new membrane technology, such as permeation, reverse osmosis, nanofiltration, u₽ltrafiltration and dialysis, can effectively avoid secondary pol♥lution.
As a new separation technology, membrane technology can effectively purify the waste wat er, and recycle the useful material, and has the characteristics of energy saving,α low consumption, no pollution, simple equipment, convenie✘nt operation, so it shows broad prospects in terms of pH of the was♥te water treatment. 1. Acid environment
Acid solutions (part) that have been tested:
20% H2SO4
20% HCl
30% H3PO4
4% HNO3
Typical applications in acid environment:
Purify acid and remove metal cations
Recovery of acid after leaching operation
Mineral acid decolorization
Recovery of dissolved chemicals
Concentration and recovery of ions in an acid solution
Some conventional applications that need to be used for¥ corrosive strong acid cleaning
Chemical industry: the recovery of acid and the final product in the process of producing ♥acid medium
Food, beverage and dairy industry: purify the acid after the uΩse of the CIP process and reuse in the process of productio♠n and the cleaning of equipment.
Recovery of metals from the extractive solution, such as copper, zin↓c, cobalt, molybdenum, tungsten, uranium, gold, etc..
Reducing the cost of operation and sewage treatment
Recovery of high value metals from emission and industrial waσste water
Pre separation of copper and gold in the process of carbon slurry to impro↓ve the extraction rate of subsequent gold.
2. Alkaline environment
The tested alkaline solutions include:
4% NaOH
10% NaOH
20% NaOH
20% KOH
Typical applications in alkaline environment
Recovery of alkaline current (sodium hydroxide, potassium hydroxide)
Recovery of metal in alkaline flow
Recovery of used electrolyte
Reducing COD content before neutralizing industrial was↔te water
Recovery of alkaline solution for cleaning containers and e quipment
Some conventional applications that need caustic alkalφi cleaning
Pulp and artificial fiber: purification of caσustic soda from hemicellulose and other organic pollutants to make sodium hydrox±ide reusable up to 95%
Food, beverage and dairy products: Purifi₹cation of waste lye washing flow (CIP) solution and regenerated solution (in Decolorization of sugar) after ion exchange, to make the repeated use rate of sod ium hydrate up to 95%;
Chemical: alkali recovery and final product concentration used& in many alkaline environmental production operations.
