Purifying recovery method of gallic acid production wastewater

Abstract

The invention relates to a method for purifying and recycling the waste water produced in the production of gallic acid, wherein, the waste water is produced during the hydrolyzation or refining process of the production of the gallic acid with nutgall or tala as the raw materials. The concrete process is as follows: the waste water is neutralized with 30 percent NaOH to a PH value between 4.5 and 5 and then is vaporized condensed in vacuum, centrifugated to reclaim salt, cooled to between 10 DEG C and 15 DEG C to precipitate gallic acid crystals, and centrifugally filtered to removel gallic acid crystals and obtain gallic acid; the filtrate is neutralized to the neutralization by adding into milk of lime, after the clarification, the clear liquid is decolored by coal-based activated carbon, then the waste water is subject to biochemical treatment by a biochemical pool to reach the drainage standard. The recycling of the gallic acid can be used to produce products such as pyrogallic acid, gallate and so on, the reclaimed salt can be taken as whitening agent, the boiler softened water and the lime can be used to produce bricks; the invention has less investment, simple process, low cost and good waste water treatment effect.

Description

Technical field [0001] The invention relates to a method for purifying and recycling gallic acid production wastewater. Background technique [0002] The production of gallic acid is made from the forest plant gallnut or tara as raw materials through alkaline hydrolysis and refining processes. It is widely used in anti-corrosion agents, integrated circuit detergents and other applications. It is an important fine organic chemical . [0003] my country is rich in forest resources and is the main producer of gallic acid. However, the hydrolysis and refining process of gallic acid production will produce a lot of waste water. The gallic acid production wastewater mainly comes from the following three channels: 1. Hydrolysis wastewater: the wastewater is brown, the pH is about 1.5, and the content of various harmful substances: BOD 5 About 1000mg / L, COD Cr About 2500mg / L, volatile matter 0.015mg / L, suspended matter 400~450mg / L, salt 20~22% mg / L, and also contains about 2% residual ga...

AI Technical Summary

Problems solved by technology

These wastewaters are extremely polluting to the environment, and the wastewater treatment process is complex and costly, which has become a major problem in the production of gallic acid

Previously, it was used to directly recycle refined waste water as water for hydrolysis of gallnut or Tara raw materials, but practice found that although this method can recover gallic acid in the mother liquor, it will affect the quality of gallic acid products, and the purity cannot meet the requirements, especially The content of metal ions exceeds the standard, so it cannot be used in fields that require high-purity gallic acid, such as the electronics industry, and its use is limited