Method for treating and recycling process waste water generated during production of 1,2-Benzisothiazolin-3-One

Abstract

The invention provides a method for treating and recycling process waste water generated during the production of 1,2-Benzisothiazolin-3-One. The production of 1,2-Benzisothiazolin-3-One is as follows: dithio-salicylic acid is used as a raw material and is subjected to acylating chlorination, chloro-substitution, distillation, alkaline hydrolysis using ammonia, bleaching, acidification and refining. The method for treating and recycling the process waste water includes the following steps: adjusting the pH of the process waste water to be about 8, carrying out two-level serially connected preferential adsorption on 1,2-Benzisothiazolin-3-One using ultra-high cross-linked polystyrene-divinylbenzene polymeric adsorbent bed layer, the effluent after the second level of adsorption is subjected to triple effect evaporation, a part of the distillation effluent returns to the original production process for being used indiscriminately, and another part of the distillation effluent is subjected to aerobic biological treatment, and the treated effluent can reach national first-level discharge standards; the residual after distillation is subjected to cooling, crystallization and centrifugation, and then crude sodium chloride is recycled; the polymeric adsorbent used dilute sodium hydroxide solution is regenerated through desorption; all levels of resins can be used repeatedly; the desorption solution can be directly applied to the bleaching process of the original production process; recycling of organic matters is realized while the waste water is treated by using the method.

Description

technical field [0001] The present invention relates to the treatment and treatment of process wastewater produced by obtaining 1,2-benzisothiazol-3-one from dithiodibenzoic acid as a raw material through acid chlorination, chlorination, distillation, aqueous ammonia alkali hydrolysis, decolorization, and acidification. Resource method. Background technique [0002] 1,2-Benzisothiazol-3-one is also called 1,2-benzisothiazolin-3-one. The synthetic route applicable to this method is to use dithiodibenzoic acid as a raw material to obtain 1,2-benzisothiazole-3 - Ketone sodium salt, after being decolorized by activated carbon, acidified and refined with hydrochloric acid to obtain 1,2-benzisothiazol-3-one, the main principle is as follows: [0003] [0004] Using the above production process, one stream of waste water will be produced after acidification with hydrochloric acid and centrifugation, and another stream of waste water will be produced after washing with water. B...

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Problems solved by technology

Each ton of product will produce 20~22m of waste water 3 , the wastewater is reddish brown, CODc r 23000-24000mg / L, of which 1,2-benzisothiazol-3-one content is 6100-6600mg / L, and sodium chloride content is 100-130g / L. Due to the high salt content in wastewater, now The treatment method is mainly to concentrate the process wastewater and treat it as hazardous solid waste, which not only costs a lot, but also wastes the expensive 1,2-benzisothiazol-3-one and sodium chloride; or use Ethyl acetate extraction method recovery, the recovery rate is only about 63%, and because ethyl acetate is volatile and has a certain solubility in water, so the consumption is relatively large, and the energy consumption is high, so there is no economical and effective treatment of the process wastewater. method

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