Method for treating o-nitrophenol production wastewater

Abstract

The invention belongs to the field of chemical wastewater treatment and particularly relates to a method for treating o-nitrophenol production wastewater. For wastewater produced after o-nitrochlorobenzene is hydrolyzed to prepare o-nitrophenol, ethanol is adopted as a desorbent in the method; and under the premise of utilizing existing process equipment and basis procedures, valuable o-nitrophenol can be effectively recovered without the need of toxic / expensive chemical agents, special treatment equipment or extra energy consumption. On this basis, the method can achieve effective utilizationof an o-nitrophenol recovery product, improve the overall process efficiency for preparing the o-aminophenol and the recovery efficiency of salts and other by-products, and avoid secondary pollution.The invention further provides a method for producing o-aminophenol related to the aforementioned method for treating wastewater.

Description

technical field [0001] The invention belongs to the field of chemical wastewater treatment, and in particular relates to a treatment method for o-nitrophenol production wastewater. Background technique [0002] Ortho-aminophenol, also known as 2-aminophenol, is an organic compound widely used in the manufacture of dyes, medicines, and plastic curing agents. The industrial synthesis route of o-aminophenol is as follows: o-nitrochlorobenzene is used as the starting material, and o-nitrophenol is obtained by alkaline hydrolysis and acid neutralization, and then hydrogenated to reduce the nitro group to an amino group. [0003] In the whole process of this reaction, a large amount of chemical wastewater will be produced in the production process of o-nitrophenol as an intermediate. This type of wastewater is characterized by high salt content, high chroma, high concentration of nitroaromatic compounds, and high toxicity. , complex components, poor biodegradability, and great di...

AI Technical Summary

Problems solved by technology

But the shortcoming of this method is just as said in this background art document, because methanol is contained in the waste water, thereby the COD of the effluent that resin adsorbs is extremely high, and NaCl can't be reclaimed; Acidification to obtain o-nitrophenol (rather than its phenol sodium salt), which not only increases the input of chemical raw materials, but also further generates salts such as NaCl that cannot be recycled, and at the same time, o-nitrophenol is partially dissolved in the eluent , resulting in a decrease in the overall recovery rate

There are also industrial operations that use methanol instead of NaOH aqueous solution as a desorbent. Although the aforementioned problems such as acidification and salt production can be avoided, in order to reduce the COD and TOC of wastewater, an additional methanol rectification device is required to recover methanol and o-nitrophenol respectively. This not only increases the cost of equipment investment and energy consumption, but methanol, as a highly toxic chemical, will also face problems such as raw material purchase, worker protection, and factory management under increasingly strict policy supervision. Promising Alternatives

[0005] In addition, in the prior art, the final product of the wastewater treatment method for o-nitrophenol production can only be an impure o-nitrophenol mixture, and when using it as a raw material for hydrogenation reduction of o-aminophenol, additional dissolution and ingredients are required , feeding operation, thus introducing an additional process step