Method for synergistically pretreating TDI production wastewater by using chemical wastes

Abstract

The invention relates to the field of wastewater treatment, in particular to a method for synergistically pretreating TDI production wastewater by utilizing chemical waste. The method comprises the following steps: heating hydrogenated wastewater and acidic wastewater in the TDI production process to 70-100 DEG C, mixing the heated hydrogenated wastewater and acidic wastewater with one or more high-temperature wastewater in the TDI production process to obtain mixed wastewater with the pH value of 1-4, adding a catalyst and hydrogen peroxide into the mixed wastewater, and reacting at 130-180 DEG C under the pressure of 0.2-2 MPa for 10-120 min to implement wastewater treatment; or adding a catalyst, the chemical waste containing methylsulfonyl chloride and hydrogen peroxide into the mixedwastewater, and reacting for 10-120 minutes at the temperature of 130-180 DEG C and the pressure of 0.2-2 MPa, so as to realize the treatment of the wastewater. According to the method disclosed by the invention, impurities such as mononitrotoluene and dinitrotoluene in the wastewater do not need to be separated in advance, condensed precipitates, chemical sludge and volatile gas are not generatedin the treatment process, the operation environment is improved, and the operation cost is reduced.

Description

technical field [0001] The invention relates to the field of wastewater treatment, in particular to a method for synergistically pretreating TDI production wastewater by using chemical waste. Background technique [0002] TDI (toluene diisocyanate) is widely used in the manufacture of polyurethane foams, polyurethane elastomers, coatings, adhesives, and can also be used for vinyl polymer films, surface processing of natural rubber, chemical resistance additives for coatings, textile processing etc. TDI production includes ODC hydrochloric acid electrolysis workshop, coal gas workshop and ammonia synthesis workshop. ODC electrolysis uses TDI photochemical by-product hydrochloric acid as raw material to produce chlorine gas, which is used to prepare phosgene. The carbon monoxide produced by coal gasification is the raw material for the preparation of phosgene, and the hydrogen produced is used for the catalytic hydrogenation of dinitrotoluene to prepare diaminotoluene. Synt...

AI Technical Summary

Problems solved by technology

This method requires cooling and precipitation of the raw water, which produces DNT waste; catalytic reduction, catalytic oxidation and neutralization flocculation precipitation process produces a large amount of chemical sludge, the operating environment is harsh, and the cost of sludge disposal is high

[0010] CN102491584B (a method for mixed treatment of explosive wastewater and nitrobenzene and aniline wastewater) adopts activated carbon adsorption, limestone+liquid caustic neutralization, flocculation and precipitation to remove nitrobenzene and aniline in wastewater, and also produces a large amount of waste activated carbon and chemical pollution mud, these hazardous wastes are not only difficult to dispose of, but also costly to deal with

Among these methods, the precipitate from the condensation and precipitation of TDI wastewater contains a large amount of impurities, which is difficult to purify; if it is treated as hazardous waste, it is flammable and explosive, and almost no hazardous waste treatment enterprises are willing to accept it; if it accumulates in the production area, it will face huge safety hazards. risk

In addition, when the soluble nitro and benzene ring substances in the wastewater are removed by adsorption, oxidation, precipitation and other methods, a large amount of chemical sludge will be produced, and the disposal cost of the chemical sludge produced per ton of wastewater is about 100 yuan. The operation of the facilities caused a lot of cost pressure. At the same time, due to the open operation, the unpleasant gas in the sewage volatilized, and the on-site production environment was harsh; and the above-mentioned treatments were the main methods for the wastewater and nitrobenzene-containing wastewater generated from the production of TDI. The objects to be treated are all dissolved

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