Method for separating and purifying mixed salt in aromatic compound nitrification wastewater

Abstract

The invention provides a separation and purification method of a mixed solution containing sodium nitrate and sodium sulfate, which combines two stages of nanofiltration and at least two stages of reverse osmosis treatment steps, not only can effectively realize efficient separation of sodium nitrate and sodium sulfate in the solution, but also realizes the concentration effect through nanofiltration and reverse osmosis at the same time. The energy consumption of later concentration and crystallization is greatly reduced, the economic value is remarkably improved, the application prospect is wide, and the method can be better used for separating and purifying the mixed salt in the aromatic compound nitrification wastewater.

Description

technical field [0001] The invention relates to the technical field of separation and purification, in particular to a method for separation and purification of mixed salts in aromatic compound nitrification wastewater. Background technique [0002] Nitration products of aromatic compounds such as nitrobenzene, m-dinitrobenzene, p / o / m-nitrochlorobenzene, 3,4- / 2,5-dichloronitrobenzene, etc. are important pesticides, medicines, dyes, and pigments And other chemical intermediates. At present, aromatic compounds are mainly produced by mixed acid process, and nitrification wastewater will be generated during the process. Nitrification wastewater contains aromatic hydrocarbons and their derivatives, nitration products, nitrophenol and its sodium salt (referred to as total phenol), sodium sulfate, sodium nitrate, etc. Due to its high toxicity, high salt content, poor biodegradability, and high treatment costs. According to the characteristics of nitrification wastewater, physical...

AI Technical Summary

Problems solved by technology

Nitrification wastewater contains aromatic hydrocarbons and their derivatives, nitration products, nitrophenols and their sodium salts (referred to as total phenols), sodium sulfate, sodium nitrate, etc. Due to high toxicity, high salt content, poor biodegradability, and high treatment costs

According to the characteristics of nitrification wastewater, physical and chemical methods such as adsorption, oxidation and other pretreatment methods are usually used to reduce the concentration of organic matter in wastewater and improve the biodegradability of wastewater, but the separation and purification of mixed salts in nitrification wastewater are not considered, resulting in waste of resources

[0003] CN1233570C discloses a resin adsorption recovery process of nitrochlorobenzene in nitrochlorobenzene production wastewater, adopts the styrene-divinylbenzene resin adsorption scheme, separates and recovers nitrochlorobenzene in wastewater, and desorbs and regenerates saturated resin vapor to realize Recovery of nitrochlorobenzene in wastewater, but the price of the resin is high, and the high temperature of the steam desorption regeneration method increases the risk of resin aging

[0004] CN111018264A discloses a process method for treating nitrate wastewater, which adopts the combination scheme of advanced oxidation unit, electrodialysis unit, evaporation unit and biochemical unit, which can realize the recovery of sodium sulfate, the discharge of water up to the standard and the reduction of sludge at the same time. However, there are many processes, and there is no mention of the separation and recovery of nitrate in wastewater

[0005] In 2020, Pei Xudong et al. realized the separation of sodium sulfate, sodium chloride and sodium nitrate through fractional crystallization of miscellaneous salts in high-salt wastewater. Difficult (see "Research on Separation Process of Sodium Sulfate-Sodium Chloride-Sodium Nitrate in Coal Chemical Wastewater", Pei Xudong et al., Industrial Water Treatment, Vol. 40, No. 1, pp. 63-65)

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