Method for separating and recovering diethyl phosphate sodium salt from fluorescent whitening agent synthesis liquid

Abstract

The invention provides a method for separating and recovering diethyl phosphate sodium salt from a fluorescent whitening agent synthetic liquid, which comprises the following steps: S1, distilling the fluorescent whitening agent synthetic liquid, and recovering a solvent to obtain a concentrate A1; s2, adding hot water into the concentrate A1, uniformly dissolving, cooling to room temperature, and filtering to obtain a solid phase B1 and a liquid phase C1; s3, distilling the liquid phase C1 to obtain a concentrate A2, and filtering to obtain a solid phase B2 and a liquid phase C2; s4, continuously distilling the liquid phase C2 to obtain a concentrate A3, adding an alcohol solvent in batches under stirring reflux, uniformly dissolving, cooling to room temperature, and filtering to obtain a solid phase B3 and a liquid phase C3; and S5, distilling the liquid phase C3 to obtain a concentrate A4, cooling, and crushing to obtain the diethyl phosphate sodium salt. The method improves the quality and yield of the diethyl phosphate sodium salt, and solves the problems of difficult recovery, high energy consumption, low yield, poor quality and the like of the diethyl phosphate sodium salt at present.

Description

technical field [0001] The invention relates to the technical field of recovery of by-products of fluorescent whitening agent production, in particular to a method for separating and recovering diethyl phosphate sodium salt from fluorescent whitening agent synthetic liquid. Background technique [0002] Fluorescent whitening agent 4,4′-bis-(2-sulfonate styryl) biphenyl, referred to as CBW, was originally developed by Swiss Ciba-Geigy (now Ciba Fine Chemicals) in the late 1960s Successfully, its process is formed by benzylation of biphenyl, esterification with phosphite, and condensation with sodium o-sulfonate benzaldehyde. For every molecule of CBW produced, two molecules of diethyl phosphate sodium salt are simultaneously produced. At present, most domestic enterprises adopt the above-mentioned process, and the process adjustment is basically to replace the solvent and catalyst. However, the recycling of diethyl phosphate sodium salt, a by-product in the CBW production pr...

AI Technical Summary

Problems solved by technology

At present, most domestic enterprises adopt the above-mentioned process, and the process adjustment is basically to replace the solvent and catalyst. However, the recycling of diethyl phosphate sodium salt, a by-product in the CBW production process, has become an important problem for enterprises to manage waste residue and improve economic benefits.

[0003] At present, there are no relevant reports on the treatment and recovery of diethyl phosphate sodium salt in the CBW synthetic liquid

However, the traditional treatment method only adopts distillation method and solid-liquid separation, and there are problems such as high material viscosity, relatively similar physical properties of each component in the system, and low recovery and purity of diethyl phosphate sodium salt, which restricts diethyl phosphate The further development and utilization of sodium salt has affected the large-scale processing and recovery of diethyl phosphate sodium salt in enterprises

[0004] In addition, if the diethyl phosphate sodium salt in the CBW synthetic liquid is not effectively recycled, a large amount of organophosphorus resources will be wasted, and at the same time, it will be discharged into the wastewater, resulting in high COD wastewater, which will increase the difficulty of wastewater treatment. It is conducive to the environmental protection and green production of enterprises, and seriously restricts the sustainable, healthy and stable development of fluorescent whitening agent enterprises

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