Method for recovering and recycling hydrochloric acid in waste acid liquid of D-glucosamine hydrochloride
A technology of glucosamine hydrochloride and waste acid solution, which is applied in the direction of chlorine/hydrogen chloride purification, chlorine/hydrogen chloride, etc., to achieve the effect of increasing the concentration of hydrochloric acid and simple operation
Active Publication Date: 2011-03-30
林大昌
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[0004] In order to solve the problem of hydrochloric acid treatment in the waste acid liquid of the glucosamine hydrochloride production process, the purpose of the present invention is to provide a kind of simple operation, which is suitable for large-scale recovery of low-concentration hydrochloric acid and reuse for the production of glucosamine hydrochloride for hydrolysis of chitin. Methods
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[0012] A detailed description will be given below of specific embodiments of the present invention.
[0013] 1. The principle of mutual solubility of dichloromethane and acetic acid is adopted to remove acetic acid in low-concentration hydrochloric acid (≤25%).
[0014] The hydrochloric acid recovered in the waste acid liquid of glucosamine hydrochloride is added with dichloromethane and fully stirred and mixed (in a closed container, and a reflux condenser is equipped), and separated according to the density difference, the addition of dichloromethane is the 10% to 12% of liquid. The liquid, liquid and liquid are separated by centrifugation, and the centrifuge must be closed when it is working, and the part of the centrifuge that is in contact with the liquid is made of polytetrafluoroene.
[0015] The lower layer separation liquid (mixed solution of acetic acid and dichloromethane) is heated to 40°C-45°C, the low boiling point dichloromethane (boiling point 40°C) is evapora...
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The invention relates to a method for recovering and recycling hydrochloric acid in waste acid liquid resulted from the process for the preparation of D-glucosamine hydrochloride. The method for recovering and recycling hydrochloric acid in waste acid liquid of D-glucosamine hydrochloride comprises the following steps of: (1) adding dichloromethane to the hydrochloric acid recovered from the waste acid liquid of D-glucosamine hydrochloride for being sufficiently stirred and mixed, subjecting the liquid to liquid-liquid centrifugal separation to obtain an upper separating liquid and a lower separating liquid; (2) heating up the lower separating liquid to 40 to 45 DEG C, and evaporating and recovering the dichloromethane with acetic acid remained; (3) heating up the upper separating liquid to 45 to 50 DEG C to remove the residual dichloromethane; and (4) feeding in chlorinated hydrogen to the upper separating liquid for enrichment so as to prepare the hydrochloric acid with the concentration not less than 31%. The method of the invention is simple in operation and suitable for the recovery and the utilization of large-scale low concentration hydrochloric acid, and the hydrochloric acid recovered has the concentration not less than 31% and the content of acetic acid not more than 0.5% as well as can be used for the circulated preparation of D-glucosamine hydrochloride.
Description
technical field [0001] The invention relates to a method for recovering and recycling hydrochloric acid from process waste acid liquid for preparing glucosamine hydrochloride. Background technique [0002] Chitin is hydrolyzed with concentrated hydrochloric acid at high temperature (95-110°C) to prepare glucosamine hydrochloride. Regardless of the primary or secondary hydrolysis, every ton of glucosamine hydrochloride produced will produce 5-8 tons of waste acid. The waste acid solution is decompressed and concentrated to recover hydrochloric acid, the concentration of the recovered hydrochloric acid is 16%-25%, and at the same time, it contains 4%-5% acetic acid. The acid is re-used to hydrolyze chitin, and the hydrolysis rate is very low, both below 10%. After dilution, it can only be used to prepare chitin by decalcifying shrimp shells. [0003] For glucosamine hydrochloride production enterprises, self-made chitin is difficult to produce chitin due to environmental prot...
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IPC IPC(8): C01B7/07
Inventor 林大昌江先登
Owner 林大昌