| Solvent crystallization is a common method in the production of cephalosporin antibiotics like ampicillin sodium. There is a large number of crystallizing mother liquid includes numerous isooctoate salt generated during the solvent crystallization production process which use sodium 2-ethylhexanoate as salt forming agents. Currently, the domestic enterprises only recycle the solvent, but the waste after solvent recovery usually disposed by landfill or incineration on the recovery process of crystallization mother liquor, it brings to not only environment pollution and also huge wastefulness. Therefore, it will be have great benefits of economic and environmental to separate and recycle the isooctoate salt from the waste of ampicillin sodium production process.In this paper, a method about recycling sodium 2-ethylhexanoate from the waste after solvent recovery of ampicillin sodium production process is proposed, and also study this process from experiment systematically.The experiment research focus on plus acid process, vacuum distillation process, and sodium 2-ethylhexanoate synthesis process.The effect of the acid types and pH value of the waste on purity of crude 2-ethtyhexanic acid are studied, determine the acid types and pH value of the waste used in the plus acid process. The effect of reflux ratio and pressure on purity and yield of fine 2-ethtyhexanic acid in vacuum distillation process is discussed, determine distillation operating pressure and reflux ratio. The effect of alkali species, reaction temperature, reaction time and stirring rate on purity and conversion ratio of 2-ethylhexanoate acid in sodium 2-ethylhexanoate synthesis process, obtained the better technological conditions, the purity of sodium 2-ethylhexanoate can reach 97.66 %.The environmental indicators of the waste before and after separation and recovery were analyzed, it indicates that the total amount of COD and NH3-N decreased by about 11.33 % and 8.18 %, respectively, after this treatment process. Rough economic about the separation and recovery by this process was analysed, it will be gains 3.1 millions per year while the output of ampicillin sodium is 200 tons per year. |
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