| Colistin sulphate,a kind of basic peptide antibiotics,Shows strong antibacterial effect on most gram-negative bacteria.Usually it is used as feed antibiotics.The current colistin extraction process is based on ion exchange resin method which is water-consuming,and results in great emission of pollutants.In order to ease these problems and shorten the process cycle,in this dissertation,precipitation method is investigated,mainly focusing on the subprocess of flocculation,sedimentation,metal ion removal,decoloring and other processes and main conclusions are as follows.(1)The result showed that: the stability of colistin will be better when the PH was 6.And the stability would be destroyed by over acid or alkali.The advanced structure and spatial structure would destroyed mostly in alkali solution.In a certain temperature range increasing temperature will help to improve potency.And at the same PH,the longer time,the more serious structural damage of colistin,and the worse stability.Stirring speed will not have a significant effect on the stability of colistin sulphate.(2)The flocculation experiments showed a good fermentation flocculation broth after PAC and chitosan trentment.It means that it can be used as coagulant and flocculant.The best dosage of PAC was 0.2%,the optimal dosage of chitosan was 0.15%.Then,the adding order,temperature,pH,time and other conditions of flocculation were studied in this paper.And it obtained a set of optimal flocculation conditions,when the temperature was 45℃,pH of 3,coagulation time was 15 min.And the flocculation was better by adding flocculant after cohesion flocculant(3)Precipitation pH,temperature,precipitation time,stirring speed and concentration of alkali and other process parameters were studied in this dissertation.And the optimum precipitation conditions was ultimately determined when the pH of 12.1 and a temperature of 20 ℃,the processing time of 2 hours,stirring speed 120 r / min,the concentration of alkali 2.5mol / L,the maximum yield occurred,while the degradation rate of the liquor and the residual rate was lower.(4)It is studied that the removal process polymyxin broth metal ions,chelating resin adsorption desalination and main applications of this research material was removed by complexing metal ions,complexing agent through screening,disodium edetate as a complexing agent of the present study.And then temperature,pH,and other conditions of the order of addition were studied to obtain a set of optimal conditions,when disodium edetate was added in an amount of 0.8% and a temperature of 55℃,pH 8,before the crystals were added disodium edetate,low loss of potency,the metal ion removal was better.By desalting resin filter,001 × 16 resin may be used in the present study desalting resin.Dynamic adsorption experiments to determine the optimum flow rate of the study,when the flow rate was 2BV / h,the resin had good bleaching properties and metal ion removal capacity.(5)Polymyxin decolorization process has also been studied by bleaching agents screened to select powdered activated carbon as a bleaching agent and optimize its decolorization.When added in an amount of 1%,bleaching time was between 20 to 30 min,bleaching temperature was 30℃,the content and the yield of colistin was higher,bleaching effect was good. |
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