| The paper focused on 7-amino-cephalosporanic acid(7-ACA)in industrial wastewater and exploringly studied the possibility in the recovering process of7-ACA by using hollow fiber supported liquid membrane(HFSLM).Based on the mass transfer mechanism analysis of complexing–decomplexing of 7-ACA,a mathematical model of HFSLM process was proposed and verified.Finally,a reliable theoretical and experimental basis was provided for the industrial application in the field of pharmaceutical wastewater treatment by the techno-economic evaluation of the HFSLM technology.Firstly,the complexation extraction system consisted of methyl trioctyl ammonium chloride(TOMAC)and butyl acetate was selected based on the simulate7-ACA wastewater from a certain domestic pharmaceutical enterprise.The main effect factors of extraction and back-extraction were studied and the optimal operating conditions were obtained by optimization.The results showed that the single-stage extraction and back-extraction partition coefficient had a maximum value when the reaction temperature was 25 ?,the concentraction of 7-ACA was 0.2 g/L,the concentration of complexing agent was 5 mmol/L,the extraction pH was 7,the back-extraction pH was 2,the extraction phase ratio was 0.5,the back-extraction phase ratio was 0.4.The extraction rate and back-extraction rate after fourstage extraction were 96.3% and 95.9% respectively.The extraction and back-extraction partition coefficient had no significant decrease after reusing complexing agent five times,and the reaction was exothermic.Secondly,the hollow fiber supported liquid membrane with stripping dispersion(HFSLM-SD)was studied in the process of recovering 7-ACA.The polypropylene membrane module was employed to determine the appropriate operation conditions.The results showed that the extraction rate was 85% when the dipping time of membrane was 2 h,the stirring time was 300 rpm,the transmembrane pressure was0.04 MPa,the flow rate of tube side and shell side were 0.0177 m/s and 0.007695 m/s respectively.The extraction rate had no significant decrease after reusing of complexing agent three times,the liquid membrane had a good stability.Based on the abovementioned experimental results,a mass transfer mathematical model was proposed,and the model was solved,verified and applied to analyze the mass transfer performance.The results showed that the order of magnitudes of the model value and the experiment value were the same and the error was 14.6%,which verified the model was reliable.The mass transfer resistance mainly existed in the liquid membrane and the shell side.HTU = 0.453 m,NTU = 0.283,the total mass transfer resistance was small.The calculation value was consistent with the analysis results of mass transfer resistance under different flow rates of the tube side and the shell side,which further verified the accuracy of the model.Finally,a foundation was layed for its industrial application in the field of pharmaceutical wastewater treatment by a preliminary techno-economic evaluation of HFSLM-SD. |
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