响应曲面法优化MBfR中PVDF/pDOPA改性膜的表面改性条件
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摘要
膜生物膜反应器研究中,常用疏水性微孔膜存在氧传质性能、耐污染性能较差等问题,论文以课题组自制疏水性PVDF中空纤维膜为原膜,采用自聚合法以左旋多巴为单体对原膜进行表面改性,采用响应曲面法针对左旋多巴浓度、自聚合时间及热处理温度对于改性膜性能的影响进行系统研究,模拟得到改性膜氧传质性能参数K_(La)的二次回归方程模型,结果表明:最佳表面改性条件(L-DOPA质量浓度1.54 g/L、自聚合时间3.0 h、热处理温度37.0℃)下,改性膜K_(La)的实测结果(1.61×10~(-2 )min~(-1))与响应曲面拟合所得模型的预测值(1.60×10~(-2 )min~(-1))基本吻合,该模型可用于优化PVDF/p DOPA改性膜的表面改性条件。最佳表面改性条件下,PVDF/p DOPA改性膜与原膜机械性能相近,氧气传质性能显著优于原膜,K_(La)自原膜0.95×10~(-2 )min~(-1)提高至1.61×10~(-2 )min~(-1),为原膜的1.70倍,改性膜表面亲水性提高(接触角自原膜75.2°降至41.4°)。
Aiming at the insufficient oxygen supply capacity and poor antifouling properties of hydrophobic microporous membrane in membrane biofilm reactor(MBf R),surface modified composite membrane was prepared by self-made hydrophobic PVDF hollow fiber membrane with self-polymerization of L-DOPA.The response surface methodology(RSM)was adopted to explore the influence of L-DOPA concentration,polymerization time and heat treatment temperature on modified composite membrane properties.Quadratic regression of oxygen mass transfer performance coefficient K_(La)of modified membrane was simulated.The results showed that,under the optimum conditions of surface modification(L-DOPA concentration,polymerization time and heat treatment temperature was 1.54 g/L,3.0 h and 37.0℃respectively),the measured value of KLa of the modified membrane was 1.61×10~(-2)min~(-1),which was in good agreement with the predicted value of 1.60×10~(-2)min~(-1),the model could be used to optimize the surface modification of PVDF/p DOPA modified membrane.The PVDF/p DOPA modified membrane had similar mechanical strength compared with the original membrane,and its oxygen transfer coefficient K_(La)improved from 0.95×10~(-2)min~(-1)to 1.61×10~(-2)min~(-1),1.70 times as much as the original.The surface hydrophilic of the modified membrane was improved(contact angle decreased from 75.4°to 41.4°).
Aiming at the insufficient oxygen supply capacity and poor antifouling properties of hydrophobic microporous membrane in membrane biofilm reactor(MBf R),surface modified composite membrane was prepared by self-made hydrophobic PVDF hollow fiber membrane with self-polymerization of L-DOPA.The response surface methodology(RSM)was adopted to explore the influence of L-DOPA concentration,polymerization time and heat treatment temperature on modified composite membrane properties.Quadratic regression of oxygen mass transfer performance coefficient K_(La)of modified membrane was simulated.The results showed that,under the optimum conditions of surface modification(L-DOPA concentration,polymerization time and heat treatment temperature was 1.54 g/L,3.0 h and 37.0℃respectively),the measured value of KLa of the modified membrane was 1.61×10~(-2)min~(-1),which was in good agreement with the predicted value of 1.60×10~(-2)min~(-1),the model could be used to optimize the surface modification of PVDF/p DOPA modified membrane.The PVDF/p DOPA modified membrane had similar mechanical strength compared with the original membrane,and its oxygen transfer coefficient K_(La)improved from 0.95×10~(-2)min~(-1)to 1.61×10~(-2)min~(-1),1.70 times as much as the original.The surface hydrophilic of the modified membrane was improved(contact angle decreased from 75.4°to 41.4°).
引文
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[2]MAITIN K J,NERENBERG R.The membrane biofilm reactor(MBf R)for water and wastewater treatment:Principles,applications,and recent developments[J].Bioresource Technology,2012,122(3):83-94.
[3]HIBIYA K,TSUNEDA S,HIRATA A.Formation and characteristics of nitrifying biofilm on a membrane modified with positively-charged polymer chains[J].Colloids&Surfaces B Biointerfaces,2000,18(2):105-112.
[4]徐又一,蒋金泓,朱利平,等.多巴胺的自聚合-附着行为与膜表面功能化[J].膜科学与技术,2011,31(3):32-38.
[5]AZARI S,ZOU L.Using zwitterionic amino acid L-DOPA to modify the surface of thin film composite polyamide reverse osmosis membranes to increase their fouling resistance[J].Journal of Membrane Science,2012,401-402:68-75.
[6]MURALIDHAR R V,CHIRUMAMILA R R.A response surface approach for the comparison of lipase production by Canida cylindracea using two different carbon sources[J].Biochemical Engineering Journal,2001,9(1):17-23.
[7]张利娟,袁晓彤,王暄,等.MBf R中PVDF/p DOPA改性膜耐污染性能研究[J].水处理技术,2016,42(8):62-67.
[8]邢明皓.表面改性制备MABR用中空纤维膜[D].天津:天津大学,2012.