The Correlation Research Of UF Membranes Interface Properties And BSA, HA Membrane Fouling Behavior

In this paper, using polyvinylidene fluoride (PVDF) and polyethersulfone (PES)as the main membrane material, the hydrophilic polymer and the charged modifiedpolymer as blending additives, different interface characteristics parameter of modifiedultrafiltration membrane were prepared for testing. Humic acid (HA) and bovine serumalbumin (BSA) were selected as the typical representatives of foulants, By use ofextending colloidal space stability theory (XDLVO theory) prediction, atomic forcemicroscopy analysis technology to detect and analyze the interface microscopic forcebetween the membrane and the foulants, and combining with membrane foulingevaluation method during the ultrafiltration filtration, the effect and influence ofultrafiltration membrane interface characteristic such as hydrophilic/hydrophobic,charge, membrane structure parameters to HA and BSA fouling behavior werecomprehensively analyzed. And it provided a research basis of constructing andpreparing ultrafiltration membrane interface parameters which had high anti-foulingcharacteristic. The results showed that:Firstly, PVDF/PVA blend membrane (PA) and PVDF/PVP blend membrane (PP)with hydrophilic/hydrophobic characteristics, as well as carboxymethyl modificationof PES ultrafiltration membrane (CMPES) and quaternary ammonium modified PESultrafiltration membrane (QAPES) with charge characteristics, were prepared byimmersion precipitation phase catalysis. By the use of infrared spectra (IR), contactangle (CA), flow potential and Zeta potential, as well as the pore size and porosity,SEM, AFM and other technical analysis methods, two types of typical interfaceparameters of ultrafiltration membranes were obtained, respectively. Secondly, in the different pH circumstances, HA and BSA to two types ofultrafiltration membrane (with interface characteristics) fouling behavior werepredicted by XDLVO theory analysis. And the results showed, HA and BSA on PVDFand PES ultrafiltration membrane fouling behavior was majorly influenced by AB freeenergy of changing pH. PVDF ultrafiltration membrane fouling was exacerbated bylow pH. PP membrane with less hydrophilic membrane was more easy to be fouled.Compared with BSA, HA is more likely to be polluted on ultrafiltration membraneinterface. The interaction of foulants and ultrafiltration membrane fouling dominatesthe process. In the different pH circumstances, during the adhesion stage of BSA onthree kinds of PES ultrafiltration membrane, the absolute value of static electricityinterfacial free energy is minimum, and the impact on membrane fouling is weak.Compared with the PS membrane, the adhesion free energy between BSA and chargedmodified membrane has been reduced to some extent, additionally, the adhesion freeenergy between negative charged CM membrane and BSA was relatively small, andmembrane fouling trend is smallThirdly, with self-modified probe, the microscopic force of HA and BSA on thetwo types of ultrafiltration membrane interface were analyzed and calculated by AFMdetection technology in different pH circumstances. Force datas showed that theadhesion force between two kinds of foulants and ultrafiltration membrane was greaterthan cohesion force between foulants and foulants, that is to say, during the membranefiltration process, membrane fouling was dominated by the adhesion force betweentwo kinds of foulants and ultrafiltration membrane. However, in the latter part of themembrane filtration process, the cohesion between foulants and foulants has become amajor factor affecting their late membrane fouling behavior.Finally, in different pH environments, HA and BSA ultrafiltration membranefouling analysis confirmed that under the condition of the same pH, in the initialfiltering stages for two foulants, PP membrane flux declined dramatically, and then,the flux gradually stabilized. In addition, PA membrane flux decline rate and loss rateis much lower than the PP membrane's. And with decreasing of the solution pH, fluxdecline rate of two membranes increased. Under different pH conditions, the fluxdecline curve of BSA on three kinds of PES ultrafiltration membranes showed a similar change tendency. Comparing with the PS membrane, charge-modified CM andQA membrane flux decline rate and irreversible fouling has decreased to some extent.Generally, with three analyzed methods and techniques including theoreticalprediction, equipment testing, ultrafiltration experiments operation, membrane foulingprocess of two foulants on ultrafiltration membrane interface, which had differentinterfacial properties, were explored. As a result, the various data and test results canbe verified and complemented each other. And it provided a more detailed basicresearch data for revealing the formation, development and prevention of membranefouling.