Development of magnetophoretic actuation composite membranes for removal of humic acid
| dc.contributor.author | Ng Qi Hwa | |
| dc.date.accessioned | 2021-04-26T03:36:02Z | |
| dc.date.available | 2021-04-26T03:36:02Z | |
| dc.date.issued | 2016-06-01 | |
| dc.description.abstract | Membranes used for potable water production have remarkable progressed over the past few years due to the compact design of the membrane module, lowered energy consumption, and reliable effluent quality. Nevertheless, membrane fouling caused by the deposition of fouling materials on the membrane remains a critical issue in many applications of water filtration processes and is the dominant factor that restricts the widespread application of membranes. Thus, this study investigates the efficiency of humic acid (HA) removal by a magnetophoretic actuation composite membrane through magnetic actuation to reduce the membrane fouling propensity. First, the bare magnetite nanoparticles (MNPs) were functionalized to increase its colloidal stability, to ensure the homogenous distribution of the MNPs on the membrane surface. Thus, different concentration of water-soluble poly(sodium 4-styrene sulfonate) (PSS) were coated around the surface of MNPs, where the optimum PSS/MNPs molar ratio was found at 6:1. Prior to end-capping the functionalized-MNPs (F-MNPs) onto the membrane surface, Quartz Crystal Microbalance with Dissipation (QCM-D) technique is used to investigate the interaction affinity between F-MNPs with a specific surface of a membrane. The QCM-D results demonstrated a good interaction between F-MNPs and polyethersulfone (PES) membrane in the presence of polyelectrolytes PSS and poly(diallyldimethylammonium chloride) (PDDA). Next, the extent of magnetophoretic actuation based on the presence of different concentrations of F-MNPs (e.g., 100, 1000, and 2500 ppm) coated on the membrane surface were also studied. The results shown that the best performance of the magnetophoretic actuation composite membrane was obtained by spin coated the 2500 ppm F-MNPs onto the PSS-PDDA-PES modified membrane surface at the spinning rate of 3000 rpm and 8 s of the spinning time. Subsequently, the influence of pH-fluctuated aqueous mediums toward the stability of the magnetic-responsive functional layer laid on the composite membrane was also being evaluated. Based on the analyses, the best operating pH for the composite membrane were found in the range of pH 2-10. Last but not least, the developed membranes with the best filtration performance were subjected to the fouling mechanisms study, and membrane longevity performance evaluation to reveal the potential of magnetophoretic actuation composite membrane in HA removal. Filtration results indicate a transition of membrane fouling mechanism, from a standard pore blocking to the formation of cake layer throughout the filtration processes but cake fouling was identified as the most critical factor that contributes to the membrane fouling. While for the membrane longevity study, the membrane operated under an external oscillating magnetic field established excellent membrane anti-fouling capability by retaining 96 % of the initial flux (Jo= 9.44×10-6 m3/m2s) after 48 h of filtration with HA rejection of 99.4±0.14 %. The enhanced filtration performance was due to the magnetophoretic actuation motions of F-MNPs that reduces concentration polarization near the top surface of the membrane and consequently reduces the potential for membrane fouling. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/13138 | |
| dc.language.iso | en | en_US |
| dc.subject.lcsh | Humic acid | |
| dc.title | Development of magnetophoretic actuation composite membranes for removal of humic acid | en_US |
| dc.type | Thesis | en_US |
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