Browsing by Author "Lai, Gwo Sung"

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Citation - WoS: 32
Citation - Scopus: 39
Development of Thin Film Nanocomposite Membrane Incorporated With Plasma Enhanced Chemical Vapor Deposition-Modified Hydrous Manganese Oxide for Nanofiltration Process
(ELSEVIER SCI LTD, 2019) Lai, Gwo Sung; Lau, Woei Jye; Goh, Pei Sean; Karaman, Mustafa; Gürsoy, Mehmet; Ismail, Ahmad Fauzi
This study presents the development of novel thin film nanocomposite (TFN) membranes incorporated with poly (hexafluorobutyl acrylate)-modified hydrous manganese oxide (PHFBA-modified HMO) nanomaterials for nanofiltration application. The HMO surface is modified via single-step plasma enhanced chemical vapor deposition (PECVD) technique in order to improve its dispersion quality in organic solvent and minimize agglomeration in the resultant membranes. TFN membranes are prepared by dispersing HMO and PHFBA-modified HMO in the organic solvent that is used to prepare TFN1 and TFN2 membranes, respectively. The experimental results reveal that the TFN2 membrane (containing 0.05 w/v% PHFBA-modified HMO) exhibits the highest pure water permeability, which was 66.6% and 21.9% higher than the thin film composite (TFC) and TFN1 membranes, respectively. The remarkable enhancement in water permeability of the TFN2 membrane could be attributed to even distribution of modified HMO over the membrane surface. It is also found that the embedment of modified nanomaterials tends to enhance the polyamide cross-linking degree as well as membrane surface negativity, leading to promising rejection towards Na2SO4 (98.6%) and MgSO4 (97.6%). Furthermore, the TFN2 membrane is demonstrated to possess higher fouling resistance against inorganic and organic foulants. The filtration findings are consistent with the results obtained from instrumental analyses.
Citation - WoS: 30
Citation - Scopus: 34
Rapid and Eco-Friendly Technique for Surface Modification of Tfc Ro Membrane for Improved Filtration Performance
(ELSEVIER SCI LTD, 2021) Khoo, Ying Siew; Lau, Woei Jye; Liang, Yong Yeow; Karaman, Mustafa; Gürsoy, Mehmet; Lai, Gwo Sung; Ismail, Ahmad Fauzi
In this work, an environmentally friendly plasma enhanced chemical vapor deposition (PECVD) technique was employed to rapidly alter the surface properties of commercial thin film composite extra-low energy (XLE) reverse osmosis (RO) membrane to improve its fouling resistance and desalination performance. Hereafter, two different hydrophilic precursors, i.e., aniline monomer and oxygen (O-2) gas were respectively introduced to the membrane's polyamide surface at different plasma treatment duration (15 s and 60 s). At 15-s plasma treatment, our results revealed that the O2-modified membrane outperformed the polyaniline (PANI)-modified membrane and unmodified membrane, attributed to the polar functional groups presented on the polyamide surface. Compared to plasma polymerization of aniline, O-2 plasma etching can lower polyamide densification degree which potentially reduce membrane resistance. Evidently, the O-2-modified membrane exhibited higher pure water permeability (6.64 L/m(2).h.bar) compared to the PANI-modified membrane (5.57 L/m(2).h.bar). The enhanced surface hydrophilicity of O-2-modified membrane could be noticed when its water contact angle was reduced from 88.39 degrees (unmodified) to 79.46 degrees in just 15-s plasma treatment. Furthermore, this O-2-modified membrane achieved an outstanding NaCl and Na2SO4 rejection with an increment of 4.2% and 2.6%, respectively compared to the unmodified membrane. However, prolonged gas plasma treatment (60 s) should be avoided as it can damage polyamide selective layer. With respect to fouling resistance, the best O-2-modified membrane demonstrated higher flux recovery rate (96%) than that of unmodified membrane (76.5%) after being used to filter 1000-ppm sodium alginate solution. These results highlighted the versatility of O-2 plasma treatment to improve RO membrane performance.