Browsing by Author "Ismail, Ahmad Fauzi"

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Citation - WoS: 36
Citation - Scopus: 39
Boron Removal and Antifouling Properties of Thin-Film Nanocomposite Membrane Incorporating Pecvd-Modified Titanate Nanotubes
(WILEY, 2019) Ng, Zhi-Chien; Chong, Chun-Yew; Lau, Woei-Jye; Karaman, Mustafa; Ismail, Ahmad Fauzi
BACKGROUND Incorporation of nanofillers into the polyamide (PA) layer of thin-film composite (TFC) membrane could improve membrane surface properties for enhanced water separation efficiency. However, most nanofillers do not disperse well in organic medium. In this work, the surface of titanate nanotubes (TNTs) was modified via the plasma-enhanced chemical vapour deposition (PECVD) method in order to promote its dispersion rate (in organic medium) during thin-film nanocomposite (TFN) membrane fabrication. RESULTS Fourier transform infrared (FTIR) analysis confirmed the surface chemistry of TNTs coated by hexafluorobutyl acrylate (HFBA) or hydroxyethyl methacrylate (HEMA) via PECVD method. The effects of embedding modified TNTs into the PA layer on membrane surface morphology, hydrophilicity and performance were also investigated and the results were further compared with commercial reverse osmosis (RO) membranes. It was found that the incorporation of HFBA- and HEMA-modified TNTs could enhance the membrane water permeability by >25% and >40%, respectively, without compromising their salt rejection. The boron rejections of TFN membranes incorporated with HFBA- and HEMA-modified TNTs meanwhile were recorded at 75.56% and 70.73%, respectively; these values were relatively higher than those for the self-synthesized TFC (68.57%) and commercial RO membranes (37-39%). The developed TFN membranes also exhibited higher fouling tolerance than the commercial RO membranes, achieving >94% of water flux regeneration as a result of enhanced membrane surface hydrophilicity. CONCLUSION Compared to hydrophilic modification using HEMA, nanofillers modified by hydrophobic HFBA proved more effective at producing a PA layer with better nanofiller distribution, making the resultant TFN membrane more suitable for desalination processes. (c) 2019 Society of Chemical Industry
Citation - WoS: 8
Citation - Scopus: 10
Development of Surface Modified Pu Foam With Improved Oil Absorption and Reusability Via an Environmentally Friendly and Rapid Pathway
(Elsevier Sci Ltd, 2022) Seah, Mei Qun; Ng, Zhi Chien; Lau, Woei Jye; Gürsoy, Mehmet; Karaman, Mustafa; Wong, Tuck-Whye; Ismail, Ahmad Fauzi
Although the commercial polyurethane (PU) foams are hydrophobic in nature, they generally show low degree of reusability for oil and organic solvent absorption. In this work, we proposed a solvent-free and rapid surface functionalization approach based on chemical vapor deposition (CVD) process to improve the surface characteristics of PU foam, increasing not only its reusability but also its absorption capacity. Among the monomers used to functionalize the surface of foam, our results showed that only hexamethyldisiloxane (HMDSO) and 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) were promising to increase the absorption performance of the control PU foam, owing to the enhanced foam's surface hydrophobicity (with contact angle increased from similar to 106 degrees to 120-135 degrees) without altering the foam's porosity. These promising features are attributed to the formation of ultrathin highly hydrophobic yet uniform layer on the foam surface. Further investigation indicated that the modified foams outperformed the control foam for the multicycle cyclohexane and crude oil absorption (up to 10 cycles) by showing significantly higher absorption capacity. The reusability of the modified foams could be further improved when ethanol was employed to rinse the saturated foam after each absorption cycle. Such solvent rinsing help in maintaining the foam absorption capacity. In conclusion, the proposed greener surface modification method clearly demonstrated its effectiveness in functionalizing the PU foam, leading to higher absorption capacity against cyclohexane and crude oil as well as higher degree of reusability.
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: 47
Citation - Scopus: 62
Eco-Friendly Surface Modification Approach To Develop Thin Film Nanocomposite Membrane With Improved Desalination and Antifouling Properties
(Elsevier, 2022) Khoo, Ying Siew; Lau, Woei Jye; Liang, Yong Yeow; Karaman, Mustafa; Gürsoy, Mehmet; Ismail, Ahmad Fauzi
Introduction: Nanomaterials aggregation within polyamide (PA) layer of thin film nanocomposite (TFN) membrane is found to be a common issue and can negatively affect membrane filtration performance. Thus, post-treatment on the surface of TFN membrane is one of the strategies to address the problem. Objective: In this study, an eco-friendly surface modification technique based on plasma enhanced chemical vapour deposition (PECVD) was used to deposit hydrophilic acrylic acid (AA) onto the PA surface of TFN membrane with the aims of simultaneously minimizing the PA surface defects caused by nanomaterials incorporation and improving the membrane surface hydrophilicity for reverse osmosis (RO) application. Methods: The TFN membrane was first synthesized by incorporating 0.05 wt% of functionalized titania nanotubes (TNTs) into its PA layer. It was then subjected to 15-s plasma deposition of AA monomer to establish extremely thin hydrophilic layer atop PA nanocomposite layer. PECVD is a promising surface modification method as it offers rapid and solvent-free functionalization for the membranes. Results: The findings clearly showed that the sodium chloride rejection of the plasma-modified TFN membrane was improved with salt passage reduced from 2.43% to 1.50% without significantly altering pure water flux. The AA-modified TFN membrane also exhibited a remarkable antifouling property with higher flux recovery rate (>95%, 5-h filtration using 1000 mg/L sodium alginate solution) compared to the unmodified TFN membrane (85.8%), which is mainly attributed to its enhanced hydrophilicity and smoother surface. Furthermore, the AA-modified TFN membrane also showed higher performance stability throughout 12-h filtration period. Conclusion: The deposition of hydrophilic material on the TFN membrane surface via eco-friendly method is potential to develop a defect-free TFN membrane with enhanced fouling resistance for improved desalination process. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of Cairo University.
Citation - WoS: 26
Citation - Scopus: 29
Environmentally Friendly Approach for the Fabrication of Polyamide Thin Film Nanocomposite Membrane With Enhanced Antifouling and Antibacterial Properties
(ELSEVIER, 2021) Khoo, Ying Siew; Seah, Mei Qun; Lau, Woei Jye; Liang, Yong Yeow; Karaman, Mustafa; Gürsoy, Mehmet; Ismail, Ahmad Fauzi
In this work, we employed an environmentally friendly approach based on plasma enhanced chemical vapour deposition (PECVD) to modify titania nanotubes (TNTs), aiming to obtain better dispersion of nanofillers in polyamide (PA) layer of thin film nanocomposite (TFN) reverse osmosis membrane. Owing to the hydrophilic nature of TNTs, dispersing it homogenously in organic solvent during interfacial polymerization process is difficult to achieve. Therefore, the TNTs are mildly modified by PECVD technique in order to ameliorate its stability in organic solvent. Our results showed that depositing thin layer of methyl methacrylate (MMA) on the TNTs surface could enhance its dispersion quality in organic solvent and further improve the properties of PA layer by enhancing membrane water flux by 16% without compromising NaCl rejection. More importantly, the developed TFN membrane showed excellent fouling resistance by recording flux recovery rate of 85.77% compared to 57.94% shown by the control membrane. Its antibacterial property was also obviously better than that of control membrane. Overall, the developed TFN membrane demonstrated good performance stability with respect to NaCl rejection and water permeability and the trace amount of nanofillers detected in the water sample (in the level of mu g/L) did not negatively influence the membrane filtration performance.
Citation - WoS: 46
Citation - Scopus: 49
A Green Approach To Modify Surface Properties of Polyamide Thin Film Composite Membrane for Improved Antifouling Resistance
(ELSEVIER, 2020) Khoo, Ying Siew; Lau, Woei Jye; Liang, Yong Yeow; Karaman, Mustafa; Gürsoy, Mehmet; Ismail, Ahmad Fauzi
A green approach based on plasma enhanced chemical vapour deposition (PECVD) method was adopted in this work to modify surface properties of thin film composite (TFC) membranes for improved antifouling resistance during desalination process. Two types of hydrophilic monomers, i.e., acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) was respectively deposited onto the surface of commercial TFC membranes (XLE and NF270) and the effect of plasma deposition time (15 s, 1 min and 5 min) on the membrane physiochemical properties was investigated using different analytical instruments. The deposition of AA and HEMA was able to improve the membrane hydrophilicity owing to the presence of hydroxyl and carboxyl functional groups. However, prolonged plasma polymerization period was not encouraged as it led to the formation of thicker skin layer that significantly reduced water permeability. With 15-s plasma deposition time, AA and HEMA-modified XLE and NF270 membranes could achieve higher NaCl and Na2SO4 rejections as well as demonstrate 100% flux recovery rate. The improved antifouling resistance of modified TFC membranes is mainly due to the improved surface hydrophilicity coupled with greater surface charge properties. This work demonstrated a rapid solvent-free surface modification method that can be employed to enhance TFC membrane properties for desalination process.
Citation - WoS: 22
Citation - Scopus: 23
A Green Approach To Modify Surface Properties of Polyurethane Foam for Enhanced Oil Absorption
(MDPI, 2020) Ng, Zhi Chien; Roslan, Rosyiela Azwa; Lau, Woei Jye; Gürsoy, Mehmet; Karaman, Mustafa; Jullok, Nora; Ismail, Ahmad Fauzi
The non-selective property of conventional polyurethane (PU) foam tends to lower its oil absorption efficiency. To address this issue, we modified the surface properties of PU foam using a rapid solvent-free surface functionalization approach based on the chemical vapor deposition (CVD) method to establish an extremely thin yet uniform coating layer to improve foam performance. The PU foam was respectively functionalized using different monomers, i.e., perfluorodecyl acrylate (PFDA), 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA), and hexamethyldisiloxane (HMDSO), and the effect of deposition times (1, 5 and 10 min) on the properties of foam was investigated. The results showed that all the modified foams demonstrated a much higher water contact angle (i.e., greater hydrophobicity) and greater absorption capacities compared to the control PU foam. This is due to the presence of specific functional groups, e.g., fluorine (F) and silane (Si) in the modified PU foams. Of all, the PU/PHFBA(i)foam exhibited the highest absorption capacities, recording 66.68, 58.15, 53.70, and 58.38 g/g for chloroform, acetone, cyclohexane, and edible oil, respectively. These values were 39.19-119.31% higher than that of control foam. The promising performance of the PU/PHFBA(i)foam is due to the improved surface hydrophobicity attributed to the original perfluoroalkyl moieties of the HFBA monomer. The PU/PHFBA(i)foam also demonstrated a much more stable absorption performance compared to the control foam when both samples were reused for up to 10 cycles. This clearly indicates the positive impact of the proposed functionalization method in improving PU properties for oil absorption processes.
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.
Citation - WoS: 22
Citation - Scopus: 22
Rapid Surface Modification of Ultrafiltration Membranes for Enhanced Antifouling Properties
(MDPI, 2020) Said, Noresah; Khoo, Ying Siew; Lau, Woei Jye; Gürsoy, Mehmet; Karaman, Mustafa; Ting, Teo Ming; Ismail, Ahmad Fauzi
In this work, several ultrafiltration (UF) membranes with enhanced antifouling properties were fabricated using a rapid and green surface modification method that was based on the plasma-enhanced chemical vapor deposition (PECVD). Two types of hydrophilic monomers-acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) were, respectively, deposited on the surface of a commercial UF membrane and the effects of plasma deposition time (i.e., 15 s, 30 s, 60 s, and 90 s) on the surface properties of the membrane were investigated. The modified membranes were then subjected to filtration using 2000 mg/L pepsin and bovine serum albumin (BSA) solutions as feed. Microscopic and spectroscopic analyses confirmed the successful deposition of AA and HEMA on the membrane surface and the decrease in water contact angle with increasing plasma deposition time strongly indicated the increase in surface hydrophilicity due to the considerable enrichment of the hydrophilic segment of AA and HEMA on the membrane surface. However, a prolonged plasma deposition time (>15 s) should be avoided as it led to the formation of a thicker coating layer that significantly reduced the membrane pure water flux with no significant change in the solute rejection rate. Upon 15-s plasma deposition, the AA-modified membrane recorded the pepsin and BSA rejections of 83.9% and 97.5%, respectively, while the HEMA-modified membrane rejected at least 98.5% for both pepsin and BSA. Compared to the control membrane, the AA-modified and HEMA-modified membranes also showed a lower degree of flux decline and better flux recovery rate (>90%), suggesting that the membrane antifouling properties were improved and most of the fouling was reversible and could be removed via simple water cleaning process. We demonstrated in this work that the PECVD technique is a promising surface modification method that could be employed to rapidly improve membrane surface hydrophilicity (15 s) for the enhanced protein purification process without using any organic solvent during the plasma modification process.