Ng Qi Hwa
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Preferred name
Ng Qi Hwa
Official Name
Ng, Qi Hwa
Alternative Name
Ng, Q. H.
Qi, Hwa Ng
Ng, Qi H.
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Scopus Author ID
54413018300
Researcher ID
A-9192-2019

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Synthesis and Characterisation of Self-Cleaning TiO2/PES Mixed Matrix Membranes in the Removal of Humic Acid

2023-04-01 , Poon Y.K. , Siti Kartini Enche Ab Rahim , Ng Qi Hwa , Hoo Peng Yong , Abdullah N.Y. , Amira Mohd Nasib , Abdullah N.S.

Membrane application is widespread in water filtration to remove natural organic matter (NOM), especially humic acid. However, there is a significant concern in membrane filtration, which is fouling, which will cause a reduction in the membrane life span, a high energy requirement, and a loss in product quality. Therefore, the effect of a TiO2/PES mixed matrix membrane on different concentrations of TiO2 photocatalyst and different durations of UV irradiation was studied in removing humic acid to determine the anti-fouling and self-cleaning effects. The TiO2 photocatalyst and TiO2/PES mixed matrix membrane synthesised were characterised using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscope (SEM), contact angle, and porosity. The performances of TiO2/PES membranes of 0 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% were evaluated via a cross-flow filtration system regarding anti-fouling and self-cleaning effects. After that, all the membranes were irradiated under UV for either 2, 10, or 20 min. A TiO2/PES mixed matrix membrane of 3 wt.% was proved to have the best anti-fouling and self-cleaning effect with improved hydrophilicity. The optimum duration for UV irradiation of the TiO2/PES mixed matrix membrane was 20 min. Furthermore, the fouling behaviour of mixed matrix membranes was fitted to the intermediate blocking model. Adding TiO2 photocatalyst into the PES membrane enhanced the anti-fouling and self-cleaning properties.

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Parameters adjustments for facile synthesis of high magnetization iron oxide nanoparticles from natural sand

2024-02-01 , Wahfiudin A. , Pramata A.D. , Wicaksono S.T. , Ng Qi Hwa , Amira Mohd Nasib , Siti Kartini Enche Ab Rahim , Mohd Riduan Jamalludin , Hoo Peng Yong

This study explores the synthesis of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) by leveraging natural iron sand and steel wool as primary raw materials within the co-precipitation method, which reduces the cost of production compared to the commercial counterparts. The research systematically investigated the influence of the diethylamine percentage, annealing time and annealing temperature on the SPIONs’ synthesis from natural iron sand by the co-precipitation method. Fe3O4 with varying crystallite sizes, ranging from 11.5 to 14.7 nm, were confirmed. SEM highlighted the nanoparticle agglomeration, a concern addressable through surface modification techniques, as further emphasized by TEM, which confirmed the nano-scale dimensions. Magnetic saturation values were confirmed by VSM, ranging from 37 to 51 emu/g. These values established the superparamagnetic behavior, rendering the nanoparticles suitable for versatile applications. The study identifies a potential threshold effect of the diethylamine concentration on the magnetic saturation and suggests an optimum annealing temperature for energy efficiency. This research contributes valuable insights into harnessing natural iron sand for SPION synthesis, advancing cost-effective and sustainable approaches in nanomaterial development, while emphasizing the importance of parameter customization for producing high-quality SPIONs.

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Sulfonated magnetic multi-walled carbon nanotubes with enhanced bonding stability, high adsorption performance, and reusability for water remediation

2023 , Lim Chuan Chuan , Siew Hoong Shuit , Ng Qi Hwa , Siti Kartini Enche Ab Rahim , Wei Ming Yeoh , Hoo Peng Yong , Soon Wah Goh

In view of the simple and rapid conveniency of magnetic separation, magnetic nanocomposites had notably gained attention from researchers for environmental field applications. In this work, carboxylated magnetic multi-walled carbon nanotubes (c-MMWCNTs) and novel sulfonated MMWCNTs (s-MMWCNTs) were synthesized by a facile solvent-free direct doping method. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, energy dispersive X-ray, vibrating sample magnetometer, and point of zero charge analyses confirmed the successful doping of the Fe3O4 nanoparticles into the functionalized MWCNTs to form MMWCNTs. Besides, the bonding stabilities of both c-MMWCNTs and s-MMWCNTs were compared, and results showed that s-MMWCNTs possessed more substantial bonding stability than that of c-MMWCNTs with significantly less leaching amount of Fe3O4. The adsorption capacity of s-MMWCNTs was higher than that of c-MMWCNTs owing to the stronger electronegativity sulfonic group in s-MMWCNTs. Moreover, the reusability experiments proved that the adsorbent remained consistently excellent MB removal efficiency (R > 94%) even reused for twelve cycles of batch adsorption. The finding of the present work highlights the simple fabrication of novel s-MMWCNTs and its potential to be served as a promising and sustainable adsorbent for water remediation owing to its enhanced bonding stability, high adsorption performance, magnetic separability, and supreme recyclability.

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An insight into the adsorptive, kinetic, and mechanistic behavior of the sulfonated magnetic multi-walled carbon nanotubes adsorbent in the removal of Methylene blue

2025 , Chuan Chuan Lim , Ng Qi Hwa , Siew Hoong Shuit , Soon Wah Goh , Siti Kartini Enche Ab Rahim , Hoo Peng Yong

A simple and environmentally friendly, facile solvent-free direct doping (FSFDD) approach was employed to synthesize sulfonated magnetic multi-walled carbon nanotubes (s-MMWCNTs) which in turn employed for the eliminating of methylene blue (MB) dye from aqueous solution. While prior studies have emphasized the synthesis and innovation points of s-MMWCNTs, this work delves into the fundamental adsorption behaviors (adsorption isotherm, kinetic, thermodynamic and mechanism analysis) to provide a deeper understanding of the interactions between the adsorbent and methylene blue (MB). The developed s-MMWCNTs were characterized by zeta potential analysis, transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). Moreover, the characterization of spent s-MMWCNTs by X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray (SEM-EDX) and Fourier transform infrared (FT-IR) were carried out to compare their characteristics to the freshly synthesized s-MMWCNTs. Results indicated that the Freundlich isotherm model was the best-fitted model, providing a maximum adsorption capacity of 44.64 mg g− 1. As for the adsorption kinetic studies, the MB adsorption onto s-MMWCNTs was discovered to comply with the pseudo-second-order model. Besides, the thermodynamic results suggested that the adsorption process of MB onto s-MMWCNTs occurred endothermically with spontaneity. Furthermore, the adsorption mechanisms encompassed electrostatic interaction, hydrogen bonding and π–π stacking interaction with the electrostatic interaction as the most salient attractive force in the MB adsorption onto s-MMWCNTs.

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Glycerolysis of Lauric Acid with Strontium Enhanced 12-Tungstophosphoric Acid Incorporated SBA-15: Material Characterization and Reusability Elucidation

2022-01-01 , Samsun N.S. , Hoo Peng Yong , Abdullah A.Z. , Enche Ab Rahim S.K. , Teoh Y.P. , Shuit S.H. , Ng Qi Hwa

SBA-15 was modified with strontium before being functionalized with HPW acid to investigate its performance and stability in the glycerolysis of lauric acid. The physical and chemical characteristics of the catalyst was analyzed using Fourier Transformed Infrared (FTIR), Scanning Electron Morphology (SEM), Surface analysis (BET), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). The collective evidence and finding from material characterizations, including the successfully formed and retained SBA-15 mesopores after modification twice, SrO formation and disappearance, post SrO modification and HPW incorporation, respectively, further strengthen the claim of the strong anchoring of HPW onto the SBA-15 via the strontium-salt bridge. The reusability of the lauric acid conversion was also evaluated. The superior stability of the synthesized catalyst (HPW/SrSBA-15) was demonstrated minimal to none change in both lauric acid conversion (75.34%) and monolaurin yield (38.9%). Such result was attributed to the good interaction between HPW and SBA-15 via strontium modification and proved that the catalyst does not undergo severe deactivation and showed good catalytic activity in recycled use.

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Facial synthesis of colloidal stable magnetic nanoparticles coated with high hydrophilic negative charged poly(4‐styrenesulfonic acid co‐maleic acid) sodium for water remediation

2023 , Lim Chuan Chuan , Ng Qi Hwa , Hoo Peng Yong , Siti Kartini Enche Ab Rahim , Mohd Riduan Jamalludin , Amira Mohd Nasib , Sigit Tri Wicaksono , Azzah Dyah Pramata , Siti Zullaikah

The enhancement of the colloidal stability of magnetite nanoparticles (MNPs) for environmental‐related fields has greatly attracted researchers' attention. This study used a high hydrophilic negatively charged polyelectrolyte, poly(4‐styrenesulfonic acid co‐maleic acid) sodium (PSAAS), to enhance the colloidal stability of MNPs. Coating of the naked MNPs with PSAAS polyelectrolyte is a simple and rapid method to obtain colloidally stable MNPs while sustaining the chemical reactivity of MNPs in water purification. The prepared PSAAS‐coated MNPs were characterized by scanning electron microscope, energy dispersive X‐ray, Fourier transform infrared, zeta potential analysis, transmission electron microscope and X‐ray diffraction. Moreover, the colloidal stability and adsorption performance tests of these naked MNPs and PSAAS‐coated MNPs (with different concentrations of PSAAS coated) were investigated and compared. PSAAS‐coated MNPs with 0.001 g/ml PSAAS coating possessed the best colloidal stability and the highest methylene blue (MB) dye removal efficiency (94.53 ± 0.69%). The adsorption isotherm and kinetic studies for the adsorption of MB onto PSAAS‐coated MNPs were well‐described by the Langmuir model and pseudo‐second‐order kinetic model. These magnetic adsorbents, with high separation efficiency, simple and low production cost and recyclable property, are promising as practicable adsorbents in water treatment.

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Development of high reusability trifunctional polyethersulfones microspheres for the removal of methyl orange

2023 , Wei Yang Tan , Siew Hoong Shuit , Steven Lim , Shiau Foon Tee , Yean Ling Pang , Ng Qi Hwa

This study focused on the synthesis of trifunctional microspheres with adsorption, degradation, and magnetic responsive properties. Firstly, polyethersulfones (PES) encapsulated poly(diallyldimethyl ammonia) chloride (PDDA) functionalized iron oxide (Fe3O4) microspheres were produced via phase inversion method. The PDDA/Fe3O4-PES microspheres were further coated with Fe3O4 nanoparticles (NPs) on the surface to provide the degradation ability to the formed c-PDDA/Fe3O4-PES microspheres. Characterization results such as FTIR analysis confirmed the coating of PDDA on Fe3O4 NPs, while the TGA analysis proved the excellent thermal stability of microspheres after the incorporation of PDDA/Fe3O4 NPs. BET specific surface area of microspheres was measured at 13.90 m2/g. Besides, the pH drift method confirmed the presence of positive charge on microspheres surface, which is important for the removal of anionic pollutants. Moreover, porous structure of microspheres was also observed under SEM. Formulation study was also carried out to investigate the suitable concentration for the synthesis of microspheres, including the concentration of PES polymer (1–20 wt%), the loading of PDDA/Fe3O4 NPs (1–5 wt%), and the concentration of polyethylene glycol (PEG) (1–20 wt%). The microspheres synthesized from different formulations were subjected to the batch removal of methyl orange (MO). Results showed that a 72.53 % removal of MO can be obtained under the following microspheres synthesis formulations: 10wt% of PES polymer, 2 wt% of PDDA/Fe3O4 NPs, and 5 wt% of PEG polymer. Lastly, the c-PDDA/Fe3O4-PES microspheres also demonstrated an excellent reusability as compared to pure PES microspheres. The c-PDDA/Fe3O4-PES microspheres could be reused up to 5 cycles without the need of regeneration while still maintaining high MO removal efficiency.

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Facile synthesis of magnetophoretic augmented adsorbent for water remediation

2024-03 , Chuan Chuan Lim , Ng Qi Hwa , Siti Kartini Enche Ab Rahim , Hoo Peng Yong , Siew Hoong Shuit , Sigit Tri Wicaksono

In this new era of globalization, magnetic adsorbents have gained vast attention from researchers in wastewater treatment applications. In this study, sulphonated magnetic multi-walled carbon nanotubes (S-MMWCNTs) were used to remove methylene blue (MB) from an aqueous solution. The S-MMWCNTs are characterized by various analytical methods to investigate their adsorbent features. Adsorption behaviours of the as-prepared composites affected by solution pH and contact time were systematically studied and discussed. The adsorption kinetic data fit the pseudo-second-order kinetic model well. Moreover, the MB removal efficiency of S-MMWCNTs only drops slightly (~6.5%) after five consecutive adsorption cycles, showing their good stability and recyclability.

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Structural and composition modification of Harum Manis mango (Mangifera indica) leaves via chemical pretreatment for bioethanol production

2023 , Mahadevan Tarrsini , Ng Qi Hwa , Yi Peng Teoh , Siew Hoong Shuit , Zhong Xian Ooi , Kunasundari Balakrishnan

Harum Manis mango leaves are considered lignocellulosic (LC) biomass that could contribute to the production of second generation (2G) bioethanol. However, pretreatment should be conducted to overcome the recalcitrance of LC biomass prior to bioethanol production. Hence, this study aims to elucidate the structural changes of the biomass of Harum Manis mango leaves after single-stage and two-stage chemical pretreatment. The Harum Manis mango leaves were treated with only acid, only alkaline, acid-alkaline, or alkaline-acid process. One per cent (v/v) sulphuric acid and 1% (w/v) sodium hydroxide were used as the acid and alkaline hydrolysing agent in the four approaches of pretreatment, respectively. Consequently, the pretreated biomass was enzymatically hydrolysed to produce reducing sugar followed by the conversion into bioethanol through yeast fermentation. Acid-alkaline pretreatment yielded the highest holocellulose composition of 95.26%, with the highest delignification effect of 86.97 ± 1.26%. Furthermore, Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffraction (XRD) validated the acid-alkaline pretreated biomass to be the most feasible substrate for bioethanol production in this study. Finally, the maximum fermentable sugar content and bioethanol concentration of 415.02 ± 7.01 mg/g and 1.57 ± 0.06 mg/ml, respectively, were obtained.

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Effect of Glycerol as plasticizing agent on the mechanical properties of Polyvinyl Alcohol/Banana peel powder blended film

2023-09 , Yee Ling Tan , Yi Peng Teoh , Zhong Xian Ooi , Siew Hoong Shuit , Ng Qi Hwa , Hoo Peng Yong , Sim Siong Leong , Chong Yu Low

Nowadays, plastic pollution becomes more serious due to the abundance of petroleum-based plastic bags. Hence, economical viable biodegradable plastic is seen as a viable solution. Polyvinyl alcohol (PVA) can blend with banana peel powder (BPP) to form biodegradable film that can be degraded easily. Different compositions of glycerol (0–2.0 ml) were added to the blend to investigate the mechanical properties of the PVA/BPP blended films. PVA/BPP blended films prepared using the solution casting method were analyzed using attenuated total reflectance spectroscopy (ATR), thermogravimetric analysis (TGA), and biodegradability test. Besides, the mechanical properties of PVA/BPP blended films were analyzed using the tensile test to determine their tensile strength, elongation at break, and elastic modulus. The increment in the glycerol composition was found to decrease both tensile strength and elastic modulus of the blended films. However, the elongation at break increases as the composition of glycerol increases. The tensile strength and elastic modulus of PVA/BPP blended film without glycerol (6.65 MPa, 81.9 MPa) are higher than the PVA/BPP blended films with glycerol (4.318 MPa to 3.616 MPa, 49.99 MPa to 30.14 MPa). Moreover, the elongation at break of the PVA/BPP blended films that contain glycerol (34.27% to 48.31%) is higher than the blended film without glycerol (32.72%). After two weeks of biodegradability test, the PVA/BPP blended films that contain 2 ml of added glycerol have the highest biodegradability (11.55%) among all PVA/BPP blended films. As compared to the tested commercial plastic bag film, the BPP/PVA blended films show better biodegradable performance.

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