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.
Main Affiliation
Scopus Author ID
54413018300
Researcher ID
A-9192-2019

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A Novel Tri-Functionality pH-Magnetic-Photocatalytic Hybrid Organic-Inorganic Polyoxometalates Augmented Microspheres for Polluted Water Treatment

2023-02-01 , Yee L.Y. , Ng Qi Hwa , Siti Kartini Enche Ab Rahim , Hoo Peng Yong , Chang P.T. , Ahmad A.L. , Low S.C. , Shuit S.H.

The severe water pollution from effluent dyes threatens human health. This study created pH-magnetic-photocatalytic polymer microspheres to conveniently separate the photocatalyst nanoparticles from the treated water by applying an external magnetic field. While fabricating magnetic nanoparticles’ (MNPs) microspheres, incorporating 0.5 wt.% iron oxide (Fe3O4) showed the best magnetophoretic separation ability, as all the MNPs microspheres were attracted toward the external magnet. Subsequently, hybrid organic–inorganic polyoxometalates (HPOM), a self-synthesized photocatalyst, were linked with the functionalized magnetic nanoparticles (f-MNPs) to prepare augmented magnetic-photocatalytic microspheres. The photodegradation dye removal efficiency of the augmented magnetic-photocatalytic microspheres (f-MNPs-HPOM) was then compared with that of the commercial titanium dioxide (TiO2) photocatalyst (f-MNPs-TiO2). Results showed that f-MNPs-HPOM microspheres with 74 ± 0.7% photocatalytic removal efficiency better degraded methylene orange (MO) than f-MNPs-TiO2 (70 ± 0.8%) at an unadjusted pH under UV-light irradiation for 90 min. The excellent performance was mainly attributed to the lower band-gap energy of HPOM (2.65 eV), which required lower energy to be photoactivated under UV light. The f-MNPs-HPOM microspheres demonstrated excellent reusability and stability in the photo-decolorization of MO, as the microspheres retained nearly the same removal percentage throughout the three continuous cycles. The degradation rate was also found to follow the pseudo-first-order kinetics. Furthermore, f-MNPs-HPOM microspheres were pH-responsive in the photodegradation of MO and methylene blue (MB) at pH 3 (acidic) and pH 9 (alkaline). Overall, it was demonstrated that using HPOM photocatalysts in the preparation of magnetic-photocatalytic microspheres resulted in better dye degradation than TiO2 photocatalysts.

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Photocatalytic Degradation of Methylene Blue Using Polyoxometalate as Photocatalyst

2023-06-09 , Siti Kartini Enche Ab Rahim , Azahri E.N.A. , Hoo Peng Yong , Ng Qi Hwa , Abdullah N.S.

Polyoxometalates (POM), Na2C6H4NO2. [PW12O40] have been synthesized under hydrothermal conditions and characterized. The SEM result indicates that morphology of photocatalyst was homogeneous. The performance of POM was then tested on photocatalytic degradation of methylene blue at different operating conditions. The degradation of methylene blue was dependent on several parameters, such as its initial concentration, HPOM loading and temperature. Langmuir–Hinshelwood model is usually used to describe the kinetics of this photocatalytic process. It was found that rate constant, kapp decreased with increasing initial concentrations of methylene blue. However, as increases in HPOM loading improved methylene blue degradation. The activation energy obtained was low due to this photocatalytic process being less dependent on temperature.

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Arthropods-mediated green synthesis of Zinc oxide nanoparticles using cellar spider extract a biocompatible remediation for environmental approach

2024-06 , Muzamir Isa , Muhammad Nur Aiman Uda , M. A. R. Irfan , Uda Hashim , Subash Chandra Bose Gopinath , Hafiza Shukor , MRM Huzaifah , Maimunah Mohd Ali , Nur Hulwani Ibrahim , Muaz Mohd Zaini Makhtar , Ng Qi Hwa , Mohd Khairul Rabani Hashim , Zainal Abidin Arsat , Nor Azizah Parmin , Liyana Ahmad Sofri , Mahfuz Affif Mohd Ruslan , Tijjani Adam

This study presents an eco-friendly approach to synthesizing zinc oxide nanoparticles (ZnO NPs) using extracts from cellar spiders, addressing environmental and health concerns associated with conventional methods. The spider extract efficiently reduced zinc acetate dihydrate, and the synthesized ZnO NPs underwent comprehensive quantitative characterization, including size, shape, morphology, surface chemistry, thermal stability, and optical properties using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential measurements, thermogravimetric analysis (TGA), and UV-vis spectroscopy. The nanoparticles exhibited intended characteristics, and their adsorption capability for methylene blue (MB) was quantitatively assessed using the Freundlich isotherm model and pseudo-second-order kinetic model, providing numerical insights into MB removal efficiency. The study demonstrates the potential of these green-synthesized ZnO NPs for applications in environmental remediation, wastewater treatment, and antibacterial therapies, contributing to both sustainable nanomaterial development and quantitative understanding of their functional properties.

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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

2023-04-01 , Lim C.C. , Ng Qi Hwa , Hoo Peng Yong , Siti Kartini Enche Ab Rahim , Mohd Riduan Jamalludin , Nasib A.M. , Wicaksono S.T. , Pramata A.D. , Zullaikah S.

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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Integrating advanced Keggin-structure polyoxometalate into polymeric membrane to enhance photocatalytic self-cleaning and antifouling functionalities

2022-04-01 , Koo D.C.H. , Tan N.N. , Ng Qi Hwa , Siti Kartini Enche Ab Rahim , Low S.C. , Yeo R.Y.Z.

The high photocatalytic activity of environmentally benign Keggin-type polyoxometalate (POM) was introduced into polyethersulfone (PES) membrane to promote membrane anti-fouling and self-cleaning functionality. Neat PES and POM/PES hybrid membranes were synthesized via phase inversion method. X-ray diffraction (XRD) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy proved the success of synthesizing Keggin-type POM. The traits of the membranes were evaluated using scanning electron microscopy (SEM), ATR-FTIR, contact angle measurement, porosity and porometer. The hydrophilicity of all the POM/PES hybrid membranes was enhanced and resulted in the reduction of contact angle of the membrane (52.21±0.1101°, 45.11±0.6657° and 50.30±0.1054°) for 0.025, 0.05 and 0.1 wt% POM/PES hybrid membranes, respectively, compared to that of the neat PES membrane (57.30±0.0817°). Additionally, all the POM/PES hybrid membranes showed excellent anti-fouling and self-cleaning characteristics as compared to that of the neat PES membrane. 0.05 wt% POM/PES hybrid membrane outstood all the other membranes, which marks the HA rejection at 77.12% and was able to achieve flux recovery ratio (FRR) of 111.34% with temporal superhydrophilicity effect in just merely 150 seconds at 254 nm UV irradiation.

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Removal of methylene blue using magnetic multi-walled carbon nanotubes: process optimization study

2020-12-18 , Lim C.C. , Shuit S.H. , Siti Kartini Enche Ab Rahim , Hoo Peng Yong , Ng Qi Hwa

Adsorption is the most common methods used in industry for the removal of dye. In this study, magnetic multi-walled carbon nanotubes (MMWCNTs) was served as adsorbent for the removal of methylene blue (MB). Statistical optimization of the MB removal efficiency via response surface methodology coupled with central composite design was performed and reported. It was observed that all three experimental parameters: adsorption temperature (25-50 C), MB concentration (10-50 ppm) and MMWCNTs dosage (0.01-0.05 g/20mL) were significant in the removal of MB. The optimized conditions of 99.21 % MB removal efficiency can be achieved at adsorption temperature of 38 C, MB concentration of 23 ppm and MMWCNTs dosage of 0.033 g/20mL. The verification of the prediction was performed with 3 repeated experiments and the results were found to be in good agreement with the experimental data with only 0.21 % error.

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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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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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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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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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