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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  • Publication
    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.
  • Publication
    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.
  • Publication
    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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