Ho Li Ngee
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Ho Li Ngee
Official Name
Ho, Li Ngee
Alternative Name
Li Ngee, Ho
Ho, Li Ngee
Ngee, Ho Li
Ho, L. N.
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Scopus Author ID
57219028372
Researcher ID
DDY-6348-2022

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  • Publication
    Effect of Sodium Aluminate on the Fresh and Hardened Properties of Fly Ash-Based One-Part Geopolymer
    ( 2022-01-01)
    Wan-En O.
    ;
    Yun-Ming L.
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Shee-Ween O.
    ;
    Sandu A.V.
    The one-part geopolymer binder was synthesis from the mixing of aluminosilicate material with solid alkali activators. The properties of one-part geopolymers vary according to the type and amount of solid alkali activators used. This paper presents the effect of various sodium metasilicate-to-sodium aluminate (NaAlO2/Na2SiO3) ratios on fly ash-based one-part geopolymer. The NaAlO2/Na2SiO3 ratios were set at 1.0 to 3.0. Setting time of fresh one-part geopolymer was examined through Vicat needle apparatus. Mechanical and microstructural properties of developed specimens were analysed after 28 days of curing in ambient condition. The study concluded that an increase in NaAlO2 content delayed the setting time of one-part geopolymer paste. The highest compressive strength was achieved at the NaAlO2/Na2SiO3 ratio of 2.5, which was 33.65 MPa. The microstructural analysis revealed a homogeneous structure at the optimum ratio. While the sodium aluminium silicate hydrate (N-A-S-H) and anorthite phases were detected from the XRD analysis.
      20  8
  • Publication
    Cold-pressed fly ash geopolymers: effect of formulation on mechanical and morphological characteristics
    ( 2021)
    Ong Shee-Ween
    ;
    Heah Cheng Yong
    ;
    Lynette Wei Ling Chan
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ho Li Ngee
    ;
    Liew Yun Ming
    ;
    Ooi Wan-En
    ;
    Ng Yong-Sing
    ;
    Nur Ain Jaya
    This research uses low alkali activator content and cold pressing technique for fly ash-based geopolymers formation under room temperature condition. The geopolymers were prepared using four different parameters: fly ash/alkali activator ratio, sodium hydroxide concentration, sodium silicate/sodium hydroxide ratio and pressing force. The results indicated that the compressive strength (114.2 MPa) and flexural strength (29.9 MPa) of geopolymers maximised at a fly ash/alkali activator ratio of 5.5, a 14 M sodium hydroxide concentration, a sodium silicate/sodium hydroxide ratio of 1.5 and a pressing force of 5 tons (pressing stress of 100.0 MPa and 155.7 MPa for compressive and flexural samples, respectively). The degree of reaction (40.1%) enhanced the structure compactness with minimum porosity. The improved mechanical properties confirmed that a high strength pressed geopolymer could be formed at low alkali activator content without the aid of temperature.
      1  36
  • Publication
    Towards greener one-part geopolymers through solid sodium activators modification
    ( 2022-12-10)
    Ooi Wan En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Bin Khalid M.S.
    ;
    Foo Kai Loong
    ;
    Ong Shee Ween
    ;
    Pei Seng T.
    ;
    Hang Yong Jie
    ;
    Khairunnisa Zulkifly
    This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.
      1
  • Publication
    A hybrid photocatalytic fuel cell integrated electro-Fenton system for Amaranth dye degradation and electricity generation
    ( 2021-02-23)
    Thor S.H.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Che Zulzikrami Azner Abidin
    ;
    Heah Cheng Yong
    A dual-chambered hybrid system of photocatalytic fuel cell (PFC) and electro-Fenton (EF) process has become an emerging sustainable green approach for organic pollutant degradation and electricity generation. This hybrid system of PFC and EF (PFC-EF hybrid system) is an integration of two popular organic pollutants treatment methods, PFC and EF process. The double-cathodes configuration of PFC-EF hybrid system enhanced the oxygen reduction reaction reactivity in both PFC and EF. PFC-EF hybrid system with double cathodes achieved colour removal efficiencies of 86.2% and 84.7% in PFC and EF. Power density of 1.2211 μW cm-2 was obtained in this PFC-EF hybrid system. Results revealed that this PFC-EF hybrid system was effective in the Amaranth dye degradation and power production simultaneously.
      4  15
  • Publication
    Towards greener one-part geopolymers through solid sodium activators modification
    ( 2022-12-10)
    Ooi Wan-En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Bin Khalid M.S.
    ;
    Foo Kai Loong
    ;
    Ong Shee-Ween
    ;
    Pei Seng T.
    ;
    Hang Yong Jie
    ;
    Khairunnisa Zulkifly
    This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.
      1
  • Publication
    Effect of sodium aluminate on the fresh and hardened properties of fly ash-based one-part geopolymer
    ( 2021)
    Ooi Wan-En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Ho Li Ngee
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ong Shee-Ween
    ;
    Andrei Victor Sandu
    The one-part geopolymer binder was synthesis from the mixing of aluminosilicate material with solid alkali activators. The properties of one-part geopolymers vary according to the type and amount of solid alkali activators used. This paper presents the effect of various sodium metasilicate-to-sodium aluminate (NaAlO2/Na2SiO3) ratios on fly ash-based one-part geopolymer. The NaAlO2/Na2SiO3 ratios were set at 1.0 to 3.0. Setting time of fresh one-part geopolymer was examined through Vicat needle apparatus. Mechanical and microstructural properties of developed specimens were analysed after 28 days of curing in ambient condition. The study concluded that an increase in NaAlO2 content delayed the setting time of one-part geopolymer paste. The highest compressive strength was achieved at the NaAlO2/Na2SiO3 ratio of 2.5, which was 33.65 MPa. The microstructural analysis revealed a homogeneous structure at the optimum ratio. While the sodium aluminium silicate hydrate (N-A-S-H) and anorthite phases were detected from the XRD analysis.
      7  17
  • Publication
    Geopolymer via Pressing Method: Aluminosilicates/Alkaline Solution Ratio as the Determining Factor
    ( 2020-07-09)
    Shee Ween O.
    ;
    Heah Cheng Yong
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ho Li Ngee
    ;
    Wan En O.
    Aluminosilicates/alkaline solution (FA/AA) ratio has a great influence on the morphology and mechanical properties of geopolymer fabricated via pressing method. The aim of this paper is to evaluate the effect of FA/AA ratio on the performance of pressed geopolymer. The geopolymer mixtures were prepared at FA/AA ratio of 4.5-7.0 and compacted with uniaxial hydraulic press. The resultant specimens were cured at room temperature (30°C) for 7 and 28 days. The physical properties of the specimens were measured by porosity and water absorption analysis. The microstructure and strength of pressed geopolymers were determined. The results revealed that the pressed geopolymer with FA/AA ratio of 5.5 had the lowest porosity and water absorption. Furthermore, SEM micrographs proved that FA/AA ratio of 5.5 yielded the formation of well-compacted structure. Maximum compressive strength of 78.54 MPa was achieved.
      2
  • Publication
    A sustainable photocatalytic fuel cell integrated photo-electro-Fenton hybrid system using KOH activated carbon felt cathodes for enhanced Amaranth degradation and electricity generation
    ( 2022-07-01)
    Thor S.H.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Che Zulzikrami Azner Abidin
    ;
    Heah Cheng Yong
    ;
    Ong Y.P.
    ;
    Yap K.L.
    Photo-electro-Fenton (PEF) process was integrated with photocatalytic fuel cell (PFC) through the connection of electrodes and the cathodes were responsible for the acceptance of electrons. In this study, potassium hydroxide (KOH) was used to activate the carbon felt (CF) to improve the oxygen reduction reaction reactivity on cathodes for effective PFC integrated PEF hybrid system (PFC-PEF system) in Amaranth removal and electricity generation simultaneously. The results revealed that KOH activated CF cathodes had improved the electro-generation of hydrogen peroxide in both PFC and PEF and contributed to decolourisation efficiencies of 99.25% (PFC) and 96.10% (PEF). The maximum power density (4.218 μW cm−2) achieved by KOH activated CF cathode was 22% higher than that of pristine CF. The results revealed that air flow rate of 1000 mL min−1 favoured the generation of more reactive species for effective Amaranth degradation under the dissolved oxygen enrichment condition. The highest decolourisation rates were respectively achieved in PFC (0.5965 h−1) and PEF (0.2919 L mg−1 h−1) at air flow rate of 1000 mL min−1.
      2  34
  • Publication
    Comparative mechanical and microstructural properties of high calcium fly ash one-part geopolymers activated with Na2SiO3-anhydrous and NaAlO2
    ( 2021-11-01)
    Ooi Wan-En
    ;
    Liew Yun Ming
    ;
    Heah Cheng Yong
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Li L.Y.
    ;
    Ho Li Ngee
    ;
    Foo Kai Loong
    ;
    Ong Shee-Ween
    ;
    Ng Hui-Teng
    ;
    Ng Yong-Sing
    ;
    Nur Ain Jaya
    This paper investigates the effect of varying solid alkali activators on the fresh and hardened properties and microstructural changes of one-part geopolymers (OPGs). Single and binary solid alkali activators were used to activate high calcium fly ash. The alkali activators were either solely sodium metasilicate (Na2SiO3) or a combination of sodium aluminate (NaAlO2) and sodium metasilicate (Na2SiO3). The OPG activated with anhydrous Na2SiO3 achieved an excellent 28-day compressive strength of 83.6 MPa while OPG activated with NaAlO2 and Na2SiO3 attained a compressive strength of 45.1 MPa. The Na2SiO3-activated OPG demonstrated better fluidity than the OPG activated with NaAlO2 and Na2SiO3 due to the thixotropic behaviour caused by the NaAlO2. The Na2SiO3-activated OPG consisted of sodium-calcium aluminium silicate hydrate ((N,C)-A-S-H) gel phase, while the OPG activated with NaAlO2 and Na2SiO3 comprised of the coexistence of sodium aluminium silicate hydrate (N-A-S-H) and calcium aluminium silicate hydrate (C-A-S-H) gel phases. Regardless of the distinctive properties, the OPGs are adequate for building materials applications.
      2
  • Publication
    Discovering the roles of electrode distance and configuration in dye degradation and electricity generation in photocatalytic fuel cell integrated electro-Fenton process
    ( 2022-01-01)
    Thor S.H.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Che Zulzikrami Azner Abidin
    ;
    Heah Cheng Yong
    ;
    Nordin N.
    ;
    Ong Y.P.
    ;
    Yap K.L.
    Photocatalytic fuel cell (PFC) integrated electro-Fenton (EF) system (PFC-EF system) was considered as an eco-friendly approach for dye degradation and electricity generation simultaneously. The modification on configuration of PFC-EF system was aimed to improve the dye degradation and power output. Effect of electrode distance on the efficiency of PFC-EF system was investigated as it was a crucial factor in the mass transfer of ions in PFC-EF system. Closer electrode distance reduced the resistance flow of ions and enhanced the mass transfer of ions between the electrodes in both PFC and EF, eventually yielded higher concentration of reactive species for removal of dye. Four different electrode configurations by varying the number of cathodes in PFC and EF were investigated to discover the most efficient operating configuration for this PFC-EF system. The dye decolourization rate was evaluated and compared by using pseudo-first order and second order in both PFC and EF system, respectively. Results revealed that single cathode PFC-EF system was the most effective configuration in dye degradation while double cathodes PFC-EF system was the optimal configuration to be used for power output.
      30  1