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
    Biotreatment of sulfonated dyestuffs with energy recovery in microbial fuel cell: Influencing parameters, kinetics, degradation pathways, mechanisms, and phytotoxicity assessment
    ( 2021-08-01)
    Tan S.M.
    ;
    Ong Soon An
    ;
    Ho Li Ngee
    ;
    Wong Y.S.
    ;
    Che Zulzikrami Azner Abidin
    ;
    Thung W.E.
    ;
    Teoh T.P.
    Removal of recalcitrant sulfonated dyestuff intermediates from wastewater has been an urgent challenge for environmental technologies. In this regard, the biodegradations of monoazo Methyl Orange (MO) and diazo dyes Reactive Black 5 (RB5) towards wastewater treatment and bioelectricity generation in microbial fuel cell were investigated and compared through the studies on azo dye concentration, aeration, sampling points arrays, and electrode spacings. The degradation of diazo RB5 yielded higher chemical oxygen demand removal, decolourization efficiencies, and power generation over monoazo MO. The decolourization efficiency of RB5 (97.62%) increased with an increase of RB5 concentration (50 mg/L), suggesting that the system has the capability of removing higher RB5 concentration. However, contrary results were obtained with MO due to its toxicity. This study also demonstrated that the decolourization rate of diazo RB5 (0.1533 h-1) was ≈ 53% higher than monoazo MO (0.0727 h-1). The findings revealed that the degradation kinetic was remarkably influenced by the chemical structure of dye, where dye with more electron-withdrawing groups at para position are more susceptible to be reduced. Higher output voltage (568.59 mV) and power generation (108.87 mW/m2) were attained with RB5 due to electron donor availability and electron-shuttling characteristics of RB5 decolourized intermediates. Furthermore, detailed degradation pathways of MO and RB5 were presented based on the UV-vis and GC-MS results. The phytotoxicity assessment via Sorghum bicolor seeds had further verified the reduction in toxicity after the treatment of azo dyes.
  • Publication
    Transformation from biofiltration unit to hybrid constructed wetland-microbial fuel cell: Improvement of wastewater treatment performance and energy recovery
    ( 2023-05-01)
    Teoh T.P.
    ;
    Koo C.J.
    ;
    Ho Li Ngee
    ;
    Wong Yee Shian
    ;
    Nabilah Aminah Lutpi
    ;
    Tan S.M.
    ;
    Yap K.L.
    ;
    Ong Soon An
    This study aimed to compare the performance of biofiltration, constructed wetland, and constructed wetland microbial fuel cell (CW-MFC). The transformation from a biofiltration unit to a hybrid CW-MFC was demonstrated with the advantages of improvement of wastewater treatment while generating electricity simultaneously. The introduction of plants to the upper region of the bioreactor enhanced the DO level by 0.8 mg/L, ammonium removal by 5 %, and COD removal by 1 %. The integration of electrodes and external circuits stimulated the degradation rate of organic matter in the anodic region (1 % without aeration and 3 % with aeration) and produced 5.13 mW/m3 of maximum power density. Artificial aeration improved the nitrification efficiency by 38 % and further removed the residual COD to an efficiency of 99 %. The maximum power density was also increased by 3.2 times (16.71 mW/m3) with the aid of aeration. In treating higher organic loading wastewater (3M), the maximum power density showed a significant increment to 78.01 mW/m3 (4.6-fold) and the COD removal efficiency was 98 %. The ohmic overpotential dominated the proportion of total loss (67-91 %), which could be ascribed to the low ionic conductivity. The reduction in activation and concentration loss contributed to the lower internal resistance with the additional aeration and higher organic loading. Overall, the transformation from biofiltration to a hybrid CW-MFC system is worthwhile since the systems quite resemble while CW-MFC could improve the wastewater treatment as well as recover energy from the treated wastewater.
  • Publication
    Hydroxyl radical formation in the hybrid system of photocatalytic fuel cell and peroxi-coagulation process affected by iron plate and UV light
    ( 2020-04-01)
    Nordin N.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Ibrahim A.H.
    ;
    Abdul Latif Abdul Rani
    ;
    Lee S.L.
    ;
    Ong Y.P.
    The hybrid electrochemical system of photocatalytic fuel cell - peroxi-coagulation (PFC-PC) is a combined technology of advanced oxidation process (AOP) which involve the hydroxyl radical formation for simultaneous degradation of organic pollutant and electricity generation. The p-nitrosodimethylaniline (RNO) spin trapping technique was applied by analyzing the RNO bleaching performance to detect the OH[rad] at the PFC and PC reactors. The presence of UV light showed higher RNO bleaching rate at the PFC reactor (11.7%) with maximum power density (Pmax = 3.14 mW cm−2). Results revealed that the optimum of maximum power density was observed at iron plate size of 30 cm2. UV light became a limiting factor in the PFC system as a power source in the PFC-PC system. Meanwhile, iron plate plays an important role to supply the soluble Fe2+ ions by oxidation process and become a suitable catalyst for in-situ production of H2O2 and OH[rad] through the PC process to degrade the organic molecules.
  • Publication
    Comparative study of dihydroxybenzene isomers degradation and bioelectricity generation using CuO as cathodic catalyst in double chambered microbial fuel cell
    ( 2022-10-01)
    Yap K.L.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Guo K.
    ;
    Liew Y.M.
    ;
    Thor S.H.
    ;
    Tan S.M.
    ;
    Teoh T.P.
    A double chambered microbial fuel cell (MFC) showed enormous capacity in the simultaneous degradation of synthetic wastewater and dihydroxybenzene isomers (catechol, resorcinol and hydroquinone) and concurrently with bioelectricity generation. Operating parameter such as effect of catalyst on MFC system was evaluated using bare carbon plate and copper (II) oxide (CuO) loaded carbon plate as cathodes, respectively, in terms of chemical oxygen demand (COD) and dihydroxybenzene isomers removal efficiency, maximum voltage output and power density. Results revealed that the application of CuO loaded carbon plate was more effective in the COD removal of synthetic wastewater in the anodic chamber and degradation of dihydroxybenzene isomers in the cathodic chamber. Compared with the bare carbon plate as cathode, the COD removal efficiency of synthetic wastewater, removal rate of dihydroxybenzene isomers and maximum voltage output increased 20, 100 and 31 %, respectively, when CuO was applied as cathodic catalyst. Among the dihydroxybenzene isomers, hydroquinone exhibited the best performance in both absence and presence of catalyst in the MFC. The position of the substituent of hydroxyl groups possessed significant effect on the reaction rate, reactivity and conductivity of dihydroxybenzene isomers. Hydroquinone was more susceptible to be degraded than that of catechol and resorcinol due to its lower dipole moment which eased the bond cleavage. The intermediate products of degradation of catechol, resorcinol and hydroquinone were determined using gas chromatograph-mass spectrometer and the degradation pathways were proposed.
  • Publication
    Crucial roles of aeration and catalyst on caffeine removal and bioelectricity generation in a double chambered microbial fuel cell integrated electrocatalytic process
    ( 2021-02-01)
    Yap K.L.
    ;
    Ho Li Ngee
    ;
    Ong Soon An
    ;
    Guo K.
    ;
    Oon Y.S.
    ;
    Ong Y.P.
    ;
    Thor S.H.
    The effects of aeration and catalyst on caffeine removal in the cathodic chamber and electricity generation of a double chambered microbial fuel cell (MFC) integrated electrocatalytic process were investigated. The overall performances of MFC in caffeine removal and electricity generation were significantly enhanced under the presence of copper (II) oxide (CuO) and aeration. CuO was synthesized using a hydrothermal method and was immobilized on the carbon plate for application as cathode. The CuO particles and CuO loaded carbon plate (CuO/C) were characterized by using X-ray diffractometer and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. The effective transfer of electrons from anodic chamber to cathodic chamber for oxygen reduction reaction (ORR) accelerated the removal of caffeine using CuO/C cathode under aerated condition. Results revealed that 15-fold higher removal efficiency of caffeine was obtained using CuO/C cathode (52.16 %) as compared with that of bare carbon plate (bare C) (3.41 %) at the first 24 h under aerated condition. The highest maximum power density and current density (28.75 mW m-2 and 253.33 mA m-2) were obtained for CuO/C cathode under aerated condition. Bare C cathode possessed the lowest maximum power density and current density (9.75 mW m-2 and 106.67 mA m-2) under unaerated condition. The circuit connection greatly improved the chemical oxygen demand removal of synthetic wastewater in the anodic chamber when the cathodic chamber was under aerated condition. The detailed mechanisms of the effects of CuO catalyst and aeration on the ORR at cathodic chamber were discussed.
  • Publication
    Caffeine-containing wastewater treatment and bioelectricity generation in up-flow constructed wetland-microbial fuel cell: Influence of caffeine concentration, operating conditions, toxicity assessment, and degradation pathway
    ( 2022-04-01)
    Teoh T.P.
    ;
    Ong Soon An
    ;
    Ho Li Ngee
    ;
    Wong Yee Shian
    ;
    Nabilah Aminah Lutpi
    ;
    Oon Y.L.
    ;
    Tan S.M.
    ;
    Ong Y.P.
    ;
    Yap K.L.
    This study explored the potential of caffeine being utilized as the fuel for the microbes to produce electrons for electricity generation in up-flow constructed wetland-microbial fuel cell (UFCW-MFC). The effect of caffeine concentration was investigated to identify the availability of UFCW-MFC in the conversion of caffeine to electrons for electricity production; and the effect of operating conditions (circuit connection, supplementary aeration, and plant) was studied to determine their significance in the treatment of caffeine containing wastewater. The UFCW-MFC achieved about 98% of decaffeination efficiency regardless of caffeine concentration; while a decrease of efficiency was observed when UFCW-MFC operated without supplementary aeration and plant (~93%). COD removal efficiency decreased correspondingly to the increase of caffeine concentration, which could be contributed by the higher concentration of caffeine and its intermediates. The degradation pathway of caffeine in UFCW-MFC was explored in this study. It was remarkable that ammonia was produced and converted to ammonium ions during caffeine catabolism. Supplementary aeration and macrophyte play a crucial role in removing excess caffeine, intermediates as well as accumulated ammonium ions. The toxicity assessment revealed that caffeine was degraded to less toxic products. The closed circuit connection not only contributed to electricity generation but also enhanced the caffeine and COD removal efficiency by 4.6 and 5.4% in the anaerobic region, respectively. The increase of voltage and maximum power density from phase I to phase IV indicated that caffeine could be converted to electrons by the anaerobes for electricity production.
  • Publication
    Comparative study of different polyatomic ions of electrolytes on electricity generation and dye decolourization in photocatalytic fuel cell
    ( 2020-10-01)
    Ong Y.P.
    ;
    Ho Li Ngee
    ;
    Ong S.A.
    ;
    Banjuraizah Johar
    ;
    Ibrahim A.H.
    ;
    Lee S.L.
    ;
    Nordin N.
    Developing an effective interface interaction between photoanode and electrolyte is crucial for achieving superior photocatalytic fuel cell (PFC) performance. In this aspect, the contribution of the medium or electrolyte properties in the PFC system such as dye concentration, ionic nature and active radicals play a decisive role. Herein, we constructed a PFC with ZnO loaded nickel foam (ZnO/Ni) photoanode to study the influence of initial dye concentration, pH and supporting electrolytes of different polyatomic anions on the PFC performance. The optimum initial dye concentration and pH for the PFC with reactive red 120 as organic pollutants were found to be 30 mg L−1 and 7.5, respectively. The PFC performance can be synergistically enhanced by the addition of three types of polyatomic anions (Na3PO4, Na2SO4 and NaNO3) as supporting electrolytes. In turn, PO43- had the greatest influence on the reduction of internal resistance (highest short circuit current, Jsc) which corresponded to the conductivity of dye solution. Eventually, the higher charge of polyatomic ions could contribute to higher energy conversion efficiency in PFC. Nonetheless, SO42- anions favoured the cleavage of aromatic compounds by the advantage of recycling between SO42- and SO4[rad]- through hole scavenging activity. Comprehensively, our findings provided new insight into the selection of supporting electrolyte as well as the proposed mechanism of active radicals involved in PFC. Additionally, the ZnO/Ni photoanode demonstrated its excellent recyclability as it retained high PFC performance after five consecutive runs.
  • Publication
    Up-flow constructed wetland-microbial fuel cell: Influence of floating plant, aeration and circuit connection on wastewater treatment performance and bioelectricity generation
    ( 2020-08-01)
    Teoh T.P.
    ;
    Ong Soon An
    ;
    Ho Li Ngee
    ;
    Wong Yee Shian
    ;
    Oon Y.L.
    ;
    Oon Y.S.
    ;
    Tan S.M.
    ;
    Thung W.E.
    The influence of floating plant (Eichhornia crassipes), supplementary aeration and circuit connection on wastewater treatment performance and electricity production using up-flow constructed wetland-microbial fuel cell (UFCW-MFC) were investigated in this study. This study was operated for four stages, where stage I was conducted without plant and aeration; stage II was planted with Eichhornia crassipes; supplementary aeration was provided in stage III; stage IV was operated in open circuit. The supplementary aeration showed the most significant effect on the performance of UFCW-MFC compared to floating plant and circuit connection. The optimum performance of wastewater treatment and electricity production was found in stage III as the oxygen was supplied by the floating plant and supplementary aeration for the degradation of organic matters as well as the generation of bioelectricity. The chemical oxygen demand (COD), NH4+ and NO3− removal efficiencies were 99 %, 96 % and 44 %, respectively. E. crassipes and supplementary aeration improved the dissolved oxygen (DO) concentration at the cathodic region and enhanced the NH4+ removal by 10 % (Stage II) and 67 % (Stage III) compared to the non-planted bioreactor (stage I). Closed circuit also performed 6 % better than open circuit at sampling point 1 (S1) in COD reduction. The maximum power density, voltage output, coulombic efficiency and normalized energy recovery were 45.46 ± 3.83 mW/m3, 291 ± 62 mV, 2.15 %, 15.09 Wh/kg COD and 0.31 W/m3, respectively.
  • Publication
    Insights into the decolorization of mono and diazo dyes in single and binary dyes containing wastewater and electricity generation in up-flow constructed wetland coupled microbial fuel cell
    ( 2023-02-01)
    Teoh T.P.
    ;
    Ong Soon An
    ;
    Ho Li Ngee
    ;
    Wong Yee Shian
    ;
    Nabilah Aminah Lutpi
    ;
    Oon Y.L.
    ;
    Tan S.M.
    ;
    Ong Y.P.
    ;
    Yap K.L.
    The treatment of single and binary azo dyes, as well as the effect of the circuit connection, aeration, and plant on the performance of UFCW-MFC, were explored in this study. The decolorization efficiency of Remazol Yellow FG (RY) (single dye: 98.2 %; binary dye: 92.3 %) was higher than Reactive Black 5 (RB5) (single: 92.3 %; binary: 86.7 %), which could be due to monoazo dye (RY) requiring fewer electrons to break the azo bond compared to the diazo dye (RB5). In contrast, the higher decolorization rate of RB5 in binary dye indicated the removal rate was affected by the electron-withdrawing groups in the dye structure. The closed circuit enhanced about 2% of color and 4% of COD removal. Aeration improved the COD removal by 6%, which could be contributed by the mineralization of intermediates. The toxicity of azo dyes was reduced by 11–26% and the degradation pathways were proposed. The dye removal by the plants was increased with a higher contact time. RB5 was more favorable to be uptook by the plant as RB5 holds a higher partial positive charge. 127.39 (RY), 125.82 (RB5), and 58.66 mW/m3 (binary) of maximum power density were generated. The lower power production in treating the binary dye could be due to more electrons being utilized for the degradation of higher dye concentration. Overall, the UFCW-MFC operated in a closed circuit, aerated, and planted conditions achieved the optimum performance in treating binary azo dyes containing wastewater (dye: 87–92%; COD: 91%) compared to the other conditions (dye: 83–92%; COD: 78–87%).
  • 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.
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