Ho Li Ngee
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Preferred name
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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Impact of secondary phases content on the mechanical properties of cordierite

2017-01-01 , Eing Kuan Kok , Banjuraizah Johar , Ho Li Ngee , Zabar Yahidah

The Cordierite ceramic body had been synthesized through conventional techniques solid state reaction by using non-stoichiometric composition (2.5 MgO. 1.8 Al2O3. 5 SiO2). The sintering temperature study was carried out by heat treated the samples at several degree of sintering temperature (1250 °C, 1275 °C, 1300 °C, 1325 °C, 1350 °C and 1375 °C). The qualitative and quantitative of crystalline phase analysis was accomplished by using X-ray Diffraction (XRD) technique and Rietveld structural refinement. The Scanning electron microscopy (SEM) was employed for morphology analysis. The mechanical properties of samples were determined by Vicker's Hardness test. Rietveld quantitative phase analysis results show that α phase Cordierite constitutes up to 96.4 wt% when the samples was sintered for 2 hours at sintering temperature of 1375 °C and obtained densified and orderly crystal structure arrangement in SEM micrograph except the mechanical strength. The sample obtained the uppermost α phase Cordierite content gained the lowest hardness values (4.0±0.8GPa). Conversely, the sample contains 90 wt% α-cordierite and 1.4 wt% magnesium titatnate achieve highest hardness which is about 4.9±0.79GPa.

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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.

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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.

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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.

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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.

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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.

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Towards greener one-part geopolymers through solid sodium activators modification

2022-12-10 , Wan-En O. , Yun-Ming L. , Cheng-Yong H. , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Bin Khalid M.S. , Foo Kai Loong , Shee-Ween O. , Pei Seng T. , Yong Jie H. , Zulkifly K.

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.

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UVA-irradiated dual photoanodes and dual cathodes photocatalytic fuel cell: mechanisms and Reactive Red 120 degradation pathways

2022-11-01 , Ong Y.P. , Ho Li Ngee , Ong S.A. , Ibrahim A.H. , Banjuraizah Johar , Thor S.H. , Lee S.L. , Teoh T.P.

To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and dual photoanodes PFC (PFC-AAC) were established. Results revealed that PFC-AAC yielded the highest decolorization rate (1.44 h−1) due to the promotion of active species such as superoxide radical (•O2−) and hydroxyl radical (•OH) when the number of photoanode was doubled. The results from scavenging test and UV-Vis spectrophotometry disclosed that •OH was the primary active species in dye degradation of PFC. Additionally, PFC-AAC also exhibited the highest power output (17.99 μW) but the experimental power output was much lower than the theoretical power output (28.24 μW) due to the strong competition of electron donors of doubled photoanodes to electron acceptors at the single cathode and its high internal resistance. Besides, it was found that the increments of dye volume and initial dye concentration decreased the decolorization rate but increased the power output due to the higher amount of sacrificial agents presented in PFC. Based on the abovementioned findings and the respective dye intermediate products identified from gas chromatography-mass spectrometry (GC-MS), the possible degradation pathway of RR120 was scrutinized and proposed.

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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.

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Pilot scale single chamber up-flow membrane-less microbial fuel cell for wastewater treatment and electricity generation

2017-04-06 , Thung W.E. , Ong Soon An , Ho Li Ngee , Wong Yee Shian , Fahmi Muhammad Ridwan , Oon Yoong Ling , Oon Yoong Sin , Harvinder Kaur Lehl

Pilot scale up-flow membrane-less microbial fuel cell (UFML-MFC) was constructed to study feasibility of the bioreactor for simultaneous degradation of organic substance and electricity generation. The performance of the UFML-MFC was evaluated with different anode electrode (cube carbon felt and stacked carbon felt) in terms of voltage output, chemical oxygen demand (COD) and Coulombic efficiency (CE). Carbon flake were used as cathode in the UFML-MFC. UFML-MFC was operated in three stages where included batch-fed, end of batch fed and semi-continuous. The Cube carbon felt as anode have the better performance in terms of voltage output and electricity generation in all 3 stages. Maximum voltage output was 0.311 ± 0.004 V at 75% of COD reduction and thus CE was 0.15%. The result shows the operational mode is the key to improve the voltage output and also COD reduction.

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