Liew Yun Ming
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Preferred name
Liew Yun Ming
Official Name
Liew Yun Ming
Alternative Name
Yun-Ming, Liew
Liew, Y. M.
Yun Ming, Liew
Ming, Liew Yun
Liew, Yun Ming
Ming, L. Y.
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Scopus Author ID
57204242778
Researcher ID
S-7164-2019

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Primary insights into the effects of organic pollutants and carbon-based cathode materials in a double chambered microbial fuel cell integrated electrocatalytic process

2021-12-01 , Yap K.L. , Ho Li Ngee , Ong Soon An , Guo K. , Liew Yun Ming , Oon Y.S. , Thor S.H. , Tan S.M. , Teoh T.P.

Cathode plays an important role on the oxygen reduction reaction (ORR) reactivity in the microbial fuel cell integrated electrocatalytic process for the effective degradation of organic pollutants. Comparative study of caffeine and phenol as the organic pollutants in the cathodic chamber was investigated in terms of removal efficiency and bioelectricity generation. Results revealed that the highest removal efficiency of phenol (96.89 ± 1.26%) and maximum power density (33.37 ± 4.62 mW m−2) were attained by copper (II) oxide loaded carbon felt (CuO/CF) cathode. Besides, the removal efficiency of phenol was nearly 12-fold higher (24.85 ± 1.36%) using CuO/CF cathode compared with that of caffeine (2.14 ± 0.36%) at the first 24 h. The effect of carbon-based cathode materials on the mineralization of caffeine in the cathodic chamber was evaluated using carbon felt (CF) and carbon plate (CP). Both CuO/CP and bare CP cathodes surpassed CuO/CF and bare CF cathodes in the chemical oxygen demand (COD) removal and bioelectricity generation. Higher crystallinity nature and electrical conductivity (3.57 × 105 Ω−1 m−1) of CP compared with that of amorphous structure and lower electrical conductivity of bare CF (3.33 × 104 Ω−1 m−1) contributed to higher ORR reactivity and efficient transport of electrons for bioelectricity generation. The COD removal efficiency of synthetic wastewater in the anodic chamber and bioelectricity generation of this integrated system were affected by the types of organic pollutants and carbon-based cathode materials in the cathodic chamber.

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Properties of polyaniline/graphene oxide (PANI/GO) composites: effect of GO loading

2021-09-01 , Mutalib T.N.A.B.T.A. , Tan Soo Jin , Foo Kai Loong , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah

Polyaniline/graphene oxide (PANI/GO) composites at different wt% of GO were prepared via solution method. PANI was mixed with the GO synthesized from the improved Hummer’s method. The formation of GO was confirmed via Raman and C/O ratio. Based on the FT-IR, XRD and SEM results, it confirmed the presence of both PANI and GO characteristics at 10.9°, 25.8° and 27.8° and interactions between PANI and GO particles in PANI/GO composites at different GO loading. SEM micrographs showed a folding and wrinkled surface of GO due to the defect upon oxidation process. This means that the weak π–π interactions or the agglomeration of GO have caused PANI unable to attach on the large conjugated basal planes of GO sheets. The defective domains made GO as an insulator as it contained distortions and oxygen-containing functional groups and their local decoration. Low-conductivity domain had conquered most of the GO region which later reduced the pathway of the current flow; therefore, conductivity is affected. The wrinkled structure also resulted in the low conductivity as it weakens the interfacial interaction between PANI and GO and thus disrupted the electron movement in the composites. Due to this, the electrical conductivity reached up to 1.83 × 10−10 S/cm as the GO loading increased to 50 wt%.

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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.

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Sintered and unsintered pressed fly ash geopolymer: A comprehensive study on structural transformation in nitric and sulfuric acid

2024-09-15 , Shee-Ween O. , Heah Cheng Yong , Liew Yun Ming , Ho Li Ngee , Wei-Hao L. , Mohd. Mustafa Al Bakri Abdullah , Wei-Ken P. , Yong-Jie H. , Pin-Hsun L.

Acidic attacks contribute to the degradation of cementitious materials, diminishing the structural service life and increasing the requirement for maintenance of the structure. To address the limited understanding of the impact of the sintering process on the acid resistance of pressed geopolymer, an investigation and comparison of the acid resistance of room-cured (RPG) and sintered (SPG) pressed geopolymer was performed. Specimens were immersed in 3 % and 8 % nitric (HNO3) and sulfuric (H2SO4) acids for 7 and 28 days. Despite the higher sorptivity, SPG demonstrated better mechanical strength retention than that of RPG. Specifically, the compressive strength of SPG after 3 % of HNO3 immersion for 28 days increased (+14.2 %), surpassing the control specimen, while RPG experienced a 14.5 % strength drop. The strength increment in SPG was due to the further geopolymerization during acid immersion. In RPG, a new crystalline phase of NaNO3 was observed after immersion in 8 % HNO3 for 28 days. In contrast, SPG showed no evidence of NaNO3 formation, indicating lower reactivity with HNO3 compared to RPG. Additionally, both RPG and SPG exhibited gypsum formation after immersion in H2SO4. The presence of gypsum induced crack formation in RPG, whereas SPG, with its intensive cross-linked structure, effectively compensated for gypsum expansion, preventing crack formation. This finding is crucial for practical applications where exposure to aggressive acids is a concern, as it provides a method to enhance the acid resistance of geopolymer structures.

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Functionalized Carbon Nanotube-Modified ELISA for Early Detection of Heart Attack

2023-12-01 , Chow E.M.Y. , Foo Kai Loong , Subash Chandra Bose Gopinath , Tan Soo Jin , Kashif M. , Heah Cheng Yong , Liew Yun Ming

A warning issue of heart attacks in young adults needs immediate attention lately. Enzyme-linked immunosorbent assay (ELISA) is an easy and commonly used method for detecting early stages of heart attack. Cardiac troponin I (cTnI) is a responsible biomarker for acute myocardial infarction. However, the conventional ELISA system was only able to detect at 100 pM of cTnI. To improve the system, enhancements were introduced through the integration of functionalized carbon nanotube (fCNT) to amplify cTnI detection signals. By utilizing the advantage of fCNT, a noticeable improvement in results can be obtained. The detection limit was lowered down to an impressive 10 pM. Furthermore, the change of absorbance increased from 31.90% for conventional ELISA surge to 98.61 for modified ELISA system. This three-fold increase in sensitivity shows remarkable improvement through the introduction of fCNT in modified ELISA technique.

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Recent Developments in Steelmaking Industry and Potential Alkali Activated Based Steel Waste: A Comprehensive Review

2022-03-01 , Ikmal Hakem Aziz , Mohd. Mustafa Al Bakri Abdullah , Mohd Arif Anuar Mohd Salleh , Liew Yun Ming , Li L.Y. , Sandu A.V. , Vizureanu P. , Nemes O. , Mahdi S.N.

The steel industry is responsible for one-third of all global industrial CO2 emissions, putting pressure on the industry to shift forward towards more environmentally friendly production methods. The metallurgical industry is under enormous pressure to reduce CO2 emissions as a result of growing environmental concerns about global warming. The reduction in CO2 emissions is normally fulfilled by recycling steel waste into alkali-activated cement. Numerous types of steel waste have been produced via three main production routes, including blast furnace, electric arc furnace, and basic oxygen furnace. To date, all of the steel waste has been incorporated into alkali activation system to enhance the properties. This review focuses on the current developments over the last ten years in the steelmaking industry. This work also summarizes the utilization of steel waste for improving cement properties through an alkali activation system. Finally, this work presents some future research opportunities with regard to the potential of steel waste to be utilized as an alkali-activated material.

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Titanium Dioxide Loaded Reduced Graphene Oxide Nanocomposite Film as Counter Electrodes for Dye-Sensitized Solar Cells

2021-12-21 , Low F.W. , Heah Cheng Yong , Liew Yun Ming , Md. Aminul Islam

The demands on conventional fossil fuels are increasing especially developing countries. The growth of population among countries also put a lot of pressure on coil consumption and resulted effect of greenhouse. These phenomena will dramatically increase the global warming and pollutes the nature of earth. For the worse, it would forming some erratic patterns like flood, draughts, wildfire, and so on. Therefore, renewable solar energy is the key target to reduce the fossil fuel consumption, minimize global warming issues, and involuntary minimizes the erratic weather patterns. Dye-sensitized solar cell (DSSCs) is one of the promising prospects for efficient renewable resources. Most of the researchers were tried to use platinum as counter electrode to perform the photovoltaic studies. However, the platinum material will made higher for the entire fabrication cost. Recently, we demonstrated a counter electrode in DSSCs system using the low-cost titanium dioxide (TiO2) decorated reduced graphene oxide (rGO) nanocomposite film. The TiO2-rGO nanocomposite (TiO2-rGO NC) as counter electrode is addressed to minimize electron losses and hence rapid the rate of dye regeneration at ground state. Practically, TiO2-rGO NC synthesized via one-step hydrothermal method. The crystallinity, functional groups, element composition, and morphology of TiO2-rGO NC were comprehensively studied. One-step hydrothermal method revealed that Ti particles (∼60 nm) have capable bonded with rGO thin film, as agreement with XRD and FTIR results. In DSSCs photovoltaic performance, the optimized power conversion energy (PCE) of TiO2-rGO NC as counter electrode achieved a 2.90%, which achieved a desire performance as comparable with rGO and TiO2. In this work, the low-cost TiO2-rGO NC as counter electrode with suppressed recombination in DSSCs is studied.

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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 Kea Lee , Ho Li Ngee , Ong Soon An , Guo K. , Liew Yun Ming , Thor Shen Hui , Tan Sing Mei , Teoh Tean Peng

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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Microbial fuel cell for simultaneous caffeine removal and bioelectricity generation under various operational conditions in the anodic and cathodic chambers

2022-02-01 , Yap Kea L.ee , Ho Li Ngee , Ong Soon An , Guo K. , Liew Yun Ming , Oon Yoong Sin , Thor Shen-Hui , Tan Sing Mei , Teoh Tean Peng

A series of studies of the effects of operational parameters including organic substrate loading concentration, initial caffeine concentration, circuit connection, external resistance and salinity were carried out to evaluate the optimal performance of a double chambered microbial fuel cell for the treatment of caffeine. The increment of organic substrate loading concentration at anode increased the maximum power density from 7.84 ± 0.59 to 14.18 ± 0.87 mW m−2 but deteriorated the removal efficiency of caffeine in which only half of the removal efficiency of caffeine attained at 72 h at 1.500 g L−1 acetate (46.28 ± 3.66 %) than that of 0.375 g L−1 (96.89 ± 0.48 %). Initial caffeine concentration of 20 mg L−1 (95.31 ± 1.83 %) achieved 2.40-fold higher removal efficiency of caffeine than that of 50 mg L−1 (39.58 ± 2.83 %) at 48 h as saturated caffeine molecules hindered the oxygen reduction reaction and thus, fewer hydroxyl radicals were produced for the decomposition of caffeine. An optimal external resistance of 1000 Ω exhibited the best performance in terms of pollutants removal efficiency and power generation than that of 500 and 5000 Ω. Sodium chloride concentration of 0.580 g L−1 produced the highest maximum power density of 11.78 ± 0.68 but reduced to 8.26 ± 0.41 mW m−2 at 0.696 g L−1 as high concentration of sodium ions caused dehydration of anodophilic cells which decreased the electron transfer ability of electrochemically active bacteria.

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Effect of Sodium Aluminate on the Fresh and Hardened Properties of Fly Ash-Based One-Part Geopolymer

2022-01-01 , Ooi Wan En , Liew Yun Ming , Heah Cheng Yong , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Ong Shee Ween , 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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