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A synergistic heterostructured ZnO/BaTiO3 loaded carbon photoanode in photocatalytic fuel cell for degradation of Reactive Red 120 and electricity generation

Ong YP, Ho LN, Ong SA, Banjuraizah J, Ibrahim AH, Lee SL, et al.

Chemosphere, 2019 Mar;219:277-285.
PMID: 30543963 DOI: 10.1016/j.chemosphere.2018.12.004

Photocatalytic fuel cell (PFC) is considered as a sustainable green technology which could degrade organic pollutant and generate electricity simultaneously. A synergistic double-sided ZnO/BaTiO3 loaded carbon plate heterojunction photoanode was fabricated in different ratios by using simple ultrasonication and mixed-annealed method. The double-sided design of photoanode allowed the lights irradiated at both sides of the photoanode. The ferroelectricity fabricated photoanode was applied in a membraneless PFC with platinum-loaded carbon as the cathode. Results revealed that the photoanode with 1:1 ratio of BaTiO3 and ZnO exhibited a superior photocatalytic activity among all the photoanodes prepared in this study. The heterojunction of this photoanode was able to achieve up to a removal efficiency of 93.67% with a maximum power density of 0.5284 μW cm-2 in 10 mg L-1 of Reactive Red 120 (RR120) without any supporting electrolyte. This photoanode was able to maintain at high performance after recycling 3 times. Overloading of ZnO above 50% on BaTiO3 could lead to deterioration of the performance of PFC due to the charge defects and light trapping ability. The interactions, interesting polarizations of the photocatalysts and proposed mechanism of the n-n type heterojunction in the photoanode of ZnO/BaTiO3 was also discussed.
A highly sustainable hydrothermal synthesized MnO2 as cathodic catalyst in solar photocatalytic fuel cell

Ong YP, Ho LN, Ong SA, Banjuraizah J, Ibrahim AH, Thor SH, et al.

Chemosphere, 2021 Jan;263:128212.
PMID: 33297171 DOI: 10.1016/j.chemosphere.2020.128212

A unidirectional flow solar photocatalytic fuel cell (PFC) was successfully developed for the first time to offer alternative for electricity generation and simultaneous wastewater treatment. This study was focused on the synthesis of α-, δ- and β-MnO2 by wet chemical hydrothermal method for application as the cathodic catalyst in PFC. The crystallographic evolution was performed by varying the ratios of KMnO4 to MnSO4. The mechanism of the PFC with the MnO2/C as cathode was also discussed. Results showed that the catalytic activity of MnO2/C cathode was mainly predominated by their crystallographic structures which included Mn-O bond strength and tunnel size, following order of α- > δ- > β-MnO2/C. Interestingly, it was discovered that the specific surface areas (SBET) of different crystal phases did not give an impact on the PFC performance. However, the Pmax could be significantly influenced by the micropore surface area (Smicro) in the comparison among α-MnO2. Furthermore, the morphological transformation carried out by altering the hydrothermal duration demonstrated that the nanowire α-M3(24 h)/C with 1:1 ratio of KMnO4 and MnSO4 yielded excellent PFC performance with a Pmax of 2.8680 μW cm-2 and the lowest Rint of 700 Ω.
Fulltext Metformin Use in Gestational Diabetes: Awareness, Attitude, and Practice among Healthcare Professionals in Malaysia

Daud NAA, Mohiuddin SG, Ong YP, Yusof F, Yusoff F, Harun SN, et al.

J Pharm Bioallied Sci, 2021 05 26;13(2):230-237.
PMID: 34349484 DOI: 10.4103/jpbs.JPBS_542_20

Background: Metformin has been added in the Malaysian clinical practice guideline (CPG) as one of the first-line options in the management of gestational diabetes mellitus (GDM); however, the uptake on this practice among healthcare professionals is unknown.
Objective: The objective of the study is to determine the awareness, attitude, and practice and their predictors on the use of metformin for GDM among healthcare professionals in Malaysia.
Materials and Methods: This was a multicenter, cross-sectional study in three tertiary hospitals in Malaysia. Medical doctors and pharmacists working in several departments were invited to participate in a survey using self-administered questionnaires.
Results: From 350 questionnaires distributed, 225 were completed by medical doctors (43.1%), pharmacists (40.4%), and specialists (7.5%). Less than 30% of them were aware on the option of using metformin as one of the first-line agents in GDM. Education level, department, and profession were found to be associated with the awareness level (P = 0.016, P = 0.004, and P = 0.001, respectively). 70.2% of the respondents showed a positive attitude toward metformin use in GDM. Only 64 (28.4%) of the respondents have prescribed/dispensed metformin for GDM before, although more than half will consider doing so in the future. Having postgraduate qualifications increased the likelihood of having a good awareness (odds ratio [OR]: 2.44, 95% confidence interval [CI] 1.23-4.85) and to consider prescribing/dispensing metformin for GDM patients (OR: 2.27, 95% CI 1.08-4.78).
Conclusion: Despite a positive attitude toward metformin use in GDM among healthcare professionals in Malaysia, their awareness level on this practice was low as they currently prefer the use of insulin over metformin.
Elucidating the effects of different photoanode materials on electricity generation and dye degradation in a sustainable hybrid system of photocatalytic fuel cell and peroxi-coagulation process

Nordin N, Ho LN, Ong SA, Ibrahim AH, Lee SL, Ong YP

Chemosphere, 2019 Jan;214:614-622.
PMID: 30292044 DOI: 10.1016/j.chemosphere.2018.09.144

The hybrid system of photocatalytic fuel cell - peroxi-coagulation (PFC-PC) is a sustainable and green technology to degrade organic pollutants and generate electricity simultaneously. In this study, three different types of photocatalysts: TiO2, ZnO and α-Fe2O3 were immobilized respectively on carbon cloth (CC), and applied as photoanodes in the photocatalytic fuel cell of this hybrid system. Photocatalytic fuel cell was employed to drive a peroxi-coagulation process by generating the external voltage accompanying with degrading organic pollutants under UV light irradiation. The degradation efficiency of Amaranth dye and power output in the hybrid system of PFC-PC were evaluated by applying different photoanode materials fabricated in this study. In addition, the effect of light on the photocurrent of three different photoanode materials was investigated. In the absence of light, the reduction of photocurrent percentage was found to be 69.7%, 17.3% and 93.2% in TiO2/CC, ZnO/CC and α-Fe2O3/CC photoanodes, respectively. A maximum power density (1.17 mWcm-2) and degradation of dye (93.8%) at PFC reactor were achieved by using ZnO/CC as photoanode. However, the different photoanode materials at PFC showed insignificant difference in dye degradation trend in the PC reactor. Meanwhile, the degradation trend of Amaranth at PFC reactor was influenced by the recombination rate, electron mobility and band gap energy of photocatalyst among different photoanode materials.
Hydroxyl radical formation in the hybrid system of photocatalytic fuel cell and peroxi-coagulation process affected by iron plate and UV light

Nordin N, Ho LN, Ong SA, Ibrahim AH, Abdul Rani AL, Lee SL, et al.

Chemosphere, 2020 Apr;244:125459.
PMID: 31790991 DOI: 10.1016/j.chemosphere.2019.125459

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 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 through the PC process to degrade the organic molecules.
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

Teoh TP, Ong SA, Ho LN, Wong YS, Lutpi NA, Oon YL, et al.

Environ Sci Pollut Res Int, 2023 Feb;30(7):17546-17563.
PMID: 36197611 DOI: 10.1007/s11356-022-23101-w

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

Ong YP, Ho LN, Ong SA, Ibrahim AH, Banjuraizah J, Thor SH, et al.

Environ Sci Pollut Res Int, 2022 Nov;29(54):81368-81382.
PMID: 35729394 DOI: 10.1007/s11356-022-21413-5

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.
Enhancement of energy recovery from caffeine wastewater in constructed wetland-microbial fuel cell through operating conditions

Teoh TP, Ong SA, Ho LN, Wong YS, Lutpi NA, Tan SM, et al.

Environ Sci Pollut Res Int, 2023 Jul;30(35):84397-84411.
PMID: 37358771 DOI: 10.1007/s11356-023-28362-7

The enhancement of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) performance in energy retrieval from caffeine containing wastewater has been explored via various operating conditions (hydraulic retention time (HRT), multianode (MA), multicathode current collector (MC), external resistance). The anaerobic decaffeination and COD removal improved by 37 and 12% as the HRT extended from 1 to 5 d. The increment in contact time between the microbes and organic substrates promoted the degradation and contributed to higher power output (3.4-fold), CE (eightfold), and NER (14-16-fold). The MA and MC connections facilitated the electron transfer rate and the degradation rate of organic substrates in the multiple anodic zones, which enhanced the removal efficiency in the anaerobic compartment (Caffeine: 4.2%; COD: 7.4%) and led to higher electricity generation (Power: 4.7-fold) and energy recovery (CE: 1.4-fold; NER: 2.3-2.5-fold) compared to SA. The lower external resistance favored the growth of electrogens and induced higher electron flux, where the best treatment performance and electricity production was obtained when the external resistance approached the internal resistance. Overall, it was noteworthy that the optimum operating conditions were achieved with 5 d HRT, MA, and MC connection along with external resistance of 200 Ω, which significantly outperformed the initial conditions (1 d HRT, SA connection, and 1000 Ω) by 43.7 and 29.8% of caffeine and COD removal in the anaerobic compartment, respectively as well as 14-fold of power generation.