Banjuraizah Johar
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Preferred name
Banjuraizah Johar
Official Name
Banjuraizah, Johar
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Scopus Author ID
36782257500
Researcher ID
ELA-9787-2022

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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.

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Effect of sintering temperature on dielectric and electrical properties of bio-waste derived beta-dicalcium silicate

2023-11-01 , Mohd Yunus S.N.H. , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng , Mohd Tarmizi E.Z. , Talib Z.A.

Beta-dicalcium silicate ceramics were synthesized by mechanochemical-assisted solid-state reaction route using rice husks and chicken eggshells as silica and calcium oxide sources. The ceramics were sintered at 900, 1000, and 1100 °C for 2 h in air. The effect of sintering temperature on these ceramics' morphological, breakdown strength, dielectric, and electrical properties was investigated. It was found that the ceramic sintered at the optimized temperature of 1100 °C formed the pure β-dicalcium silicate (β-Ca2SiO4). Scanning electron micrographs showed that with the increase in sintering temperature, the average grain size and pore size of the sintered ceramics increased while the grain boundary density decreased, which promoted the breakdown path and resulted in a decrease in breakdown strength. The dielectric behavior examined from 25 to 300 °C and in a frequency range of 4–5 MHz found that the dielectric constant and loss tangent decreased with increasing frequency. Nyquist plot of impedance confirmed a non-Debye type relaxation, and grain and grain boundary contributions were revealed from equivalent circuit fitting. Variations of impedance spectroscopy reflect the positive and negative temperature coefficient of resistance behavior for these ceramics. Electric modulus spectra revealed that with the sintering temperature increase, the samples' conductivity activation energies increased from 0.35 to 0.46 eV. All the sintered samples attained low dielectric loss (0.004 < tanδ < 0.1) above 103 Hz, which makes them suitable materials for capacitor application.

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Phase Analysis of Bio-Based Derived Tricalcium Disilicate From 2CaO:1SiO2 By X-ray Diffraction

2021-12-14 , Siti Nur Hazwani Yunus , Fhan K.S. , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng

In this paper, tricalcium disilicate was formed from dicalcium silicate compound powder, synthesised via a mechanochemical technique using a stoichiometric 2CaO:1SiO2. Compound CaO and SiO2 were derived from the bio-waste of eggshell and rice husk at the calcination temperature of 900oC and 800oC, respectively. The dicalcium disilicate powder was sintered for 2 hours at different temperatures ranging from 1150oC to 1350oC. Using X-ray diffraction with Rietveld analysis, it was found that the amount of tricalcium disilicate with monoclinic (beta) crystal structure increases on sintering temperature at the expense of dicalcium silicate. The complete formation of single-phase tricalcium disilicate began at a sintering temperature of 1300oC. The effect of sintering temperatures on the crystallisation and phase transition of dicalcium silicate is reported. The size of crystallites depends on the sintering temperature. The finding of this study rebound to the benefit of society by reducing the risk-off pollution cause by accessive redundant bio-waste eggshell and rice husk and also reduced the amount of CaO and SiO2 used in the fabrication of Ca3Si2O7

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Formation of Bio-based Derived Dicalcium Silicate Ceramics via Mechanochemical Treatment: Physical, XRD, SEM and FTIR Analyses

2023-07-01 , Yunus S.N.H. , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Jakfar N.H. , Cheng Ee Meng , Tarmizi E.Z.M. , Talib Z.A.

Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure beta-dicalcium silicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.-4 SiO4.

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