Conference Publications
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PublicationEffect of latex coating on the physical properties of Calcium Alginate beads(Springer, 2023-09)Alginate has been commonly applied in encapsulation due to its gelling capacity, biocompatibility, and environmentally friendly properties. Alginates can produce a thermally stable and biocompatible hydrogel in the presence of divalent cations such as calcium. However, the high porosity and low physical stability of calcium alginate beads can lead to encapsulation loss and degradation of encapsulated materials. It is speculated that latex coating on the beads can overcome the issues. Hence, this study aims to investigate the effect of latex coating on the physical properties of Ca-alginate beads. An extrusion dripping method was adopted to produce Ca-alginate beads. The beads were multilayer coated with a 5% latex solution. The size and shape of uncoated and coated beads were analyzed using 2D image analysis. The thickness of the latex coating layers was measured layer by layer using a thickness gauge. The results indicated that as the number of coating layers increased, the size of the beads also increased. However, the sphericity of the beads is decreased as the number of layers of latex coating is increased. The thickness of the latex coating increased layer by layer, from 0.017 mm to 0.112 mm. In short, the calcium alginate beads can be coated by latex. The diameter of the bead is significantly increased after two layers of latex coating, and the sphericity of the beads is reduced considerably after two layers of latex coating.
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PublicationGreen synthesis and characterization of Graphene quantum dots from key lime juice(Springer, 2023)Graphene quantum dots (GQDs) are one of the members of graphene family with unique properties such as quantum confinement effect, photoluminescence effect, and strong conductivity. This work prepared the GQDs using lime juice obtained from the waste of locally grown key limes as the precursor. The hydrothermal method was used in the preparation of the GQDs. The fluorescence effect of the GQDs was observed under a UV lamp irradiation while other characterization was conducted using high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), X-ray powder diffraction (XRD), and Raman spectroscopy. The GQD preparation was successful with the emission of a strong blue color when the GQD was put under a 365 nm UV light irradiation. It was found that the particle size of the prepared GQDs was in the range of 0.7–2.8 nm with an average diameter of 1.3 ± 0.5 nm. The characterization results proved the formation of GQDs as one of the graphene nanomaterials.
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PublicationNitrate adsorption using spent coffee ground: kinetics, isotherm, and thermodynamic studies(Springer, 2023-09)Excess amount of nitrate in water bodies can have harmful effects on humans and aquatic life. In this current study, the effectiveness of spent coffee grounds as adsorbents in nitrate adsorption from an aqueous solution was investigated. Spent coffee ground (SCG) was activated using hydrochloric acid (HCl) and used in the batch adsorption experiment. The removal performance was evaluated at different contact times ranging between 1 and 6 h. Removal efficiency was increased with the longest contact time of 6 h. Meanwhile, when nitrate concentration was increased from 100 to 500 mg/L, the removal efficiency was also increased from 39 to 78%. A temperature range of 298–328 K was applied in this study and the optimum operating temperature for nitrate adsorption was found to be at 308 K. Based on the experimental data, the Freundlich model showed R2 at 0.9802, which was the highest for the adsorption of nitrate using SCGs. In addition, the pseudo-first order kinetics model fitted the nitrate adsorption trend the best (R2 = 0.9652). The thermodynamic parameters obtained from this study described nitrate adsorption using SCG as endothermic in nature that required an external energy source for the interaction. This study has proven that spent coffee grounds activated by HCl have the potential of being an adsorbent for nitrate removal.
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PublicationProtein extraction of Momordica Charantia seed assisted by ultrasound extraction(Springer, 2023)The Momordica charantia is a tropical and subtropical plant with high nutritional value that has been implemented in traditional folk medicine as an antifungal, antimutagenic, Anthelmintic, anticancer, antifertility, and antidiabetic agent. The seeds contain rich source of antifungal protein that can be explored to be used against various fungus disease. In this study, the antifungal protein was extracted by using ultrasound assisted extraction (UAE) via one-factor-at-a-time (OFAT) technique with following the parameter sodium chloride, NaCl concentration (0.5, 1.0, 1.5, 2.0 and 2.5 M), solute ratio (0.1, 0.2, 0.3, 0.4 and 0.5 g/mL) and extraction time (4, 6, 8, 10 and 12 min). After extraction, the extract was further centrifuged and assayed by standard Bradford method before analysing the protein content at 595 nm. The result shows the optimum conditions for protein content is 6.445 mg/mL achieved after treatment with 1.5 M NaCl, 1w;10v (g/mL) in 10 min with p-value < 0.01 from each of parameter. Results showed that Momordica charantia seed had desired protein source with optimal parameter and promising antifungal bioresources with prospective applications in food and other industries.
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PublicationDevelopment of MCSF (M=La, Ba) cathode materials for proton conducting fuel cell application(AIP Publishing, 2020-03)Two cathode materials for proton-conducting fuel cell (PCFC), La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) were investigated regarding their microstructural and electrical properties under air containing atmosphere. The respective sample was prepared via a modified sol-gel method using an activated carbon as a dispersing agent and anodic aluminium oxide (AAO) templating method assisted with sol-gel process. The powders were subjected to X-ray Diffractometer (XRD) and Brunauer-Emmet-Teller (BET). A symmetrical half-cell of LSCF|BCZY|LSCF and BSCF|BCZY|BSCF (BCZY = BaCe0.54Zr0.36Y0.1O2.95)was fabricated and characterized using an electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). After calcined at T = 900 °C, both of the LSCF and BSCF demonstrated their single-phase structure and exhibited highly dispersed powders with large surface area as proven by BET result. For electrical analyses, impedance spectrum of the cathodes was referred only to the two main contributions of cathode responses which were charge transfer at cathode/electrolyte interface and oxygen adsorption/dissociation on the cathode surface. At 600 °C, the polarization resistance of LSCF half-cell (Rp = 4.94 ω.cm2) was comparable to BSCF (Rp = 4.50 ω.cm2). SEM images revealed no delamination along the electrolyte/ electrode interface after EIS measurements as no sign of crack was observed for both samples. It can be concluded that the microstructure of the cathode layer can be tailored by altering the sample's preparation route which in turn to enhance the PCFC performance.