IJFAC (Indonesian Journal of Fundamental and Applied Chemistry)
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The Influence of Hydrogen Flow Rate and Humidifier Temperature on Performance of a PEMFC with Ti-Co/C Catalyst
Full text linkThis study explores the effect of hydrogen flow rate and humidifier temperature on the performance of the Membrane Electrode Assembly (MEA) using Ti-Co/C catalyst at the cathode and Pt/C at the anode in a single-cell Proton Exchange Membrane Fuel Cell (PEMFC). MEAs were fabricated by the spraying method and characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to determine their electrochemical surface area (ECSA) and conductivity. The results showed that the optimized ECSA value reached 8.38 cm2/g, and the electrical conductivity was 3.76 × 10-8 S/cm. The best performance was achieved at a hydrogen flow rate of 100 mL/min and room temperature humidification. Under the hydrogen flow rate test, the maximum power density reached 0.364 mW/cm2, while in the humidifier temperature variation, a maximum power density of 0.375 mW/cm2 was obtained at a current density 2.4 mA/cm2. These findings suggest that Ti-Co/C is a promising low-cost catalyst alternative to Pt and that operational conditions play a critical role in MEA performanc
Study of Mangan Peroxidase (Mnp) Enzymes from Pleurotus Ostreatus Produced using Coffee Grounds and Rice Bran as Substrates through Response Surface Methodology
Full text linkThis study aimed to optimize the production of Manganese Peroxidase (MnP) enzyme from Pleurotus ostreatus using agricultural waste substrates such as coffee grounds (CG) and rice bran (RB) through Response Surface Methodology (RSM) approach. Optimization was conducted using a Central Composite Design (CCD) with three main variables, namely MnSO₄ concentration (0.5-1.5) mM, incubation temperature (25-35) °C, and reaction time (20-30) min. The enzyme fractionation process was carried out by ammonium sulfate saturation (0-20%), (20-40%), (40-60%), followed by dialysis, and SDS-PAGE analysis. The results showed that the 0-20% fraction of CG:RB (50:50) substrate had the highest enzyme activity, which was 20.588 ± 0.141 U/mL, with the highest specific activity of 76.967 ± 0.325 U/mg. The highest protein content was found in CG:RB (0:100) substrate at 0.825 ± 0.016 mg/mL. However, the enzyme activity was lower due to the presence of non-enzymatic proteins and natural inhibitors. This study successfully demonstrated that the substrate combination of CG:RB (50:50) provided optimal results for MnP production. The Response Surface Methodology proved effective in optimizing process variables, providing great potential for biotechnology applications using agricultural waste as an environmentally friendly raw material.Keywords: Pleurotus ostreatus, Manganese Peroxidase, Coffee Dregs, Rice Bran, RSM, SDS-PAG
Antibacterial and Antibiofilm Activity Testing of Black Betel Leaves (Piper betle L. var. nigra) Ethanol Extract on Staphylococcus aureus and Pseudomonas aeruginosa Using Microdilution Method
Full text linkThe use of antibiotics is key to treating infected wounds. However, its effectiveness has begun to decrease due to the high bacterial resistance, which is caused by the phenomenon of biofilm. Therefore, it’s necessary to discover new antibacterial and antibiofilm activity agents that can be used as alternative therapies. This study aims to test the antibacterial and antibiofilm activity of black betel leaves (Piper betle L. var. nigra) ethanol extract. Antibacterial and antibiofilm activity test was conducted using the microdilution method against Staphylococcus aureus and Pseudomonas aeruginosa with concentration variations 4; 2; 1; 0.5; 0.25; and 0.125 mg/mL, also used positive control kanamycin 10 mg/mL and negative control DMSO 1%. The results showed that the black betel leaves ethanol extract had low antibacterial activity with MIC50 > 4 mg/mL for both bacteria and vigorous antibiofilm activity with MBIC50 < 0.125 mg/mL for S. aureus and MBIC = 0.491 mg/mL for P. aeruginosa. The antibacterial activity of the black betel leaves ethanol extract was lower than it’s antibiofilm activity, the antibacterial and antibiofilm activities of the black betel leaves ethanol extract were higher against S. aureus than P. aeruginosa.Keywords: Antibacterial, Antibiofilm, Piper betle L. var. nigr
Synthesis and Characterization of Schiff Base Compound Benzaldehyde- 2,4-Dinitrophenylhydrazone as a Carbonate Anion Sensor
Full text linkBenzaldehyde-2,4-dinitrophenylhydrazone was synthesized via the condensation of benzaldehyde with 2,4- dinitrophenylhydrazine. The product was analyzed using UV–Vis and FT-IR spectroscopy, and its solvatochromic properties were investigated in DMF, acetone, and ethanol. Its application as a carbonate anion sensor was evaluated under optimized conditions. Schiff base formed orange crystalline solids with a 91.86% yield. UV-Vis spectra showed maximum absorption wavelength at 260 nm (π-π*) and 390 nm (n-π*). FT-IR analysis proves the presence of azomethine band (HC=N) at 1618 cm-1 and the shift of the N-H stretching band region from 3325 to 3284 cm-1. Among the solvents studied, DMF exhibited the highest solubility and color stability, acetone showed the greatest absorbance but poor stability, and ethanol showed low solubility with the formation of a precipitate. Functioning as a carbonate anion sensor, the Schiff base exhibited a noticeable color change from yellow to red, along with a bathochromic shift from 390 nm to 495 nm (π→π*), reaching its maximum response after 30 minutes
Antidiabetic Activity and Analysis Chemical Compound of Fractions of Leucas lavandulifolia leaves
No full textLeucas lavandulifolia is one traditional medicine that has been used for the treatment of rheumatism, skin diseases, wounds, diabetes, and migraine treatment. This research aimed to test the antidiabetic activity of the leaf fractions of Leucas lavandulifolia and to identify the chemical content of the selected column fraction. Fractionation was carried out using the graded extraction method with the solvents n-hexane, ethyl acetate, methanol. Testing of antidiabetic activity was performed using the α-glucosidase inhibition method and analysis of the chemical composition content of the selected fraction was performed using the GC-MS method. The research results showed the Ethyl acetate fraction provided the highest antidiabetic activity (IC50 = 4.985 µg/mL) compared to the other fractions and even higher compared to the positive control acarbose (IC50 = 67.07 µg/mL). Separation of the ethyl acetate fraction showed subfractions F6.3 and F6.5 showed the simplest spot pattern. Identification of chemical content with GC-MS showed subfraction F6.3 contained the main component naphthalenepropanal derivative (17.21%) and subfraction F6.5 with the main component fatty acid. Subfractions F6.3 and F6.5 also showed antidiabetic activities with IC50 values of 17.3 and 36.72 µg/mL, respectively, with a very strong category. This indicates the ethyl acetate fraction of L. lavandulifolia leaves is potential to be developed as a source of antidiabetic compound
The Effect of Oxidative Stress on Growth and Antioxidant Activity of Microalgae Oocystis sp
Full text linkThis study was conducted to see the effect of growth and antioxidant activity of microalgae Oocystis sp before and after adding NaOCl to Growmore medium combined with urea. Antioxidant activity test was conducted by calculating IC50 spectrophotometrically with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Oocystis sp extract was obtained by sonication and maceration process with methanol solvent. The results showed the best growth curve for the growth of microalgae Oocystis sp in a mixture of Growmore medium 0.02% b/v and Urea 0.002% b/v. These results also showed a decrease in Oocystis sp growth in a mixture of Growmore medium 0.02% b/v and Urea 0.002% b/v with the lowest growth decrease in the addition of NaOCl with a concentration of 0.01%. The IC50 value of Oocystis sp extract in methanol solvent has high antioxidant activity in Growmore 0.02% b/v + Urea 0.002% b/v medium, which is 55.5862 mg/L. It can be concluded that NaOCl affects the growth and antioxidant activity of microalgae Oocystis sp, but at certain concentrations NaOCl experienced a negative effect.Keywords: Microalgae, Oocytis sp, Oxidative Stress, Growth, Antioxidan
Synthesis Of CoFe2O4 Nanoparticle and Antibacterial Activity Test
No full textCobalt ferrite (CoFe₂O₄) is a spinel ferrite-based material known for its excellent magnetic properties and chemical stability, making it as a promising candidate for biomedical applications as well as an antibacterial agent. This study aims to synthesize CoFe₂O₄ nanoparticles by a coprecipitation methode and evaluate their antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The synthesized products were characterized by using several instruments includes X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), FTIR spectroscopy and Vibrating Sampel Magnetometer (VSM) in order to determine its crystal structure, particle morphology, functional groups, and magnetic properties. Antibacterial activity was assessed by using the disk diffusion method. The results showed that CoFe₂O₄ nanoparticles were successfully synthesized with nanometer-scale crystallite sizes and exhibited strong ferromagnetic properties. Antibacterial tests demonstrated inhibition zones against the growth of S. aureus and E. coli, indicating that CoFe₂O₄ has potential as an antibacterial agent. The effectiveness of antibacterial activity was influenced by nanoparticle concentration and the type of tested bacteria. This research opens up further opportunities for the development of CoFe₂O₄ applications in health and environmental fields
Modification of Activated Carbon from Palm Kernel Shells with Fe₃O₄ Magnetic for Water Treatment of Enim River
Full text linkThe economical, easy-to-implement, and regenerative treatment methods are essential to obtain clean water. In this study, activated carbon was synthesized from palm kernel shells using ZnCl₂ as an activator. The activated carbon was then modified with Fe₃O₄. The resulting activated carbon and activated carbon-Fe₃O₄ product were characterized using XRD, SEM-EDX, VSM, and BET surface area analysis. Furthermore, activated carbon-Fe3O4 was applied to reduce Fe ions, turbidity, and total suspended solids (TSS) and increase the pH value in Enim river water. The resulting activated carbon has met SNI standards, with a moisture content of 8.81%, ash content of 5.475%, and an iodine adsorption capacity of 1763.86 mg/L. The synthesized activated carbon-Fe₃O₄ exhibits strong magnetic properties, with a saturation magnetization value of 68.82 emu/g and a surface area of 355.42 m²/g. Optimal conditions for the treatment of Enim river water were obtained at an adsorbent dose of 40 mg/L, a stirring rate of 120 rpm, and a stirring time of 120 minutes. Under these conditions, the Fe ion reduction efficiency reached 96.95%, turbidity 89.83%, and TSS 80.74%, while the pH increased from 6.23 to 6.74. FTIR analysis showed a change in peak intensity in the activated carbon-Fe₃O₄ after the adsorption process, indicating interaction with contaminants. The adsorption process of Fe ions by activated carbon-Fe₃O₄ follows a pseudo-second-order kinetic model
Thermogravimetric Analysis of EFB and Palm Shells as Gasification Fuels: Kinetic and Activation Energy Study
Full text linkSolid waste from palm oil industry such as EFB and palm kernel shells pose environmental challenges if not properly managed. This study investigated the thermal characteristics and decomposition kinetics of EFB and palm kernel shells through proximate analysis and thermogravimetric analysis (TGA). The results indicate that palm kernel shells have a greater fixed carbon content (21.03–21.35%) than does EFB (19.60–20.06%), whereas EFB has a greater ash content (4.74–5.38%) than does palm kernel shells (1.25–1.31%). EFB showed a weight loss of 94.67% after 233.33 minutes of heating, whereas it was 99% for the palm kernel shells. The peak temperatures reached were 936.67 °C for the EFB and 930 °C for the palm kernel shells. At 600°C, EFB produced more syngas than palm kernel shells did. The calculated activation energies were 4482.19 J/mol for EFB and 4484.97 J/mol for palm kernel shells. This research enhances the understanding of the gasification efficiency of these materials, aiding in the optimization of eco-friendly energy production.Keywords: Empty fruit bunches, palm kernel shells, activation energy, thermogravimetric analysis, gasificatio
Study of Congo Red Adsorption by Chitosan-Graphene Oxide (Chitosan-GO) Composite Synthesize with Hydrothermal Synthetic Method: Optimization and Determination Condition
No full textThis research aims to synthesize chitosan-graphene oxide (chitosan-GO) material using the hydrothermal method at varying material ratios and adsorption studies on Congo red. Chitosan-GO composites were synthesized with mass ratios of (1:1), (1:3) and (1:5). The synthesized chitosan-GO composite was applied to absorb Congo red dye. The adsorption process is carried out by varying pH, contact time, concentration and temperature. The chitosan-GO composite was characterized using XRD, BET and SEM-EDS. The results of XRD characterization of the chitosan-GO composite with a ratio of 1:1 showed a diffractogram of 2θ = 22.3°, at a ratio of 1:3 the diffractogram angle was 2θ = 22.1°, while the ratio (1:5) of the diffractogram peak obtained was 2θ = 22.8°. The surface area obtained in chitosan-GO composite was 11.60 m2/g. The morphology of the chitosan-GO composite (1:5) is in the form of crystalline lumps with the constituent elements C (65.98%), O (32.68%), Na (0.22%) and S (0.09%). Adsorption of Congo red dye using chitosan-GO composite obtained optimum conditions at pH 7, contact time 50 minutes, Congo red concentration 45 mg/L and temperature 50°C. The adsorption isotherm is in accordance with the Langmuir isotherm model and the maximum adsorption capacity (Qm) is 10.245 mg/g