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EFFECT OF CRYSTALLINITY TO OVERPOTENTIAL ON Ni₃Fe ALLOY AS ELECTROCATALYST IN HYDROGEN EVOLUTION REACTION
Get PDFEFFECT OF CRYSTALLINITY TO OVERPOTENTIAL ON Ni3Fe ALLOY AS ELECTROCATALYST IN HYDROGEN EVOLUTION REACTION. Ni-Fe alloys can be used as electrocatalyst for the hydrogen evolution reaction (HER) in an alkaline solution. HER consumed highly energy and overpotential driven. The overpotential value corresponding to the electron transfer in reaction can be affected either by metal combination or alloy as a cathode. Ni₃Fe alloy had been successfully synthesized by the electrodeposition method using direct-current (DC) on a 304 L type stainless steel substrate. The modified Watts bath deposition was used NiCl2·6H2O and FeCl3·6H2O as precursors of the alloy. The optimum conditions of the reaction were obtained at pH of the solution is 2.20±0.02 with 25 mA/cm² current density at 55 °C for 160 minutes. Ni₃Fe alloy was characterized by Powder X-ray Diffraction (PXRD), Energy-Dispersive X-ray Spectroscopy (EDX), and Scanning Electron Microscopy (SEM). The electrocatalytic property of Ni3Fe alloy was electrochemically measured in 1 M KOH solution by polarization method using a Tafel plot with a scanning rate of 1 mV/s. As a result, the mass ratio of Ni²+ /Fe³+ in bath deposition influenced the electrocatalytic property of Ni₃Fe alloy. Ni₃Fe alloy with a higher crystallinity lowered the overpotential value of HER up to 67% compared to Ni metal
SIMULATION OF IRON CORROSION IN LEAD-MAGNESIUM EUTECTIC (LME) USING OXYGEN INHIBITOR
Get PDFSIMULATION OF IRON CORROSION IN LEAD-MAGNESIUM EUTECTIC (LME) USING OXYGEN INHIBITOR. Lead-magnesium (Pb-Mg) is a metal that considered to have potential as a coolant raw material in the heat transfer system of nuclear reactors. However, the coolant in the form of Pb-Mg eutectic is corrosive to structured materials (eg steel cladding) used in reactors. In this research, steel material is represented by pure iron to simplify the simulation and calculation. This research aims to determine the effect of temperature on iron corrosion and the effect of adding oxygen as an inhibitor to reduce the iron corrosion rate in LME. In this study, corrosion was observed by looking at (coefficient) the diffusion of iron atoms into LME. A large iron diffusion coefficient represents high iron corrosion. To see inhibition effectivity with oxygen, the most effective oxygen concentration that can reduce the iron diffusion coefficient is searched. Simulations of iron corrosion and inhibition are performed using molecular dynamics simulation. The result of this research showed that oxygen concentration mixed into LME for effective inhibition of iron corrosion was in the range of 0.125 wt% - 0.135 wt% (for temperatures of 973K). Thus, oxygen is believed that able to inhibit iron corrosion in Pb-Mg eutectic up to 98.44
Isotherm, Thermodynamic, and Kinetics Studies of Iodide Adsorption on The Al_SBA-16 Mesoporous Nanomaterial as Radiopharmaceutical Vehicle Candidate
No full textIn order to investigate the potential of Al_SBA-16 Mesoporous Nanomaterial as a candidate for radiopharmaceutical vehicles, the studies of kinetics, thermodynamic, and in vitro stability of Iodide adsorption onto the nanomaterial have been carried out. The adsorption study was conducted at different temperature, time, and iodide concentration and observed with spectrophotometric techniques. The isotherm adsorption was fitted with Langmuir and Freundlich model and the thermodynamic parameters were determined at temperatures of 293K, 301K, 308K, and 313K. Moreover, the adsorption kinetics was analyzed in terms of pseudo first order model for Al_SBA-16 Mesoporous Nanomaterial and Iodide and pseudo second order in overall reaction. The activation energy was determined by using Arrhenius equation, meanwhile, the in vitro stability testing was conducted in phosphate buffer saline at pH variation for 5.5 to 7.0, and at temperature variation for 20C to 45C and at testing time variation for 6 to 48 hours. The result indicate that the adsorption obeys the Langmuir isotherm model and has a tendency to be chemical adsorption with a value of H was -116.641 kJ/mol and the nature of spontaneous reactions. The adsorption process followed the pseudo-first-order model and the apparent activation energy was 41.26 kJ/mol. In the present research work, the in vitro stability data were evaluated using P-Value and the theory of Hypothesis Testing or Fisher's significance test. The result of hypothesis testing show that, the adsorption of iodide onto Al_SBA-16 Mesoporous Nanomaterial were highly stable under the experimental conditions adopted
Microstructure of Oxide Dispersion Strengthened Steel With Cr Content Variation
Get PDFMicrostructure and phase distribution of innovative Oxide Dispersion Strengthened (ODS) steel based on Fe-Cr-ZrO2 particularly for application at high temperature reactor with variation of Cr content was analysed. The alloy was synthesized with Cr composition variation of 15, 20 and 25 wt.% Cr, while zirconia dispersoid kept constant at 0.50 wt.%. The samples was synthesized by mechanical alloying comprising of high energy milling for 3 hours followed by vibrated compression with iso-static load at 20 ton. The final consolidation was performed via sintering process for 4 minutes using the Arc Plasma Sintering (APS) technique, a new method developed in BATAN especially for synthesizing high temperature materials. The samples were then characterized by means of scanning electron microscopy (SEM) with energy dispersed X-ray (EDX) analysis capability and X-ray diffraction. The mechanical property of hardness was measured using standard Vickers micro hardness tester to confirmed the microstructure analysis. The results show that the microstructure of the ODS alloy samples in all variation of Cr content consists generally of cubic Fe-Cr matrix phase with small of porosity and Zirconia particles distributed homogenously in and around the matrix grains. The achievable hardness was between 142 and 184 HVN dependent consistently on Cr content in which Cr element may cause grain refining that in turn increase the hardness
RADIATION SYNTHESIS OF POLY(VINYL ALCOHOL) PVA–(POLYVINYL PYRROLIDONE) PVP FOR IMMOBILIZATION OF CAPTOPRIL
Get PDFRADIATION SYNTHESIS OF PVA POLY(VINYL ALCOHOL)–PVP (POLYVINYLPYRROLIDONE) for IMMOBILIZATION OF CAPTOPRIL. The aim of this work is to prepare Polyvinyl alcohol (PVA)- Polyvinylpyrrolidone (PVP) hydrogel with varying irradiation doses and drug dose to be used as a matrix for immobilization and control drug release of captopril. Immobilization and release of captopril in PVA-PVP hydrogel copolymer have been carried out. A mixture of PVA-PVP (6:4 w/w) solution containing captopril (10-20 mg), freeze-thawing, irradiated using gamma rays at various irradiation doses (0-20 kGy). The gel fraction and water absorption were determined gravimetrically. The pores structure of hydrogels were observed using SEM (Scanning Electron Microscope). The captopril released from hydrogel in NaCl 0.9% solution was measured using a UV-Vis spectrophotometer. After evaluated, it was found that with increasing dose up to 20 kGy, the gel fraction increases, and water absorption decreases, and the cumulative drug released decreases. SEM measurement showed that hydrogel had heterogeneous pores. PVA-PVP hydrogel prepared using gamma rays can be considered as a matrix for drug release
BIOSYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES AND THEIR INTERACTION STUDY WITH METFORMIN
Get PDFBIOSYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES AND THEIR INTERACTION STUDY WITH METFORMIN. Synthesis of gold nanoparticles successfully carried using Imperata cylindrica L leaf extract. In this study, the approach used through green synthesis method is a reaction betwen of the HAuCl4 solution (concentration variation as 3; 5; 7 x 10-4 M) with Imperata cylindrica L leaf extract. Results of UV-Vis showed of gold nanoparticles has a maximum wavelength at 530 nm with absorbance value of 1.4. Results of FTIR shows a shift the absorption peak at wavenumber of 3392 cm-1 to 3404 cm-1. PSA and PZC showed the distribution of gold nanoparticles was 48.84 nm with a charge of 20.5 mV. Gold nanoparticles has a spherical shape and an average particle size of 20 nm which can be seen from the results of the characterization using TEM. XRD showed crystalize size average of gold nanoparticles as 20.47 nm. The interaction between of gold nanoparticles with metformin can be seen in the absorbance decrease of 0.38 at a wavelength of 531 nm and the results of PSA shows an average particle size of AuNPs@metformin is 122 nm. From the characterization data can be concluded the gold nanoparticles were successfully synthesized using natural bioreductors by utilizing secondary metabolites from Imperata cylindrica L leaf extract
SYNTHESIS AND CHARACTERIZATION OF HPMC/HAp/Fe3O4 COMPOSITE FOR HYPERTHERMIA APPLICATION
Get PDFSYNTHESIS AND CHARACTERIZATION OF HPMC/HAp/Fe3O4 COMPOSITE FOR HYPERTHERMIA APPLICATION. Magnetic material become subject of intense research for hyperthermia application, and injectable magnetic hyperthermia for bone cancer is one of this research interest. In this study, composite of hydroxyapatite (HAp) and Fe3O4 in Hydroxypropyl-methyl cellulose (HPMC) matrix (HPMC/HAp/Fe3O4) has been synthesized in gel form that are expected can be applied for injectable bone substitute (IBS) in hyperthermia therapy. Composites were made using conventional methods by mixing HAp powder with ferrofluid Fe3O4 in HPMC solution. The composition of the composites were varied with the mass comparison of HPMC: HAp: Fe3O4 was 1: 0: 0; 1: 3: 0; 1: 2: 0.5; 1: 1: 0.25; and 1: 0: 3. The physical, chemical, and magnetic properties of the composites were characterized using X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectrometry (FT-IR), Particle Size Analyzer (PSA), and Vibrating Sample Magnetometer (VSM). The XRD characterization results of the HPMC/HAp/Fe3O4 composite showed the crystalline phase of the constituent components. Saturation magnetization of the HPMC/HAp/Fe3O4 composite was 2.72 emu/g and 1.79 emu/g for the composition of 1: 2: 0.5 and 1:1:0.25 respectively. HPMC/HAp/Fe3O4 composite has superparamagnetic and biocompatible properties, so that can be applied as IBS in hyperthermia therapy for bone cancer
ELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY
Get PDFELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY. Research on stainless steel corrosion resistance continues to grow today. This reality cannot be separated from the needs of stainless steels in various fields, one of which is bio-implant. In this research, the effect of grain size on the corrosion behavior of iron-chromium (Fe-Cr) alloy was investigated. Coarse grain Fe-Cr alloy was first processed with equal channel angular pressing (ECAP) for eight cycles to obtain ultrafine grain structure. The coarse and ultrafine grain samples then were then tested using XRD, SEM-EBSD, and the pitting corrosion properties tested using potentiodynamic polarization method in NaCl 1 M solution. The result of XRD dan SEM-EBSD shows that the initial sample is truly has a coarse grain structure, while ECAP produces an ultrafine grain structure. Corrosion test results showed that the ultrafine grain sample had better pitting corrosion resistance compared to the coarse grain sample. This behavior is related to the rate of passivation that depends on non-equilibrium grain boundaries, which can be easily observed in the ultrafine grain structure. Based on these results, it can be concluded that the ultrafine grain Fe-Cr alloy has a better corrosion resistance compared to the coarse grain