Standard rate constants of charge transfer for the redox couple Ti(IV)/Ti(III) in chloride-fluoride melts with the different cationic composition

The influence of the second coordination sphere of titanium complexes on the charge transfer kinetics of the Ti (IV)/Ti (III) redox couple in melts of alkali metal halides was studied by cyclic voltammetry method. Diffusion coefficients in the CsC-CsF (10 wt. %) melt were calculated. The standard rate constants of charge transfer have been determined by the Nicholson method. The activation energies of the charge transfer process in (NaCl- KCl)equimol-NaF (10 wt. %) — K2TiF6, KCl-KF (10 wt. %) — K2TiF6 and CsCl-CsF (10 wt. %) — K2TiF6 melts were calculated.

Electrochemical profiles of bacteria isolated from crude oil on simple benzene compounds detection

Five polyaromatic hydrocarbons (PAHs) degrading bacterial species had been isolated from crude oil samples. All bacteria were positive Gram-stained, except one; and had positive results on the catalase test. After sequencing bacterial DNA, three bacterial genera were obtained with 99-100% certainty, namely: Pseudomonas sp., Staphylococcus sp., and Bacillus sp. All bacteria were known strongly to form a biofilm, thus can be applied for biosensing and/or bioremediation techniques. Using minimal mineral media growth assay as media culture, all bacteria were able to degrade naphthalene and anthracene, Staphylococcus sp. shown the strong degradation affinity. Meanwhile, Bacillus sp. tended to form strong biofilm. Electrochemical data were obtained with the cyclic voltammetry method, with a scan rate of 100 mV/s. Voltammogram profiles of all bacteria against simple benzene compounds (benzene, toluene, and xylene; concentration for each compound 1μL/mL) showed irreversible oxidation peaks at 0.20-0.40 V ppm of the analyte, producing current 50-100 μA. The measurements were taken when the solution was more stable (±10 seconds) after vigorous shaking to homogenize benzene compounds and introducing O2 into the solution. The peaks were decreasing over the next cycles, indicating the lower bioavailability of benzene compounds to be degraded with O2.

Elektroplating Grafena-Polianilina pada Stainless Steel sebagai Elektroda pada Elektrolisis Air untuk Produksi Hidrogen

Hydrogen production by water electrolysis can be optimalized by improve the working electrode. Stainless steel as working electrode was coated with graphene and polyaniline by using cyclic voltammetry method with Ag/AgCl as reference electrode and Pt as counter electrode. Coated electrodes were characterized by SEM-EDS and cyclic voltammetry method. Furthermore, the synthesized electrode was applied for water electrolysis by adding 1- 5 g/L NaHCO3. The characterization data showed that Stainless steel/Graphene-Polyaniline electrode can be synthesized by using cyclic voltammetry. The coating process was conducted at sweeping rate 10 mV/s on voltage -0.2 to 0.8 V for 10 cycles. The voltammograms showed that the highest cathodic peak current of electrolysis obtained at 0.491 mA by addition 2 g NaHCO3 on SS/G-PANi0,5 electrode, and the highest anodic peak current obtained at 0.191 mA by addition 2 g NaHCO3 on SS/G-PANi0,5 electrode. Based on the overpotential data, the smallest average potential difference of H+ adsorption obtained by SS/G-PANi1,0 electrode, and the smallest average potential difference of H+ desorption obtained by SS/G-PANi0,5 electrode. Keywords: Stainless steel, hydrogen production, electroplating, electrocatalyst, electrolysis

An Electrochemical Sensor Based on Amino Magnetic Nanoparticle-Decorated Graphene for Detection of Cannabidiol

For detection of cannabidiol (CBD)—an important ingredient in Cannabis sativa L.—amino magnetic nanoparticle-decorated graphene (Fe3O4-NH2-GN) was prepared in the form of nanocomposites, and then modified on a glassy carbon electrode (GCE), resulting in a novel electrochemical sensor (Fe3O4-NH2-GN/GCE). The applied Fe3O4-NH2 nanoparticles and GN exhibited typical structures and intended surface groups through characterizations via transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), and Raman spectroscopy. The Fe3O4-NH2-GN/GCE showed the maximum electrochemical signal for CBD during the comparison of fabricated components via the cyclic voltammetry method, and was systematically investigated in the composition and treatment of components, pH, scan rate, and quantitative analysis ability. Under optimal conditions, the Fe3O4-NH2-GN/GCE exhibited a good detection limit (0.04 μmol L−1) with a linear range of 0.1 μmol L−1 to 100 μmol L−1 (r2 = 0.984). In the detection of CBD in the extract of C. sativa leaves, the results of the electrochemical method using the Fe3O4-NH2-GN/GCE were in good agreement with those of the HPLC method. Based on these findings, the proposed sensor could be further developed for the portable and rapid detection of natural active compounds in the food, agricultural, and pharmaceutical fields.

The production of supercapacitor carbon electrodes based on sugar palm fronds using chemical and physical activation combination

Abstrak. Pembuatan elektroda karbon superkapasitor berbasis limbah pelepah aren dengan kombinasi pengaktifan kimia dan fisika telah berhasil dilakukan. Aktivasi kimia dilakukan dengan menggunakan agen pengaktif 0,3 M KOH dan aktivasi fisika menggunakan gas CO2 pada suhu 900oC selama 2,5 jam. Karakterisasi sifat fisis elektroda meliputi susut massa, tebal, diameter, densitas dan derajat kristalinitas. Karakterisasi sifat elektrokimia elektroda dilakukan dengan menggunakan metode siklis voltametri. Setelah proses karbonisasi-aktivasi fisika, massa, tebal, diameter dan densitas elektroda mengalami penurunan persentase masing-masing adalah 60,87; 30,43; 24,08 dan 5,71%. Elektroda PA-0,3 memiliki struktur semi kristalin, yang ditandai dengan adanya dua puncak yang lebar pada sudut hamburan sekitar 25o dan 46o. kapasitansi spesifik elektroda PA-0,3 berdasarkan variasi laju pemindaian adalah 90 F g-1 untuk 1 mV s-1, 82 F g-1 untuk 2 mV s-1, dan 71 F g-1 untuk 5 mV s-1. Abstract. The production of supercapacitor carbon electrodes based on sugar palm frond waste using chemical and physical activation combinations have been successfully carried out. The chemical activation was carried out using 0.3 M KOH activating agent and the physical activation using CO2 gas at a temperature of 900oC for 2.5 h. Characterization of the physical properties of the electrodes includes mass loss, thickness, diameter, density and degree of crystallinity. The electrochemical properties characterization of the electrodes was carried out using the cyclic voltammetry method. After the carbonization-physical activation process, the mass, thickness, diameter, and density of the electrodes decreased in the percentage of 60.87, 30.43, 24.08, and 5.71%, respectively. The PA-0.3 electrode has a semi crystalline structure, which characterized by the presence of two broadening peaks at a scattering angle around of 25o and 46o. The specific capacitance of the PA-0.3 electrode based on the scan rate variations is 90 F g-1 for 1 mV s-1, 82 F g-1 for 2 mV s-1, and 71 F g-1 for 5 mV s-1.Keywords: Sugar palm fronds, Chemical activation, Physical activation, Carbon electrode, Supercapacitor

Laser Photocatalysis of the Chlorophyll Dye Using the Cyclic Voltammetry Method

Cyclic voltammetry is a widely used technique in electrochemistry due to its simplicity and large amount of data and information that can be obtained. This study utilises this technique to study chlorophyll a and total chlorophyll (Tchl) alongside a laser light to induce photosynthesis. No oxidative peak was observed, regardless of the solution pH in either a dark or light environment when using a solution with an electrolyte of tetrabutylammonium perchlorate (TBAP) in both dichloromethane (DCM) and acetonitrile (MeCN), whereas in a solution of aqueous HCl a small anodic peak was observed. The concentration of the droplet of Tchl pigment on the surface of macro glassy carbon electrode (GCE) was increased, which resulted in a similar trend and the oxidation peak was observed to be slightly larger when in the presence of light. It was observed that the filtered solution of Tchl pigment produced a weaker signal than the unfiltered solution and there were slightly reduced oxidative peak currents when the concentration of VK1 was increased. were no observed changes in the peak charges or currents over a wide potential range (0.0, 0.2, 0.4, 0.6 and 0.8 V) in the presence or absence of light by using coulometry and amperometry methods, therefore, more information on the 3-D formation is required for the photoreduction processes.

PEPPSI complexes as potential prodrugs: enzyme inhibition, antioxidant activity, electrochemical characterization, molecular docking analysis

In this study, enzyme inhibition and antioxidant activity analyzes of previously characterized pyridine-enhanced precatalyst preparation stabilization and initiation (PEPPSI)-type Palladium(II) complexes with benzimidazole-type ligands {dichloro[L]pyridine palladium(II), L1: 1-(2-methyl-2-propenyl)-3-[benzylbenzimidazole]-2-ylidene, L2: 1-(2-methyl-2-propenyl)-3-[4-chloro benzylbenzimidazole]-2-ylidene, L3: 1-(2-methyl-2-propenyl)-3-[3-methylbenzylbenzimidazole]-2-ylidene, L4: 1-(2-methyl-2-propenyl)-3-[3,4,5-thrimethoxybenzylbenzimidazole]-2-ylidene, L5: 1-(2-methyl-2-propenyl)-3-[3-naphthylbenzylbenzimidazole]-2-ylidene, L6: 1-(2-methyl-2-propenyl)-3-[anthracen-9-ylmethylbenzimidazole]-2-ylidene} were performed and evaluated as potential drugs for neurodegenerative disorders such as Alzheimer disease and Parkinson disease. Inhibition of tyrosinase enzyme of N-heterocyclic carbenes (NHC) complexes was determined for the first time in literature. Chelating activities of the complexes were determined and compared with EDTA. Electrochemical characterization was performed using cyclic voltammetry method. Moreover, global reactivity descriptors and electronic transitions were evaluated by DFT/TDDFT methods and molecular docking interactions with human acetylcholine esterase, human butyrylcholine esterase and oxidoreductase were studied.