Vanadium is a significant metal, and its derivatives are widely employed in industry. One of the essential vanadium compounds is vanadium pentoxide (V₂O₅), which is mostly recovered from titanomagnetite, uranium–vanadium deposits, phosphate rocks, and spent catalysts. A smart method for the characterization and recovery of vanadium pentoxide (V₂O₅) was investigated and implemented as a small-scale benchtop model. Several nondestructive analytical techniques, such as particle size analysis, X-ray fluorescence (XRF), inductively coupled plasma (ICP), and X-ray diffraction (XRD) were used to determine the physical and chemical properties, such as the particle size and composition, of the samples before and after the recovery process of vanadium pentoxide (V₂O₅). After sample preparation, several acid and alkali leaching techniques were investigated. A noncorrosive, environmentally friendly extraction method based on the use of less harmful acids was applied in batch and column experiments for the extraction of V₂O₅ as vanadium ions from a spent vanadium catalyst. In batching experiments, different acids and bases were examined as leaching solution agents; oxalic acid showed the best percent recovery for vanadium ions compared with the other acids used. The effects of the contact time, acid concentration, solid-to-liquid ratio, stirring rate, and temperature were studied to optimize the leaching conditions. Oxalic acid with a 6% (w/w) to a 1/10 solid-to-liquid ratio at 300 rpm and 50 °C was the optimal condition for extraction (67.43% recovery). On the other hand, the column experiment with a 150 cm long and 5 cm i.d. and 144 h contact time using the same leaching reagent, 6% oxalic acid, showed a 94.42% recovery. The results of the present work indicate the possibility of the recovery of vanadium pentoxide from the spent vanadium catalyst used in the sulfuric acid industry in Jordan.

While platinum electrode shows hyperactivity towards adsorption and surface processes, iodine-coated platinum electrode offers remarkable inertness toward them. Therefore, iodine-coated platinum electrodes lend themselves to probe chemical species in the bulk solution without intervention from adsorption and surface processes. The current work presents utilization of iodine-coated polycrystalline platinum electrode as a voltammetric sensor for determination of dopamine in serum and urine samples. Differential pulse voltammetry (DPV) at iodine coated polycrystalline platinum electrode is the technique of choice whenever higher sensitivity is sought. DPV with a scan rate of 5 mV/s was applied for determination of dopamine in PBS at pH 7. The anodic peak related to dopamine oxidation in the above-mentioned solution was centered at ~0.1V vs. Ag/AgCl quasi reference electrode. The linear range for the developed method was between 1.0 and 100 µM. The anodic peak current showed excellent linearity with dopamine concentration (R² =0.9977) over the above-mentioned range. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.29 µM and 0.96 µM respectively which attests to the high sensitivity of the developed method. The proposed method was successfully applied to the analysis of dopamine in serum and urine samples. The percent recovery values ranged from 94.4 to 104.5% attesting to the accuracy of the developed method and absence of determinate errors.

Aim: By modifying the Pt electrode with polyvinylpyrrolidone, the distinct oxidation potentials of L and D-serine were markedly increased for both isomers.Methods & results: CV was used for Pt electrode modification with PVP. Twenty cycles was reasonable for Pt modification. K₃[Fe(CN)₆] CV experiments investigated reversibility of the Fe(III) redox reaction and the enhancement of electron transfer at the PVP-Pt electrode. L and D-serine showing an oxidation peak potential at 0.394 V and 0.468 V, respectively. A linear relationship between the anodic oxidation current extracted from the CVs and the standard concentrations of L-serine and D-serine solutions was obtained with R² = 0.99. The dynamic range for D-serine was from 0.5 to 20 mM with a LOD of 0.16 mM, while for L-serine, was from 2.5 to 20 mM with a detection limit of 0.27 mM. Using DPV, the dynamic range was 0.05-1.0 µM for D-serine with a detection limit of 0.0103 µM. The standard deviation ranged from 0.212 to 0.38 across ten determinations per concentration.Conclusion: A separation by 74 mV between the oxidation peaks of L and D-serine was achieved with remarkable enhancement in oxidation current for both isomers. PVP-Pt electrode can detect D-serine in the presence of DL-serine.

Objective: The present investigation aims to utilize the extract of vanadium pentoxide from spent vanadium catalyst in a tabletop vanadium redox flow battery (VRFB) and a home-designed cell stack. The most commonly used redox couples in VRFB systems are V ²⁺ /V ³⁺ and V ⁴⁺ /V ⁵⁺ which typically require the use of costly VOSO ₄ standard solution. In this study we propose an alternatve approch by substituting these expensive solutions with more affordable and environmentally friendly option: a V ₂ O ₅ solution derived from spent catalyst. Method: Characterization of the recovered vanadium solutions, incorporation of these solutions were performed in a three electrode cell and in a real bench-top vanadium storage battery model, and the performance of the constructed battery was tested using different electrochemical techniques such as cyclic voltammetry. Result: The increasing current and potential observed were proportional to the concentration of the recovered solution. Furthermore, an in-house tabletop VRFB utilizing the recovered electrolyte exhibited promising electrochemical properties, achieving a maximum discharge potential of 2.0 V after 180 minutes of electrical charging and a maximum current of 83.5 mA. These results are encouraging for the utilization of recovered vanadium solutions in VRFBs. Conclusion: This study results are encouraging for the utilization of recovered vanadium solutions in VRFBs. This work suggests a novel technique that utilizes waste vanadium solutions from the sulfuric acid industry for sustainable VRFB applications.