Electrocoagulation (EC) processes have emerged as an efficient solution for different inorganic and organic effluents. The main characteristics of this versatile process are its ease of operation and low sludge production. The literature indicates that EC can be successfully used as a single process or a step within a combined treatment system. If used in a combined system, this process could be employed as a pre-, a post-, or middle treatment step. Additionally, the EC process has been used in both continuous and batch modes. In most studies, EC has achieved significant improvements in the treated water quality and relatively low total energy consumption. This review presents a comprehensive evaluation and analysis of standalone and combined continuous EC processes. The influence of key operational parameters on continuous EC performance is thoroughly discussed. Furthermore, recent advancements in reactor design, modeling, and process optimization are addressed. The benefits of integrating other treatment processes with the EC process, such as advanced oxidation, membranes, chemical coagulation, and adsorption, are also evaluated. The performance of most standalone and combined EC processes used for organic pollutant treatment and published in the last 25 years is critically analyzed. This review is expected to give researchers many insights to improve their treatment scenario with recent and efficient environmental experiences, sustainability, and circular economy. The clearly presented information is expected to guide researchers in selecting efficient, cost-effective, and time-saving treatment alternatives. The findings ensure the considerable potential of continuous EC treatment processes for organic pollutants. However, more research is warranted to enhance process design, operational efficiency, scale-up, and economic viability.

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.

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.