Electrochemical oxidation of Rhodamine B on RuO2–PdO–TiO2/Ti electrode

Enhancing photocatalytic wastewater treatment: investigating the promising applications of nickel ferrite and its novel nanocomposites

Water contamination ranks highest among the challenges posed by the rapidly increasing environmental contamination, which is thought to be the most pressing issue globally. The development of innovative techniques for the successful removal of diverse types of undesirable pollutants from wastewater would therefore yield a huge return on investment. Nowadays, the removal of many organic and synthetic pollutants from the environmental matrix is anticipated to be possible by photocatalytic degradation, owing to its low energy consumption, high catalytic activity, and low overall cost. In this context, magnetic nanoparticles received greater attention as photocatalytic materials from the scientific community in wastewater treatment for the removal of different kinds of pollutants due to their specific properties. The present study provides an overview of the recent advances in water treatment using nickel ferrite nanoparticles and their nanocomposites as photocatalysts. Furthermore, a proposed mechanism for these photocatalysts to generate active free radicals under visible and ultraviolet light has been described. The review concludes that photocatalysts based on NiFe2O4 have potential applications in water purification technologies. However, more research is still needed to determine their practical application in water treatment facilities.

Potential of low-cost TiO2-PVC composite in photoelectrocatalytic degradation of reactive orange 16 under visible light

In recent years, previously reported studies revealed a high efficiency of pollutant degradation by coupling photocatalysis and electrochemical processes (PECs) using titanium dioxide (TiO₂) photoelectrode rather than using photocatalysis or electrocatalysis alone. However, some of the TiO₂ photoelectrodes that have been reported were not cost-effective. This is due to the use of expensive chemicals and certain expensive equipment in the fabrication process, other than involving complicated preparation steps. Therefore, this study is aimed at investigating the PEC performance and stability of low-cost TiO₂-polyvinyl chloride (TiO₂-PVC) composite photoelectrode for Reactive Orange 16 (RO16) degradation. The materials characterisation using the ATR-FTIR, XRD and UV-Vis DRS proved that TiO₂ and TiO₂-PVC were successfully synthesised. The micrograph obtained for the surface characterisation using the FESEM showed that the smooth surface of freshly prepared photoelectrodes turned slightly rough with tiny pits formation after five continuous PEC processes. Nevertheless, the photoelectrode retained its original shape in good condition for further PEC processes. By PEC process, the fabricated photoelectrode showed 99.4% and 51.1% of colour and total organic carbon (TOC) removal, respectively, at optimised PEC parameters (1.0 mol L^-1 NaCl concentration, 10 V applied voltage, 120 min degradation time and initial pH 2). Moreover, the fabricated photoelectrode demonstrated sufficient reusability potential (~ 96.3%) after five cycles of PEC processes. In summary, a low-cost and stable composite photoelectrode with high efficiency in RO16 degradation was successfully fabricated and could be potentially applied for other emerging pollutants degradation via the PEC degradation technique.

Preparation of Ti/SnO2-Sb/Rare Earth Electrodes Containing Different Contents of Ni Intermediate Layer for Efficient Electrochemical Decolorization of Rhodamine B

Water contamination by dyes discharged from many industries is an environmental issue of great matter. Electrochemical oxidation is an advanced approach for wastewater treatment. In this study, the composite electrodes of Ti/SnO2-Sb-Ni/rare earth have been modified using rare earth elements (Re) Gd, Ce, Eu, and Er and various molar ratios of tin and nickel intermediate layer, and their electrochemical oxidation effects were scrutinized. To analyze the decolorization performance of the electrodes, Rhodamine B (RhB) dye was utilized as a target pollutant. Accelerated life testing indicated that the longer service life could be observed in Ni (3.5%)/Re and Ni (5%)/ Re electrodes compared with other modified Ni (0%, 1%, and 2%)/Re electrodes. Compared with the color removal efficiencies of the Ni (2%)/Re electrodes, the decolorization rate of 90% after treatment for 60 min and the low energy consumption of 3.621 kW h·m−3 can be achieved at the Ni (2%)/Gd electrode under the experimental condition of 100 mg·L−1 RhB. The best decolorization rate was observed at the Ni (2%)/Re electrodes among other Ni and no adding Ni-doped Re electrodes. The characterization of the electrodes was described, consisting of surface morphology, oxygen evolution potential, and a crystallographic and elemental combination of the coatings.

Electrochemical degradation of diclofenac using three-dimensional electrode reactor with multi-walled carbon nanotubes

The electro-oxidation treatment of aqueous solution containing diclofenac (DCF) on a Ti/RuO₂-TiO₂ electrode in the presence of multi-walled carbon nanotubes (MWCNTs) was studied in a three-dimensional electrochemical (3DE) reactor. The response surface methodology (RSM) based on central composite design (CCD) was utilized to determine the influence of different factors. The results revealed that the obtained polynomial experimental model had a high coefficient of determination (R² = 0.9762) based on analysis of variance. The optimum condition for the removal of DCF by the 3DE process was obtained with the initial pH of 3.8, the initial DCF concentration of 4 mg/L, the current density of 20 mA/cm², the particle electrode concentration of 70 mg/L, and the electrolysis time of 85 min. The quadratic model developed for DCF removal and subsequently the analysis of the F value illustrated that the initial pH was the most important factor in the removal of DCF. The comparative experiments between electrochemical processes showed the high electrocatalytic activity and removal efficiency of the 3DE reactor with the MWCNT particle electrode. The results also showed that the Ti/RuO₂-TiO₂ electrode, in addition to its high stability, had a very good electrocatalytic activity in the 3D reactor. The stability and reusability test proved that MWCNTs, as a particle electrode, had a potential to improve the long-term electrocatalytic degradation of DCF in the aqueous solutions. Based on the identified intermediate compounds along with the results of other studies, a possible pathway for the electrochemical oxidation of DCF by the 3DE process catalyzed with MWCNTs was proposed.

Fabrication of Ag3PO4/GO/NiFe2O4 composites with highly efficient and stable visible-light-driven photocatalytic degradation of rhodamine B

Effective visible-light-driven Ag3PO4/GO/NiFe2O4 Z-scheme magnetic composites were successfully fabricated by a simple ion-exchange deposition method. The Ag3PO4/GO/NiFe2O4 (8%) composite exhibited excellent photocatalytic activity (degradation efficiency was ∼96% within 15 min and kinetic constant reached 0.1956 min-1) and stability when compared to Ag3PO4, NiFe2O4, and Ag3PO4/NiFe2O4 for rhodamine B (RhB) degradation. Furthermore, by electrochemical and fluorescence measurements, the Ag3PO4/GO/NiFe2O4 (8%) material also showed larger transient photocurrent, lower impedance, and longer fluorescence lifetime (7.82 ns). Comparing the activity result dependence with characterization results, it was indicated that photocatalytic activity depended on fast charge transfer from Ag3PO4 to NiFe2O4 through GO sheet. The h+ and ·O2 - species played important roles in RhB degradation under visible-light. A possible Z-scheme mechanism is proposed over the Ag3PO4/GO/NiFe2O4 (8%) composite. This study might provide a promising visible light responsive photocatalyst for the photocatalytic degradation of organic dyes in wastewater.

Highly efficient visible-light-driven photocatalytic degradation of rhodamine B by a novel Z-scheme Ag3PO4/MIL-101/NiFe2O4 composite

An Ag₃PO₄/MIL-101/NiFe₂O₄ composite was fabricated by an in situ precipitation method. The results implied that introduction of the MOF enhanced the rapid transfer of electrons from Ag₃PO₄ to NiFe₂O₄.

Electrochemical Degradation of Rhodamine B over Ti/SnO2-Sb Electrode

Electrochemical degradation of rhodamine B (C28H31ClN2O3) over Ti/SnO2-Sb anode was investigated in a rectangular cell. The degradation reaction follows pseudo-first-order kinetics. The degradation efficiency of rhodamine B attained >90.0% after 20 minutes of electrolysis at initial concentrations of 5 to 200 mg/L at a constant current density of 20 mA/cm2 with a 10 mmol/L Na2SO4 supporting electrolyte solution. Rhodamine B (50 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9 and 86.7%, respectively, at the optimal conditions after 30 minutes of electrolysis. The results showed that the energy efficiency of rhodamine B (50 mg/L) degradation at the optimal current densities from 2 to 30 mA/cm2 were 23.2 to 84.6 Wh/L, whereas the electrolysis time for 90% degradation of rhodamine B with Ti/SnO2-Sb anode was 36.6 and 7.3 minutes, respectively. The electrochemical method can be an advisable option for the treatment of dyes such as rhodamine B in wastewater.

Preparation and characterization of a novel porous Ti/SnO2–Sb2O3–CNT/PbO2 electrode for the anodic oxidation of phenol wastewater

Porous Ti/SnO₂–Sb₂O₃–CNT/PbO₂ electrodes were successfully fabricated using a thermal decomposition technique and electro-deposition technologies.