Electrochemical oxidation of Florfenicol in aqueous solution with mixed metal oxide electrode: Operational factors, reaction by-products and toxicity evaluation.

Veterinary antibiotics have become an emerging pollutant in water and wastewater sources due to excess usage, toxicity and resistance to traditional water and wastewater treatment. The present study explored the degradation of a model antibiotic- Florfenicol (FF) using electrochemical oxidation (EO) with Ti-RuO2/IrO2 anode. The anode material was characterized using SEM-EDS studies expressing stable structure and optimal interaction of the neighboring metal oxides with each other. The EDS results showed the presence of Ru, Ir, Ti, O and C elements with 6.44%, 2.57%, 9.61%, 52.74% and 28.64% atomic weight percentages, respectively. Optimization studies revealed pH 5, 30 mA cm-2 current density and 0.05 M Na2SO4 for 5 mg L-1 FF achieved 90% TOC removal within 360 min treatment time. The degradation followed pseudo-first order kinetics. LC-Q-TOF-MS studies revealed six predominant byproducts illustrating hydroxylation, deflourination, and dechlorination to be the major degradation mechanisms during the electrochemical oxidation of FF. Ion chromatography studies revealed an increase in Cl-, F- and NO3- ions as treatment time progressed with Cl- decreasing after the initial phase of the treatment. Toxicity studies using Zebrafish (Danio rerio) embryo showed the treated sample to be toxic inducing developmental disorders such as pericardial edema, yolk sac edema, spinal curvature and tail malformation at 96 h post fertilization (hpf). Compared to control, delayed hatching and coagulation were observed in treated embryos. Overall, this study sets the stage for understanding the effect of mixed metal oxide (MMO) anodes on the degradation of veterinary antibiotic-polluted water and wastewater sources using electrochemical oxidation.

TiO2 nanoparticles: green synthesis, characterization, and investigation of antimicrobial properties, and developmental toxicity in zebrafish (Danio rerio) embryos.

The present study was designed to green synthesize titanium dioxide nanoparticles (G-TiO2 NPs) using Salacia reticulata leaf extract as a reducing and capping agent to assess antidiabetic, anti-inflammatory, and antibacterial effects as well as toxicity evaluation in zebrafish. Besides, zebrafish embryos were employed to study the effect of G-TiO2 NPs on embryonic development. Zebrafish embryos were treated with TiO2 as well as G-TiO2 NPs at four different concentrations, i.e., 25, 50, 100, and 200 µg/ml for 24-96-hour post-fertilization (hpf). The SEM analysis of G-TiO2 NPs confirmed that the size was in the range of 32-46 nm and characterized by EDX, X-ray diffraction (XRD), FTIR, UV-vis spectra. During 24-96-hour post-fertilization (hpf), the results showed that 25-100 µg/ml of TiO2 and G-TiO2 NP instigated developmental acute toxicity in these embryos, causing mortality, hatching delay, and malformation. TiO2 and G-TiO2 NPs exposure induced axis bent, tail bent, spinal cord curvature, yolk-sac, and pericardial edema. Exposure of larvae to the highest concentrations of 200 µg/ml TiO2 and G-TiO2 NPs caused maximum mortality at all time points and reached 70% and 50%, respectively, at 96 hpf. Besides, both TiO2 and G-TiO2 NP revealed antidiabetic and anti-inflammatory effects in vitro. In addition, G-TiO2 NPs exhibited antibacterial effects. Taken together, this study provided a valuable insight into the synthesis of TiO2 NPs using green methods and the synthesized G-TiO2 NPs possess moderate toxicity and potent antidiabetic, anti-inflammatory and antibacterial activities.

Iron-engineered mesoporous biocarbon composite and its adsorption, activation, and regeneration approach for removal of paracetamol in water.

Three-dimensional multi-porous Iron Oxide/carbon (Fe2O3/C) composites derived from tamarind shell biomass were synthesized by a single-step co-pyrolysis technique and utilized for Paracetamol (PAC) dismissal in the combined adsorption, and advanced oxidation such as electrochemical regeneration techniques. The Fe2O3/C composites were prepared by different pyrolysis temperatures, and named as TS750 (without Fe2O3at 750 °C), MTS450 BCs (Low-450 °C), MTS600 BCs (Moderate-600 °C) and MTS750 BCs (high-750 °C), respectively. As-prepared Fe2O3/C composite was characterized by FE-SEM, XRD, BET, and XPS analysis. The specific surface area and the spatial interaction between the interlayers of Fe2O3 and C were significantly improved by increasing the pyrolysis temperatures from 450 to 750 °C, which improved the adsorption capacity of Fe2O3/C composites in terms of higher rate constants and chemisorption kinetics. The Pseudo-second-order kinetics model fitted in the adsorption test results of Fe2O3/C composites with the highest correlation co-efficiency. The Langmuir-isotherms model fitted in the adsorption test of the TS750 and MTS450 BCs. The Freundlich isotherms model is more fit with MTS600 and MTS750 BCs. Based on the isotherm results, the MTS750 BCs achieved 46.9 mg/g of maximum PAC adsorption capacity. The optimized MTS750 composites could be completely recovered by using an advanced electrochemical oxidation regeneration approach within 180 min. Also, with the adsorption and recovery process, the TOC removal rate improved to ∼79.4%. After the 6th cycle electrochemical oxidation process, the obtained results of the re-adsorption test showed the stabile adsorption activity of the sorbent material. The data outcomes herein propose that this type of combined adsorption and electrochemical approach will be useful in commercial water treatment plants.

Insight into BDD electrochemical oxidation of florfenicol in water: Kinetics, reaction mechanism, and toxicity.

Antibiotics in the environment provoke serious consequences on living beings and can be effectively remediated by prominent advanced oxidation process. In this study, electrochemical advanced oxidation treatment in a lab-scale reactor for the degradation of florfenicol (FLO) was studied with the aid of boron-doped diamond anode (BDD). The results exhibited that the FLO degradation follows pseudo-first-order kinetics. As the current intensity rose from 60 mA to 250 mA, the FLO removal efficiency increased and the corresponding reaction rate constant increased from 0.0213 to 0.0343 min-1, which was likely due to the more efficient participation of free hydroxyl radical (•OH) generated at the BDD anode. Faster degradation and higher mineralization of electrolyzed FLO solution were achieved at higher current intensity as well as in higher SO42- concentration medium, as a consequence of catalytic participation of oxidants (free •OH as well as sulfate radical (SO4•-) and persulfate (S2O82-)). The increase in FLO concentration from 30 to 50 mg L-1 resulted in a reaction rate constant decrease (from 0.0235 to 0.0178 min-1). Eight transformation by-products (m/z = 372.99, 359.8, 338.0, 324.04, 199.00, 185.02, 168.99 and 78.989) and three inorganic ions (NO3-, Cl- and F-) were analyzed by UPLC‒Q‒TOF‒MS/MS and Ion‒chromatography, respectively. The Vibrio fischeri bioluminescence inhibition revealed an increase of toxicity during the electrochemical oxidation that could be attributed mostly to the generated organic chlorinated by-products (m/z = 372.99, 359.8) and inorganic species (ClO2- and ClO3-).

Electrochemical degradation of psychoactive drug caffeine in aqueous solution using graphite electrode.

In this study, the electrochemical degradation of caffeine (1,3,7-trimethylxanthine) in aqueous solution by a graphite electrode was investigated. Electrochemical degradation was tested by the cyclic voltametry technique performed in the potential range of -1.0 to +1.0 V versus Ag/AgCl, which confirmed the electro-activity of the selected caffeine. The effects of the treatment process variables, such as initial pH, current density, electrolyte concentration and electrolysis time on the degradation of caffeine, were explored. During the various stages of electrolysis, parameters such as chemical oxygen demand (COD), total organic carbon (TOC) were analysed. The maximum COD and TOC removal efficiencies of 85% and 77% were achieved at neutral pH 7, operated at a current density of 5.1 mA/cm2, electrolyte (Na2SO4) concentration of 0.1 M and at 240 min electrolysis time. From this study, it can be concluded that the electrochemical treatment process could effectively reduce the COD and TOC from the caffeine in aqueous medium. The degradation of the caffeine was confirmed by UV spectra, IR spectra and HPLC analysis.