Degradation Efficiency Of Diclofenac Research Articles

A magnetically induced self-assembly of Ru@Fe3O4/rGO cathode for diclofenac degradation in electro-Fenton process

In this study, a novel magnetic nanocomposite of Ru@Fe3O4/rGO was successfully synthesized by a simple hydro-thermal method. The Ru@Fe3O4/rGO particles were assembled and immobilized for innovative magnetically assembled electrode (MAE) without any binder, and the electrode was further applied in heterogeneous electro-Fenton (hetero-EF) process for the degradation of diclofenac (DCF). The results showed that rGO could remarkably enhance the conductivity and catalyze the two-electron oxygen reduction, which greatly improved the generation of H2O2. In addition, the mixture valence of Fe and Ru species might provide rich reaction sites and enhance electron transfer by synergy. Thus, the Ru@Fe3O4/rGO MAE exhibited a stable and high electrocatalytic activity in the hetero-EF process for DCF degradation over a wide pH range from 2 to 9 owing to the higher electroactive surface area (EASA) and lower charge/mass-transfer resistance. The DCF degradation efficiency could reach about 100% within 90 min under pH 5 and current 40 mA, and the Ru@Fe3O4/rGO MAE showed high stability and reusability after five cycles. Theoretically, 1O2 and •OH were the main reactive oxygen species (ROS) participating in DCF degradation in the Ru@Fe3O4/rGO MAE hetero-EF process. Furthermore, according to the LC-MS/MS intermediates, the possible DCF degradation pathway was deduced including dechlorination, hydroxylation and ring opening attacked by ROS. Eleven intermediates were detected during DCF degradation in the MAE hetero-EF process, and the ecological risk of DCF degradation in Ru@Fe3O4/rGO MAE hetero-EF process was significantly reduced. This study provides new insights into the magnetically assembled electrode of Ru@Fe3O4/rGO and displays a new practical application prospect of the materials for high-efficient removal and degradation of DCF from wastewater.

Comparative investigation of diclofenac degradation by Fe2+/chlorine and Fe2+/PMS processes

The degradation of diclofenac (DCF), a commonly used nonsteroidal anti-inflammatory drug, by Fe2+/chlorine and Fe2+/PMS processes was comparatively investigated. The influencing factors of pH, Fe2+ and oxidant dosage on DCF degradation efficiency were evaluated and optimized. Typically, with an initial solution pH of 5, an Fe2+ dosage of 70 μM, and a chlorine or PMS dosage of 70 μM, the degradation efficiency of DCF using the Fe2+/chlorine and Fe2+/PMS processes reached 94.2% and 79.7%, respectively, within 10 min. Quenching tests indicated the coexistence of •OH and RCS in the Fe2+/chlorine system, and both SO4●– and •OH were identified in the Fe2+/PMS system. In addition, Fe(IV) was also identified to participate in DCF degradation in two systems based on the oxidation of PMSO to PMSO2. The degradation products and pathways of DCF were elucidated by LC/TOF/MS analysis and DFT calculations. It was assumed that the degradation pathway of DCF involves hydroxylation, dechlorination, decarboxylation, cleavage of the C-N bond, and chlorine substitution. In addition, trichloromethane (TCM), dichloroacetaldehyde (DCAL), dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM) were also detected in the Fe2+/chlorine process, and these chlorinated DBPs initially increased and then decreased with prolonged reaction time, indicating that Fe2+/chlorine is capable of controlling DBPs formation. Finally, the acute and chronic toxicity of DCF and its degradation products were evaluated by the ECOSAR program.

Microwave-assisted synthesis of RuTe2/black TiO2 photocatalyst for enhanced diclofenac degradation: Performance, mechanistic investigation and intermediates analysis

• The crystallized RuTe 2 acted as a cocatalyst for photocatalysis was reported for the first time. • 0.5% RuTe 2 /B-TiO 2 achieved 95.2% DCF degradation efficiency, which was 1.2 times higher than that of pure B-TiO 2 . • The intermediates for the photodegradation of DCF were detected and removal pathways was rationalized. Seeking active and low-cost cocatalysts is a vital task for solving the sluggish kinetics of photocatalysis process in environmental management. Herein, we report a novel and high-efficiency crystallized RuTe 2 cocatalyst, and loaded it onto black TiO 2 to form photocatalytic heterostructure (denoted as RuTe 2 /B-TiO 2 ) for diclofenac (DCF) degradation. To the best of our knowledge, the RuTe 2 as a cocatalyst for photocatalysis based on swift electron capture has not been documented yet. The degradation efficiency of DCF over 0.5% RuTe 2 /B-TiO 2 reached 95.2% for 120 min, which is 1.2 times higher than that of pure B-TiO 2 . In addition, the effects of different calcination temperatures, catalyst amounts, DCF concentrations and solution pH of the as-prepared catalysts were also investigated in depth. Spectroscopy/electrochemistry showed that 0.5% RuTe 2 /B-TiO 2 exhibited a narrower band gap, more active sites and better electrical conductivity than pure B-TiO 2 . Experiments with trapping agents have shown that O 2 – was the main active substance under irradiation. Furthermore, intermediates for the photodegradation of DCF were detected by liquid chromatography mass system (LC-MS) and density functional theory (DFT) calculations. Finally, the degradation pathway was rationalized and a possible photocatalytic mechanism for 0.5% RuTe 2 /B-TiO 2 was proposed.

H2O2-assisted Sonophotocatalytic Degradation of Diclofenac using a Visible Light-Active Flower-like Micron-sized TiO2 Photocatalyst

The recovery of TiO2 nanoparticles after utilization is a major challenge that hinders the wide-scale implementation of photocatalytic technology in wastewater treatment. In this study, an easily recoverable flower-shaped micron-sized TiO2 (MST) photocatalyst was synthesized from nano-sized TiO2 seeds via a hydrothermal process. The synthesized MST photocatalyst displayed an average particle size of 1.577 μm with 2.7 eV bandgap energy and 100.18 m2/g surface area. The photocatalytic performance of the synthesized material was evaluated for the degradation of diclofenac (DCF) from aqueous solution under visible light. The degradation efficiency under visible light reached 52.87% in 120 min. When photocatalysis was coupled with ultrasonication (US), namely sonophotocatalysis, the DCF degradation efficiency increased to 62.61%. The highest DCF degradation efficiency (86.92%) was achieved under the optimized conditions of 30 kHz US frequency, 0.4 g/L of TiO2 loading, 10 ppm initial concentration of DCF, and 1.0 mM H2O2 dosage. The synergy index of sonophotocatalysis was 1.25, indicating the synergistic effects of both sonocatalysis and photocatalysis on DCF degradation efficiency. The MST photocatalyst was easily recovered through centrifugation after reaction and reused for another two cycles of sonophotocatalysis. The photocatalyst was significantly stable under these process conditions, with only a 5.19% decrease in degradation after three consecutive cycles.

Enhanced degradation of complex organic compounds in wastewater using different novel continuous flow non – Thermal pulsed corona plasma discharge reactors

The presence of pharmaceutically active compounds (PhAcs) in water bodies is a major concern due to their persistence, biological activity, and detrimental environmental effects. The present study focuses on the application of pulsed corona plasma technology to degrade such compounds. Three different plasma reactors, namely, sequential flow plasma reactor (SFR), continuous flow top discharge plasma reactor (TDPR) and continuous flow side discharge plasma reactor (SDPR), are designed and fabricated for their performance evaluation with respect to PhAC degradation. In all the reactors, wastewater was discharged as fine droplets for better interaction between the reactive oxidizing species (ROS) generated in the system and the pollutants. Enhanced degradation of the selected pharmaceutical compounds, i.e., diclofenac (DCF) and verapamil hydrochloride (VPL), is achieved with decreased treatment time and lower energy consumption. In SFR reactor water was recycled, whereas in continuous flow reactors hydraulic retention times (HRTs) were varied. The degradation efficiency of DCF (1 mg/L) and VPL (1 mg/L) was 99 % in SDPR, at HRTs of 9 and 12 min, respectively. Deposited energies (SFR- 71 W, TDPR - 92 W, SDPR- 51 W) varied due to the difference in reactor geometries. In the SDPR reactor, 99 % degradation of mixed pollutants with an initial concentration of 10 mg/L was achieved, at a HRT of 21 min. With an input power of 51 W, good energy efficiency (EEO) of 3.8 kWh/m3 and high yield (G) of 256.2 mg/kWh were obtained. . Nitrate formation was reduced by 73.2 % in TDPR and 85.0% in SDPR (32.1–8.6 mg/L) as compared to SFR (32.1 mg/L). The operating cost estimated was 0.71 $/m3, 0.80 $/m3 and 0.67 $/m3 for SFR, TDPR and SDPR, respectively. The results clearly indicate that the continuous flow reactor with side discharge is a viable alternative to traditional plasma reactors.

ABTS as an electron shuttle to accelerate the degradation of diclofenac with horseradish peroxidase-catalyzed hydrogen peroxide oxidation

Horseradish peroxidase (HRP)-catalyzed hydrogen peroxide (H2O2) oxidation could degrade a variety of organic pollutants, but the intrinsic drawback of slow degradation rate limited its widespread application. In this study, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) was introduced into HRP/H2O2 system as an electron shuttle to enhance diclofenac degradation under neutral pH conditions. The green-colored ABTS radical (ABTS•+), generated by the oxidation of ABTS with HRP-catalyzed H2O2 oxidation, was proved to be the main reactive species for the rapid degradation of diclofenac in HRP/H2O2/ABTS system. There was no destruction of ABTS/ABTS•+ in HRP/H2O2/ABTS system, and ABTS was verified as an ideal electron shuttle. The reaction conditions including solution pH (4.5–10.5), HRP concentration (0–8 units mL−1) and H2O2 concentration (0–500 μM) would impact the formation of ABTS•+, and affect the degradation of diclofenac in HRP/H2O2/ABTS system. Moreover, compared with Fenton and hydroxylamine/Fenton systems, HRP/H2O2/ABTS system had better diclofenac degradation efficiency, higher H2O2 utilization efficiency and stronger anti-interference capacity in actual waters. Overall, the present study provided a meaningful and promising way to enhance the degradation of organic pollutants in water with HRP-catalyzed H2O2 oxidation.

Photocatalytic-persulfate- oxidation for diclofenac removal from aqueous solutions: Modeling, optimization and biotoxicity test assessment

In this paper, the influence of several aquatic factors (the nature of catalyst, the initial pH and the initial concentration of the pollutant) on the photocatalytic degradation of diclofenac (DFC), one of the most widely prescribed anti-inflammatory non-steroidal drug, was studied. Also, in order to examine the intensification process, the variation of the photocatalytic DFC degradation in the presence of sodium persulfate (PPS) was analyzed. It was found that, compared to titanium dioxide (TiO2), the zinc oxide (ZnO) photocatalyst performed exceptionally well, with a 96.13% DFC degradation efficiency after 150 min. The photodegradation of DFC by ZnO catalyst fitted well the Langmuir–Hinshelwood kinetic model. The maximum efficiency is 97.27% for simulated solar-UVA/ZnO/PPS and 77% for simulated solar-UVA/ZnO. In order to determine the optimal conditions leading to the maximization of DFC removal, an artificial neural network (ANN) modeling approach combined with genetic algorithm (GA) was applied. The best ANN determined had a correlation of 0.999 and it was further used in the process optimization where a 99.7% degradation efficiency was identified as the optimum under the following conditions: DFC initial concentration 37,9 mg L−1, pH 5,88 and PPS initial concentration 500 mg L−1. The effectiveness of the process and the toxicity of the pharmaceutical pollutants and their by-products were also evaluated and confirmed by the biological tests using liver and kidney of Mus musculus mice.

New insight in the O2 activation by nano Fe/Cu bimetals: The synergistic role of Cu(0) and Fe(II)

This study demonstrated that as-synthesized nano Fe/Cu bimetals could achieve significant enhancement in the degradation of diclofenac (DCF), as compared to much slow removal of DCF by Cu(II) or zero valent iron nanoparticles (nZVI), respectively. Further observations on the evolution of O2 activation process by nano Fe/Cu bimetals was conducted stretching to the preparation phase (started by nZVI/Cu2+). Interesting breakpoints were observed with obvious sudden increase in the DCF degradation efficiency and decrease in solution pH, as the original nZVI just consumed up to Fe(II) and Cu(II) appeared again. It suggested that the four-electrons reaction of O2 and Cu-deposited nZVI would occur to generate water prior to the breakpoints, while Cu(0) and Fe(II) would play most important role in activation of O2 afterwards. Through the electron spin resonance (ESR) analysis and quenching experiments, OH was identified as the responsible reactive species. Further time-dependent quantifications in the cases of Cu(0)/Fe(II) systems were carried out. It was found that the OH accumulation was positively and linearly correlated with nCu dose, Fe(II) consumption, and Fe(II) dose, respectively. Since either Cu(0) or Fe(II) would be inefficient in activating oxygen to produce OH, a stage-evolution mechanism of O2 activated by nano Fe/Cu bimetals was proposed involving: (a) Rapid consumption of Fe(0) and release of Fe(II) based on the Cu-Fe galvanic corrosion, (b) adsorption and transformation of O2 to O22− at the nCu surface, and (c) Fe(II)-catalyzed activation of the adsorbed O22− to OH.

Degradation of diclofenac sodium using UV/biogenic selenium nanoparticles/H2O2: Optimization of process parameters

The resistance of diclofenac (DCF), one of the most popular nonsteroidal anti-inflammatory drugs, to biodegradation processes and its abundance in the aquatic environment made it an environmental concern. Degradation by ultraviolet (UV) irradiation in the presence of various catalysts has possibility to eliminate DCF from water resources. In the present study, optimization of DCF degradation under UV light irradiation using biogenic selenium nanoparticles (Se NPs) in the presence of H2O2 (assisted by central composite design) in a photoreactor followed by identification of the produced metabolites (using GC-MS (EI) technique) was evaluated. To assess the influence of parameters on the UV/Se NPs/H2O2-assisted degradation efficiency of DCF, four main factors including light intensity (W/m2), Se NPs concentration (μg/mL), pH, and H2O2 concentration (mM) were chosen. Predicted values of degradation efficiency were found to be in good agreement with experimental values (Pre-R2 = 0.9982 and Adj-R2 = 0.9953). Optimization results showed that maximum degradation efficiency (97.43%) was achieved at the optimum conditions including Se NPs concentration of 32 μg/mL, UV light intensity of 30 W/m2, pH 7.5, and H2O2 concentration of 0.05 mM. 1-(2, 6-dichlorophenyl)-2-indolinone was found to be the main product among several peaks in the GC-MS chromatogram of the DCF treated sample.

Degradation of diclofenac in aqueous solution by ionizing radiation in the presence of humic acid

Diclofenac (DFC) is becoming a ubiquitous pollutant and pose a risk to ecosystem and human beings, which is usually used as a nonsteroidal anti-inflammatory drug for treating painful diseases. In this study, the degradation of DFC in aqueous solution by ionizing radiation was investigated in the presence of various concentrations of humic acid, due to its wide existence in water matrix as natural organic matter (NOM). The experimental results showed that the removal efficiency of DFC was 80.8% at 0.8 kGy absorbed dose and initial concentration of 30 mg/L. The DFC degradation by ionizing radiation could be described by pseudo first-order kinetics model. Humic acid had negative influence on the degradation efficiency of DFC, which decreased from 80.8% to 62.9% when humic acid concentration was 30 mg/L, mainly due to the competition between humic acid and DFC for OH radicals. Several intermediate products were identified by LC-MS analysis during DFC degradation process, and a possible degradation pathway of DFC by ionizing radiation was proposed.

Efficiency and mechanism of diclofenac degradation by sulfite/UV advanced reduction processes (ARPs)

Diclofenac (DCF) is a non-steroidal anti-inflammatory drug which is frequently detected in the aqueous environment. The synergistic treatment using sulfite and UV irradiation is proposed to be one of the most effective advanced reduction processes (ARPs) to degrade refractory contaminants. This paper systematically investigated the performance and mechanism of DCF degradation by sulfite/UV ARP under various conditions. A significant enhancement in degradation efficiency of DCF was exhibited via sulfite/UV ARP compared with direct UV photolysis, which is primarily due to the generation of reductive radicals (eaq− and H). This process was well described by a pseudo first-order kinetic model with a rate constant of 0.154 min−1. The influence of solution pH, sulfite dosage, initial DCF concentration and UV intensity were evaluated. Results revealed that DCF more favorably reacted with H in an acidic environment than with eaq− under alkaline conditions. A positive impact on the DCF decomposition was observed with increasing sulfite dosage, but with an inhibiting trend at high sulfite concentrations. The degradation rate constant was accelerated by increasing the UV intensity, while decreased by promoting the initial DCF concentration. Degradation mechanisms at different pH levels revealed that the reduction reactions were induced by eaq− at pH 9.2, and dominated by H at pH 6.0. Complete dechlorination was readily achieved with all chlorine atoms in DCF released as chloride ions under sulfite/UV ARP, which may lead to a decreased toxicity of the degradation products. This observation emphasized the advantages of sulfite/UV ARP on DCF degradation, in comparison with that under direct UV photolysis.

Preparation of FeCeOx by ultrasonic impregnation method for heterogeneous Fenton degradation of diclofenac

FeCeOx has been successfully synthesized by ultrasonic impregnation method and applied in diclofenac removal in heterogeneous Fenton process. The effects of ultrasonic density, impregnation time, mole ratio of Fe and Ce and calcination temperature were investigated. Nitrogen adsorption/desorption, SEM, XRD, HRTEM, Raman and XPS analyses were characterized. Stability and reusability of FeCeOx were evaluated. The results indicated that 83% degradation efficiency of diclofenac was achieved by FeCeOx under the optimum preparation conditions. Fe ions were distributed uniformly in crystal structure and the solid solution structure of FeCeOx with a lattice constriction was formed. Exposed crystalline plane (200) with a relatively high surface energy may be the main reason to provide high catalytic activity of FeCeOx. Oxygen vacancies took part in catalytic process and a portion of them were oxidized after reaction. FeCeOx showed an excellent chemical stability and reusability in heterogeneous Fenton process.