Degradation Of Diclofenac Research Articles

Hydroxylamine enhanced the degradation of diclofenac in Cu(II)/peracetic acid system: Formation and contributions of CH3C(O)O•, CH3C(O)OO•, Cu(III) and •OH

The slow reduction of Cu(II) into Cu(I) through peracetic acid (PAA) heavily limited the widespread application of Cu(II)/PAA system. Herein, hydroxylamine (HA) was proposed to boost the oxidative capacity of Cu(II)/PAA system by facilitating the redox cycle of Cu(I)/Cu(II). HA/Cu(II)/PAA system was quite rapid in the removal of diclofenac within a broad pH range of 4.5–9.5, with a 10-fold increase in the removal rate of diclofenac compared with the Cu(II)/PAA system at an optimal initial pH of 8.5. Results of UV−Vis spectra, electron paramagnetic resonance, and alcohol quenching experiments demonstrated that CH3C(O)O•, CH3C(O)OO•, Cu(III), and •OH were involved in HA/Cu(II)/PAA system, while CH3C(O)OO• was verified as the predominant reactive species of diclofenac elimination. Different from previously reported Cu-catalyzed PAA processes, CH3C(O)OO• mainly generated from the reaction of PAA with Cu(III) rather than CH3C(O)O• and •OH. Four possible elimination pathways for diclofenac were proposed, and the acute toxicity of treated diclofenac solution with HA/Cu(II)/PAA system significantly decreased. Moreover, HA/Cu(II)/PAA system possessed a strong anti-interference ability towards the commonly existent water matrix. This research proposed an effective strategy to boost the oxidative capacity of Cu(II)/PAA system and might promote its potential application, especially in copper-contained wastewater.

Poly(m-phenylene isophthalamide) (PMIA) membranes as a support for WO3/g-C3N4 for the degradation of diclofenac in water

One of the obstacles hampering large-scale semiconductor photocatalysis is the requirement for the recovery and reuse of photocatalytic nanoparticles. Polymeric membranes are viable and practical support materials for photocatalytic nanoparticles to result in multifunctional photocatalytic membranes. PMIA membranes were applied as support for photocatalytic WO3/g-C3N4 nanoparticles and evaluated for the photodegradation of diclofenac (DFC). The PMIA photocatalytic membranes were prepared using the conventional phase inversion method in which the photocatalyst was embedded into the membranes. SEM, XRD, XPS, and FTIR analysis confirmed the incorporation of WO3/g-C3N4 into PMIA membranes. The contact angle of the PMIA/WGC membranes was reduced from 56.3° for the pure PMIA membrane to 37.5°, and porosity was increased from 74.7 up to 85.3%. The photocatalytic membranes were irradiated in the visible light region. M5, which contains 2% of WO3/g-C3N4 in the PMIA membrane, presented the highest degradation of DFC (85%) after 150 min compared to the other membranes. The degradation performance of DFC using PMIA/WGC was mainly driven by hydroxyl radicals and singlet oxygen. The photodegradation performance within 10 cycles had a difference of less than 5%, indicating the stability of membranes. The PMIA membranes are viable photocatalyst support materials with potential dual functionality in water treatment.

Enhanced Diclofenac Photomineralization under Solar Light Using Ce1−xZnxO2−x Solid Solution Catalysts: Synergistic Effect of Photoexcited Electrons and Oxygen Vacancies

The present work describes the synthesis, characterization, and photomineralization activity of synthesized Ce1−xZnxO2−x solid solution catalysts allowing the degradation of diclofenac as a model of anti-inflammatory medicines in water. The oxygen-deficient photocatalyst Ce1−xZnxO2−x (CeZnx), produced by mixing ZnO and CeO2, is characterized for its crystallographic parameters, specific surface area, and morphology. Photomineralization activity determination using TOC analysis shows efficient diclofenac photo-oxidation under sunlight. Moreover, the results indicate that the coexistence of Zn2+ and Ce4+ and the oxygen vacancies rate in CeZnx solid solution are key factors for strong drug mineralization. Ultimately, CeZn0.1, which is one of the photocatalysts synthesized in the present work, represents a cheap and efficient reagent for organic matter photomineralization in wastewater.

A sustainable solution for diclofenac degradation from water by heterojunction bimetallic nanocatalyst

BackgroundDiclofenac (DCF), a recalcitrant pharmaceutical compound, poses severe environmental concerns due to several health hazards. The Fenton, photo-Fenton, and photo-Fenton-like processes are popular advanced oxidation processes for eliminating toxins from water bodies. Due to its high reactivity and surface properties, nanotechnology has opened newer technological advances in the Fenton-like advanced treatment processes. MethodA facile and one-pot synthesis produces the nanocomposite materials. The natural phytochemicals, in situ, produce the nanoparticles of Fe(NPs) and Ag(NPs), and bentonite is supported with these nanoparticles to create an innovative heterojunction nanocatalyst BN@(Fe(NPs)+(AgNPs)). Additionally, the batch investigations utilize these materials in the photo-Fenton-like degradation of diclofenac in aqueous mediums. Significant findingsThe heterojunction nanocatalyst showed synergistic effects in the remediation of DCF. The nanocatalyst is highly efficient in degrading the DCF (2.0 mg L−1) and removes 83 and 70% of DCF within 2 h under UV-A and LED light irradiations, respectively. Interestingly, the degradation process mineralizes DCF to 74% under UV-A irradiation. Moreover, degrading DCF in a heterogeneous light-assisted Fenton-like process was favorably influenced by increased Fe(II) concentration in the bulk solution. The BN@(Fe(NPs)+Ag(NPs)) nanocatalyst possessed reasonably high stability and reusability for practical applications. Further, the nanocatalyst showed relatively high selectivity in the degradation of DCF using two different natural water samples.

Atomic hydrogen-mediated enhanced electrocatalytic hydrodehalogenation on Pd@MXene electrodes

In this study, a Pd@MXene catalyst was synthesized to enhance the electrocatalytic hydrodehalogenation (ECH) of emerging halogenated organic pollutants (HOPs) by improving the dispersibility, catalytic activity, and stability of palladium (Pd). The average size of Pd nanoparticles (NPs) was reduced to 3.62 ± 0.34 nm with a more intensive peak of Pd (111), which facilitated atomic hydrogen (H*) production. The Pd@MX/CC electrode demonstrated superior ECH activity for diclofenac (DCF) degradation, with a reaction rate constant (kobs) 2.48 times higher than that of Pd/CC (without MXene). The satisfactory ECH performance of Pd@MX/CC remained consistent within a wide range of initial DCF concentrations (5–100 mg/L), and no significant ECH attenuation was observed even after up to 10 batches. Furthermore, the high activity of Pd@MX/CC was also observed in the ECH of other halogenated organic pollutants (levofloxacin, tetrabromobisphenol A, and diatrizoate). Density functional theory (DFT) calculations revealed that electronic configuration modulation of the Pd@MXene catalyst optimized binging energies to H* , DCF, and dechlorinated products, thereby enhancing the ECH efficiency of DCF.

Heat induced superfast diclofenac removal in Cu(II)–activated peracetic acid system: Mediation from non-radical to radical pathway

A Cu(II)/heat coactivated peracetic acid (PAA) system for enhancing diclofenac (DCF) degradation was proposed in this work. The superiority of this synergetic activation strategy for PAA, working reactive species, catalytic mechanism and effects of reaction parameters on DCF elimination in this system were simultaneously investigated. Based on our results, the DCF loss rate in Cu(II)-heat/PAA process at pH 8.0 was about 49.3 and 4.2 times of that in Cu(II)/PAA and heat/PAA processes, respectively. Increasing the reaction temperature to 60 оC not only motivated the conversion of Cu(II) to Cu(I) but also facilitated the one-electron transfer between Cu(I) and PAA, boosting the generation of radicals. Organic radicals (mainly CH3C(O)O• and CH3C(O)OO•) were evidenced to be the core oxidizing substances dominating in the destruction of DCF while hydroxyl radical (•OH) made a minor contribution in this system by electron paramagnetic resonance (EPR) method together with scavenging experiments. This study broads the eyes into enhanced PAA activation initiated by homogenous Cu(II), providing a simple but efficient tool to degrade micropollutants.

Diclofenac Degradation by New AOP System Zero-Valent Aluminium–Acid (ZVAl/H+) Process and its Modifications

Drugs and other pharmaceutical compounds are often used substances around the world. Diclofenac is one of the widely used anti-inflammatory drug for the treatment of acute and chronic pain, rheumatoid and osteoarthritis. In recent years diclofenac was considered as a new emerging environmental contaminant of water and soil ecosystems. In the present work the new AOP system based on the ZVAl/H+ and its modifications was applied to degrade diclofenac water solutions with its initial concentration of 25 mg L−1. The effects of initial pH, dosage of Al0 , addition of hydrogen peroxide, ferrous, ferric and aluminium ions were studied in the dark experiments. In addition, effects of irradiation with sunlight lamp were also investigated. Finally, environmental toxicity studies were conducted according to OECD tests with terrestrial plants. Degradation efficiency was measured by UV-VIS spectroscopy. After all experiments the degree of resulting TOC removal was determined. Concentration of dissolved oxygen in reaction mixture during and after reaction was also monitored. The results showed that all used systems are able efficiently remove diclofenac. The best diclofenac removal reached 98 % efficiency at pH of 3.0 in 4 hours, with Al0 dosage used of 2.0 g L−1 and with addition of 10 mg L−1 of aluminium ions (Al3+). The best TOC removal (83 %) was achieved under experimental condition of ZVAl/H+ with Al0 dosage of 4.0 g L−1 at pH of 3.0 after 4 hours. Negative results with the utilization of radical scavenger for hydroxyl radicals (methanol) led us to conclusion that degradation process in the first steps of reaction proceeds parallel by both two different mechanisms – reductive dehalogenation and hydrogenolysis. Finally, before and after treatment processes toxicity tests according to OECD Guideline 208 were performed. Resulted toxicity values showed that diclofenac solutions in concentration range from 5 to 25 mg L−1 and solutions after treatment processes had only a low toxic effect on terrestrial plants.

Rapid spectrophotometric determination of peroxydisulfate in water via oxidative coloration of 2,2′azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) using ferrous ion as catalyst

In this study, a rapid, sensitive and reliable spectrophotometric method for peroxydisulfate (PDS) determination in water was established. The proposed spectrophotometric method was based on the oxidation of 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) to form stable and green-colored ABTS radical (ABTS•+) by ferrous ion (Fe(II))-catalyzed PDS. The formed ABTS•+ performed well linear relationship with PDS concentration (R2 > 0.999) in the range of 0–60 μM at four wavelengths of 415, 650, 732, and 820 nm under optimized conditions. The proposed Fe(II)-ABTS spectrophotometric method was highly sensitive with the absorptivity of 3.595 × 104 M−1 cm−1, 1.530 × 104 M−1 cm−1, 1.945 × 104 M−1 cm−1 and 1.768 × 104 M−1 cm−1 at four detection peaks of 415, 650, 732 and 820 nm, respectively. Additionally, the proposed Fe(II)-ABTS spectrophotometric method possessed well anti-interference capacity to common natural water constituents and was reliable to determine PDS concentration in water. What’s more, the proposed Fe(II)-ABTS spectrophotometric method was successfully applied in monitoring the change of PDS concentration during the degradation of diclofenac in heat-activated PDS process. In a word, the proposed Fe(II)-ABTS spectrophotometric method could be employed as a promising approach for the rapid and accurate measurement of PDS in water, and this study provided a new perspective for the measurement of PDS by the visible spectrophotometry.

Removal of diclofenac by UV-B and UV-C light-emitting diodes (LEDs) driven advanced oxidation processes (AOPs): Wavelength dependence, kinetic modelling and energy consumption

In this study, the degradation of diclofenac (DCF), a frequently detected non-steroidal pharmaceutical, was evaluated by using UV-B and UV-C (265, 285, and 310 nm) light-emitting diodes (LEDs) alone and in combination with hydrogen peroxide (UV/H2O2) and free chlorine (UV/FC). The degradation of DCF followed a pseudo first-order kinetic, and their trend reflected the pattern of the molar absorption coefficients of the DCF and the oxidants. A positive synergistic factor was found for the UV-LED driven advanced oxidation processes in almost all cases, but despite the higher degradation rates, the overall electricity demand is similar to UV alone due to the oxidants’ energy cost. The rigorous kinetic degradation mechanisms at different wavelengths were proposed for the two processes, UV/H2O2 and UV/FC, where the predicted values were respectively kHO = 9.12 · 109 M−1 s−1 and kCl = 1.30 · 1010 M−1 s−1. No significant synergy (p > 0.05) was found for the dual-wavelength system (265 + 285 nm), and the time-based constants in all cases changed linearly with lamp intensity. Finally, dissolved organic carbon and phytotoxicity analysis revealed low mineralisation (around 20–30%) associated with the formation of stable dimers and a decrease in toxicity towards tomato and radish seeds. In the main, this work shows the great potential of implementing wavelength-specific LEDs in water treatments and effectively designing the reactor playing with adjustable intensities and kinetic degradation rates.

Enhanced photo-degradation of diclofenac using a new and effective composite (O-g-C3N4/TiO2/α-Fe2O3): Degradation pathway, toxicity evaluation and application for real matrix

Removing persistent pharmaceutical compounds from wastewater, such as sodium diclofenac (DCF), has become challenging in recent years. This study aimed to introduce a simple and navel method for synthesizing a new O-g-C3N4/TiO2/α-Fe2O3 (OCNTF) photocatalyst and examine its performance in DCF degradation from aqueous solutions. During 60 min reaction time, a complete of 10 mg/L DCF was removed by a 1.0 g/L catalyst in a 40 ml DCF solution at pH 6.75 while 41.75% of total organic carbon (TOC) was removed under the same conditions. In the same situation, the photocatalytic efficiency for natural wastewater was 97.36% in 3 h. CO32- and HPO42- were the most to cause diclofenac degradation inhibited.A Mott-Schottky analysis, measurements of band edge location, and active species trapping were used to predict the mechanism of the S Scheme. •OH played an essential role in the photo-degradation of DCF by OCNTF and displayed excellent photocatalytic reactivity for DCF over 5 cycles. LC-MS was used to identify various intermediates formed during photocatalysis, and degradation pathways were investigated. In addition, the ECOSAR program predicted that UVA/OCNTF could be classified as an eco-friendly process. It has been shown that this catalyst can be considered for eliminating emerging pollutants from water environment.

Z‐scheme ZnSnO3/Bi2WO6 with synergistic polarized electric field for efficient removal of diclofenac

The built‐in electric field induced by piezoelectric effect for suppressing the electron–hole recombination has gained substantial attention recently. In this study, a novel Z‐scheme ZnSnO3/Bi2WO6 (ZSO/BWO) piezo‐photocatalyst with synergistic polarized electric field was synthesized by a simple impregnation method. The optimized 1% ZSO/BWO shows high piezo‐photodegradation efficiency (99.9%, 60 min) and mineralization (42%, 60 min) of diclofenac (DCF) under the synergistic action of ultrasound and light, far exceeding that under sole ultrasound or illumination. The remarkable enhanced piezo‐photocatalytic activity of ZSO/BWO composite was attributed to the increased absorption, improved charge transfer, Z‐scheme heterojunction, and tight surface contact between ZSO and BWO. Moreover, the Z‐scheme mechanism of ZSO/BWO composites is studied in depth and confirmed by the free radical capture experiment and electron spin resonance technology. In addition, the corresponding intermediates of DCF degradation and the possible degradation pathways that were proposed on ZSO/BWO composites were analyzed by liquid chromatography–mass spectrometry and DFT. This work offers an efficient approach for constructing and preparing the highly efficient piezo‐photocatalysts for converting solar and mechanical vibration energies.

Coordinating the exciton-mediated and carrier-mediated photocatalytic mechanisms of carbon nitride using acetylacetone for enhancing emerging contaminants removal

The neglect of exciton-mediated energy and electron transfer mechanisms and the lack of efficient co-catalysts are two essential obstacles to expanding the application of photocatalysis in emerging contaminant treatment. Herein, acetylacetone (AA) was indirectly excited in the visible light region with the assistance of oxygen-doped carbon nitride (OCN) and showed a unique co-catalyst effect through coordinating exciton-mediated and carrier-mediated energy and electron transfer pathways. Specifically, introducing AA enhances the energy transfer efficiency of OCN, promotes reactive oxygen species generation through carrier-mediated and triplet exciton-mediated pathways, and improves exciton-mediated direct energy and electron transfer to diclofenac. As expected, the OCN/AA system showed superior activity for photocatalytic degradation of diclofenac and several other emerging contaminants. Hence, this study offers a ground-breaking viewpoint on the effective co-catalyst effect of AA and an in-depth understanding of how AA coordinates on multiple exciton-mediated and carrier-mediated photocatalytic mechanisms.

Phosphate enhanced Cu(II)/peracetic acid process for diclofenac removal: Performance and mechanism

Since limitedly existing researches suggested Cu(II) had deficiently catalytic ability to PAA, in this work, we tested the oxidation performance of Cu(II)/PAA system on diclofenac (DCF) degradation under neutral conditions. It was found that overwhelming DCF removal could be obtained in Cu(II)/PAA system at pH 7.4 using phosphate buffer solution (PBS) compared to poor loss of DCF without PBS, and the apparent rate constant of DCF removal in PBS/Cu(II)/PAA system was 0.0359 min−1, 6.53 times of that in Cu(II)/PAA system. Organic radicals (i.e., CH3C(O)O• and CH3C(O)OO•) were evidenced as the dominant contributors to DCF destruction in PBS/Cu(II)/PAA system. PBS motivated the reduction of Cu(II) to Cu(I) through chelation effect, and then the activation of PAA by Cu(I) was facilitated. Besides, due to the steric hindrance of Cu(II)-PBS complex (CuHPO4), PAA activation was mediated from non-radical-generating pathway to radical-generating pathway, leading to desirably effective DCF removal by radicals. The transformation of DCF mainly experienced hydroxylation, decarboxylation, formylation and dehydrogenation in PBS/Cu(II)/PAA system. This work proposes the potential of coupling of phosphate and Cu(II) in optimizing PAA activation for organic pollutants elimination.

Complete Biodegradation of Diclofenac by New Bacterial Strains: Postulated Pathways and Degrading Enzymes.

The accumulation of xenobiotic compounds in different environments interrupts the natural ecosystem and induces high toxicity in non-target organisms. Diclofenac is one of the commonly used pharmaceutical drugs that persist in the environment due to its low natural degradation rate and high toxicity. Therefore, this study aimed to isolate potential diclofenac-degrading bacteria, detect the intermediate metabolites formed, and determine the enzyme involved in the degradation process. Four bacterial isolates were selected based on their ability to utilize a high concentration of diclofenac (40 mg/L) as the sole carbon source. The growth conditions for diclofenac degradation were optimized, and bacteria were identified as Pseudomonas aeruginosa (S1), Alcaligenes aquatilis (S2), Achromobacter spanius (S11), and Achromobacter piechaudii (S18). The highest percentage of degradation was recorded (97.79 ± 0.84) after six days of incubation for A. spanius S11, as analyzed by HPLC. To detect and identify biodegradation metabolites, the GC-MS technique was conducted for the most efficient bacterial strains. In all tested isolates, the initial hydroxylation of diclofenac was detected. The cleavage step of the NH bridge between the aromatic rings and the subsequent cleavage of the ring adjacent to or in between the two hydroxyl groups of polyhydroxylated derivatives might be a key step that enables the complete biodegradation of diclofenac by A. piechaudii S18, as well as P. aeruginosa S1. Additionally, the laccase, peroxidase, and dioxygenase enzyme activities of the two Achromobacter strains, as well as P. aeruginosa S1, were tested in the presence and absence of diclofenac. The obtained results from this work are expected to be a useful reference for the development of effective detoxification bioprocesses utilizing bacterial cells as biocatalysts. The complete removal of pharmaceuticals from polluted water will stimulate water reuse, meeting the growing worldwide demand for clean and safe freshwater.

Insights into catalyst-free, highly effective degradation of pharmaceutical contaminant in aqueous solution by a dielectric barrier discharge system

The emerging pharmaceutical wastewater including non-steroidal anti-inflammatory drugs has posed a serious threat to the ecological environment and human health, and therefore effective treatment technologies are being urgently needed. Herein, a novel horizontal continuous-flow dielectric barrier discharge (DBD) system without catalyst was developed for the highly effective degradation of diclofenac in aqueous solution. The degradation efficiency of 10 mg/L diclofenac reached about 90% in 14 min, and the corresponding energy efficiency was 0.181 g/kWh. Furthermore, the treated water quality was evaluated in terms of TOC, BOD5/COD and toxicity. The biodegradability rapidly improved with the increasing of DBD treatment time as be expected, although the mineralization efficiency of diclofenac was still low. To gain insight into the degradation mechanism, short-lived transient and long-lived species have been identified during DBD process, in which transient species (·OH, ·O2–) were the major contribution to the oxidation of diclofenac. Furthermore, based on the intermediates identified by LC-MS, a possible degradation pathway of diclofenac by DBD system in aqueous solution was proposed. Therefore, the novel DBD reactor with horizontal continuous-flow appears to be more promising for the treatment of pharmaceutical wastewater in practical applications.

Algae-derived metal-free boron-doped biochar acts as a catalyst for the activation of peroxymonosulfate toward the degradation of diclofenac

In this study, plain seaweed biochar (SW) and boron-doped seaweed biochar (BSW) were prepared through a simple pyrolysis process using Undaria pinnatifida (algae biomass) and boric acid. The BSW catalyst was utilized to degrade organic pollutants in aqueous environments by activating peroxymonosulfate (PMS). Surface characterization of the BSW demonstrated successful doping of boron into the biochar materials. BSW600 exhibited greater catalytic activity than SW600, as evidenced by the former's maximum adsorption capacity of diclofenac (DCF) onto BSW600 (qmax = 30.01 mg g−1) and the activation of PMS. Complete degradation of DCF was achieved in 30 min using 100 mg L−1 BSW600, 0.5 mM PMS, and 6.5 initial solution pH as critical parameters. The pseudo-first-order kinetic model accurately described the DCF degradation kinetics. The scavenger experiment displayed that radical and non-radical reactive oxygen species (ROS) formed in the BSW600/PMS system. Furthermore, the generation of ROS in the BSW600/PMS system was confirmed by electron spin resonance spectroscopy (ESR). The percentage contribution of ROS was assessed to be 12.3, 45.0, and 42.7% for HO•, SO4•–, and 1O2, respectively. Additionally, the electron transfer pathway was also confirmed by electrochemical analysis. Moreover, the influence of water matrics on the BSW600/PMS system was demonstrated. The co-existence of anions and humic acid (HA) did not affect the catalytic activity of the BSW600/PMS system. The recyclability of BSW600 was assessed by DCF removal (86.3%) after three cycles. Ecological structure-activity relationships software was used to assess by-product toxicity. This study demonstrates the efficacy of non-metallic heteroatom-doped biochar materials as eco-friendly catalysts in groundwater applications.

Plasma-microbubble treatment and sustainable agriculture application of diclofenac-contaminated wastewater

The demand for efficient wastewater treatment is becoming increasingly urgent due to the rising threat of pharmaceutical residues in water. As a sustainable advanced oxidation process, cold plasma technology is a promising approach for water treatment. However, the adoption of the technology encounters several challenges, including the low treatment efficiency and the potentially unknown environmental impact. Here, microbubble generation was integrated with cold plasma system to enhance treatment of wastewater contaminated with diclofenac (DCF). The degradation efficiency depended on the discharge voltage, gas flow, initial concentration, and pH value. The best degradation efficiency was 90.9% after 45 min plasma-bubble treatment under the optimum process parameters. The hybrid plasma-bubble system exhibited strongly synergistic performance heralded by up to seven-times higher DCF removal rates than the two systems operated separately. The plasma-bubble treatment remains effective even after addition of SO42−, Cl−, CO32−, HCO3−, and humic acid (HA) as interfering background substances. The contributions of •O2−, O3, •OH, and H2O2 reactive species to the DCF degradation process were specified. The synergistic mechanisms for DCF degradation were deduced through the analysis of the degradation intermediates. Further, the plasma-bubble treated water was proven safe and effective to stimulate seed germination and plant growth for sustainable agriculture applications. Overall, these findings provide new insights and a feasible approach with a highly synergistic removal effect for the plasma-enhanced microbubble wastewater treatment, without generating secondary contaminants.

Complete oxidative degradation of diclofenac via coupling free radicals and oxygenases of a micro/nanostructured biogenic Mn oxide composite from engineered Pseudomonas sp. MB04R-2

Oxidative degradation can effectively degrade aromatic emerging contaminants (ECs). However, the degradability of lone inorganic/biogenic oxides or oxidases is typically limited when treating polycyclic ECs. Herein, we report a dual-dynamic oxidative system comprising engineered Pseudomonas and biogenic Mn oxides (BMO), which completely degrades diclofenac (DCF), a representative halogen-containing polycyclic EC. Correspondingly, recombinant Pseudomonas sp. MB04R-2 was constructed via gene deletion and chromosomal insertion of a heterologous multicopper oxidase cotA, allowing for enhanced Mn(II)-oxidizing activity and rapid formation of the BMO aggregate complex. Additionally, we characterized it as a micro/nanostructured ramsdellite (MnO2) composite using multiple-phase composition and fine structure analyses. Furthermore, using real-time quantitative polymerase chain reaction, gene knockout, and expression complementation of oxygenase genes, we demonstrated the central and associative roles of intracellular oxygenases and cytogenic/BMO-derived free radicals (FRs) in degrading DCF and determined the effects of FR excitation and quenching on the DCF degradation efficiency. Finally, after identifying the degraded intermediates of 2H-labeled DCF, we constructed the DCF metabolic pathway. In addition, we evaluated the degradation and detoxification effects of the BMO composite on DCF-containing urban lake water and on biotoxicity in zebrafish embryos. Based on our findings, we proposed a mechanism for oxidative degradation of DCF by associative oxygenases and FRs.

Z-Scheme CdIn2S4/Bi2WO6 Heterojunction for High Piezo-Photo Synergetic Performance

The piezoelectric effect triggered by mechanical energy could establish an internal electric field to effectively modulate the separation behavior of carriers. Herein, a novel CdIn2S4/Bi2WO6 (CIS/BWO) piezo-photocatalyst for removing diclofenac (DCF) from water was constructed for the first time. Encouragingly, the photocatalytic degradation activity of CIS/BWO was effectively promoted through the piezoelectric effect. Specifically, 10% CIS/BWO exhibited promising DCF degradation performance under co-excitation of light irradiation and ultrasonic vibration, with a degradation efficiency of 99.9% within 40 min, much higher than that of pure photocatalysts (72.3%) and piezocatalysts (60.3%). Meanwhile, an in-depth study of the charge carrier separation mechanism of the CIS/BWO composite under the piezo-photo synergy condition was proposed. Both the built-in electric field induced by the piezoelectric effect in BWO and the Z-scheme transfer path of the CIS/BWO heterojunction are beneficial to interfacial charge transfer. Moreover, the Z-scheme mechanism was further demonstrated by trapping experiments and the electron spin resonance (ESR) technique. Finally, the corresponding intermediates of DCF over CIS/BWO composites and possible degradation pathways were also investigated by DFT calculations and liquid chromatography-mass spectrometry.

Mesostructured lead dioxide grown on titania nanotubes for diclofenac water removal through electrocatalytic and photoelectrocatalytic processes

Mesostructured PbO2/TiO2 materials were synthesized to perform electrocatalysis (as electrooxidation, EO) and photoelectrocatalysis for removing diclofenac (DCF), 15 ppm concentration in 0.1 M NaSO4 solutions, at different pH conditions (3.0, 6.0 and 9.0) by applying 30 mA cm−2. Titania nanotubes (TiO2NTs)-based materials were prepared to synthetize with a massive PbO2 deposit on this support to obtain TiO2NTs/PbO2 and a TiO2NTs:PbO2 material consisting in a dispersed PbO2 deposit on TiO2-NTs that allowed the formation of a heterostructured surface of combined composition (TiO2 and PbO2). Organics removal (DCF and byproducts) was monitored through UV–vis spectrophotometry and high-performance liquid chromatography (HPLC) during degradation tests. TiO2NTs/PbO2 electrode was tested in both processes, removing DCF at neutral and alkaline solution conditions in EO while an unimportant photoactivity was registered at this material. Conversely, TiO2NTs:PbO2 was used as electrocatalytic material in EO experiments, achieving more than 50% of DCF removal at pH 6.0 by applying 30 mA cm−2. Also, for first time, the synergic effect was investigated when it was exposed to UV irradiation in photoelectrocatalytic experiments, enhancing its efficacy (⁓more than 20%) to remove DCF from a solution with 15 ppm over performance removals achieved (56%) when EO was applied under similar conditions. Chemical Oxygen Demand (COD) analyses showed that significantly higher DCF degradation is reached under photoelectrocatalysis, since COD values decrease a 76% against a 42% decrease achieved with electrocatalysis. Scavenging experiments showed a significant participation on the pharmaceutical oxidation process through the generation of photoholes (h+), hydroxyl radicals and sulfate-based oxidants.