Degradation Of Benzoic Acid Research Articles

Potential of homogeneous persulfate activation as a strategy for the oxidative treatment of tetramethylammonium hydroxide: Superiority of sulfate radical over hydroxyl radical in the oxidation of methylammoniums

Tetramethylammonium hydroxide (TMAH) as the etching and chelating agent exhibits the extreme recalcitrance to advanced oxidation processes utilizing hydroxyl radical (OH). This study showed that based on the relative position of PDS/heat and PDS/UV against H2O2/UV in terms of TMAH degradation efficiency, sulfate radical (SO4−) was superior to OH in oxidizing TMAH. PDS/heat (at 60 °C) and PDS/UV at the initial pH = 7 achieved TMAH degradation efficiency of ∼ 80–90 % within 1 h whereas H2O2/UV barely eliminated TMAH, which contrasted with H2O2/UV decomposing phenol faster than the activated PDS. The high susceptibility of TMAH (in which four methyl groups bonded to nitrogen removed the lone pair of electrons) to oxidation by SO4− aligned with the pH–dependent efficiency of PDS/heat for the treatment of methylamines. PDS/heat effectively degraded methylammoniums (lacking nitrogen lone pair available for electron transfer due to amine protonation) under non–alkaline conditions, whereas acidification caused the efficiency loss of ∼ 90 % for H2O2/UV. Methylammoniums as radical scavengers retarded benzoic acid degradation by PDS/heat to a more pronounced extent than counterparts with deuterated N–methyl groups, which implied that hydrogen–atom abstraction primarily contributed to the SO4−–induced oxidation of methylammoniums. Estimation of the bimolecular reaction rate constants using laser flash photolysis and electron paramagnetic resonance spectroscopic detection of TMAH–derived carbon–centered radical supported the superiority of SO4− over OH in TMAH oxidation. These findings suggested the potential of homogeneous persulfate activation in the pH-insensitive oxidative treatment of alkylamines and quaternary ammonium cations structurally analogous to TMAH.

Chloride-mediated enhancement in Cu(II)-catalyzed Fenton-like reaction: The overlooked reactive chlorine species

The practical application of Cu(II)-catalyzed Fenton-like reaction (Cu(II)/H2O2) exhibits a low efficiency in the degradation of refractory compounds of wastewater. The impact of chloride ions (Cl−) on Fenton-like reactions have been investigated, but the influence mechanism is still unclear. Herein, the presence of Cl− (5 mM) significantly accelerated the degradation of benzoic acid (BA) under neutral conditions. The degradation of BA follows pseudo-first-order kinetics, with a degradation rate 7.3 times higher than the Cu(II)/H2O2 system. Multiple evidences strongly demonstrated that this reaction enables the production of reactive chlorine species (RCS) rather than HO• and high-valent copper (Cu(III)). The kinetic model revealed that Cl− could shift reactive species from the key intermediate (Cu(III)-chloro complexes) to RCS. Dichlorine radicals (Cl2•-) was discovered to play a crucial role in BA degradation, which was largely overlooked in previous reports. Although the reaction rate of Cl2•- with BA (k = 2.0 × 106 M−1 s−1) is lower than that of other species, its concentration is 10 orders of magnitude higher than that of Cu(III) and HO•. Furthermore, the exceptional efficacy of the Cu(II)/H2O2 system in BA degradation was observed in saline aquatic environments. This work sheds light on the previously unrecognized role of the metal-chloro complexes in production the RCS and water purification.

Photoelectrochemical degradation of selected organic pollutants on tungsten trioxide photoanodes

This study describes the photoelectrochemical degradation of model aromatic pollutants, viz. a herbicide (“monuron”, 3-(4-chlorophenyl)-1,1-dimethylurea) and an antimicrobial preservative (benzoic acid) on WO3 films prepared by aerosol pyrolysis. Crystalline WO3 films had a monoclinic structure, 4 μm thickness and a photocurrent density of 1 mA cm−2 at 1.2 V vs. RHE and illumination under 1 sun (simulated). The chemical and photoelectrochemical stability of WO3 films at various pH was evaluated. The dissolution rate at pH 1 and 4 was low (0.5 nm·h−1), whereas at pH 6 an increase in the dissolution rate to 15 nm·h−1 was observed. The course of the photoelectrochemical oxidation of selected pollutants was examined using HPLC. The achieved Faradaic efficiency of photoelectrooxidation of 1 mM benzoic acid divided by the number of charge equivalents per 1 mol of oxidised compound R, f/z, was 13 % and 12 % at pH 1 and 4, respectively, and for 1 mM monuron 7.2 % at pH 1 and 7.5 % at pH 4. Although the concentration of pollutants decreased significantly, UV–VIS and TOC (total organic carbon) analyses showed the prevalent presence of intermediates during the degradation. During the degradation of benzoic acid, hydroxybenzoic acid (salicylic acid) was found by HPLC as an early intermediary product.

Trivalent Copper Ion-Mediated Dual Oxidation in the Copper-Catalyzed Fenton-Like System in the Presence of Histidine.

The Cu(II)/H2O2 system is recognized for its potential to degrade recalcitrant organic contaminants and inactivate microorganisms in wastewater. We investigated its unique dual oxidation strategy involving the selective oxidation of copper-complexing ligands and enhanced oxidation of nonchelated organic compounds. L-Histidine (His) and benzoic acid (BA) served as model compounds for basic biomolecular ligands and recalcitrant organic contaminants, respectively. In the presence of both His and BA, the Cu(II)/H2O2 system rapidly degraded His complexed with copper ions within 30 s; however, BA degraded gradually with a 2.3-fold efficiency compared with that in the absence of His. The primary oxidant responsible was the trivalent copper ion [Cu(III)], not hydroxyl radical (•OH), as evidenced by •OH scavenging, hydroxylated BA isomer comparison with UV/H2O2 (a •OH generating system), electron paramagnetic resonance, and colorimetric Cu(III) detection via periodate complexation. Cu(III) selectively oxidized His owing to its strong chelation with copper ions, even in the presence of excess tert-butyl alcohol. This selectivity extended to other copper-complexing ligands, including L-asparagine and L-aspartic acid. The presence of His facilitated H2O2-mediated Cu(II) reduction and increased Cu(III) production, thereby enhancing the degradation of BA and pharmaceuticals. Thus, the Cu(II)/H2O2 system is a promising option for dual-target oxidation in diverse applications.

Self-enhanced oxidation of resistant monocyclic aromatic compounds during ozone treatment: Applicability in groundwater remediation

The Peroxone process—which utilizes a combination of ozone and hydrogen peroxide to generate hydroxyl radicals—is frequently used in groundwater remediation to effectively remove ozone-resistant contaminants. However, some monocyclic aromatic compounds with low ozone reactivity have been found to be removed by ozone solely (without the need for hydrogen peroxide) through a self-enhanced mechanism. This self-enhanced removal occurs when the interaction of ozone with hydroxide ion generates sufficient amount of hydroxyl radicals, initiating a radical reaction that subsequently propagates through the degradation intermediates. This study leverages the self-enhanced degradation mechanism for the treatment of ozone-resistant compounds during groundwater remediation. Key environmental conditions, including water alkalinity and contaminant concentration, were investigated for their effect on the self-enhanced degradation of para-chloro benzoic acid (pCBA), which served as a model for ozone-resistant compounds. High pCBA removal was observed during ozonation in the concentration range of 0.5–5 μM, where the decay kinetics of pCBA and ozone significantly dependent on the initial pCBA concentration. Furthermore, decreased pCBA removal was noted in water matrices with increased alkalinity, largely due to the scavenging of OH radicals by carbonate species. Finally, pCBA removal was investigated in natural groundwater, where co-existing substances acted as ozone/radical scavengers, leading to reduced pCBA removal. Overall, this study highlights the importance of the self-enhanced removal mechanism of monocyclic aromatic contaminants when treating water with high contamination levels and low-to-moderate alkalinities.

Unexpectedly enhanced degradation of acetaminophen by sulfoxides probe in Fe(II)-activated persulfate oxidation: The mechanism and the selectivity

Sulfoxides are widely recognized as probes for identifying and evaluating the generation and contribution of high-valent metals in advanced oxidation processes. However, this paper was surprising to find that the presence of sulfoxides selectively enhanced the degradation of specific pollutants in the Fe(II)/PS system. Represented by methyl phenyl sulfoxide (PMSO), scavenging experiments for active species showed that the presence of PMSO transformed the mechanism from radical dominated (55.60 %) to nonradical dominated (60.91 %), greatly improving the anti-interference ability of the system. Determining the concentration of Fe(Ⅱ) and total iron (Fetot) in solution revealed that the presence of PMSO improved the utilization efficiency of Fe(II) and PS by enhancing the redox reaction between Fe(II) and PS, and resulted in the generation of Fe(IV) more favorably than the generation of SO4·− and ·OH. Additionally, comparing the proven high-valent iron dominated Fe(II)/PI system with the free radical dominated Fe(II)/PS system of this paper, it was revealed that the selectively enhanced oxidation of PMSO specifically targets the free radical dominated system. Experiments have shown that the degradation of acetaminophen, ibuprofen, phenol, and p-chlorophenol was enhanced by PMSO, while the degradation of norfloxacin, primidone, chloramphenicol, sulfamethoxazole, p-nitrophenol, benzoic acid, and nitrobenzene was inhibited. Based on density functional theory (DFT) calculations, PMSO has a selectively enhanced degradation effect for organic pollutants with ionization potential (IP) below 8.66 eV, and vice versa, it has an inhibitory effect. The present study provides new insights into the contribution of sulfoxide to the assessment of high-valent metals and sheds new light on the mechanism of active species.

Halotolerant Benzoic Acid-Degrading Bacteria of the Genus <i>Dietzia</i>

Six benzoic acid-degrading bacteria of the genus Dietzia were isolated from the saline ecotopes of the Verkhnekamskoe and Yakshinskoe salt deposits (Perm region, Komi Republic, Russia). Benzoic acid (BA) may accumulate in ecosystems through technogenic processes, as well as during the microbiological decomposition of complex organic compounds containing an aromatic ring. The strains studied here were found to be closely related to D. psychralcaliphila, D. kunjamensis subsp. kunjamensis, D. cercidiphylli, and D. maris. It was shown that they are halotolerant and able to thrive on BA as their sole carbon and energy source in the absence of salt or in the presence of 50–70 g/L NaCl. They also contain benA genes encoding the α-subunit of benzoate 1,2-dioxygenase, the key enzyme of BA degradation. The highest level of similarity (79.32–91.38%) was observed between the nucleotide sequences of the benA genes of the strains considered and the homologous sequences of Actinomycetes representatives from genera such as Dietzia, Mycolicibacterium, Geodermatophilus, Pseudonocardia, Corynebacterium, and Raineyella. The described active BA degraders belonging to the genus Dietzia have the potential to aid in the development of bioremediation techniques for environmental objects contaminated with mono(poly)aromatic pollutants and subject to salting.

Mechanism of the generation of benzaldehyde and benzoic acid on Pd (1 1 1) surface during the destruction of toluene: Verification of experiments and models

Catalytic oxidation technology is still the mainstream technology of VOCs treatment at present, and it is of great significance to study the main active components of catalysts and clarify the evolution and transformation process of intermediate products in the catalytic process for clarifying the reaction mechanism and guiding the catalyst design. Pd was identified as the main active component in catalytic oxidation of toluene, and the important intermediate products in the degradation of toluene, i.e., benzaldehyde and benzoic acid, were obtained through experiment and In-situ DRIFT spectra. However, the specific evolution process of intermediates is difficult to observe experimentally. The conversion of toluene on Pd (111) surface was studied by DFT calculation. Benzaldehyde was the most stable intermediate and benzoic acid was the most stable energy state of the reaction products. Then the activation energies and reaction energies of all possible reaction paths from toluene to benzaldehyde or benzoic acid were calculated, and the only transition state was obtained. Two pathways for the formation of benzaldehyde and benzoic acid were identified, in which the oxidation reaction after dehydrogenation may be the common rate-determining step of the two pathways, with a maximum energy barrier of 0.80 eV.

Synergistic mechanism of Bacillus subtilis Czk1 combined with propiconazole and tebuconazole mixtures against Pyrrhoderma noxium

BackgroundBrown root rot disease is one of the devastating diseases in the rubber production process. It is not easy to be detected in the early stage of the disease. Our early research revealed that the rubber tree brown root rot fungus Pyrrhoderma noxium Pn006 was effectively inhibited by Bacillus subtilis Czk1 and 25% propiconazole–tebuconazole, and that the two agents might work in synergy. Therefore, in this investigation, we used non-targeted metabolomic method to evaluate the synergistic mechanism of B. subtilis Czk1 and 25% propiconazole–tebuconazole on Pyrrhoderma noxium Pn006.ResultsMetabolomics analysis identified 708 unique metabolic markers, including mainly lipids and lipid-like molecules, organic acids, alcohols, ketones, alkaloids and their derivatives, nucleotides and their analogues, benzene ring compounds and amino acids and their derivatives. Further screening identified 105 key metabolic markers that could be potential biomarkers to reveal the mechanism of biocontrol bacteria and chemical fungicides combination synergy. Three key metabolic pathways were found in pathway enrichment, including linolenic acid metabolism, benzoic acid degradation, and valine, leucine and isoleucine degradation.ConclusionsThe mechanism might be related to the influence of the energy supply and cell functional integrity of pathogenic fungal cells.Critical relevance statement A metabolomic method was utilized to investigate the synergistic effects of B. subtilis Czk1 and 25% propiconazole–tebuconazole use on Pyrrhoderma noxium Pn006.Graphical

Nanobubble Reactivity: Evaluating Hydroxyl Radical Generation (or Lack Thereof) under Ambient Conditions.

Nanobubble (NB) generation of reactive oxygen species (ROS), especially hydroxyl radical (·OH), has been controversial. In this work, we extensively characterize NBs in solution, with a focus on ROS generation (as ·OH), through a number of methods including degradation of ·OH-specific target compounds, electron paramagnetic resonance (EPR), and a fluorescence-based indicator. Generated NBs exhibit consistent physical characteristics (size, surface potential, and concentration) when compared with previous studies. For conditions described, which are considered as high O2 NB concentrations, no degradation of benzoic acid (BA), a well-studied ·OH scavenger, was observed in the presence of NBs (over 24 h) and no EPR signal for ·OH was detected. While a positive fluorescence response was measured when using a fluorescence probe for ·OH, aminophenyl fluorescein (APF), we provide an alternate explanation for the result. Gas/liquid interfacial characterization indicates that the surface of a NB is proton-rich and capable of inducing acid-catalyzed hydrolysis of APF, which results in a false (positive) fluorescence response. Given these negative results, we conclude that NB-induced ·OH generation is minimal, if at all, for conditions evaluated.

Mitigation of benzoic acid-driven autotoxicity in waste nutrient solution using O3 and O3/H2O2 treatments: Seed germination and root growth of Lactuca sativa L.

Benzoic acid (BA), a secondary metabolite released through root exudates, is considered to be the most common inhibitor that leads to plant autotoxicity, even at low concentrations in closed hydroponic systems. In this study, to mitigate BA-driven autotoxicity, the effects of O3 and O3/H2O2 oxidation treatment (O3 concentration: 1, 2, 4, 8 mg L−1, H2O2 concentration: 4, 8 mg L−1) on waste nutrient solution (WNS) were investigated in terms of BA degradation, the rate of germination inhibition (GI), and the rate of root growth inhibition (RI). In the case of O3 treatment, the BA degradation rate improved up to 14.1% as the O3 concentration increased, while alleviation of GI was insignificant (94.6–100%), confirming that a single O3 treatment was unsuitable for mitigating autotoxicity. On the other hand, O3/H2O2 treatment increased BA degradation by up to 24.8%, thereby significantly reducing GI (up to 7.69%) and RI (up to 0.88%). Both the highest BA mineralization rate and phytotoxicity mitigation was observed at BA125 (4–4) (BA mineralization: 16.7%, GI: 12.82%, RI: 11.69%) and BA125 (1–8) (BA mineralization: 17.7%, GI: 7.69%, RI: 0.88%) at each H2O2 concentration. In addition, the operating costs were evaluated by a chemical and electricity cost analysis at the different treatments. As a result, the operating costs of BA125 (4–4) and BA125 (1–8) were calculated to be 0.40 and 0.42 $ L−1 mg−1 of mineralized BA, respectively. After consideration of the mineralization rate, autotoxicity mitigation, and operating cost, BA125 (1–8) was suggested for the optimal treatment condition and our findings would contribute to the alleviation of BA-driven autotoxicity.

Synthesis of graphene-based Ag-doped CuFe2O4 composite for improved photocatalytic activity against industrial effluents

Copper ferrite (CuFe2O4, CF) and silver-doped copper ferrite (Ag-CuFe2O4, ACF) were prepared via co-precipitation method. While nano-composite of ACF with rGO was prepared by ultra-sonication approach. Degradation of crystal violet (CV) and benzoic acid (BA) by CF, ACF, and ACF@rGO was conducted under sunlight. Because of tremendous stability and immense surface area of rGO, it shows good ability to transfer electrons during photocatalysis.Band gap for CF and ACF were tuned having values 1.36 and 1.67 eV. Ag-CuFe2O4@rGO has exhibited greater photo-catalytic activity than a bare and doped sample. 82.7% and 48.4% were degradation % of CV and BA by Ag-CuFe2O4@rGO respectively. Ag-CuFe2O4@rGO showed 1.3 times higher efficiency than bare CuFe2O4. ACF was sonicated with rGO and composite was formed which was not reported before and I was the novelty of this paper. The photodegradation ability and cyclic stability etc. was increased after the formation of composite.

A novel strategy using sulfite for bromate control during UV/persulfate oxidation of bromide-containing waters

The ultraviolet/persulfate (UV/PS) process has attracted more and more attention for water treatment. However, it runs the risk of producing bromate in the presence of bromide ions. In this work, we propose a new strategy using sulfite to inhibit bromate formation. The results show that the addition of sulfite significantly reduced the formed bromate in the UV/PS system by 61.2% and 24.5% in 30 min and 120 min, respectively. Increasing sulfite dosage or pH could enhance bromate control. From the standpoint of reaction kinetics, sulfite is likely to inhibit bromate formation by reducing bromine radicals (Br) back to bromide ions, the energy profile of which was quantified by density functional theory (DFT) calculations. In the UV/PS/sulfite system, the conversion of SO3− to HO was observed, indicating that sulfite also served as a source of reactive radicals. Moreover, sulfite apparently promoted the degradation of benzoic acid and phenol in a UV/PS system, showing advantages over other inorganic reductants. As a result, we discovered that sulfite could not only help control bromate formation in UV/PS but also improve the system’s oxidation capacity.

Integration of 2D graphene oxide sheets with MgFe2O4/ZnO heterojunction for improved photocatalytic degradation of organic dyes and benzoic acid

The versatile process of photo-catalysis is used to treat water pollution and other environmental issues. Another way for solving environmental pollution remediation is metal ferrite with a spinel structure, which is widely used as a photocatalyst. In this work, the fabrication of all the materials was followed by using the co-precipitation method, while graphene oxide was prepared by hummer's method. Synthesized samples were characterized by using various techniques like XRD, SEM, UV–visible and FT-IR. For the identification of functional groups FT-IR was used. Surface morphology was determined by SEM. The band gap was calculated with the help of the Tauc plot. Methyl orange, crystal violet (as coloured dyes), and benzoic acid (as colourless effluent) were chosen to evaluate the photocatalytic performance of fabricated samples. The photocatalytic degradation (%) of composite is higher than heterojunction and pristine Magnesium ferrite and Zinc oxide. In the case of methyl orange, the degradation percentage was 80% by the composite (MgFe2O4-ZnO-GO, MF/ZO/GO) while 78% by heterojunction (MgFe2O4-ZnO, MF/ZO), 74% by ZnO (ZO) and 65% by MgFe2O4(MF). Further, crystal violet showed % a degradation 80% by composite and 72% by heterojunction, 74% by MgFe2O4(MF) and 65% by ZnO (ZO). Similarly, MF, ZO, MF/ZO and MF/ZO/GO showed 36%, 39%, 43% and 45% for benzoic acid, respectively. For the degradation of pollutants, the synthesized material will attract the attention of the researcher.

Comprehensive effect of water matrix on catalytic ozonation of chloride contained saline wastewater

Chloride ion (Cl−) is one of the most common anions in wastewater and saline wastewater, but its elusive effects on organics degradation are not clear yet in many cases. In this paper, the effect of Cl− on organic compounds degradation is intensively studied in catalytic ozonation of different water matrix. It was found that the effect of Cl− is almost completely reflected by transforming ·OH to reactive chlorine species (RCS), which is simultaneously competitive with organics degradation. The competition between organics and Cl− for ·OH directly determines the ratio of their consumption rate of ·OH, which depends on their concentration and reactivity with ·OH. Especially, the concentration of organics and solution pH may change greatly during organics degradation process, which will correspondingly influence the transformation rate of ·OH to RCS. Therefore, the effect of Cl− on organics degradation is not immutable, and may dynamically change. As the reaction product between Cl− and ·OH, RCS was also expected to affect the degradation of organics. But we found that Cl· had no significant contribution to the degradation of organics in catalytic ozonation, which may due to its reaction with ozone. Catalytic ozonation of a series of benzoic acid (BA) with different substituents in chloride contained wastewater was also investigated, and the results showed that the electron-donating substituents can weaken the inhibition of Cl− on BAs degradation, because they increase the reactivity of organics with ·OH, O3 and RCS.

Insights into characteristics of white rot fungus during environmental plastics adhesion and degradation mechanism of plastics

Since the 1980s, plastic waste in the environment has been accumulating, and little is known about fungi biodegradation, especially in dry environments. Therefore, the research on plastic degradation technology is urgent. In this study, we demonstrated that Phanerochaete chrysosporium (P. chrysposporium), a typical species of white rot fungi, could react as a highly efficient biodegrader of polylactic acid (PLA), and 34.35 % of PLA degradation was obtained during 35-day incubation. A similar mass loss of 19.71 % could be achieved for polystyrene (PS) degradation. Here, we presented the visualization of the plastic deterioration process and their negative reciprocal on cell development, which may be caused by the challenge of using PS as a substrate. The RNA-seq analysis indicated that adaptations in energy metabolism and cellular defense were downregulated in the PS group, while lipid synthesis was upregulated in the PLA-treated group. Possible differentially expressed genes (DEG) of plastic degradation, such as hydrophobic proteins, lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (Lac), Cytochrome P450 (CYP450), and genes involved in styrene or benzoic acid degradation pathways have been recorded, and we proposed a PS degradation pathway.

A facile strategy to fabricate ternary WO3/CuO/rGO nano-composite for the enhanced photocatalytic degradation of multiple organic pollutants and antimicrobial activity

A facile strategy comprising co-precipitation and ultra-sonication methods was used to fabricate WO3/CuO and WO3/CuO/rGO nanocomposites. X-ray Diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy, Scanning electron microscopy (SEM), optical, and electrochemical measurements were used for the structural, morphological, and electrical analysis of as-synthesized materials. The photocatalytic performance of synthesized materials was explored for the degradation of methylene blue (MB), Rhodamine B (RhB) and benzoic acid. The percentage degradation of MB in presence of CuO, WO3, WO3/CuO, and WO3/CuO/rGO was 56.7%, 75.1%, 86.5%, and 95.5%, respectively, within 90 min of UV-Visible light irradiation. For RhB, the percentage degradation in presence of CuO, WO3, WO3/CuO, and WO3/CuO/rGO was found to be 54.5%, 73.4%, 82.5%, and 93.1%, respectively. For benzoic acid, the percentage degradation was recorded as 35.1%, 77.3%, 84%, and 91.8% for CuO, WO3, WO3/CuO, and WO3/CuO/rGO, respectively. Evidently, during each experiment WO3/CuO/rGO showed highest capability to photodegrade the pollutants due to the generation of heterojunction interface among individual constituents. When applied for antibacterial activity, WO3/CuO/rGO showed 1.7 and 2 mm of zones of inhibition against S. Aureus and K. Pneumonia, respectively. Consequently, it can be anticipated that WO3/CuO/rGO could be used as multifunctional photocatalyst for the treatment of different environmental pollutants.

Thiosulfate enhanced Cu(II)-catalyzed Fenton-like reaction at neutral condition: Critical role of sulfidation in copper cycle and Cu(III) production

Thiosulfate (S2O32-) has been proven to be an effective promoter of Fenton-like reactions by accelerating the metal ions cycle. However, up to now, little is known about the role of sulfur transformation and intermediate sulfur in the regulation of metal chemical cycle and reactive species production. Herein, free Cu(II) was selected as catalyst for the activation of H2O2. The introduction of S2O32- significantly enhanced the degradation of benzoic acid, and the degradation rate (kobs) was 5.8 times that of Cu(II)/H2O2 system. The kinetic model revealed the transformation of sulfur species and demonstrated that sulfides (i.e., HS-/S2-, S2O32-) and S0 were the dominant electron donor for the reduction of Cu(II) into Cu(I). Consequently, the reduction and complexation roles of S2O32- significantly resolve the rate-limiting step and broaden the pH range of in Fenton-like reactions. Evidence for the critical role of high-valent copper (Cu(III)) and HO• on BA degradation was obtained by scavengers experiments, electron paramagnetic resonance and fluorescent probes. Meanwhile, the Cu(II)/H2O2/S2O32- system also exhibited satisfactory anti-interference ability of the various matrix. Overall, this study offers mechanistic insight into sulfidation in Cu chemical cycle and Cu(III) generation, and highlights the potential of S2O32- for Fenton-like reactions to control pollutants.

Spray deposited yttrium incorporated TiO2 photoelectrode for efficient photoelectrocatalytic degradation of organic pollutants

This work presents result on yttrium-doped titanium dioxide (YTO) thin films using a cost-effective spray pyrolysis technique for the photoelectrocatalytic degradation of phthalic acid (PA) and benzoic acid (BA). The physicochemical properties of YTO thin films were studied using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, UV–vis spectroscopy, etc. The obtained results confirm the presence of yttrium in the host lattice. The band bending and flat band positions were studied using Mott–Schottky analysis. The film with 1% doping amount shows the highest degradation efficiency for both the model pollutants compared to TiO2. The stability of 1% YTO film confirms excellent performance analyzed by recycling tests using a UV–vis spectrophotometer. These results highlight the significance of rare earth metal doping in TiO2 for improved photoelectrocatalytic degradation efficiency.

Synthesis and Characterization of Poly(2-vinylpyridine) and Poly(4-vinylpyridine) with Metal Oxide (TiO2, ZnO) Films for the Photocatalytic Degradation of Methyl Orange and Benzoic Acid.

In this study, composite material films of pyridine-based polymer and metal oxides (ZnO and TiO2) were successfully deposited by spin coating method for environmental remediation. Firstly, the polymers poly(2-vinylpyridine) P(2-VP), and poly(4-vinylpyridine) P(4-VP) were synthesized via solution polymerization. The analysis by grazing incidence X-ray diffraction (GIXRD) reveals semicrystalline nature and scanning electron microscopy (SEM) indicates that the poly(vinylpyridines) clusters of particles were observed on the surface of the films. It was also shown that the morphology of composite materials is completely dependent on the chemical nature of the oxide. In the case of P(2-VP)-TiO2 and P(4-VP)-TiO2, some channels or pathways of TiO2 on the surface of films were observed. However, the surface morphology of the polymer composites formulated with ZnO shows a homogeneous distribution in P(2-VP) and P(4-VP) matrix. The effectiveness of the composite materials in the photodegradation of methyl orange (MO) was evaluated by photocatalysis. According to the results, the P(4-VP)-ZnO composite exhibited the highest photodegradation of MO, allowing the separation of photogenerated species required for the photocatalytic reaction. The P(4-VP)-ZnO composite was also tested in benzoic acid (BA) photodegradation in water. The presence of some scavengers in the reaction system reveals that hydroxyl radicals (OH•), superoxide radicals (O2-•) and holes (h+) are responsible for the BA reduction by photocatalysis.