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The growing demand for low-cost and functional snacks in many developing nations called for interest in the use of locally grown crops as substitutes for costly imported wheat flour. The amino acid composition, antioxidant and anti-inflammatory properties of the cookies from whole wheat, sweet potato, rice bran and peanut (56.25:18.75:5:20; 37.50:37.50:5:20; 18.75:56.25:5:20% as WPRG 1, WPRG 2, WPRG 3) composite flour blends, respectively, were obtained in this study. The 100% whole wheat and 100% refined flours served as control 1 and 2, respectively. The level of hydrophobic and aromatic amino acids was significantly (p < 0.05) high in WPRG 2 (~ 30 and ~ 10%), respectively when compared to others. However, the branched chain amino acids and Fischer ratio was significantly (p < 0.05) high in WPRG 1 (11.40% and 1.29), respectively, which could have contributed to their improved bioactivities. Notably, the composite cookie samples WPRG 1, 2 and 3 had higher hydroxyl (73.86 − 84.16%), DPPH (76.52 − 84.60%) radical scavenging as well as ferric reducing antioxidant (0.64–0.87 mmolFe2+/mg) properties than the control samples WWF and CWF, respectively. On the contrary, the metal chelating activities of the cookies WPRG 1–3 were not significantly (p > 0.05) different from control samples WWF and CWF. The improved amino acid profile and enhanced antioxidant properties of the composite cookies might have effectively influenced their anti-inflammatory properties (IC50; < 26 μg/ml) when compared to the control samples (IC50; ~ 40 μg/ml), respectively. Hence, the cookies that comprised of antioxidants and anti-inflammatory potentials needed in human health, were acceptable by the consumers. [ABSTRACT FROM AUTHOR]

Batch heterogeneous catalytic ozonation experiments were performed using commercial and synthesized nanoparticles as catalysts in aqueous ozone. The transferred ozone dose (TOD) ranged from 0 to 150 μM, and nanoparticles were added in concentrations between 0 and 1.5 g L−1, with all experiments conducted at 20 °C and a total volume of 240 mL. A Ce-doped TiO2 catalyst (1% molar ratio of Ce/Ti) was synthesized via the sol–gel method. Response surface methodology (RSM) was applied to identify the most significant factors affecting the removal of selected pharmaceuticals, with TOD emerging as the most critical variable. Higher TOD resulted in greater removal efficiencies. Furthermore, it was found that the commercially available metal oxides α-Al2O3, Mn2O3, TiO2, and CeO2, as well as the synthesized CeTiOx, did not increase the catalytic activity of ozone during the degradation of ibuprofen (IBF) and para-chlorobenzoic acid (pCBA). Carbamazepine (CBZ) and diclofenac (DCF) are compounds susceptible to ozone oxidation, thus their complete degradation at 150 μM transferred ozone dose was attained. The limited catalytic effect was attributed to the rapid consumption of ozone within the first minute of reaction, as well as the saturation of catalyst active sites by water molecules, which inhibited effective ozone adsorption and subsequent hydroxyl radical generation (●OH). [ABSTRACT FROM AUTHOR]

Heterogeneous Advanced Oxidation Processes (H-AOPs) are considered a new process for removing emerging pollutants. In this case, the high reactivity of hydroxyl radicals is used to degrade persistent organic pollutants. This review explores the state-of-the-art catalyst for hydroxyl radical generation in AOPs. As a parasite reaction, chloride ions appear in alkaline conditions and compete with the active sites. The theoretical foundation of catalyst performance is explored, focusing on the fundamental principles that govern the efficiency and mechanism of hydroxyl or chloride radical production. The synthesis and electronic modification sections explore the modifications of catalysts. It discusses key methodologies for catalyst preparation, with a particular emphasis on electronic modification that enhances both activity and stability. Finally, laboratory and pilot applications highlight the effectiveness of novel or modified catalysts in different scenarios. These last findings provide insights into the future directions for research and application, aiming to draw attention to the gap between laboratory studies and real-world implementations. [ABSTRACT FROM AUTHOR]

Polychlorinated naphthalenes (PCNs) are a new type of persistent organic pollutant (POP) characterized by persistence, bioaccumulation, dioxin-like toxicity, and long-range atmospheric transport. Focusing on one type of PCN, monochlorinated naphthalenes (CN-1, CN-2), this study aimed to examine their photodegradation in the environment. In this work, CN-1 and CN-2 were employed as the model pollutants to investigate their photodegradation process under UV-C irradiation. Factors like the pH, initial concentrations of CN-1, and inorganic anions were investigated. Next, the roles of hydroxyl radicals (•OH), superoxide anion radicals (O2•−), and singlet oxygen (1O2) in the photodegradation process were discussed and proposed via theory computation. The results show that the photodegradation of CN-1 and CN-2 follows pseudo-first-order kinetics. Acidic conditions promote the photodegradation of CN-1, while the effects of pH on the photodegradation of CN-2 are not remarkable. Cl−, NO3−, and SO32− accelerate the photodegradation of CN-1, whereas the effect of SO42− and CO32− is not significant. Additionally, the contributions of •OH and O2•− to the photodegradation of CN-1 are 20.47% and 38.80%, while, for CN-2, the contribution is 16.40% and 16.80%, respectively. Moreover, the contribution of 1O2 is 15.7%. Based on DFT calculations, C4 and C6 of the CN-1 benzene ring are prioritized attack sites for •OH, while C2 and C9 of CN-2 are prioritized attack sites. [ABSTRACT FROM AUTHOR]

This study focuses on synthesizing a catalyst that can quickly degrade micropollutants in water with minimal ozone exposure. While ozone is an effective oxidizing agent, it can harm the environment at higher concentrations if released in gaseous form. Thus, due to their efficiency and non-toxicity, researchers prefer to use hydroxyl radicals as oxidizing agents. In this study, Fe magnetite nanoparticles (FeNPs) have been synthesized to generate hydroxyl radicals for ozonation. The stability and effectiveness of the FeNPs as an ozonation catalyst were tested under different pH levels and ozone doses. Promising results have been obtained showing complete degradation of the model pharmaceutical compound within 10 min for the catalytic ozonation process. The parameters have been optimized for the holistic picture of the process, and their significance on the % degradation has been evaluated thoroughly. The energy requirement of the process has been evaluated to compare the proposed work with the available AOPs. It was found that the heterogenous catalytic ozonation process projects a much lower energy requirement as compared to many other AOPs. [ABSTRACT FROM AUTHOR]

The Fenton reaction is known for generating highly reactive hydroxyl radicals that are applied to accelerate the polishing removal rate of chemically inert SiC substrates. However, previous research primarily focuses on the polishing removal rate acceleration on the C surfaces of SiC substrates, and very limited studies have been conducted to investigate whether the hydroxyl radicals produced by the Fenton reaction serve as the primary agents of oxidative activity. Furthermore, the oxidation ability of hydroxyl radicals on the C surface and its relationship with their concentration are still not well-established. Therefore, more extensive research is needed to gain comprehensive understanding on the role of hydroxyl radicals in the oxidative activity on the C surface and their concentration-dependent effects. In this study, the polishing results of alumina, cerium oxide, and silica containing polishing slurries with and without Fenton reaction were compared and analyzed. The material removal rate (MRR) of the C surfaces of SiC substrates was significantly improved after the introduction of the Fenton reaction in alumina-containing slurry at pH 4, resulting in a smoother surface. Low-field nuclear magnetism, atomic force microscopy (AFM), ultraviolet spectrophotometry, and X-ray photoelectron spectroscopy (XPS) were employed to gain insights on inter-particle interactions and oxidation mechanisms of C face of SiC in presence of Fenton reaction. The results revealed that while hydroxyl radicals demonstrated potent oxidation ability, they alone were incapable of oxidizing C face of SiC. [ABSTRACT FROM AUTHOR]

The study investigates the effect of different parameters for the removal of SO2 and NOx through a wet process concurrently. Two separate processes have been compared for the removal of flue gases, that is, Ozone/UV and H2O2/UV. The research aims to develop a comparative study for the removal of SO2 and NOx simultaneously using Ozone/H2O2 and UV light and find the energy consumption (also known as EEO) for each process. Combining UV with O3 and H2O2 play a crucial role in generating hydroxyl radicals. Different combinations of Ozone/H2O2, flue gas, and UV intensity were studied at different pH and temperatures of the solution to achieve maximum removal of the flue gases. For, the ozonation process it was observed that the removal% of flue gases increases with increasing UV intensity, and at higher UV intensity (250 W), the removal% for NOx is 92% and SO2 is 95% simultaneously at optimum temperature 308 K. For H2O2/UV process (250 W UV intensity), removal% for NOx is 95% and SO2 is 100% at 313 K, 0.3 LPM flow rate of flue gases. The EEO values obtained for both processes were less than 1 for 95% NOx/SO2 removal efficiency. [ABSTRACT FROM AUTHOR]

A Fe2+-EGTA(ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid)-H2O2 system emits photons, and quenching this chemiluminescence can be used for determination of anti-hydroxyl radical (•OH) activity of various compounds. The generation of •OH and light emission due to oxidative damage to EGTA may depend on the buffer and pH of the reaction milieu. In this study, we evaluated the effect of pH from 6.0 to 7.4 (that may occur in human cells) stabilized with 10 mM phosphate buffer (main intracellular buffer) on a chemiluminescence signal and the ratio of this signal to noise (light emission from medium alone). The highest signal (4698 ± 583 RLU) and signal-to-noise ratio (9.7 ± 1.5) were noted for pH 6.6. Lower and higher pH caused suppression of these variables to 2696 ± 292 RLU, 4.0 ± 0.8 at pH 6.2 and to 3946 ± 558 RLU, 5.0 ± 1.5 at pH 7.4, respectively. The following processes may explain these observations: enhancement and inhibition of •OH production in lower and higher pH; formation of insoluble Fe(OH)3 at neutral and alkaline environments; augmentation of •OH production by phosphates at weakly acidic and neutral environments; and decreased regeneration of Fe2+-EGTA in an acidic environment. Fe2+-EGTA-H2O2 system in 10 mM phosphate buffer pH 6.6 seems optimal for the determination of anti-•OH activity. [ABSTRACT FROM AUTHOR]

The lack of vertical observation of reactive nitrogen oxides in agricultural areas has posed a significant challenge in fully understanding their sources and impacts on atmospheric oxidation. Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations were conducted in the agricultural regions of the North China Plain (NCP) during the summer of 2019 to measure the vertical distributions of aerosols, nitrogen dioxide (NO2), and nitrous acid (HONO). This study aimed at revealing the spatiotemporal distribution, sources, and environmental effects of reactive nitrogen oxides in the NCP agricultural areas. Our findings indicated that the vertical profiles of aerosols and NO2 exhibited a near-Gaussian distribution, with distinct peak times occurring between 8:00–10:00 and 16:00–18:00. HONO reached its maximum concentration near the surface around 8:00 in the morning and decreased exponentially with altitude. After sunrise, the concentration of HONO rapidly decreased due to photolysis. Additionally, the potential source contribution function (PSCF) was used to evaluate the potential sources of air pollutants. The results indicated that the main potential pollution sources of aerosols were located in the southern part of the Hebei, Shanxi, Shandong, and Jiangsu provinces, while the potential pollution sources of NO2 were concentrated in the Beijing–Tianjin–Hebei region. At altitudes exceeding 500 m, the heterogeneous reactions of NO2 on aerosol surfaces were identified as one of the important contributors to the formation of HONO. Furthermore, we discussed the production rate of hydroxyl radicals (OH) from HONO photolysis. It was found that the production rate of OH from HONO photolysis decreased with altitude, with peaks occurring in the morning and late afternoon. This pattern was consistent with the variations in HONO concentration, indicating that HONO was the main contributor to OH production in the agricultural regions of the NCP. This study provides a new perspective on the sources of active nitrogen in agricultural regions and their contribution to atmospheric oxidation capacity from a vertical perspective. [ABSTRACT FROM AUTHOR]

Herein, this study has examined the influence of Zn2+ sources during a biogenic-mediated pathway to synthesize ZnO nanoparticles with highly desirable solar-responsive catalytic properties. Salts of nitrate, acetate and chloride have been utilized. The ZnO powders underwent characterization using diverse analytical tools, including XRD, FTIR, Raman, BET, SEM, TEM with EDS/elemental mapping and UV-vis absorption/emission spectroscopic analyses. Accordingly, precursors have proved to affect crystallinity, morphology, surface characteristics, optical properties and the photocatalytic degradation of methylene blue (MB) model pollutant. It was observed that ZnO derived from zinc acetate precursor (Z-AC NPs) exhibits very fast photocatalytic degradation of MB at pH 11 with superior kinetic estimates of 0.314 min−1 and t1/2 = 2.2 min over many of recent reports. In contrast, the chloride precursor is not recommended along with the employed biogenic route. The intriguing findings could be directly correlated to the decreased crystal size, augmented surface area, the hexagonal morphology of the crystals, high potency in absorbing visible photons, high efficacy in separating photogenerated charge carriers and producing high amounts of •OH radicals. Further testing of Z-AC NPs in photocatalytic remediation of water samples from Dumat Aljandal Lake in Aljouf, Saudi Arabia, contaminated with MB and pyronine Y (PY) dyestuffs, showed high dye photodegradation. Therefore, this work could lead to an extremely fast avenue for decontaminating wastewater from hazmat dyestuff. [ABSTRACT FROM AUTHOR]

The photochemistry of Fe(III)-Iminodiacetic acid complex (Fe(III)-IDA) was studied under UVA and UV/Vis irradiation. The synthesis was realised via molar ratio method modified by reaction of IDA as ligand with Fe(III) as metal. The interaction of Fe(III) with IDA was characterised using Fourier-transform infrared (FTIR) and spectroscopy UV–visible. The results confirmed the stability of the complex at pH > 5; with constant of stability (Log β = 10.02) and stoichiometry Fe(III): IDA = 1:1. In addition, the redox potential was calculated at 521 mV, which is significantly lower than E° for the Fe(III)/Fe(II) couple. The photolysis of this complex in the presence of UVA light and UV/Vis light at different pHs was carried out. This photolysis was followed by several assay Fe(II) and •OH. The results show that the Fe(III)-IDA complex present a photo-reactivities under either light source and the phenomenon is faster when the UV/Vis was used. The initial conversion rate (r0) decreased with increasing of initial pH. The formation of hydroxyl radicals via the Fenton reaction was improved at pH = 2.12 for both irradiation sources used. Reduction of total organic carbon was also studied using the total organic carbon (TOC). The feasibility of amino iron complexes to improve the Fenton process under irradiation was confirmed. Additionally, our research also evidenced the optimal conditions for the formation of hydroxyl radicals; which are the key factor in remove pharmaceuticals pollutants in aqueous media. Based on the results obtained, the Fe(III)-IDA complex could be efficiently photolysis under UV/Vis light. [ABSTRACT FROM AUTHOR]

Solar Fenton is an important and extensively used advanced oxidation process (AOP) to degrade pharmaceutical pollutants. The objective of this study was to evaluate the performance of simultaneous degradation of the mixed pollutants (amoxicillin, acetaminophen, and ciprofloxacin) for an aqueous solution using the solar Fenton process. Operating parameters such as pH, iron doses, H2O2 doses, pollutant concentrations, and time were studied. From the experimental results, the ideal conditions were obtained for the removal of mixed pollutants such as pH 3, Fe2+ 0.04 mM, H2O2 4 mM, the concentration of the mixed pollutants 5 mg/L, solar radiation 400 W/m2, and time 10 min, respectively. The pseudo-first-order kinetics were utilized to investigate the degradation efficacy of the mixed pollutants. The result of the study indicates that the degradation efficiency was > 99% for the mixed pollutants. A maximum of 63% mineralization was observed, and hydroxyl radical scavenger effects were studied. The best optimal conditions were applied to assess the spiked wastewater (municipal wastewater (MWW) and hospital wastewater (HWW)). The highest elimination rates for AMX, ACET, and CIP were observed as 65%, 89%, and 85% for MWW and 76%, 92%, and 80% for HWW, respectively. The degraded by-products were detected by LC–ESI–MS in the water matrix (aqueous solution and spiked wastewater), and ECOSAR analysis was performed for the transformed products. The study concluded that the solar Fenton technique is promising and effective for the removal of mixed pollutants from the water matrix. [ABSTRACT FROM AUTHOR]

The reactions of acetylcholine halides with H2O2 were studied at room temperature in initially deionized water, i.e., at pH ∼7. Acetylcholine (ACh), which catalyzes the decomposition of hydroperoxides and H2O2 into radicals in an organic medium, virtually does not affect the decomposition of H2O2 in aqueous solutions. In the case of AChI, hydrogen peroxide oxidizes the iodide anion to form diiodine and hydroxyl radical HO•, which was identified using the 5,5-dimethylpyrrolidine N-oxide spin trap. The rate constant of this reaction was estimated from the initial sections of the kinetic curves for the consumption of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL): k1 = (2.0±0.1)•10−3 L mol−1 s−1. A nontrivial combination of radical reactions and redox disproportionation reactions occurs in the AChI—H2O2—TEMPOL system in initially deionized water. In this medium, H2O2, iodine compounds, TEMPOL, and the formed hydroperoxide radicals HO2• have a dual ability to act as oxidants or reducing agents, which results in quasi-stationary concentrations of I2 and TEMPOL being established in the process. The I− oxidation by peroxides in acid medium, known in iodometric titration, generates hydroxide radicals when conducted in neutral solutions (pH ∼7) and can compete with the Fenton reaction in systems in which the presence of metal ions is excluded. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes (AOPs) using hydroxyl radicals (•OH) as oxidizing agents are a promising technology. Herein, a feasible strategy is developed to initially construct carbazole‐based D‐π‐A type conjugated polymer (PBNCZ) via the oxidative coupling. Additionally, introducing ─COO− through Cyano hydrolysis extends its conjugated structure and improves the energy band structure, which greatly facilitates the generation of •OH as well as the enrichment of pollutants. Detailed experiments and theoretical calculations have proved that the introduction of ─COO− enhances the adsorption of O2 and bisphenol A (BPA), optimizing the reaction path of •OH. Thus, it completely decomposes 10 ppm of BPA within just 10 min, exceeding all previously organic photocatalysts. Meanwhile, the efficiency of photocatalytic H2O2 production by PBNCZ‐COO− reaches 1719.03 µmol h−1 g−1 under visible light. This multifunctional material with high adsorption capacity, photodegradation efficiency, and photocatalytic H2O2 production activity provides a solid foundation for the preparation of organic photocatalysts. [ABSTRACT FROM AUTHOR]

Advanced oxidation processes (AOPs) using hydroxyl radicals (•OH) as oxidizing agents are a promising technology. Herein, a feasible strategy is developed to initially construct carbazole‐based D‐π‐A type conjugated polymer (PBNCZ) via the oxidative coupling. Additionally, introducing ─COO− through Cyano hydrolysis extends its conjugated structure and improves the energy band structure, which greatly facilitates the generation of •OH as well as the enrichment of pollutants. Detailed experiments and theoretical calculations have proved that the introduction of ─COO− enhances the adsorption of O2 and bisphenol A (BPA), optimizing the reaction path of •OH. Thus, it completely decomposes 10 ppm of BPA within just 10 min, exceeding all previously organic photocatalysts. Meanwhile, the efficiency of photocatalytic H2O2 production by PBNCZ‐COO− reaches 1719.03 µmol h−1 g−1 under visible light. This multifunctional material with high adsorption capacity, photodegradation efficiency, and photocatalytic H2O2 production activity provides a solid foundation for the preparation of organic photocatalysts. [ABSTRACT FROM AUTHOR]

The lifetime of hydroxyl radicals (⋅OH) in the fuel cell catalyst layer remains uncertain, which hampers the comprehension of radical‐induced degradation mechanisms and the development of longevity strategies for proton‐exchange membrane fuel cells (PEMFCs). In this study, we have precisely determined that the lifetime of ⋅OH radicals can extend up to several seconds in realistic fuel cell catalyst layers. This finding reveals that ⋅OH radicals are capable of carrying out long‐range attacks spanning at least a few centimeters during PEMFCs operation. Such insights hold great potential for enhancing our understanding of radical‐mediated fuel cell degradation processes and promoting the development of durable fuel cell devices. [ABSTRACT FROM AUTHOR]

Among pollution remediation technologies, advanced oxidation processes (AOPs) are genuinely efficient since they are based on the production of strong, non-selective oxidants, mainly hydroxyl radicals (·OH), by a set of physicochemical methods. The biological counterparts of AOPs, which may be referred to as advanced bio-oxidation processes (ABOPs), have begun to be investigated since the mechanisms of induction of ·OH production in fungi are known. To contribute to the development of ABOPs, advanced oxidation of a wide number of dyes by the white-rot fungus Pleurotus eryngii, via a quinone redox cycling (QRC) process based on Fenton's reagent formation, has been described for the first time. The fungus was incubated with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-oxalate, with and without Mn2+, leading to different ·OH production rates, around twice higher with Mn2+. Thanks to this process, the degradative capacity of the fungus increased, not only oxidising dyes it was not otherwise able to, but also increasing the decolorization rate of 20 dyes by more than 7 times in Mn2+ incubations. In terms of process efficacy, it is noteworthy that with Mn2+ the degradation of the dyes reached values of 90–100% in 2–4 h, which are like those described in some AOPs based on the Fenton reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] Cobalt-based catalysts are one of the preferred materials for effective activation of hydrogen peroxide, and metal element doping and active site dispersion are effective methods to enhance their catalytic activity. In this work, manganese-doped cobalt silicate@diatomite composites with enhanced photo-Fenton-like oxidation performance were prepared and used for degradation of methyl orange (MO) dyes. Experiments showed that manganese doping increased the specific surface area of the samples and decreased the band gap energy of the materials. Moreover, the samples doped with manganese elements had better photo-Fenton-like properties. The degradation of methyl orange by Co0.25MnSi@DE/H 2 O 2 -UV reached more than 95%. In addition, density-functional theory (DFT) calculations showed that the Mn-doped samples were more prone to activate H 2 O 2 than non-manganese-doped samples, and the synergistic effect from using a bimetallic catalyst increased the photo-Fenton oxidation activity in the system. ESR spectroscopy and bursting tests indicated that the possible degradation mechanism consisted of hydroxyl radicals and superoxide radicals generated by the synergistic effect of cobalt ions and manganese under UV radiation. This study thus presents a feasible idea for the preparation of cobalt-based photo-Fenton catalysts that also provides a basis for understanding the catalytic mechanism analysis of other types of bimetallic catalysts. [ABSTRACT FROM AUTHOR]

Industrial effluents are produced in large quantities in underdeveloped nations, where they cannot be handled using conventional treatment techniques. In this study, hydroxyl radicals (HO•) were successfully generated for the treatment of industrial wastewater represented in TOC removals by combining a ferrous catalyst with hydrogen peroxide in the Fenton reaction. The effects of operating conditions of pH, ferrous dose, H 2 O 2 dose, time, and initial TOC concentration were studied for the Fenton process and different operating parameters were studied for the coagulation process to optimize and control the removal efficiency. The results showed that Fenton oxidation processes are able to reduce about 86 % for initial TOC level of 2000 and 95 % for initial TOC level of 400 after using 0.15 g/L ferrous dose, 10 mL/L of 30 % H 2 O 2 for 30 min at acidic pH 4. Finally, this study recommends removing organic materials from industrial effluent using the Fenton oxidation method. [ABSTRACT FROM AUTHOR]

Nanosized Ag and CeO2 particles obtained through the hydrothermal method were physically mixed to obtain composite antibacterial agents. The comparative experiments of antibacterial properties showed that the antibacterial activity of the nanocomposites was improved compared to the nanoparticles alone, which indicated that the synergistic antibacterial effect existed between Ag and CeO2. On the one hand, ICP-MS results showed that the existence of CeO2 suppressed the silver ion release rate and provided the composite with the ability of antibrowning; on the other, EPR data indicated that more hydroxyl radicals (·OH) were generated by the interfacial interaction between nanosized Ag and nanosized CeO2. Hence, for the Ag-CeO2 composite antibacterial agent, hydroxyl radicals played an important role in causing bacterial death. [ABSTRACT FROM AUTHOR]

The electrochemical oxidation process has the unique advantage of in-situ •OH generation for deep mineralization of organic pollutants, which is expected to provide a solution for the globally decentralized wastewater treatment and reuse. However, it is still a great challenge to develop low-cost anodes with ultrahigh •OH yield and low energy consumption. Here, a low-cost and stable mixed metal oxide (MMO) anode (Cu-Sb-SnO2) developed by a simple and scalable preparation process presents extremely high organic pollutants degradation efficiency and low energy consumption. The tetracycline degradation kinetics constant of the Cu-Sb-SnO2 system (0.362 min-1) was 9 to 45 times higher than that of other prepared anodes, which is superior to the existing anodes reported so far. The experimental results and theoretical calculations indicate that the Cu-Sb-SnO2 has moderate oxygen evolution potential, larger water adsorption energy, and lower reaction energy barrier, which is conducive to selective water oxidation to generate •OH. Notably, it is systematically and comprehensively confirmed that the generation of •OH triggered by in situ electrogenerated Cu(III) increased •OH steady-state concentration by over four times. Furthermore, the doped Cu species can play a key role in promoting charge transfer as an "electronic porter" between Sn and Sb in the electrocatalytic process by adjusting the electronic structure of the Sb-SnO2 electrode. This work paves the way for the development of MMO anodes utilizing the advantage of the Cu redox shuttle. [ABSTRACT FROM AUTHOR]

Organic type‐I photosensitizers (PSs) which produce aggressive reactive oxygen species (ROS) with less oxygen‐dependent exhibit attractive curative effect for photodynamic therapy (PDT), as they adapt better to hypoxia microenvironment in tumors. However, the reported type‐I PSs are limited and its exacted mechanism of oxygen dependence is still unclear. Herein, new selenium‐containing type‐I PSs of Se6 and Se5 with benzoselenadiazole acceptor has been designed and possessed aggregation‐induced emission characteristic. Benefited from double heavy‐atom‐effect of selenium and bromine, Se6 shows a smaller energy gap (ΔEST) of 0.03 eV and improves ROS efficiency. Interestingly, type‐I radicals of both long‐lived superoxide anion (O2•‾) and short‐lived hydroxyl (•OH) are generated from them upon irradiation. This may provide a switch‐hitter of dual‐radical with complementary lifetimes for PDT. More importantly, simultaneous processes to produce •OH are revealed, including disproportionation of O2•‾ and reaction between excited PS and water. Actually, Se6 displays superior in–vitro PDT performance to commercial chlorin e6 (Ce6), under normoxia or hypoxia. After intravenous injection, a significantly in–vivo PDT performance is demonstrated on Se6, where tumor growth inhibition rates of 99% is higher than Ce6. These findings offer new insights about both molecular design and mechanism study of type‐I PSs. [ABSTRACT FROM AUTHOR]

The fluoroquinolone-type antibiotic ofloxacin is regularly detected in wastewaters. In this work, its hydroxyl radical (•OH) induced degradation was studied at a concentration of 0.1 mmol dm−3 in three water matrices, pure water, tap water, and purified wastewater (collected from a wastewater treatment plant). •OH was produced by γ-irradiation under conditions when it had a high yield. The •OH dosage dependencies of chemical (COD) and biochemical (BOD) oxygen demands, total organic carbon (TOC) content, oxygen uptake rate (OUR), Microtox® toxicity, and antibacterial activity values were evaluated. •OH effectively oxidized and mineralized ofloxacin; both processes were observed even at the lowest •OH dosage, 0.14 mmol dm−3 (0.5 kGy absorbed dose). When 0.28 mmol dm−3 •OH was introduced into pure or tap water, the antibacterial activity vanished. In purified wastewater, a higher dosage (0.56 mmol dm−3) was required to achieve the same effect as in pure water, due to the organic molecules of the matrix that quenched the •OH radicals. The products did not have antibacterial activity and showed little toxicity toward the test organism Vibrio fischeri. •OH preferentially attacks the pharmacophore part, the 4-quinolone unit of ofloxacin. •OH-induced reactions can be safely applied to destroy the antimicrobial potency of fluoroquinolone-type antibiotics in purified wastewater matrices. [ABSTRACT FROM AUTHOR]

The pBR322 plasmid DNA was irradiated with 35 MeV electrons, 228 MeV protons and 300 kVp X-rays to quantify DNA damage and make comparisons of DNA damage between radiation modalities. Plasmid was irradiated in a medium containing hydroxyl radical scavengers in varying concentrations. This altered the amount of indirect hydroxyl-mediated DNA damage, to create an environment that is more closely associated with a biological cell. We show that increasing hydroxyl scavenger concentration significantly reduced post-irradiation DNA damage to pBR322 plasmid DNA consistently and equally with three radiation modalities. At low scavenging capacities, irradiation with both 35 MeV electrons and 228 MeV protons resulted in increased DNA damage per dose compared with 300 kVp X-rays. We quantify both single-strand break (SSB) and double-strand break (DSB) induction between the modalities as a ratio of yields relative to X-rays, referred to as relative biological effectiveness (RBE). RBESSB values of 1.16 ± 0.15 and 1.18 ± 0.08 were calculated for protons and electrons, respectively, in a low hydroxyl scavenging environment containing 1 mM Tris–HCl for SSB induction. In higher hydroxyl scavenging capacity environments (above 1.1 × 106 s−1), no significant differences in DNA damage induction were found between radiation modalities when using SSB induction as a measure of RBE. Considering DSB induction, significant differences were only found between X-rays and 35 MeV electrons, with an RBEDSB of 1.72 ± 0.91 for 35 MeV electrons, indicating that electrons result in significantly more SSBs and DSBs per unit of dose than 300 kVp X-rays. [ABSTRACT FROM AUTHOR]

In the present study, the degradation of an azo dye Orange G (OG) by the UV/TiO2/periodate (IO4-) process has been investigated. OG was totally disappears within 10 min by the UV/TiO2/IO4-compared to UV alone, UV/TiO2 or UV/IO4-. A synergistic effect has been obtained when combining the UV/TiO2 and the UV/IO4-systems, resulting in positive interactions between both processes. Experiments conducted with specific hydroxyl radical scavengers, show that despite the inhibition effect observed, complete degradation has been achieved beyond 10 min, demonstrating that the degradation is not only initiated by hydroxyl radical, but also by other reactive entities; the involvement of iodate radical is confirmed with the use of chromium species as a competitor with periodate ions for the photogenerated electron at the conduction band. The operating parameters influencing the degradation process such as initial dye concentration, initial periodate concentration, light intensity/wavelength and initial pH solution have been explored. The presence of inorganic ions such as chloride, bromide, sulphate, carbonate and bicarbonate ions in the irradiated solution show reverse effects depending on the concentration used. The OG degradation in different water matrices is found to be sensitive to the presence of different species and their nature. Chemical oxygen demand (COD) has been partially removed after 10 min of treatment, and then this COD abatement stabilized, indicating the strength of the by-products from dye degradation by the UV/TiO2/IO4- system during the treatment time. The electrical energy consumption is estimated at 2.21kWhm3/Order. The results obtained indicate that the UV/TiO2/IO4- process could be used as a hybrid process to the treatment of dye contaminated water. [ABSTRACT FROM AUTHOR]

Acetaminophen (AP) is a widely used antipyretic analgesic belonging to the class of PPCPs, which is difficult to be effectively degraded by traditional water treatment processes. However, photocatalytic technology may be an effective approach. Herein, B-doped TiO2 photocatalytic materials were synthesized by sol–gel method, calcinated at 600℃ for 2 h, investigated by XRD, TEM, XPS, and other characterization methods. The photocatalytic efficiency and factors affecting the photocatalytic activity were assessed by degradation of AP under 365 nm UV light. Compared with undoped TiO2, 4%B-TiO2 nanopowder has smaller grain size, higher porosity, and lower bandgap energy of 3.11 eV. Scavenging experiments and ESR results show that •OH is the principal active species. Hence, the degradation efficiency of AP is as high as 98.8% in 30 min when adopting 10-mg/L AP initial concentration and 1-g/L 4%B-TiO2 loading, owing to efficient •OH generated by B-TiO2. [ABSTRACT FROM AUTHOR]

It has been documented that organic contaminants can be degraded by hydroxyl radicals (•OH) produced by the activation of H 2 O 2 by Fe(II)-bearing clay. However, the interfacial electron transfer reactions between structural Fe(II) and H 2 O 2 for •OH generation and its effects on contaminant remediation are unclear. In this study, we first investigated the relation between •OH generation sites and sulfamethoxazole (SMX) degradation by activating H 2 O 2 using nontronite with different reduction extents. SMX (5.2–16.9 µmol/L) degradation first increased and then decreased with an increase in the reduction extent of nontronite from 22% to 62%, while the •OH production increased continually. Passivization treatment of edge sites and structural variation results revealed that interfacial electron transfer reactions between Fe(II) and H 2 O 2 occur at both the edge and basal plane. The enhancement on basal plane interfacial electron transfer reactions in a high reduction extent rNAu-2 leads to the enhancement on utilization efficiencies of structural Fe(II) and H 2 O 2 for •OH generation. However, the •OH produced at the basal planes is less efficient in oxidizing SMX than that of at edge sites. Oxidation of SMX could be sustainable in the H 2 O 2 /rNAu-2 system through chemically reduction. The results of this study show the importance role of •OH generation sites on antibiotic degradation and provide guidance and potential strategies for antibiotic degradation by Fe(II)-bearing clay minerals in H 2 O 2 -based treatments. [Display omitted] [ABSTRACT FROM AUTHOR]

Fenton (H2O2/Fe2+) system is a simple and efficient advanced oxidation technology (AOT) for the treatment of organic micropollutants in water and soil. However, it suffers from some drawbacks including high amount of the catalyst, acid pH requirement, sludge formation and slow regeneration of Fe2+ ions. If these drawbacks are surmounted, Fenton system can be the best choice AOT for the removal of persistent organics from water and soil. In this work, it was attempted to replace the homogeneous catalyst with a heterogeneous natural iron-based catalyst for the decomposition of H2O2 into oxidative radical species, mainly hydroxyl (HO•) and hydroperoxyl radicals (HO2•). The natural iron-based catalyst is hematite-rich (α-Fe2O3) and contains a nonnegligible amount of magnetite (Fe3O4) indicating the coexistence of Fe (III) and Fe(II) species. A pseudo-first order kinetics was determined for the decomposition of H2O2 by the iron-based solid catalyst with a rate constant increasing with the catalyst dose. The catalytic decomposition of H2O2 into hydroxyl radicals in the presence of the natural Fe-based catalyst was confirmed by the hydroxylation of benzoic acid into salicylic acid. The natural Fe-based catalyst/H2O2 system was applied for the degradation of riluzole in water. It was demonstrated that the smaller the particle size of the catalyst, the larger its surface area and the greater its catalytic activity towards H2O2 decomposition into hydroxyl radicals. The degradation of riluzole can occur at all pH levels in the range 3.0–12.0 with a rate and efficiency greater than H2O2 oxidation alone, indicating that the natural Fe-based catalyst can function at any pH without the need to control the pH by the addition of chemicals. An improvement in the efficiency and kinetics of the degradation of riluzole was observed under UV irradiation for both homogeneous and heterogeneous Fenton systems. The results chromatography analysis demonstrate that the degradation of riluzole starts by the opening of the triazole ring by releasing nitrate, sulfate, and fluoride ions. The reuse of the catalyst after heat treatment at 500 °C demonstrated that the heat-treated catalyst retained an efficiency >90% after five cycles. The results confirmed that the natural sources of iron, as a heterogeneous catalyst in a Fenton-like system, is an appropriate replacement of a Fe2+ homogeneous catalyst. The reuse of the heterogeneous catalyst after a heat-treatment represents an additional advantage of using a natural iron-based catalyst in Fenton-like systems. [ABSTRACT FROM AUTHOR]

In order to find an effective decolorization method for dye wastewaters, the present work aims at studying the treatment efficiency of an azo dye Acid Red 14 (AR14) by Electro-Fenton process using an undivided electrochemical cell containing different electrode materials. The optimal removal efficiency was obtained using carbon felt or glassy carbon (cathode) and platinum (anode) electrodes. The method is based on the reaction of electrochemically produced hydroxyl radicals leading to oxidative degradation of the AR14. To find the best conditions for treatment of AR14 dye, the effects of Fe2+ concentration, current density, the effect of pH initial, and the nature of support electrolyte were studied. The results showed 94 % removal efficiency in 30 minutes with 120 mA/cm² of electrolysis current, 0.2 mM of Fe2+, and pH = 3. However, the decolorization efficiency measurements confirmed that the Electro-Fenton process with the platinum anode and the carbon felt cathode was more efficient. [ABSTRACT FROM AUTHOR]

The piezo‐Fenton system has attracted attention not only because it can enhance the Fenton reaction activity by mechanical energy input, but also because it is expected to realize a class of stimuli‐responsive advanced oxidation systems by regulating energy input and hydrogen peroxide self‐supply, thus greatly enriching the application possibilities of Fenton chemistry. In this work, a series of Fe‐doped g‐C3N4 (g‐C3N4‐Fe) as a piezo‐Fenton system were synthesized where the iron stably immobilized through Fe−N interaction. The piezo‐induced electrons generate on g‐C3N4 matrix support the conversion of Fe(III) to Fe(II) and promote rate‐limiting step of Fenton reaction. With the optimal Fe loading, g‐C3N4‐0.5Fe can achieve methylene blue (MB) degradation under ultrasonic treatment with first‐order kinetic rate constants of 75×10−3 min−1. Most importantly, the g‐C3N4‐Fe can maintain good catalytic activity in a wide pH range (pH=2.0∼9.0) and be cyclic used without iron leaching to solution (<0.001 μg ⋅ L−1), overcoming the disadvantage of traditional Fe‐based Fenton catalysts that can only be applied under acidic conditions and prone to secondary pollution. In addition, g‐C3N4‐0.5Fe also exhibits antibacterial properties of Escherichia coli and Staphylococcus aureus under ultrasound. Hydroxyl radicals mainly contribute to the degradation of MB and the sterilization process. Our work is an attempt to clarify the role of g‐C3N4‐Fe in the conversion of mechanical energy to ROS and provide inspirations for the piezo‐Fenton system design. [ABSTRACT FROM AUTHOR]

This study investigated the broad-spectrum bactericidal activity of non-electrolytic hypochlorite water (NEHW) and detected its hydroxyl radical content compared with that of slightly acidic electrolytic water (SAEW). Based on the results of UV scanning and storage stability, higher hypochlorite content and stronger oxidation were found to be responsible for the stronger bactericidal effect of NEHW. NEHW can achieve 99% bacterial disinfection effect by treating with 10 mg/L available chlorine concentration for more than 5 minutes. At the same time, the storage stability of NEHW was higher than that of SAEW. After 20 days of storage under sealed and dark conditions, the pH value only increased by 7.9%, and the effective chlorine concentration remained nearly 80%. The results showed that NEHW had higher germicidal efficacy and storage stability than SAEW. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) for hypoxic tumors has attracted wide attention owing to its noninvasiveness, easy maneuverability, and instantaneity. However, hypoxia in tumors and penetration depth of conventional ultraviolet light has greatly weakened its performance. To solve these problems, under NIR-II light irradiation, squaric acid nanoparticles (SQ NPs) with superior reactive oxygen, especially, hydroxyl radicals (•OH) production performance were first utilized for hypoxic tumor therapy. SQ NPs with intense light capture capability, intense NIR emission, and excellent photobleaching resistance show continuous •OH generation capabilities under NIR-II laser excitation. Through the superior PDT performance, the growth of hypoxic tumors was effectively inhibited, and the survival rate of mice was improved. This work highlights the application of NIR-II photoexcitation in deep tissue type I photodynamic therapy of hypoxic tumors, which will facilitate the development of hypoxic tumor PDT in deep depth. [ABSTRACT FROM AUTHOR]

The ozone/peroxymonosulfate (O3/PMS) system has attracted widespread attention from researchers owing to its ability to produce hydroxyl radicals (•OH) and sulfate radicals (SO4•−) simultaneously. The existing research has shown that the O3/PMS system significantly degrades refinery trace organic compounds (TrOCs) in highly concentrated organic wastewater. However, there is still a lack of systematic understanding of the O3/PMS system, which has created a significant loophole in its application in the treatment of highly concentrated organic wastewater. Hence, this paper reviewed the specific degradation effect, toxicity change, reaction mechanism, various influencing factors and the cause of oxidation byproducts (OBPs) of various TrOCs when the O3/PMS system is applied to the degradation of highly concentrated organic wastewater. In addition, the effects of different reaction conditions on the O3/PMS system were comprehensively evaluated. Furthermore, given the limited understanding of the O3/PMS system in the degradation of TrOCs and the formation of OBPs, an outlook on potential future research was presented. Finally, this paper comprehensively evaluated the degradation of TrOCs in highly concentrated organic wastewater by the O3/PMS system, filling the gaps in scale research, operation cost, sustainability and overall feasibility. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) production upon the oxygenation of reduced iron minerals is of critical importance to redox cycles of Fe and the fate of refractory organic contaminants. The environmental impact factors during this process, however, have been underappreciated. In this study, prominently enhanced production of hydroxyl radicals (•OH) was observed by oxygenation of Fe(II) with 5–50 mM phosphate. The results of spin trap electron spin resonance (ESR) experiment showed that Fe(II)-phosphate complexes facilitated the generation of •OH. The degradation experiment of p-nitrophenol (PNP) confirmed that •OH formation was dominated by a consecutive one-electron O 2 reduction (90.2–96.9 %), and the quantification of PNP degradation products revealed that Fe(II)/phosphate molar ratios regulated the O 2 activation pathways for O 2 •− or •OH production. The further experimental and theoretical investigation demonstrated that the coordination of phosphate with Fe(II) plays a dual role in ROS generation that facilitated O 2 •− formation by lowering the energy barrier for Fe(II) oxidation and altered the reaction pathway of •OH formation due to its occupation of sites for electron transfer. The present work highlights an important role of natural oxyanions in O 2 activation by Fe(II) and raises the possibility of in situ degradation of contaminants in subsurface environment. [Display omitted] • Phosphate promotes the •OH production by Fe(II) upon oxidation. • The •OH formation was dominated by a consecutive one-electron O 2 reduction. • The phosphate coordination number regulated the O 2 activation pathways for O 2 •− or •OH production. • Phosphate plays a dual role in ROS generation that facilitated O 2 •− formation and altered the •OH formation pathway. [ABSTRACT FROM AUTHOR]

Designing photocatalysts with well-defined structure-function relationships is imperative for propelling the progression of desired photocatalytic oxidation. Herein, the efficient conversion of solar energy to H 2 O 2 and subsequently to hydroxyl radicals (•OH) is achieved through a synergistic interplay between olefin linkage (-C C-) and spatially separated benzene-triazine dual reaction sites within covalent organic frameworks (COFs). The upgraded -C C- can increase the conjugation degree of COFs, which establishes an expanded superstructure for boosting charge separation/transfer and stability. This precise modulation renders more opportunities for the hot electrons to migrate to the benzene site for solar-to-H 2 O 2 generation, and to the triazine site for H 2 O 2 -to-•OH, separately. The optimized •OH generation pathway enables remarkable oxidation performances against recalcitrant organic pollutants, and pathogenic microorganisms under visible light irradiation. This work provides new insights for tuning the synergistic interactions of various building blocks within the COFs for the selective generation of highly reactive •OH for environmental remediation. [Display omitted] • COFs with decisive structure-function relationship was tailored for •OH production. • ‐C C- bridge enhances conjugation and thereof the e- transfer and stability. • Site-specific functions: benzene drives O 2 to H 2 O 2 , triazine activates H 2 O 2 to •OH. • The oxidation power was proceeded through CB-e- rather than VB-h+. [ABSTRACT FROM AUTHOR]

Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants that widely exist in the environment. Effective reduction of ARB and ARGs from soil and water could be achieved by electrokinetic remediation (EKR) technology. In water, hydroxyl radicals (·OH) are proved to play a major role in the EKR process; while the reduction mechanism of ARB and ARGs is still unclear in soil. In this study, different concentrations of hydroxyl radical scavengers (salicylic acid) were added to the EKR system to explore the possible role of ·OH in the reduction of ARB and ARGs. The results showed that generally, ·OH played a more vital role in the reduction of ARB (65.24–72.46%) compared to the reduction of total cultivable bacteria (57.50%). And ·OH contributed to a higher reduction of sul genes (60.94%) compared to tet genes (47.71%) and integrons (36.02%). It was found that the abundance of Gram-negative bacteria (Chloroflexi, Acidobacteria and norank_c_Acidobacteria) was significantly reduced, and the correlation between norank_f_Gemmatimonadaceae and sul 1 was weakened in the presence of ·OH. Correlation analysis indicated that the abundance of ARGs (especially sul 1) was closely related to the Gram-negative bacteria (Proteobacteria, Acidobacteria, and Gemmatimonadetes) in the soil EKR treatment. Moreover, changes in bacterial community structure affected the abundance of ARB and ARGs indirectly. Overall, this study revealed the reduction mechanism of ARB and ARGs by ·OH in the soil EKR system for the first time. These findings provide valuable support for soil remediation efforts focusing on controlling antibiotic resistance. [Display omitted] • Presence of ·OH scavengers leads to increase of ARB and ARGs in soil. • ·OH contributed 72.46% and 61.35% to removal of ARB and ARGs from soil in EKR. • The sul genes were more vulnerable to ·OH attack than tet genes and integrons. • The abundance of Gram-negative bacteria reduced obviously in the presence of ·OH. • ·OH influenced Gram-negative bacteria that then affected the fate of ARB and ARGs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-CN V catalysts demonstrate excellent performance in photocatalytic ozonation. • N v s exhibit opposite effect to photocatalytic activity with or without iron SAs. • Iron SAs shallow deep electron traps caused by N v s at atomic level. • Coupling iron SAs and adjacent N v s enrich surface charges around active sites. The coupling of photocatalysis and ozonation has been approved a very efficient strategy for hydroxyl radicals (•OH) production and wastewater decontamination, yet it remains challenging to enrich surface-reaching charges around reaction centers to accelerate this process. This paper explored the strategy of single-atoms (SAs) modification and defects control, aiming to enhance the activity of graphite carbon nitride (CN) in the visible light photocatalytic ozonation. It was found that the presence of iron SAs on CN greatly altered the impact of nitrogen vacancies (N V s), which behaved as recombination centers of photogenerated charge carriers and deteriorated activity of CN, while positively promoting the separation and migration of photogenerated carriers in the case for Fe-CN V (consist of iron SAs and N V s) catalysts. Based on photoluminescence (PL) emission, time-resolved PL spectra, ultrafast transient absorption spectroscopy and first-principles calculations, we found that adjacent iron SAs revived electrons trapped at N V s by elevating their energy level and mediating their interfacial transfer, leading to the decreased loss during electron transfer. This finding demonstrates the feasible tailor of energy level alignment for defect states to shallow deep electron traps. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flowerlike Co-PTA-400(Ar) MOF could be used as efficient catalyst for TCBQ-H 2 O 2 CL reaction. • The catalysis mechanism of the CL reaction was illustrated. • The CL system was used for sensitive detection of TCBQ in the environmental waters. Tetrachlorobenzoquinone (TCBQ) as one of the most toxic quinones has potential risk of causing canceration, and the monitoring of TCBQ in the environment is of significant importance. In this study, a flowerlike Co-PTA-400(Ar) metal organic frameworks (MOF) catalyzed TCBQ-H 2 O 2 chemiluminescence (CL) system was established for sensitive determination of trace TCBQ in environmental waters. The reaction between TCBQ and H 2 O 2 can result in weak CL emission, and the CL signal was enhanced about 10-fold using flowerlike Co-PTA-400(Ar) as catalyst. The luminescence mechanism was investigated through kinetic studies and free radical scavenging experiments. The strong CL emission of TCBQ mainly relied on the generation of abundant •OH by the catalysis of Co-PTA-400(Ar). This strategy allows to develop a highly sensitive method for the determination of TCBQ in the linear range of 1 ∼ 50 μM, with a detection limit of 0.56 μM (3 σ). The proposed method was applied for analysis of three spiked water samples with recoveries ranging from 95.7% to 100.5%. This method offering the advantages of rapid analysis, low costs, and high sensitivity, is appealing for detection of TCBQ in environmental waters. [ABSTRACT FROM AUTHOR]

A hydrophobic Cu 2 O cathode (Cu x O-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH) 2 nanorods by oxidizing copper foam (Cu-F) with (NH 4) 2 S 2 O 8 , followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized Cu x O-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (Ⅰ) the superior O 2 -capturing ability of Cu x O-L cathode, which led to high H 2 O 2 production due to a 2 nm thick hydrophobic gas layer facilitated O 2 -capturing; (Ⅱ) a relative high concentration of Cu+ at the Cu x O-L cathode promoted the activation of H 2 O 2 into·OH. In addition, the performance of EF with the Cu x O-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O 2 -capturing cathodes in EF processes, particularly for treating emerging organic pollutants. [Display omitted] • Bio-inspired hydrophobic Cu 2 O cathode (Cu x O-L) was designed； • ·OH concentration on Cu x O-L cathode increased approximately 7.9-fold; • A 2-3 nm gas film enhances the cathode's O 2 capturing; • Cu+ was active site for H 2 O 2 formation, favoring its activation into·OH. [ABSTRACT FROM AUTHOR]

In this study, molecularly imprinted electrochemical sensors (MIPs/MWCNTs-COOH/SPCE) were prepared by electropolymerization on a substrate electrode modified with carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) using pyrrole as the functional monomer and 2,5-DHBA as the template molecule. [Display omitted] • Development of a molecularly imprinted SPCE sensor based on MWCNTs-COOH modification. • Wide linear range for the detection of 2,5-DHBA. • Achieves highly selective detection of target substances. • The concentration of –OH can be calculated from the detection of 2,5-DHBA. Hydroxyl radicals (–OH) are reactive substances with high reactivity and extreme oxidizing power that attack all pollutants without selectivity and play a huge role in the environment. In this study, molecularly imprinted electrochemical sensors (MIPs/MWCNTs-COOH/SPCE) were prepared by electropolymerization on a substrate electrode modified with carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) using pyrrole as the functional monomer and 2,5-DHBA as the template molecule. The surface morphology and electrochemical behavior of the sensors were characterized by scanning electron microscopy (SEM) and electrochemical methods of cyclic voltammetry (CV) and electrochemical impedance (EIS). The conditions of functional monomer pyrrole dosage, number of electropolymerization turns, elution time, adsorption time, and pH of detection solution were optimized. Under the optimal experimental conditions, the oxidation peak current of the target 2,5-DHBA by differential pulse voltammetry (DPV) showed a good linear relationship with its concentration between 1 × 10−8 ∼ 1 × 10−4 mol/L. The linear equation was Ip = 0.493lgC 2,5-DHBA +4.469 (R=0.997), and the detection limit was 8.50 × 10−9 mol/L. And the experiment results sensor has good repeatability, stability and selectivity, and is a convenient, sensitive and novel method for the detection of –OH. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-TiO 2 immobilized on PMMA (NT-PMMA) by dip-coating method shows high transmittance. • NT-PMMA showed higher intensities of 1O 2 , HO•, and H 2 O 2 than NT suspension. • NT-PMMA had higher disinfection efficiency than NT suspension. • NT-PMMA sustained 99.99% disinfection efficiency within five reutilized cycles. • Biophysical properties of inactivated bacteria were identified on NT-PMMA. Photocatalysis is an efficient process for degrading organic pollutants and inactivating pathogenic microorganisms. However, this process constantly suffers from turbidity shading and particle aggregation in a catalyst suspension system, thereby reducing its photocatalytic activity. Immobilizing the photocatalyst on the light-transmissible surface is a viable solution to the obstacles. So far, the photo-inactivation efficacy between the immobilized photocatalyst and suspension systems has yet to be compared and investigated. In this study, N-TiO 2 (NT) immobilized on poly-methyl-methacrylate (PMMA) was fabricated via a dip-coating method, which has a high transmittance rate of 92 % - better than all of the previous works (50 %). By immobilizing N-TiO 2 on PMMA, up to 60 % and 19 % improvements in inactivation efficiencies against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) are achieved, respectively, relative to a photocatalyst suspension. Notably, reactive oxygen species (ROSs) detection results indicate that 5 g/L NT coated PMMA ((NT-PMMA) 5) has higher intensities of singlet oxygen (1O 2), hydroxyl radicals (HO•), and higher concentration of hydrogen peroxide (H 2 O 2) than the NT suspension. The as-made NT-PMMA sustains a 99.99 % inactivation efficiency (5-log-inactivation) against S. aureus through five consecutive photocatalysis cycles of reuse. The inactivation kinetics of S. aureus and E. coli fit well with the modified Hom model. Atomic force microscopy observations indicate that the NT-PMMA inactivation causes more severe damage to S. aureus' s cell wall than E. coli due to the different susceptibility of cell wall structure to ROSs. This study paves a substantial way for scaling up the immobilizing catalyst on PMMA for the effective photocatalytic inactivation of pathogens under visible light. [ABSTRACT FROM AUTHOR]

Although dissolved oxygen plays an important role in electro-Fenton-like processes, few investigations have revealed its underlying effects in such processes. Herein, the effect of dissolved oxygen on peroxide activation in an electro-Fenton-like system comprising electrochemical cells and peroxymonosulfate (PMS) was investigated. Cobalt phosphide-modified carbon aerogel (Co/P/CA) was used as the cathode material owing to the high conductivity and catalytic activity of Co/P/CA. Several free radicals and their effects on organic pollutant removal were observed using electron paramagnetic resonance spectrometry and quenching experiments, respectively. The observations revealed that in the presence of O 2 , hydroxyl radical (·OH), superoxide (O 2 − ·), and singlet oxygen (1O 2) served as the primary active species in the PMS activation process, while in the presence of N 2 , ·OH and sulfate radical (SO 4 −·) served as the dominant active species in this process. The factor responsible for the difference in the PMS activation pathways available under O 2 and N 2 conditions was investigated using rotating disk electrode tests and free energy calculations. The tests indicated that O 2 facilitates PMS activation to form ·OH instead of SO 4 −·. The dissolved oxygen subsequently underwent a single-electron-reduction reaction and was converted into O 2 −·, which could serve as a source of 1O 2. When N 2 was introduced, Co species, particularly Co(II), played a key role in activating PMS. The free radicals · OH and SO 4 − · were generated during the PMS activation process. This study clearly demonstrates the mediating catalysis role of dissolved oxygen in electro-Fenton-like system through experimental data and theoretical calculations, thereby positively contributing to future studies regarding the continuous activation of peroxides in composite systems and improvement of the efficiency of waterbody remediation. [Display omitted] • O 2 − · can be generated from the single-electron reduction reaction of O 2 by the Co/P/CA cathode. • In presence of O 2 , PMS activation is enhanced, leading to the generation of ·OH instead of SO 4 −. • The Co/P/CA cathode exhibits high catalytic activity for O 2 reduction, transition metal reduction, and PMS activation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new EAOP was established using TiO 2 /C electrode under a potential alternating mode. • H 2 O 2 /Ti-OH formed during the anode process decomposed to •OH during the cathode process. • The potential alternating mode provided a low energy-demanding process for •OH. • The potential alternating mode exhibited much higher oxidizing power than anodic oxidation. • The continuous CLN degradation was achieved using the potential alternating device. Electrochemical advanced oxidation processes (EAOPs) can be easily controlled via applied current/potential. However, there is still a lack of in-depth understanding on how electrochemical reaction pathways were adjusted through electrical parameters control. In this work, a novel EAOP was established by applying alternating potentials on a graphite-supported TiO 2 -modified electrode. This potential alternating mode avoided O 2 -evolution during the anodic oxidation and O 2 -aeration during the electro-Fenton reaction which were regarded as energy-intensive processes. The potential of the working electrode was optimized to 1.0 V for 300 s and −0.6 V for 100 s alternately, obtaining •OH yield of 0.07 μM·L-1·cm−2·min−1, which is about three times higher than that under anodic oxidation. The proposed reaction mechanism suggested that •OH generation involved three pathways, including direct anodic oxidation during the anode process, H 2 O 2 and Ti-OH formed during the anode process decomposing to •OH during the cathode process. Among them, the Ti-OH decomposition was found to contribute about two-thirds for the total •OH generation, and it was demonstrated as the most efficient pathway based on density functional theory (DFT) calculations. With cephalexin (CLN) as the target pollutant, the degradation efficiency reached 81.8 % under the potential alternating mode within 90 min, about 3 times higher than that under anodic oxidation (37.6 %). Furthermore, a potential alternating device was designed to realize continuous CLN degradation. Overall, the potential alternating mode provided a sustainable and eco-friendly EAOP pathway for •OH generation and shed light on designing reaction pathway through electrical parameters control. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoC/NSP catalyst is synthesized as an efficient catalyst for pollutant degradation. • MoC/NSP catalyst can selectively reduce molecular oxygen to hydroxyl radicals. • The heteroatom-doped carbon carrier supported MoC has strong electron transfer ability. • The mechanism of electrocatalytic reduction of molecular oxygen to hydroxyl radicals is determined. A treatment strategy of in situ generation and activation of hydrogen peroxide to degrade pollutants by the heterogeneous Fenton-like technology is promising for water pollution. However, the selective activation of oxygen to hydroxyl radicals (OH) by cathode materials is still challenging. Here, molybdenum carbide (MoC) supported on a heteroatoms-doped (N, P, S) carbon carrier catalyst was successfully prepared, which rapidly produced OH and degraded paracetamol (APAP) pollutants. A high APAP degradation efficiency with a specific energy consumption of 0.24 kWh g−1 TOC was achieved. After 10 sets of continuous operations, the APAP degradation rate remains unchanged. Combined with density functional theory calculations, molecular oxygen adsorption obtains one electron with proton hydrogen transfer to hydroperoxyl (OOH) on the MoC surface, and the adsorbed OOH directly activate into OH due to the ultrafast electron transfer ability of MoC. Differential charge density analysis also shows that Mo transfers electrons to O. This strategy provides a new idea for optimizing catalysts to improve the heterogeneous Fenton-like performance. [ABSTRACT FROM AUTHOR]

Herein, individual p -block bismuth (Bi) atoms are dispersed onto N-doped Ti 3 C 2 T x MXene (BiN 3 /MXene) to enhance the 3 e − oxygen reduction reaction (ORR), for the electrosynthesis of hydroxyl radicals (HO•) via the activation of molecular oxygen (O 2). Theoretical calculations and experiments reveal that the p -orbitals of Bi atoms can readily hybridize with the p- orbitals of O, which enables the transfer of charges, creates sufficient strength of adsorption for oxygen intermediates, lowers the activation energy, and modulates the rate-limiting reaction. The optimized generation of HO• is up to 26.7 μmol/(L·h·cm2) without additional chemical reagents, facilitating efficient removal of micropollutants from complex water matrices. Specifically, the rate constant (k obs) for sulfamethoxazole degradation achieves 1.027 min−1, outperforming the reported processes for micropollutants removal. This work illuminates the atomic-level construction of a p -block BiN 3 /MXene electrocatalytic membrane to efficiently perform the 3 e − ORR and highlights the substantial potential for wastewater decontamination. [Display omitted] • p -Block single Bi atoms can be anchored onto MXene via coordination engineering. • The BiN 3 /MXene membrane enabled selective O 2 electroreduction to HO• via 3 e − pathway. • A complete and rapid removal of SMX was achieved with minor energy requirements. • Underlying mechanism was unveiled based on experimental evidences and theoretical calculations. [ABSTRACT FROM AUTHOR]

E-peroxone process is an emerging electrochemical oxidation process, based on ozone and the in-situ cathodic generation of H 2 O 2 , but the stability of cathode is one of the key restraining factors. In this study, we designed a multilayer gas diffusion electrode (GDE) decorated with a commercial hydrophobic membrane for the degradation of pyridine. It was found that a proper control of membrane pore sizes and hot-pressing temperature can significantly promote the GDE stability. Subsequently, key operational parameters of the constructed E-peroxone system were investigated, including the ozone concentration, current density, pH value, electrolyte type and initial concentration of pyridine. The degradation pathways were proposed according to six identified transformation products. The toxicity variation along the degradation progress was evaluated with microbial respiration tests and Toxicity Estimation Software Tool (T.E.S.T.) calculation and an efficient detoxification capacity of E-peroxone was observed. This research provides a theoretical basis and technical support for the development of highly efficient and stable E-peroxone system for the elimination of toxic organic contaminants. [Display omitted] • The multilayer gas diffusion electrode decorated with PP membrane (0.45μm) shows a stable performance generating H 2 O 2. • The reaction parameters of gas diffusion electrode (GDE) on pyridine degradation were investigated. • The degradation pathways were proposed according to the six identified transformation products. • The acute toxicity of the transformation products was evaluated by the microbial respiration and T.E.S.T. calculation. [ABSTRACT FROM AUTHOR]

An efficient gamma radiolytic decomposition of one of the extensively used herbicides in the world quizalofo-p-ethyl (QPE) was explored under different experimental conditions. Aqueous solutions of QPE were irradiated by gamma rays emitted by a Cobalt 60 source. QPE aqueous solutions were irradiated at doses of 0.5–3 kGy with 26.31 Gy min−1 dose rate. Obtained results indicated that removal efficiency of 98.5% and 73% of QPE were obtained, respectively, in absence and in presence of dissolved oxygen. Change of absorption spectra, pH effect and Total Organic Carbon (TOC) were carried out and studied. It was found that all absorption bands decreased with increasing irradiation dose and disappear totally after 3 kGy applied dose. Three pH conditions (pH = 10, pH = 6.2 and pH = 3) were applied in radiolytic degradation of QPE showing that the best removal efficiency has been found for neutral pH. Interestingly, the % TOC removal reaches 98% at 3 kGy indicated practically total mineralization. Furthermore, spectrophotometric analyses argued in favour of a pseudo-first-order kinetic of QPE degradation. The resulting apparent rate constant value is approximately kapp = (0.012 ± 0.001) min−1. Finally, several by-products such as 6-chloroquinoxalin -2-ol, 2-(4-hydroxy-phenyoxy) propionate, 1,4-hydroquinone, quinone, 4-chlorobenzene-1,2diol and 1,2,4-benzenetriol were identified by gas chromatography–mass spectrometry (GC/MS) evidencing that radiation process starting with the fragmentation of the molecule involving the hydroxyl radical, which is generated by the radiolysis of water. Based on the identification intermediates, a degradation mechanistic schema of QPE has been proposed. [ABSTRACT FROM AUTHOR]

The reaction mechanisms Fe(II) abiotic oxidation produce ·OH by CaCO3-induced in acid mine drainage (AMD) are well-documented, but little is known about the influence of extracellular polymeric substances (EPS) secreted by microorganisms on Fe(II) oxidation in AMD. In this study, ·OH production was experimently measured from oxygenation of simulated AMD in the presence of EPS. The cumulative ·OH increased from 56.75 to 158.70 µM within 24 h at pH 3 with the increase in EPS concentration from 0 to 12 mg/L. An appropriate pH (about 6) and EPS (6 mg/L) concentration were required for the moderate rate of Fe(II) oxidation. Besides, the yield of ·OH increased remarkably with the addition of Fe3+. In the presence of EPS, ·OH production is attributed mainly the complexation of Fe(II) with EPS, of which is rich of carboxyl and hydroxyl groups. The findings provide fundamental supplement of ·OH production from Fe(II) oxidation by microorganisms in natural AMD. [ABSTRACT FROM AUTHOR]

In this study, Fe-Cu binary oxide was loaded on zeolite (Fe/Cu/zeolite) to be used as heterogeneous Fenton catalyst, and the catalytic degradation of carbamazepine (CBZ) were optimized at near-neutral pH. The results showed that the Fe and Cu oxide, mainly Fe2O3, Fe3O4, and CuO nanoparticles, were uniformly distributed on the surface of zeolite particles. Under the optimized conditions, Fe/Cu/zeolite could completely degrade CBZ when initial pH ranged from 3 to 7, and the removal efficiency of CBZ still remained above 74% even though the initial pH increased to near 10. After 8 times' repeated use, the Fe/Cu/zeolite exhibited an over 95% removal efficiency of CBZ. The hydroxyl radicals (•OH) were verified to be the main active oxidants by quenching experiments and ESR testing. The XPS of the materials revealed that the high catalytic efficiency was attributed to the synergistic effect of Fe(III)/Fe(II) and Cu(II)/Cu(I) redox cycles. This catalyst can be used for the efficient degradation of organic pollutants in heterogeneous Fenton systems. [ABSTRACT FROM AUTHOR]

Photocatalysis is a promising technology for conversion of the glycerol into formic acid, but photocatalytic oxidation of C−C bonds in glycerol exhibits poor selectivity towards formic acid because the photogenerated radicals (e.g. hydroxyl radicals) further oxidize formic acid to CO2. In this work, a synergy of photogenerated holes and superoxide radicals that achieved the selective oxidation of glycerol into formic acid over the TiO2 catalyst was revealed. The charge separation of pristine TiO2 was improved with the aid of oxygen, which resulted in efficient hole oxidation of the C−C bonds in glycerol to formic acid. Surface active species were controlled to prevent being converted to hydroxyl radicals on TiO2 by controlling the oxygen and water contents, which solved the problem of formic acid peroxidation without sophisticated catalyst modifications. Mechanism studies suggested that glyceraldehyde and glycolaldehyde were the intermediates to generate formic acid. This work provides a green and efficient approach to produce formic acid as a liquid hydrogen carrier from bio‐based alcohols. [ABSTRACT FROM AUTHOR]