Hydroxylamine Research Articles

Synthesis and Anticancer Activity of Novel Chromene Derivatives, Chromeno[2,3-d][1,3]Oxazines, and Chromeno[2,3-d]Pyrimidines.

Several chromene derivatives have a wide variety of biological and pharmacological activity. They had anticancer activity, antimicrobial activity, antituberculosis activity, anticonvulsant activity, antidiabetic activity, antichlolinesterase activity, and inhibitor of monoamine oxidase activity. The above-mentioned activities directed us to synthesize novel chromene derivatives, chromeno[2,3-d][1,3]oxazines, and chromeno[2,3-d]pyrimidines. The starting material was 2- amino-8-(2-chlorobenzylidene)-4-(2-chlorophenyl)-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile. Several novel chromene derivatives had been synthesized. Compound 1 reacted with carbon disulfide, and ethyl chloroformate to afford chromene derivatives 2, 3. Chromene derivative 3 reacted with hydrazine dydrate to give compound 4. Chromene derivative 1 reacted with acetic acid and sulphuric acid to produce compounds 5, and 6. Amino derivative 5 reacted with chloroacyl derivative to afford compounds 7a-c which cycalized in dry xylene to afford compounds 8a-c. Chromene derivative 8a reacted with hydroxyl amine to afford compound 9. The structures of novel synthesized chromene derivatives had been confirmed using mass spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis. Most of the prepared compounds were screened against liver cancer cell lines (HepG-2), human colon cancer cell lines (HT-29), and breast adenocarcinoma cell lines (MCF-7). Chromene derivative 2 had anticancer activity against human colon cancer cell lines (HT-29) higher than the reference drug doxorubicin. The rest of the tested compounds had anticancer activity against human colon cancer cell lines (HT-29) lower than that of the reference drug doxorubicin. Chromene derivative 5 had anticancer activity against liver cancer cell lines (HepG-2) higher than the reference drug doxorubicin. Several chromene derivatives had been synthesized and their structures had been confirmed using different spectroscopic techniques. Some of the chromene derivatives that were screened against different cancer cell lines showed promising anticancer activity higher than the reference standard drug. For example, chromene derivative 2 had anticancer activity against human colon cancer cell lines (HT-29) higher than the reference drug doxorubicin. Chromene derivative 5 had anticancer activity against liver cancer cell lines (HepG-2) higher than the reference drug doxorubicin. Chromene derivative 6 had anticancer activity against breast adenocarcinoma cell lines (MCF-7) higher than the standard drug.

Rapid acceleration of Cu(II)/peroxymonosulfate oxidation of phosphonate by hydroxylamine

Developing simple and effective activation approaches to degrade phosphonate is crucial due to its potential aquatic environmental risks. Recently, Cu(II)-mediated activation processes provide a feasible method via nonradical oxidation mechanism to remove phosphonate, but is yet challenged under neutral conditions. Herein, a strategy for enhancing the Cu(II)/peroxymonosulfate (PMS) process by adding hydroxylamine (HA) could efficiently degrade 1-hydroxyethane1,1-diphosphonic acid (HEDP) at pH = 7.0. After 15-min reaction, 85.7% of total phosphorus (TP) in HEDP transformed into PO43− in the Cu(II)/PMS/HA process is observed, which is 3.4 times than that in the Cu(II)/PMS process. The results of multiple experiments confirm that the presence of HA accelerates the reduction of Cu(II) and the generation of reactive species, SO4•− and Cu(III) induced intramolecular electron transfer as the primary reactive species play a significant role in the degradation of HEDP. Additionally, the removal of HEDP is inhibited with the addition of Cl− and HCO3− in the Cu(II)/PMS/HA process. However, the Cu(II)/PMS/HA process demonstrates a superior removal effectiveness of HEDP in different actual wastewater samples compared to the Cu(II)/PMS process under neutral conditions. This study provides an effective method for removing phosphonate from actual wastewater.

Hydroxylamine facilitated catalytic degradation of methylene blue in a Fenton-like system for heat-treatment modified drinking water treatment residues.

Rational treatment of drinking water treatment residues (WTR) has become an environmental and social issue due to the risk of secondary contamination. WTR has been commonly used to prepare adsorbents because of its clay-like pore structure, but then requires further treatment. In this study, a Fenton-like system of H-WTR/HA/H2O2 was constructed to degrade organic pollutants in water. Specifically, WTR was modified by heat treatment to increase its adsorption active site, and to accelerate Fe(III)/Fe(II) cycling on the catalyst surface by the addition of hydroxylamine (HA). Moreover, the effects of pH, HA and H2O2 dosage on the degradation were discussed with methylene blue (MB) as the target pollutant. The mechanism of the action of HA was analyzed and the reactive oxygen species in the reaction system were determined. Combined with the reusability and stability experiments, the removal efficiency of MB remained 65.36% after 5 cycles. Consequently, this study may provide new insights into the resource utilization of WTR.

High-performance amperometric detection of hydroxylamine on fluorine doped tin oxide electrode modified with NiCo2O4 nanoparticles

The design and development of inexpensive, and extremely sensitive sensors for Hydroxylamine (HYA) are imperative due to its toxicity to animals, plants, and aquatic life. This work proposes a high-performance enzyme-free electrochemical sensor for HYA based on its oxidation on Nickel cobaltite (NCO) spinel-modified fluorine doped tin oxide (FTO) electrode. Hydrothermally grown irregularly shaped NCO nanoparticles (NPs) of size around 10 nm are characterized by XRD, XPS, UV–visible, BET, and TEM to evaluate the structural and morphological characteristics. NCO-modified FTO (NCO@FTO) electro-oxidizes HYA at a potential of 0.66 V vs. Ag/AgCl, delivering 1.7 times the current response than bare FTO. The rich catalytically active redox couples of Ni and Co, high conductivity, and high surface area of the NCO NPs contribute to the superior electrochemical response of NCO@FTO. As an amperometric sensor, NCO@FTO detects HYA in a wide range of 10 to 4000 µM concentration with a high sensitivity of 408 μA mM−1 cm−2. The sensor has a detection limit of 0.47 μM (S/N = 3), faster response of less than 3 s, excellent selectivity, and good stability. The practical feasibility of the proposed sensor is investigated by employing it in the monitoring of real samples. This study demonstrates NCO@FTO as an efficient low-cost sensor for HYA and extends the use of spinel metal oxides in bioanalysis.

Readily Recyclable, Auto-Catalyzed Tung Oil-Derived Vitrimers and Carbon Fiber-Reinforced Composites

The high strength and durability of carbon fiber-reinforced composites (CFRCs) have made them a popular choice in aerospace, civil engineering, and sports equipment. However, the non-degradable resin matrix and non-destructive recycling of carbon fibers present a challenge for their sustainability. To address this issue, we have developed a new type of CFRCs that are readily recyclable and high-performing, using an auto-catalyzed tung oil-derived vitrimer and acid curing agents (TTMA) in combination with bisphenol A epoxy resin (DGEBA) or 4,4′-methylene bis (N,N-di glycidylaniline) (TGDOM). The DGEBA/TGDOM-TTMA networks contain abundant ester bonds, hydroxyl groups, and tertiary amine, which can undergo dynamic transesterification reactions (DTER) at high temperatures, leading to topological rearrangement of cross-linked networks. This results in an epoxy resin matrix with excellent mechanical properties, thermostability, and easy reprocessing, self-healing, and degradation at elevated temperatures. Moreover, the TGDOM-TTMA exhibits good stress relaxation properties due to the high concentrations of hydroxyl and tertiary amine. Additionally, we have found that carbon fibers can be completely recycled from CFRCs using ethanolamine via amidation reaction, with the recycled carbon fibers maintaining nearly 100% of the mechanical properties of the virgin samples. This study offers a sustainable and convenient strategy for designing readily recyclable and high-performance CFRCs, with important implications for the future of composite materials.

Efficiency of Orange Yellow II Degradation by Synergistic Hydroxylamine with Fe2+ to Activate Peroxymonosulfate Oxidation: Machine Learning Prediction and Performance Optimization

A back-propagation neural network (BPNN) was used to model and optimize the process of hydroxylamine (HA)-enhanced Fe2+ activating peroxymonosulfate (PMS). Using HA-enhanced Fe2+ to activate PMS is a cost-effective method to degrade orange II (AO7). We investigated the individual and interactive effects of the concentrations of Fe2+, HA, and PMS on the degradation of AO7. The R2 of the BPNN model was 0.99852, and the data were distributed around y = x. Sensitivity analysis showed that the relative importance of each factor was as follows: HA > Fe2+ > PMS. The optimized results obtained by the genetic algorithm were as follows: the concentration of Fe2+ was 35.33 μmol·L−1, HA was 0.46 mmol·L−1, and PMS was 0.93 mmol·L−1. Experiments verified that the AO7 degradation effect within 5 min was 95.7%, whereas the predicted value by the BPNN was 96.2%. The difference between predicted and experimental values is 0.5%. This study provides a new tool (machine learning) to accurately predict the concentrations of HA, Fe2+, and PMS to degrade AO7 under various conditions.

Formulation and Evaluation of Topical Nano-Hydrogel of Zinc and Annona Muricata Extract

A scientific method is essential for phytochemists to deliver active ingredients in a consistent manner. This can be accomplished through the development of novel drug delivery systems for active plant compounds. The current study aims to prepare Annona muricata leaves extract (ALE) containing nano zinc formulation into a nano-particulate hydrogel. The active components were extracted by cold maceration of Anona muricata leaves in ethanol and then converted into polymeric nanoparticles by gelation method based on electrostatic interaction between the Hydroxyl Amine on Chitosan and a cluster of negative charge from the polyanion NaTPP. Zinc oxide nano particles (ZNPs) was formulated by precipitating zinc acetate with sodium hydroxide. These were then incorporated with Carbopol-940 to generate the gel matrix. The result demonstrated that polymeric nanoparticles are closely spherical in shape with a z-average 358.45 ± 11.3 nm and PDI in the range of 0.440-0.812. The gels exhibited a high viscosity, a neutral pH, and acceptable spreadability. Furthermore, a stability assay demonstrates that it has chemical stability and does not cause skin irritation, making it appropriate for transdermal delivery.

Bacteria assisted green synthesis of copper oxide nanoparticles and their potential applications as antimicrobial agents and plant growth stimulants.

Copper oxide nanoparticles (CuO-NPs) have piqued the interest of agricultural researchers due to their potential application as fungicides, insecticides, and fertilizers. The Serratia sp. ZTB29 strain, which has the NCBI accession number MK773873, was a novel isolate used in this investigation that produced CuO-NPs. This strain can survive concentrations of copper as high as 22.5mM and can also remove copper by synthesizing pure CuO-NPs. UV-VIS spectroscopy, DLS, Zeta potential, FTIR, TEM, and XRD techniques were used to investigate the pure form of CuO-NPs. The synthesized CuO-NPs were crystalline in nature (average size of 22nm) with a monoclinic phase according to the XRD pattern. CuO-NPs were found to be polydisperse, spherical, and agglomeration-free. According to TEM and DLS inspection, they ranged in size from 20 to 40nm, with a typical particle size of 28nm. CuO-NPs were extremely stable, as demonstrated by their zeta potential of -15.4mV. The ester (C=O), carboxyl (C=O), amine (NH), thiol (S-H), hydroxyl (OH), alkyne (C-H), and aromatic amine (C-N) groups from bacterial secretion were primarily responsible for reduction and stabilization of CuO-NPs revealed in an FTIR analysis. CuO-NPs at concentrations of 50μgmL-1 and 200μgmL-1 displayed antibacterial and antifungal activity against the plant pathogenic bacteria Xanthomonas sp. and pathogenic fungus Alternaria sp., respectively. The results of this investigation support the claims that CuO-NPs can be used as an efficient antimicrobial agent and nano-fertilizer, since, compared to the control and higher concentrations of CuO-NPs (100mgL-1) considerably improved the growth characteristics of maize plants.

Harnessing of newly tailored poly (acrylonitrile)-starch nanoparticle graft copolymer for copper ion removal via oximation reaction as a calorimetric sensor

Purpose Herein, this study aims to use our recently tailored and fully characterized poly acrylonitrile (AN)-starch nanoparticle graft copolymer having 60.1 graft yield percentage as a starting substrate for copper ions removal from wastewater effluent after chemical modification with hydroxyl amine via oximation reaction as a calorimetric sensor. Design/methodology/approach The calorimetric sensor batch technique was used to determine the resin's adsorption capacity, while atomic adsorption spectrometry was used to determine the residual copper ions concentration in the filtrate before and after adsorption. This was done to convert the copolymer's abundant nitrile groups into amidoxime groups, and the resulting poly (amidoxime) resin was used as a copper ion adsorbent. To validate the existence of amidoxime groups, the resin was qualitatively characterized using a rapid vanadium ion test and instrumentally using Fourier transform infrared spectroscopy spectra and scanning electron microscopy morphological analysis. Findings At pH 7, 400 ppm copper ions concentration and 0.25 g adsorbent at room temperature, the overall adsorption potential of poly (amidoxime) resin was found to be 115.2 mg/g. The process's adsorption, kinetics and isothermal analysis were examined using various variables such as pH, contact time, copper ion concentration and adsorbent dose. To pretend the adsorption kinetics, various kinetics models, including pseudo-first-order and pseudo-second-order, were applied to the experimental results. The kinetic analysis indicated that the pseudo-second-order rate equation promoted the development of the chemisorption phase better than the pseudo-first-order rate equation. In the case of isothermal investigations, a study of observed correlation coefficient (R2) values indicated that the Langmuir model outperformed the Freundlich model in terms of matching experimental data. Originality/value To the best of the author's information, there is no comprehensive study for copper ions removal from waste water effluent using the recently tailored and fully characterized poly (AN)-starch nanoparticle graft copolymer having 60.1 graft yield percentage as a starting substrate after chemical modification with hydroxyl amine via oximation reaction as a calorimetric sensor.

Effects of nitrogen input on N2O production and enzyme activity in Luoshijiang Wetland sediments, China

We examined the effects of nitrate (NO3--N) and ammonium (NH4+-N) input at different concentrations (0, 1, 5 and 25 mg·kg-1) on N2O production rate from the surface sediment (0-5 cm) of Luoshijiang Wetland, located upstream from Lake Erhai. The contribution of nitrification, denitrification, nitrifier denitrification, and other factors to the N2O production rate in sediments was studied by the inhibitor method. The relationships between N2O production and the activities of hydroxylamine (HyR), nitrate (NAR), nitric oxide (NOR), and nitrous oxide (NOS) reductases in sediments were analyzed. We found that NO3--N input significantly increased total N2O production rate (1.51-11.35 nmol·kg-1·h-1), which led to N2O release, whereas NH4+-N input decreased that (-0.80 to -0.54 nmol·kg-1·h-1), causing N2O absorption. NO3--N input did not change the dominant roles of nitrification and nitrifier denitrification in N2O production in sediments, but increased the contributions of these two factors to 69.5% and 56.5%, respectively. The NH4+-N input significantly changed N2O gene-ration process, and the nitrification and nitrifier denitrification changed from N2O release to uptake. There was a positive correlation between total N2O production rate and NO3--N input. NO3--N input significantly increased NOR activity and decreased NOS activity, thereby promoting N2O production. The total N2O production rate in sediments was negatively correlated with NH4+-N input. NH4+-N input significantly increased the activities of HyR and NOR, decreased NAR activity, and inhibited N2O production. Nitrogen inputs with different forms and concentrations changed the degree of contribution and mode of N2O production by affecting enzyme activities in sediments. NO3--N input significantly promoted N2O production, acting as a source of N2O, while NH4+-N input inhibited N2O production, resulting in an N2O sink.

Nickel Catalyzed Alkylation of Oxindoles with Alkyl Alcohols

AbstractHerein, a simple and efficient nickel‐catalyzed C‐3‐selective alkylation of 2‐oxindoles using primary alkyl and allylic alcohols have been demonstrated. The catalytic protocol enables transformations in the presence of free hydroxyl group, amine, cycloalkanes, olefins, and lactam including more challenging C2‐C4 alcohols, citronellol and oleic acid derived alcohol in up to 96 % yield. Initial mechanistic studies and deuterium labelling experiments were performed. Synthetic modulations of the lactam enabled new routes for the synthesis of C‐3‐substituted indoles, indolines, and un‐symmetric urea derivatives.

Synthesis, Spectroscopic Study of new Substituted heterocyclic compounds derived from Molononitrile and Cytotoxic agents against MCF-7 Human Cancer Cells

In the present work , 4-((dicyanomethyl)diazenyl)-N-(5-methylisoxazol-3-yl)benzene sulfonamide E and 2,2'-(1E,1E')-(sulfonylbis(4,1-phenylene))bis(diazene-2,1-diyl) dimalononitrile C were synthesized from the reaction of Sulfamethaxazole and Dapsone with Malononitrile and condensed with 2,4dinitophenyl hydrazine derivatives to produce 3,5diaminopyrazole derivatives E1 and C1.condensation with hydroxyl amine hydrochloride produce isoxazole derivative E2,C2 .Treatment of E and C with urea and thiourea yielded the pyrimidine derivatives E3-E4,C3-C4 and treatment with secondary amine afforded piperazine derivatives E5,C5. While its condensation with thiosemicarbazide yielded the derivatives E6, C6. The structure of the newly synthesized compound were established on the basis of physical data and spectral methods such as IR, 1H-NMR ,13C-NMR and Mass spectra. Cytotoic evaluation of four compounds, against MCF-7 (human breast adeno carcinoma) cell lines.

Reaction mechanism and electronic properties of host-guest energetic material CL-20/HA under high pressure by quantum-based molecular dynamics simulations.

The novel host-guest material 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)/hydroxylamine (HA) improves the detonation energy of CL-20 explosives without compromising its safety. However, the reaction mechanism of CL-20/HA under high pressure is not yet fully understood for the complex host-guest structure. A multiscale shock simulation technique by quantum-based molecular dynamics was performed to investigate the reaction mechanism of CL-20/HA under shock with different velocities along different directions, focusing on charge transfer, electronic properties, reaction path and product evolution. The structural changes caused by both insertion of HA and charge overlap between CL-20 and HA are responsible for the electronic changes and gap decrease. Directional charge transfer was observed between CL-20 and HA molecular fragments during shock in all shock loading directions, causing the CL-20 molecular group to become electrically non-neutral. The C-N bond in the CL-20 cage then broke, leading to the release of nitro and nitrous oxide at high temperatures and pressures. The HA molecules or free H atoms from HA could bond with the O atom in the nitro group, leading to the N-O bond cleavage. Some free H atoms could act as an intermediary, connecting two CL-20 molecules and forming dimeric molecules briefly. Compared with the pure CL-20 system, HA can inhibit the reaction of CL-20 in the CL-20/HA system to some extent during the initial shock stage. A further understanding of the chemical reaction mechanism and energy release in dense host-guest materials can be advanced by focusing on the microscopic internal effects of the guest molecule on the host molecule reactions.

Zn(OAc)2•2H2O-catalyzed efficient synthesis of 5-Substituted 1H-tetrazoles

In this communication, condensation from different aromatic, aliphatic and heteroaromatic aldehydes, hydroxyl amine, and sodium azide in toluene reflux was used to produce electronically and structurally distinct tetrazoles with a range of yields 5-94%. Zn(OAc)2•2H2O (10 mol%) was used as a catalyst in the synthesis, which was eco-friendly, readily available, and affordable. The IR, NMR, and mass spectral studies were utilized in order to carry out a comprehensive characterization for all the 5-aryl tetrazole derivatives. This approach contributes to the current chemical synthesis of 5-substituted-1H-tetrazoles in an appealing and convenient manner thanks to its quick reaction times, good to exceptional yields, safe process, and straightforward workup.

Synthesis of Novel Biaryl Fused Thiazolo[3,2-b][1,2,4]triazol-2-amines from Thiazole Amine Involving Suzuki Coupling Reaction under Microwave Irradiation

Novel series of fused heterocycles in which amino triazole fused to biphenyl thiazole were synthesized in a multistep reaction starting from 2-aminothiazole. The amino compound with ethoxy carbonyl isothiocyanate afforded the ethyl carbamate thiomide derivative of thiazole, which further underwent intramolecular cyclization with hydroxyl amine hydrochloride in presence of DIPEA to furnish the fused thiazolotriazole amine. Haloaryl group in the fused heterocycle under Suzuki coupling condition afforded biphenyl derivatives of fused thiazolotriazole amines. All the synthesized compounds were confirmed based on their spectral data.

Chemical Cyclic Amplification: Hydroxylamine Boosts the Fenton Reaction for Versatile and Scalable Biosensing

Nucleic acid detection is undoubtedly one of the most important research fields to meet the medical needs of genetic disease diagnosis, cancer treatment, and infectious disease prevention. However, the practical detection methods based on biological amplification are complex and time-consuming and require highly trained operators. Herein, we report a simple, rapid, and sensitive method for the nucleic acid assay by fluorescence or naked eye using chemical cyclic amplification. The addition of hydroxylamine (HA) during the Fenton reaction can continuously generate hydroxyl radicals (•OH) via Fe3+/Fe2+ cycle, termed as "hydroxylamine boosts the Fenton reaction (Fenton-HA system)". Meanwhile, the reducing substances, such as terephthalic acid or o-phenylenediamine, react with •OH to generate oxidized substances that can be recognized by the naked eye or detected by fluorescence so as to realize the detection of Fe3+. The concentration of Fe3+ has a good linear relationship with fluorescence intensity in the range of 0.1 to 100 nM, and the limit of detection is calculated to be 0.03 nM (S/N = 3). Subsequently, Fe was introduced into the nucleic acid hybridization system after the Fe source was transformed into Fe3+, and the nucleic acids were indirectly determined by this method. This Fenton-HA system was used for sensing HIV-DNA and miRNA-21 to verify the validity of this method in nucleic acid detection. The detection limits were as low as 2.5 pM for HIV-DNA and 3 pM for miRNA-21. We believe that our work has unlocked an efficient signal amplification strategy, which is expected to develop a new generation of highly sensitive chemical biosensors.

Efficient activation of peroxymonosulfate via Cu2+/Cu+ cycle enhanced by hydroxylamine for the degradation of Rhodamine B.

The application of Cu2+/peroxymonosulfate (PMS) process for the elimination of refractory pollutants in industrial wastewater is limited by the slow transformation from Cu2+ to Cu+. In this research, hydroxylamine (HA) was employed to improve the degradation capacity of the Cu2+/PMS process. Rhodamine B (RhB) was selected as the target compound to indicate the performance of HA/Cu2+/PMS process. Compared with the Cu2+/PMS process, the reduction of Cu2+ to Cu+ was effectively promoted by HA in the HA/Cu2+/PMS process, which increased the decomposition rate of PMS by 29.2%, correspondingly, promoted the removal rate of RhB by 77.6%. The degradation of RhB followed pseudo-second-order kinetics in the proposed process. The active species analysis subsequently indicated hydroxyl radicals (·OH) and sulfate radicals (SO4·-) played important roles for degrading RhB with ·OH as the dominant active radical. The effects including initial pH, RhB concentration, PMS concentration, and Cu2+ concentration on the degradation of RhB were further investigated and discussed in detail. Additionally, the HA/Cu2+/PMS process exhibited effective RhB removal in simulated wastewater. From the perspective of waste utilization (Cu2+) and the remediation of organic contamination, the work would provide a valuable and promising process.

Gamma Radiation-Induced Degradation of Acetohydroxamic Acid (AHA) in Aqueous Nitrate and Nitric Acid Solutions Evaluated by Multiscale Modelling.

Acetohydroxamic acid (AHA) has been proposed for inclusion in advanced, single-cycle, used nuclear fuel reprocessing solvent systems for the reduction and complexation of plutonium and neptunium ions. For this application, a detailed description of the fundamental degradation of AHA in dilute aqueous nitric acid is required. To this end, we present a comprehensive, multiscale computer model for the coupled radiolytic and hydrolytic degradation of AHA in aqueous sodium nitrate and nitric acid solutions. Rate coefficients for the reactions of AHA and hydroxylamine (HA) with the oxidizing nitrate radical were measured for the first time using electron pulse radiolysis and used as inputs for the kinetic model. The computer model results are validated by comparison to experimental data from steady-state gamma ray irradiations, for which the agreement is excellent. The presented model accurately predicts the yields of the major degradation products of AHA: acetic acid, HA, nitrous oxide, and molecular hydrogen.

Transformation of hydroxylamine to nitrosated and nitrated products during advanced oxidation process

Recently, hydroxylamine (HAm) was introduced to drive advanced oxidation processes (AOPs) for removing organic contaminants. However, we found that HAm-driven Cu(II)/peroxymonosulfate oxidation of phenol produced p-nitrosophenol, 2-nitrophenol and 4-nitrophenol. The total nitro(so) products accounted for approximately 25.0 % of the phenol transformation at certain condition. SO4•− and •OH were identified as the primary and second significant oxidants, respectively. Reactive nitrogen species (RNS) were involved in phenol transformation. The pathway and mechanism of HAm transformation in HAm-driven transition metal ion-catalyzed AOPs were proposed for the first time in this study. The product of HAm via twice single-electron oxidation by Cu(II) is nitroxyl (HNO/NO−), which is a critical oxidation intermediate of HAm. Further oxidation of HNO by SO4•− or •OH is the initial step in propagating radical chain reactions, leading to nitric oxide radical (•NO) and nitrogen dioxide radical (•NO2) as the primary RNS. HAm is a critical intermediate in natural nitrogen cycle, suggesting that HAm can drive the oxidation processes of pollutants in natural environments. Nitro(so) products will be readily produced when AOPs are applied for ecological remediation. This study highlights the formation of toxic nitrosated and nitrated products in HAm-driven AOPs, and the requirement of risk assessments to evaluate the possible health and ecological impacts.

Sulfur and nitrogen co-doped magnetic biochar coupled with hydroxylamine for high-efficiency of persulfate activation and mechanism study

Biochar has recently become a central issue in advanced oxidation processes (AOPs) based on peroxydisulfate (PDS) activation. However, the PDS activation by biochar must be improved. In this study, S, N co-doped magnetic biochar (IBC) was prepared by a simple impregnation-pyrolysis method using Eichhornia crassipes stems with inherent sulfur and nitrogen as the raw materials for biochar. The reductant hydroxylamine (HA) was employed to further enhance PDS activation by the IBC for organic pollutant degradation. Incorporating HA in PDS activation over IBC significantly improved its compatibility with complex water, catalytic degradation, stability performance, and mineralization rate of organic pollutants. The outstanding performance of the HA/PDS/IBC system for organic degradation was due to the increased free radicals SO4·-, O2·-, and non-radical 1O2 generated, as well as the electrons transferred between IBC, PDS, and organic pollutants, which were verified by electron paramagnetic resonance (EPR) detection and electrochemical characterizations. Furthermore, HA-enhanced Fe(III)/Fe(II) cycling, surface functional groups, and S and N doping contributed to the generation of reactive oxygen species (ROS). Moreover, the toxicity assessment indicated that the toxicity of the degradation intermediates decreased. Therefore, this research proposes a new insight into the enhanced degradation of pollutants by increasing PDS activation using biochar-based catalytic materials.