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1.
Chemosphere ; 276: 130257, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34088104

RESUMO

In this work, the magnetic γ-Fe2O3-MnO2 bifunctional catalyst with oxygen vacancy was synthesized for peroxymonosulfate (PMS) activation under visible light. The activity of γ-Fe2O3-MnO2 was investigated by ciprofloxacin (cipro) degradation. Results showed that 98.3% of cipro (50 µM) was removed within 30 min in visible-light/PMS system mediated by γ-Fe2O3-MnO2 (2:1) with fine-tuned oxygen vacancy. The cipro degradation data fitted well with pseudo-first-order kinetic model with the highest kinetic constant of 0.114 min-1. Besides, the γ-Fe2O3-MnO2 exhibited stability, recyclability and practicability. High selectivity for cipro degradation was observed with coexisting anions in visible-light/γ-Fe2O3-MnO2/PMS system. Furthermore, the enhanced mechanism of PMS activation under visible light with γ-Fe2O3-MnO2 was proposed. The appropriate oxygen vacancy enhanced the separation of photo-induced carriers and Z scheme heterostructure maintained the highest redox potential. Accordingly, the synergistic effect of photocatalysis and PMS activation enhanced cipro degradation. Free radical and non-radical species including , h+, 1O2, •OH and co-existed in the coupled system. Impressively, this study provides a handy approach for oxygen vacancy regulation in metallic oxides composite and an easily recycled catalyst with high-activity in coupled oxidation system towards antibiotic degradation.


Assuntos
Ciprofloxacina , Oxigênio , Luz , Compostos de Manganês , Óxidos , Peróxidos
2.
Chemosphere ; 275: 130059, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33984914

RESUMO

The metal organic framework derived materials (CoFe2O4@NC) activated peroxymonosulfate (PMS) to degrade Norfloxacin (NOR) owing to the characteristics of high surface area (109.658 m2 g-1) and abundant mesoporous structure. The characterization results demonstrated that the optimal ratio of bimetal and of bimetallic to organic ligands (M/O) had good crystal structure and stability (Fe/Co = 3:1, M/O = 2:1). Moreover, NOR (10 mg L-1) removal of 98.78% was achievable in 60 min with an optimum concentration of PMS (0.32 mM) and dosage of CoFe2O4@NC (0.1 g L-1). The radical quenching results suggested that SO4·-, ·OH and 1O2 functioned in the presence of the system certificated by XPS spectra. The presence of Cl- and CO32-/HCO3- promoted the catalyst reaction. The recoverability revealed high removal efficiency of NOR of 93.55% could still be maintained. Furthermore, four pathways of NOR degradation were proposed, including dehydroxylation, defluorination, quinolone group conversion and piperazine ring transformation, which were attributed to the synergy of reactive oxygen species. The above results highlight that the method is of great significance to the practical application of heterogeneous catalysts in aqueous solutions.


Assuntos
Estruturas Metalorgânicas , Norfloxacino , Peróxidos , Água
3.
Water Sci Technol ; 83(10): 2327-2344, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34032613

RESUMO

Water pollution caused by refractory organics has attracted widespread concern in recent years. At this time peroxymonofulfate (PMS) has been widely used to generate sulfate radicals with high reactivity and potential. The direct reaction rate between PMS and organics is very low. However, the activated PMS has a strong oxidizing ability on organics due to its conversion into sulfate radicals. Recently, the free radicals generated by oxidant PMS and catalyst biochar have proven to be an effective species in dealing with refractory organics. In order to enable researchers to better understand the current research status of PMS/biochar, and to promote the development and application of PMS/biochar system, we have written this review. This review in detail described the mechanism of PMS activated by biochar materials, and summarized the influencing factors of refractory organics degradation in the PMS/biochar system. In addition, the active sites of PMS/biochar, the degradation mechanism of refractory organics, and the reusability of biochar catalysts were also discussed. Finally, the concluding remarks and perspectives were made for future research on the PMS/biochar system in the degradation of refractory organics.


Assuntos
Peróxidos , Água , Carvão Vegetal
4.
Food Chem ; 358: 129872, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33965743

RESUMO

Chemical profiles, distribution, and antioxidant activity of bound phenolics from brown rice were investigated. Four new dehydrodiferulic acid dimers (DFA) along with eighteen known phenolics were isolated from brown rice bound phenolic extracts and their structures were determined by multiple spectroscopic methods. Among them, ferulic acid and 8-5' DFA were the most abundant monomeric and dimeric bound phenolics in brown rice, rice bran and polished rice. In whole brown rice, polished rice contributed more than 50% of three phenolic monomers and six phenolic dimers, while rice bran contributed more than half of the other thirteen phenolics including eight monomers, four dimers, and one trimer. All the isolated compounds exhibited oxygen radical absorbance capacity. Thomasidioic acid, caffeic acid, methyl caffeate, and 8-5' DC DFA displayed potent peroxyl radical scavenging capacity, and the last three compounds also showed moderate cellular antioxidant activity.


Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Oryza/química , Fenóis/química , Grãos Integrais/química , Ácidos Cumáricos/análise , Ácidos Cumáricos/química , Ácidos Cumáricos/farmacologia , Células Hep G2 , Humanos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Peróxidos/química , Fenóis/análise , Fenóis/farmacologia , Extratos Vegetais/química
5.
Food Chem ; 358: 129834, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933972

RESUMO

Edible oils are prone to oxidation during processing and storage that may negatively affect the oil quality and human health. Determining the peroxide value (PV) of edible oils is essential because PV is one of the most typically used quality parameters to monitor lipid oxidation and control oil quality. Many approaches have been developed to determine the PV of oils. Among them, iodometric titration is the commonly used method for PV determination. Considering the limitations related to titrimetric methods, such as time and environmental concerns, several instrumental techniques have been considered as reliable alternatives. The advantages and limitations of classical titration and instrumental methods are summarized in this review. The prospects and reformative aspects for the future applications of these approaches in PV determination are also discussed.


Assuntos
Análise de Alimentos , Peróxidos/análise , Óleos Vegetais/análise , Óleos/análise
6.
Environ Sci Technol ; 55(9): 6397-6406, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33882668

RESUMO

The catalytic activation of peroxymonosulfate (PMS) is under intensive investigation with potentials as an alternative advanced oxidation process (AOP) in wastewater treatment. Among all catalysts examined, Co(II) exhibits the highest reactivity for the activation of PMS, following the conventional Fenton-like mechanism, in which free radicals (i.e., sulfate radicals and hydroxyl radicals) are reckoned as the reactive species. Herein, we report that the primary reactive species (PRS) is proposed to be a Co(II)-PMS complex (Co(II)-OOSO3-), while free radicals and Co(III) species act as the secondary reactive species (SRS) that play a minor role in the Co(II)/PMS process. This Co(II)-OOSO3- exhibits several intriguing properties including ability to conduct both one-electron-transfer and oxygen-atom-transfer reactions with selected molecules, both nucleophilic and electrophilic in nature, and strongly pH-dependent reactivity. This study provides novel insights into the chemical nature of the Co(II)-catalyzed PMS activation process.


Assuntos
Peróxidos , Purificação da Água , Radicais Livres , Oxirredução
7.
Artigo em Inglês | MEDLINE | ID: mdl-33804931

RESUMO

Advanced oxidation processes (AOPs) based on peroxydisulfate (PDS) or peroxymonosulfate (PMS) activation have attracted much research attention in the last decade for the degradation of recalcitrant organic contaminants. Sulfate (SO4•-) and hydroxyl (•OH) radicals are most frequently generated from catalytic PDS/PMS decomposition by thermal, base, irradiation, transition metals and carbon materials. In addition, increasingly more recent studies have reported the involvement of singlet oxygen (1O2) during PDS/PMS-based AOPs. Typically, 1O2 can be produced either along with SO4•- and •OH or discovered as the dominant reactive oxygen species (ROSs) for pollutants degradation. This paper reviews recent advances in 1O2 generation during PDS/PMS activation. First, it introduces the basic chemistry of 1O2, its oxidation properties and detection methodologies. Furthermore, it elaborates different activation strategies/techniques, including homogeneous and heterogeneous systems, and discusses the possible reaction mechanisms to give an overview of the principle of 1O2 production by activating PDS/PMS. Moreover, although 1O2 has shown promising features such as high degradation selectivity and anti-interference capability, its production pathways and mechanisms remain controversial in the present literatures. Therefore, this study identifies the research gaps and proposes future perspectives in the aspects of novel catalysts and related mechanisms.


Assuntos
Peróxidos , Oxigênio Singlete , Radical Hidroxila , Sulfatos
8.
Int J Mol Sci ; 22(7)2021 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-33916642

RESUMO

The available tooth whitening products in the market contain high concentrations of hydrogen peroxide (H2O2) as an active ingredient. Therefore, in order to curb the high H2O2 concentration and instability of liquid H2O2, this study evaluated the efficacy and cytotoxicity of the bleaching gel composed of 10% calcium peroxide (CaO2) and visible-light-activating nitrogen-doped titanium dioxide (N-TiO2) with methyl cellulose as a thickener. Extracted bovine teeth were discolored using coffee and black tea stain solution and were divided into two groups (n = 6). Bleaching was performed thrice on each tooth specimen in both the groups, with one minute of visible light irradiation during each bleaching time. The CIELAB L*a*b* values were measured pre- and post-bleaching. The N-TiO2 calcinated at 350 °C demonstrated a shift towards the visible light region by narrowing the band gap energy from 3.23 eV to 2.85 eV. The brightness (ΔL) and color difference (ΔE) increased as bleaching progressed each time in both the groups. ANOVA results showed that the number of bleaching significantly affected ΔE (p < 0.05). The formulated bleaching gel exhibits good biocompatibility and non-toxicity upon exposure to 3T3 cells. Our findings showed that CaO2-based bleaching gel at neutral pH could be a stable, safe, and effective substitute for tooth whitening products currently available in the market.


Assuntos
Luz , Metilcelulose , Dióxido de Nitrogênio , Peróxidos , Titânio , Clareamento Dental , Células 3T3 , Animais , Bovinos , Metilcelulose/química , Metilcelulose/farmacologia , Camundongos , Dióxido de Nitrogênio/química , Dióxido de Nitrogênio/farmacologia , Peróxidos/química , Peróxidos/farmacologia , Titânio/química , Titânio/farmacologia
9.
Molecules ; 26(8)2021 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-33920659

RESUMO

Small-vessel vasculitis (SVV) is the inflammation of the vessel wall that can result in hemorrhage and/or ischemia. Among the histological findings in SVV are increased infiltrating neutrophils, which, due to their oxidative burst and myeloperoxidase activity, release excessive reactive oxygen species, triggering a chain reaction of lipid peroxidation and yielding reactive aldehydes such as acrolein. The implication of oxidative stress in the pathogenesis of SVV was studied, focusing on acrolein immunohistochemistry in the affected skin vessels and systemic stress response. Samples from SVV patients and healthy subjects were collected and analyzed for total serum peroxides, total antioxidant capacity, inflammatory and immunological parameters, as well as for the presence of acrolein-protein adducts in the skin tissue specimens. The obtained data showed that systemic redox homeostasis and iron metabolism are altered in SVV patients. Possible biomarkers in the evaluation of oxidative status, disease activity and prevalence were indicated. Furthermore, a strong correlation between the accumulation of acrolein-protein adducts in the skin and the progression of the disease was revealed. Thus, the results of this study demonstrate that SVV is not only associated with systemic oxidative stress but also with tissue-specific oxidative stress that promotes acrolein formation and protein modification correlating with the severity of cutaneous vasculitis.


Assuntos
Acroleína/administração & dosagem , Inflamação/tratamento farmacológico , Estresse Oxidativo/efeitos dos fármacos , Vasculite/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Vasos Sanguíneos/efeitos dos fármacos , Vasos Sanguíneos/patologia , Feminino , Homeostase/efeitos dos fármacos , Humanos , Inflamação/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade , Peróxidos/metabolismo , Pele/efeitos dos fármacos , Pele/patologia , Vasculite/patologia
10.
Science ; 372(6540): 398-403, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33888639

RESUMO

The "magic methyl" effect describes the change in potency, selectivity, and/or metabolic stability of a drug candidate associated with addition of a single methyl group. We report a synthetic method that enables direct methylation of C(sp3)-H bonds in diverse drug-like molecules and pharmaceutical building blocks. Visible light-initiated triplet energy transfer promotes homolysis of the O-O bond in di-tert-butyl or dicumyl peroxide under mild conditions. The resulting alkoxyl radicals undergo divergent reactivity, either hydrogen-atom transfer from a substrate C-H bond or generation of a methyl radical via ß-methyl scission. The relative rates of these steps may be tuned by varying the reaction conditions or peroxide substituents to optimize the yield of methylated product arising from nickel-mediated cross-coupling of substrate and methyl radicals.


Assuntos
Compostos de Benzil/química , Carbono/química , Radicais Livres/química , Hidrogênio/química , Níquel/química , Peróxidos/química , Transferência de Energia , Ligação de Hidrogênio , Luz , Metilação , Oxigênio/química
11.
Bioresour Technol ; 333: 125166, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33895668

RESUMO

Anaerobic co-digestion of a cow manure-cotton straw mixture (CCM) has been shown to promote methanogenesis, but the recalcitrant crystal structure of organic polymers in CCM hinders its hydrolysis during anaerobic digestion (AD). Here, the efficacy of different pretreatment methods based on potassium ferrate (PF) and peroxymonosulfate (PMS) was evaluated to facilitate CCM decomposition and methanogenesis during AD. The maximum lignocellulosic removal rate (62.5%), the highest volatile fatty acids (VFAs) (7769.6 mg/L), and cumulative methane yield (109.4 mL CH4/g VS) were both achieved in PF-pretreated samples after the digestion process. The dominant bacterial populations in PF-pretreated CCM were affiliated with Sideroxydans, Herbinix, Clostridium, and Smithella, which played an important role in the hydrolysis and acidification of CCM. The enrichment of Methanosarcina and Methanobacterium and highly-effective acidogenesis might account for the highest methane yield in the PF-pretreated group.


Assuntos
Esterco , Microbiota , Anaerobiose , Animais , Biocombustíveis , Reatores Biológicos , Bovinos , Digestão , Feminino , Compostos de Ferro , Metano , Peróxidos , Compostos de Potássio
12.
Water Sci Technol ; 83(6): 1470-1482, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33767051

RESUMO

Antibiotics have received great attention because of their abuse and potential hazards to the human health and environment. In the current work, peroxymonosulfate (PMS) was added to a cerium oxide (CeO2)/ultrasonic (US) system for tetracycline (TC) degradation. CeO2 nanoparticles (NPs) were synthesized by a simple and cost-effective method using Stevia rebaudiana leaf extract and cerium nitrate as precursors. The as-synthesized CeO2 NPs were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis. The effects of catalyst dosage, PMS concentration, US power, initial antibiotic concentration, and pH on TC removal were investigated. The results confirmed the formation of CeO2 NPs with a fluorite structure, spherical shape, and average particle size of 29 nm. The removal efficiency of TC was 92.6% in the optimum oxidation conditions ([TC] = 15 mg/L, [PMS] = 50 mM, [CeO2] = 0.6 g/L, pH = 6, and US = 70 W) and followed the zero-order kinetics. Experiment scavenger demonstrated both sulfate and hydroxyl radicals (SO4•-, •OH) were responsible for degrading antibiotics. Biogenic CeO2 NPs and ultrasound waves-activated PMS is a promising technology for water pollution caused by contaminants such as pharmaceuticals.


Assuntos
Cério , Nanopartículas , Antibacterianos , Humanos , Cinética , Peróxidos , Ultrassom
13.
Water Res ; 195: 116973, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33677242

RESUMO

Though hydroxylamine (NH2OH) is effective for accelerating pollutants degradation in Fenton and Fenton-like systems, the effect of anions simultaneously introduced by the hydroxylamine salts have always been ignored. Herein, effect of two commonly used hydroxylamine salts, hydroxylamine hydrochloride (NH2OH·HCl) and hydroxylamine sulfate [(NH2OH)2·H2SO4], for the degradation of dimethyl phthalate (DMP) in peroxymonosulfate (PMS)/Fe(II) system was comparatively investigated. Degradation efficiency of DMP with NH2OH·HCl was 1.6 times of that with same dosages of (NH2OH)2·H2SO4. SO4·-, Fe(IV) and ·OH formed in the PMS/Fe(II)/NH2OH system, but ·OH was the major species for DMP degradation. Addition of Cl- significantly improved the production of ·OH and Cl·, and the exposure dose of ·OH (CT·OH) was more than 10 times that of CTCl· as the concentration of Cl- increased to 1 mM. Calculations based on branching ratios of Cl· and ·OH indicated that the reactions of Cl- with SO4·- and Cl· with H2O were not the only production sources of ·OH in the system. Further experiments with methyl phenyl sulfoxide (PMSO) as the probe indicated that Cl- would facilitate the shift of reactive species from Fe(IV) to radicals (SO4·- or ·OH) in the system. Both hydroxylation and nitration intermediate products were detected in the oxidation of DMP. Cl- promoted the formation of hydroxylation intermediates and reduced the formation of nitration intermediates. This study revealed for the first time that Cl- could shift reactive species from Fe(IV) to radicals in PMS/Fe(II) system, raising attention to the influence of the coexisting anions (especially Cl-) for pollutants oxidation in iron-related oxidation processes.


Assuntos
Cloretos , Peróxidos , Compostos Ferrosos , Ferro , Oxirredução
14.
Water Res ; 194: 116961, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33657492

RESUMO

In this study, we designed an integrated electrochemical filtration system for catalytic activation of peroxymonosulfate (PMS) and degradation of aqueous microcontaminants. Composites of carbon nanotube (CNT) and nanoscale zero valence copper (nZVC) were developed to serve as high-performance catalysts, electrode and filtration media simultaneously. We observed both radical and nonradical reaction pathways, which collectively contributed to the degradation of model pollutants. Congo red was completely removed via a single-pass through the nZVCCNT filter (τ <2 s) at neutral pH. The rapid kinetics of Congo red degradation were maintained across a wide pH range (from 3.0-7.0), in complicated matrixes (e.g., tap water and lake water), and for the degradation of a wide array of persistent organic contaminants. The superior activity of nZVCCNT stems from the boosted redox cycles of Cu2+/Cu+ in the presence of an external electric field. The flow-through design remarkably outperformed the conventional batch system due to the convection-enhanced mass transport. Mechanism studies suggested that the carbonyl group and electrophilic oxygen of CNT served as electron donor and electron acceptor, respectively, to activate PMS to generate •OH and 1O2via one-electron transport. The electron-deficient Cu atoms are prone to react with PMS via surface hydroxyl group to produce reactive intermediates (Cu2+-O-O-SO3-), and then 1O2 will be generated by breaking the coordination bond of the metastable intermediate. The study will provide a green strategy for the remediation of organic pollution by a highly efficient and integrated system based on catalytic oxidation, electrochemistry, and nano-filtration techniques.


Assuntos
Poluentes Ambientais , Nanotubos de Carbono , Catálise , Cobre , Oxirredução , Peróxidos
15.
Environ Sci Technol ; 55(8): 5382-5392, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33733765

RESUMO

This study is the first to demonstrate the capability of Cl- to markedly accelerate organic oxidation using thermally activated peroxymonosulfate (PMS) under acidic conditions. The treatment efficiency gain allowed heat-activated PMS to surpass heat-activated peroxydisulfate (PDS). During thermal PMS activation at excess Cl-, accelerated oxidation of 4-chlorophenol (susceptible to oxidation by hypochlorous acid (HOCl)) was observed along with significant degradation of benzoic acid and ClO3- occurrence, which involved oxidants with low substrate specificity. This indicated that heat facilitated HOCl formation via nucleophilic Cl- addition to PMS and enabled free chlorine conversion into less selective oxidizing radicals. HOCl acted as a key intermediate in the major oxidant transition based on temperature-dependent variation in HOCl concentration profiles, kinetically retarded organic oxidation upon NH4+ addition, and enabled rapid organic oxidation in heated PMS/HOCl mixtures. Chlorine atom that formed via the one-electron oxidation of Cl- by the sulfate radical served as the primary oxidant and was involved in hydroxyl radical production. This was corroborated by the quenching effects of alcohols and bicarbonates, reactivity toward multiple organics, and electron paramagnetic resonance spectral features. PMS outperformed PDS in degrading benzoic acid during thermal activation operated in reverse osmosis concentrate, which was in conflict with the well-established superiority of heat-activated PDS.


Assuntos
Cloretos , Poluentes Químicos da Água , Cloro , Temperatura Alta , Oxirredução , Peróxidos , Poluentes Químicos da Água/análise
16.
Environ Sci Technol ; 55(8): 5301-5311, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33755424

RESUMO

In this study, the effects of in situ chemical oxidation (ISCO) on the biogeochemical properties of an aquifer soil were evaluated. Microcosms packed with an aquifer soil were investigated for 4 months in two phases including oxidant exposure (phase I) and biostimulation involving acetate addition (phase II). The geochemical and microbial alterations from different concentrations (0.2 and 50 mM) of hydrogen peroxide (HP) and peroxymonosulfate (PMS) were assessed. The 50 mM PMS-treated sample exhibited the most significant geochemical changes, characterized by the decrease in pH and the presence of more crystalline phases. Microbial activity decreased for all ISCO-treated microcosms compared to the controls; particularly, the activity was severely inhibited at high PMS concentration exposure. The soil microbial community structures were shifted after the ISCO treatment, with the high PMS causing the most distinct changes. Microbes such as the Azotobacter chroococcum and Gerobacter spp. increased during phase II of the ISCO treatment, indicating these bacterial communities can promote organic degradation despite the oxidants exposure. The HP (low and high concentrations) and low concentration PMS exposure temporarily impacted the microbial activity, with recovery after some duration, whereas the microbial activity was less recovered after the high concentration PMS exposure. These results suggest that the use of HP and low concentration PMS are suitable ISCO strategies for aquifer soil bioattenuation.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Azotobacter , Peróxido de Hidrogênio , Oxirredução , Peróxidos , Solo
17.
Eur J Oral Sci ; 129(2): e12773, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33724583

RESUMO

This review compiles the literature on the antioxidants used after tooth bleaching with either low or high-concentrated carbamide and hydrogen peroxide to recover the bond strength. Antioxidants used in bleached teeth are mainly natural and non-enzymatic, except for catalase. Commonly, antioxidants are applied to remove any reactive oxygen species (ROS) residues left from bleaching gels, which adversely affect adhesive procedures, such as restorations or orthodontic brackets bonding. Even though sodium ascorbate, the most thoroughly investigated antioxidant, showed the most efficient bond strength recovery at 10% concentration, its performance depends on the type of solution and the application time. Natural extracts, such as proanthocyanidins and green tea, showed satisfactory results in the reversal of bond strength at 5% and 10% concentrations, respectively. Sodium ascorbyl phosphate, α-tocopherol, and catalase exhibited promising results, but further research is required. The adhesive system type plays an important role in the outcome of enamel bond strength after the antioxidant application. The postponement of either restorations or orthodontic brackets cementation following bleaching procedures seems to be efficiently replaced by antioxidant application prior to bonding procedures. However, the efficacy of using an antioxidant to recover bond strength depends on its type and application time.


Assuntos
Colagem Dentária , Clareamento Dental , Antioxidantes , Cimentos Dentários , Peróxidos , Resistência ao Cisalhamento , Ureia
18.
Adv Healthc Mater ; 10(9): e2002126, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33644985

RESUMO

Recently, nanoparticle-triggered in situ catalytic Fenton/Fenton-like reaction is widely explored for tumor-specific chemodynamic therapy (CDT). However, despite the great potential of CDT in tumor treatment, insensitive response to the relatively high pH of the tumor sites and the insufficient intratumoral H2 O2 level leads to limited efficiency of most Fenton/Fenton-like reactions, which greatly imped its clinical conversion. This paper reports the fabrication of Fenton-type bimetallic peroxides for ultrasensitive chemodynamic therapy with high pH-activated, synergistic effect/H2 O2 self-supply-mediated cascade Fenton chemistry for the first time. The observations reveal that these bimetallic peroxides exhibit an ultrasensitive acid-activated decomposition-mediated Fenton-like reaction at the relatively high pH of 6.5-7.0, accompanied with highly increased •OH generation efficiency (especially, 40-60-fold increase at pH 7.0) by the metal-mediated synergistic effect-enhanced Fenton chemistry as well as in situ self-generated H2 O2 supplement. Moreover, the bimetallic peroxides exhibit high tumor accumulation which along with a high-efficiency tumor catalytic-therapeutic with negligible side effects in vivo. Developing these novel bimetallic peroxides, together with the already demonstrated capacity of the key metals (Fe, Mn, Cu, etc.) for magnetic resonance imaging or photodynamic/immune-enhanced therapy, will propel interest in development of smart high-efficiency nanoplatform for cancer theranostics.


Assuntos
Nanopartículas , Peróxidos , Catálise , Linhagem Celular Tumoral , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio
19.
Chemosphere ; 275: 130058, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33652283

RESUMO

Preparation of carbonaceous catalysts by doping with boron (B) is one of the most promising strategies for substitution of toxic transition metal catalysts in advanced oxidation processes. This study was dedicated to reveal the intrinsic structure-performance relationship of peroxomonosulfate (PMS) activation by B-doped carbon nanotubes toward catalytic oxidation of pollutants. Performance tests showed the catalyst realized more than 95% phenol removal at pH 7 in 1 h and 69.4% total organic carbon removal. The catalysts were characterized using scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Characterization results indicated that the topography of carbon nanotube was not significantly changed after B doped, while the defect sites increased from 1.05 to 1.23. The newly formed active sites may be presented in the form of C3B, CBO2 and CBO3, and reactive oxygen species (ROS) including OH, SO4-•, O2-• and 1O2 might be generated after activation by the active sites. Furthermore, B-MWNT-PMS∗ was also be detected by In-situ Raman, confirming the non-radical pathway and electron transfer mechanism. Beside of phenol, the reaction system of B-MWNT/PMS also can remove methylene blue, bisphenol S and diuron at pH = 7, confirming the universality and promising of this advanced oxidation technology.


Assuntos
Nanotubos de Carbono , Boro , Catálise , Oxirredução , Peróxidos
20.
Chemosphere ; 277: 130271, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33770697

RESUMO

A new mesoporous Ag/ZnO@NiFe2O4 nanorod was prepared by a facile, low-cost, and environmentally friendly strategy from a bimetallic Fe2Ni-MIL-88 metal organic framework (MOF), as an effective catalyst and peroxymonosulfate (PMS) photo-activator. The structural, morphological, optical, and magnetic properties, as well as the material composition were investigated by XRD, FE-SEM, EDX, HR-TEM, XPS, DRS, PL, EIS, VSM, N2 adsorption-desorption and ICP-AES analysis. 1.0% w/w loading of Ag nanoparticles on ZnO0.04@NiFe2O4 led to the best catalytic activity for PMS activation under UVA in acetaminophen (ACT) degradation. The maximum degradation efficiency for ACT was 100% within 15 min (at pH = 7.0), with a first-order rate constant of 0.368 min-1. The calculated quantum yield (1.3 × 10-3 molecule/photon) of the optimum catalyst was 2.05, and 5.63 times higher than its simple constituents, ZnO0.04@NiFe2O4 and NiFe2O4, respectively. Among the various inorganic ions, Cl- and HCO3- showed significant inhibition effect in 1.0%w/w Ag/ZnO0.04@NiFe2O4/PMS/UVA system, due to radical quenching effects. Based on scavenger experiments, HO• and SO4•- were the dominant reactive species in photocatalytic process coupled with PMS. Due to presence of the Fe3+/Fe2+, and Ni2+/Ni3+ reaction cycles in the as-made catalyst, the reaction rate of PMS activation was greatly enhanced. Moreover, the formation of a hetero-junction structure with NiFe2O4 and ZnO promoted the charge separation of the photo-generated electron/hole pairs. Finally, the major intermediates produced during the reaction were detected by LC-MS analysis, and a plausible mechanism for the photocatalytic degradation of ACT was proposed and discussed in detail.


Assuntos
Nanopartículas Metálicas , Nanotubos , Óxido de Zinco , Acetaminofen , Peróxidos , Prata
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