Reduced sulfur accelerates Fe(III)/Fe(II) recycling in FeS2 surface for enhanced electro-Fenton reaction.

FeS2 is well-known for its role in redox reactions. However, the mechanism within heterogeneous electron-Fenton (Hetero-EF) systems remains unclear. In this study, a novel FeS2 based three-dimensional system (GF/Cu-FeS2) with self-generation of H2O2 was investigated for Hetero-EF degradation of sulfamethazine (SMZ). The results revealed that SMZ could be completely removed in 1.5 h, accompanying with the mineralization efficiency of 96% within 4 h. This system performed excellent stability, evidenced by consistently eliminated 100% of SMZ within 2 h over 4 cycles. The generated Reactive Oxygen Species (ROS) of •OH and •O2- in every degradation cycle were quantitatively measured to confirm the stability of the GF/Cu-FeS2 system. Additionally, the redox reaction mechanism on the surface of FeS2 was thoroughly analyzed in detail. The accelerated reduction of Fe(III) to Fe(II), triggered by S22- on the surface of FeS2, promoted the iron cycling, thereby quickening the Fenton process. Density Functional Theory (DFT) results illustrated the process of S22- to be oxidized to in detail. Therefore, this work provides deeper insight into the mechanistic role of S22- in FeS2 for environmental remediation.

Core-shell structured lignin-stabilized silver nanoprisms for colorimetric detection of sulfur ions.

Widespread occurrence of sulfides in domestic and industrial wastewater contributes to environmental pollution and poses risks to human health. Therefore, the development of highly selective, sensitive, and rapid sulfur ion (S2-) detection probes in aquatic ecosystems is of paramount importance. In this study, lignin-stabilized silver nanoprisms (EHL@AgNPRs) were prepared using the seed growth and self-assembly methods. Based on this, a novel, high-performance, and environmentally friendly S2- colorimetric detection method was proposed. Lignin is believed to coat the surface of AgNPRs through cation-π and electrostatic interactions, acting as an excellent dispersant and stabilizer to prevent aggregation and shape deformation. This allows AgNPRs to maintain localized surface plasmon resonance (LSPR) characteristics and superior colorimetric sensing sensitivity towards S2- even after 30 d. The EHL@AgNPRs exhibited remarkable selectivity towards S2- with a minimum detection limit of 41.3 nM. The conjugation of lignin with AgNPRs offers a highly promising approach for the rapid detection of S2- in natural aquatic environments and for the valorization of lignin.

Bi/mZVI Combined with Citric Acid and Sodium Citrate to Mineralize Multiple Sulfa Antibiotics: Performance and Mechanism.

The oxidative mineralization of sulfanilamide drugs (SAs) using micro-size zero-valent iron (mZVI) cooperated with a citric acid buffer solution was evaluated. In this study SM2, SMX, and SD could be removed at 66%, 89%, and 83%, respectively, in a 0.5% Bi/mZVI+CA+NaCA system within 2 h. Based on our analysis, the produced ·OH could be ascribed from the complexation between citrate iron (Fe(II)[Cit]-) and the generated H2O2 resulting from the activation of O2 on the mZVI surface in the Bi/mZVI+CA+NaCA system, further inducing the mineralization of antibiotics. The related possible degradation pathways were proposed. Two similar degradation pathways of SM2, SMX, and SD in the mixed liquid, including hydroxylation and SO2 extrusion, were solved. Meanwhile, there was an additional proposed degradation pathway for SMX to be degraded more effectively, as reflected in the opening of the N-O bond on the benzene ring. Therefore, this work provides an experimental basis and theoretical support for the efficient treatment of antibiotic wastewater in real industry by using an iron-based method.

Association between the rs3733846 in the flanking region of miR-143/145 and risk of cervical squamous cell carcinoma.

Aim: To investigate the effect of rs3733846 in the flanking region of miR-143/145 on susceptibility to cervical squamous cell carcinoma (CSCC). Materials & methods: We collected venous blood samples from 242 CSCC patients and 250 healthy controls. The rs3733846 polymorphism was genotyped by SnaPshot and Sanger sequencing. The expression of miR-143/145 in CSCC tissues was detected by quantitative real-time PCR. Results: The rs3733846 AG genotype was associated with a decreased risk of CSCC in genetic model (AGvs.AA: adjusted odds ratio [OR]: 0.44; 95% CI: 0.30-0.66; p < 0.001). Patients with the rs3733846 AG/GG genotypes had a reduced risk of developing poorly differential status (OR: 0.57; 95% CI: 0.33-0.98; p < 0.04) and lymph node metastasis (OR: 0.49; 95% CI: 0.26-0.92; p < 0.03). Conclusion: The rs3733846 in the flanking region of miR-143/145 was related to the susceptibility of CSCC.

Citrate iron complex induced dramatically enhanced oxidation of atrazine with bimetallic Bi/Fe0: Reactivity, oxidation and mechanism.

The oxidative degradation of atrazine (ATR) using bimetallic Bi/Fe0 nanoparticles cooperated with citric acid (CA) and sodium citrate (NaCA) without extra addition of H2O2 or another oxidant was conducted. Almost 73% of ATR was removed in Bi/Fe0+NaCA + CA buffer system in 3 h, and the bimetallic Bi/Fe0 performs high stability and long service life in the buffer system according to the results of cyclic degradation experiments. The citrate iron complex of Fe(II)[Cit]- played the key role for the degradation process since it could quickly react with the generated H2O2 to produce free radicals in the Bi/Fe0+NaCA + CA system, which broadened the applicable pH range of the traditional Fenton reaction and promoted the oxidative degradation process of ATR. The possible degradation pathways of ATR were also investigated. In the Bi/Fe0+NaCA + CA buffer system, twelve kinds of ATR intermediate products were detected, of which the main products were dechlorination products and alkyl oxidative products. Due to the pH controllable of the Bi/Fe0+NaCA + CA system, it could reduce the acidity impact on the environment and makes the additional impact on the environment lower. Therefore, this work provides a new strategy for the degradation of ATR.

Fabrication of novel Ag4Bi2O5-x towards excellent photocatalytic oxidation of gaseous toluene under visible light irradiation.

In this work, a novel oxide combined with bismuth (Bi) and silver (Ag) was prepared via simple ball milling. This substance was optimized by adjusting the amount of pre-source. Preliminary characterization results confirmed the successful synthesis of Ag4Bi2O5. Subsequently, gaseous toluene was selected as model compound to evaluate the photocatalytic activity of Ag4Bi2O5 photocatalyst. According to the degradation results, Ag4Bi2O5 performed excellent visible light-driven photocatalytic activity with high stability. For the oxidation process of gaseous compound, reactive oxygen species (ROS) were responsible for the achievement, and the formation of oxygen vacancies on Ag4Bi2O5 were involved in the generation of ROS to promote the transfer of photogenerated electrons, and improving photocatalytic activity. DFT calculations revealed the theoretical band gap of Ag4Bi2O5 bulk is 1.758 eV. And the work function of Ag4Bi2O5 (112)ov was ca. at 4.447 eV. The material was easily fabricated and a reliable path was provided for the synthesis of new and efficient photocatalyst for the remediation of polluted indoor air.

Oxygen vacancies enhanced photocatalytic activity towards VOCs oxidation over Pt deposited Bi2WO6 under visible light.

A novel Pt assisted self-modified Bi2WO6 composites (Pt/Bi-BWO) with high oxygen vacancies concentration was successfully fabricated via a simple in-situ NaBH4 reduction method in presence of H2PtCl6•6H2O. The Pt/Bi-BWO performed excellent photocatalytic activity on the degradation of gaseous toluene under visible light illumination. The photocatalytic reaction rate of 0.15% Pt/Bi-BWO was 2.88 times higher than that of Bi2WO6. Over 90% gas phase toluene was removed by 0.15% Pt/Bi-BWO in one hour and over 80% of which was degraded into CO2 and H2O. The Pt/Bi-BWO also performed great stability confirmed by circulating runs test. The mechanism of the promotion was explored by electron paramagnetic resonance (EPR) and DFT calculations. The produced oxygen vacancies were below conduction band (CB) of Bi2WO6, leading to a narrowed band gap. Meantime, the generated oxygen vacancies could activate O2 to enhance the production of reactive oxygen species (ROS), such as O2- and OH. In addition, the added Pt could act as electron trap to suppress the recombination of electrons-holes pairs. In a word, this work produced a novel simply made photocatalyst to remove volatile organic compounds.

Synergistic utilization of inherent halides and alcohols in hydraulic fracturing wastewater for radical-based treatment: A case study of di-(2-ethylhexyl) phthalate removal.

The degradation of di-(2-ethylhexyl) phthalate (DEHP) was examined as an example to capitalize on the potential interactions of peroxydisulfate (PS) and ferrous iron (Fe2+) in the model Day-1/Day-90 and on-site hydraulic fracturing wastewater (FWW). The primary oxidative radicals in the Fe2+/PS system (i.e., SO4- and OH) were less effective for the degradation of DEHP (6.45%) in ultrapure water. Both chloride (Cl-) and bromide (Br-) at equivalent molar ratio with PS enhanced DEHP degradation (15.6% and 45.5%, respectively) via the generation of Cl and Br radicals, whereas the degradation rate was inhibited by the excessive amount of Cl- or Br- in the Day-1/Day-90 FWW. However, the co-presence of ethylene glycol (C2H4(OH)2, 0.043% v/v in the FWW) and halide ions (Cl- or Br-, 0.05 mM) resulted in the highest removal efficiency of 82.6 - 88.5% within 10 min by Fe2+/PS. Further investigation revealed that the formation of reductive alcohol radicals (C2H3(OH)2) slowed down or replenished the Fe2+ exhaustion. This study demonstrated that the Fe2+/PS-based advanced oxidation may show a synergistic interplay with Cl-/Br- and C2H4(OH)2 in the FWW, which depends on their relative concentrations. Thus, the inherent constituents in the fracturing wastewater can be utilized for the catalytic degradation of co-existing organic contaminants.

Photocatalytic production of dihydroxyacetone from glycerol on TiO2 in acetonitrile.

In this paper, photocatalytic production of dihydroxyacetone (DHA) from glycerol in acetonitrile on TiO2 was investigated. HPLC-MS analysis showed that glycerol was converted to DHA, glyceraldehyde (GAD), glyceric acid and several other chemicals. Using acetonitrile as the reaction medium instead of water not only provided a more selective process for production of DHA but also increased the glycerol conversion. After 300 min, with 1 g L-1 catalyst loading and 4 mM initial glycerol concentration, glycerol conversion and DHA selectivity were 96.8% and 17.8% in acetonitrile compared to 36.1% and 14.7% in water, respectively. The half-life of glycerol decreased by a factor of 6.2, from 467 min to 75 min, by changing the solvent from water to acetonitrile. Experiments using biodiesel-derived crude glycerol verified the effectiveness of the proposed process for the photocatalytic production of DHA from crude glycerol. A mechanism was proposed to explain the higher selectivity towards DHA over GAD in this process.

Sunflower stalk-derived biochar enhanced thermal activation of persulfate for high efficient oxidation of p-nitrophenol.

Sunflower stalk-derived biochars (BC) were prepared at various temperatures (i.e., 500, 650, and 1000 °C) and demonstrated as a highly efficient catalyst in persulfate (PS) activation for the oxidation of p-nitrophenol (PNP) at 60 °C. The apparent PNP oxidation rate constant in the BC500 (0.1543 L mol-1 S-1), BC650 (0.6062 L mol-1 S-1), or BC1000 (2.1379 L mol-1 S-1) containing PS system was about 2, 8 and 28 times higher than that in PS/PNP (0.0751 L mol-1 S-1) system, respectively. The effect of reaction temperature on PNP oxidation was also investigated. Furthermore, the radical quenching tests and electron paramagnetic resonance spectroscopy (EPR) were employed to investigate the sulfate and hydroxyl radicals for PNP oxidation. The Raman results suggested that the defective sites on biochars possess vital role for oxidation of PNP in PS system. The possible activation pathway of PS/BC was proposed that the defective sites on BC were involved for weakening the O-O bond in PS and subsequently cleaving O-O bond by heat to generate sulfate radical. The oxidation of PNP at low concentration (below 100 µg L-1) was completely removed in urban wastewater by PS/BC system within 30 min. This work would provide new insights into PS activation by BC catalyst and afford a promising method for organic pollutant removal in high-temperature wastewater.

A genetic variant rs13293512 in the promoter of let-7 is associated with an increased risk of breast cancer in Chinese women.

Growing evidence has demonstrated that single-nucleotide polymorphisms (SNPs) in the promoter of miRNA may influence individuals' susceptibility to human diseases. We examined two SNPs rs10877887 and rs13293512 in the promoters of let-7 family to determine if the two SNPs were related to the occurrence of breast cancer (BC). Genotyping of the two SNPs was performed by PCR and restriction fragment length polymorphism analysis or TaqMan assay in 301 BC patients and 310 age matched controls. We found a higher frequency of rs13293512 CC genotype and rs13293512 C allele amongst BC patients (CC vs TT: adjusted odds ratio (OR) = 1.78; 95% CI: 1.14-2.80; P=0.012; C vs T: adjusted OR = 1.33; 95% CI: 1.06-1.67; P=0.013). Stratification analysis showed that rs13293512 CC genotype was associated with an increased risk of BC in patients with negative estrogen receptor (adjusted OR = 2.39; 95% CI: 1.32-4.30; P=0.004), patients with negative progesterone receptor (adjusted OR = 1.92; 95% CI: 1.11-3.33; P=0.02), patients with T1-2 stage cancer (adjusted OR = 1.77; 95% CI: 1.07-2.93; P=0.03), and patients with N1-3 stage cancer (adjusted OR = 1.89; 95% CI: 1.13-3.17; P=0.015). These findings suggest that rs13293512 in the promoter of let-7a-1/let-7f-1/let-7d cluster may be a possible biomarker for the development of BC in Chinese women.

Novel visible light enhanced Pyrite-Fenton system toward ultrarapid oxidation of p-nitrophenol: Catalytic activity, characterization and mechanism.

The activities of heterogeneous Fenton and Photo-Fenton processes using pyrite (FeS2) prepared via a solvethermal method were evaluated by oxidation of p-nitrophenol (PNP). PNP could be completely ultrarapidly oxidized by Pyrite-Photo-Fenton (Pyrite-PF) system within 4 min, versus 10 min in Pyrite-Fenton (Pyrite-F) system. The excellent oxidation performance obtained by Pyrite-PF might be due to accelerated circulation between ferrous ions and ferric ions under visible light illumination, which improved generation of reactive oxygen species (ROS). X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) were applied to ascertain the morphology and crystal structure of fresh-pyrite as well as used-pyrite. According to these results, the synthesized pyrite particles performed eminent stability, and used-pyrite could even generated more ROS including hydroxyl radicals (OH) and superoxide radicals (O2-). EPR testing and quenching experiments also confirmed the generations of OH, O2- and holes (h+) during oxidation processes of PNP in both Pyrite-F and Pyrite-PF systems. The reaction pathway was proposed based on the detected intermediate products including 4-nitrocatechol, 4-nitropyrogallol, hydroquinone, benzoquinone, 1,2,4-trihydroxybenzene and 2,4-dinitrophenol. The mechanisms of PNP degradation in Pyrite-F and Pyrite-PF systems have also been studied by DFT calculations. Pyrite (111) should be responsible for the generations of free OH and surface OH.

Photosensitized diastereoisomer-specific degradation of hexabromocyclododecane (HBCD) in the presence of humic acid in aquatic systems.

Humic acids (HA) are the most important photosensitizers in the ocean and generate highly reactive oxygen species (ROS), known as photochemically produce reactive intermediates (PPRI), which degrade organic pollutants. Thus, to reveal the fate of organic pollutants in an aqueous environment, it is important to understand the natural photodegradation phenomenon caused by HA. Three ROS generated from HA, 1O2, O2-, and OH, were measured using different probe compounds and instrumental techniques. In this study, HBCD (hexabromocyclododecane), a newly listed one of persistent organic pollutants (POPs) under the Stockholm Convention, was studied to understand the phototransformation mechanism, which has not been sufficiently investigated in terms of its environmental fate and transport, despite the distinctive features of its diastereoisomers. The results showed that the diastereoisomer-specific distributions of α-, ß-, and γ-HBCD were related to the acceleration and retardation of photodegradation in the presence of AHA (Aldrich Humic Acid) under simulated solar light, and only α-HBCD was rapidly photodegraded as the amount of AHA increased relative to the absence of AHA. This study provides the first characterization of the behavior of photosensitized HBCD degradation in aquatic systems.

Self-Generation of Reactive Oxygen Species on Crystalline AgBiO3 for the Oxidative Remediation of Organic Pollutants.

In this study, we synthesized a novel perovskite nanomaterial consisting of AgBiO3 nanoparticles (NPs) via an ion-exchange method for remediation of polluted environments. The AgBiO3 NPs could self-produce significant amounts of reactive oxygen species (ROS) without light illumination or any other additional oxidant due to the controllable release of lattice oxygen from the crystalline AgBiO3, resulting in the formation of ROS somehow. The self-produced 1O2, O2•-, and •OH were confirmed by electron spin resonance spectroscopy using a spin trap technique. We found that the AgBiO3 NPs could be reused for the mineraliztion of most recalcitrant organic compounds alone, including Rhodamine B (RhB), phenol, 4-chlorophenol, 2,4-dichlorophenol, and bisphenol A. After the repeated eight cycles of continious treatment of RhB, AgBiO3 NPs still achieved 79% of degradation after 30 min of treatment. Characterization results revealved that the lattice oxygen inside AgBiO3 was activated to form active oxygen (O*), which resulted in consecutive formation of ROS. This study provides new insight on the lattice oxygen activation mechanism of silver bismuthate and its application to the remediation of polluted waters.

Molybdenum-Tungsten Mixed Oxide Deposited into Titanium Dioxide Nanotube Arrays for Ultrahigh Rate Supercapacitors.

A novel method involving the fabrication of Mo-W mixed oxide (MoxW1-xO3) is proposed to modify the modest reaction kinetics and poor cycling stability of MoO3 material. By a simple coelectrodeposition method, a series of MoxW1-xO3 oxides is deposited on a TiO2 nanotube array substrate. Because of the differences between Mo6+ and W6+ in nature, there is significant distortion existing in the mixed oxides, leading to their decreased crystallite size and enlarged lattice space, which facilitates ion diffusion in the solid. As results, the mixed oxides show much better balance between specific capacitance and cycling stability than the bare MoO3 or WO3 sample, which suffers from either poor cycling stability or low electrochemical activity. Impressively, the optimal Mo-W mixed oxide exhibits a high specific capacitance of 517.4 F g-1 at 1 A g-1, and, moreover, it retains 89.3% of the capacitance even at a high current density of 10 A g-1, demonstrating ultrahigh rate capability. These findings reveal the potential of the Mo-W mixed oxide for constructing advanced ultrahigh power supercapacitors.

Enhancing the reactivity of bimetallic Bi/Fe(0) by citric acid for remediation of polluted water.

In this study, the environmentally benign citric acid (CA) was utilized to improve the aerobic degradation of 4-chlorophenol (4-CP) over bismuth modified nanoscale zero-valent iron (Bi/Fe(0)). The characterization results revealed the existence of bismuth covering on the Fe(0) surface under zero-valent state. And, the Bi/Fe(0)-CA+O2 system performed excellent reactivity in degradation of 4-CP due to the generation of reactive oxygen species (ROS), which was confirmed by electron spin resonance (ESR) spectroscopy. After 30min of reaction, 80% of 4-CP was removed using Bi/Fe(0)-CA+O2 accompanying with high dechlorination rate. The oxidative degradation intermediates were analyzed by HPLC and LC-MS. We found that CA could promote the bismuth-iron system to produce much reactive oxygen species ROS under both aerobic and anaerobic conditions due to its ligand function, which could react with Fe(3+) to form a ligand complex (Fe(III)Cit), accompanying with a considerable production of Fe(2+) and H2O2. This study provides a new strategy for generating ROS on nZVI and suggests its application for the mineralization of many recalcitrant pollutants.

Novel self-assembled bimetallic structure of Bi/Fe(0): the oxidative and reductive degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX).

A novel self-assembled bimetallic zero-valent bismuth/iron (Bi/Fe(0)) composite was synthesized, characterized, and used successfully to remove hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from wastewater. To assess the oxidative and reductive reactivities of Bi/Fe(0) nanoparticles (NPs), RDX degradation experiments were conducted in either ambient or anaerobic conditions, respectively. The best RDX degradation was achieved using 4%-Bi/Fe(0) (atomic ratio) NPs. In ambient conditions, concentrations of Fe(2+) ions and H2O2 were lower in the Bi/Fe(0) solution than in the Fe(0) solution; this difference indicates that most Fe(2+) ions and H2O2 reacted to produce hydroxyl radicals (*OH) and superoxide radical anions (O2(*-)), thereby resulting in the remarkable degradation of RDX. In anaerobic conditions, the presence of Bi increased the electron generation rate from the surfaces of the Bi/Fe(0) NPs. This increase was responsible for the excellent reductive degradation of RDX. Based on Density Functional Theory (DFT) calculations, the adsorption of water was endothermic on Fe(0) NPs and exothermic on Bi/Fe(0) NPs. Therefore, only the dissociation reactions of H2O in the Bi/Fe(0) system were spontaneous, and these reactions resulted in the prominent reactivity of the Bi/Fe(0) NPs.

Fabrication of novel oxygen-releasing alginate beads as an efficient oxygen carrier for the enhancement of aerobic bioremediation of 1,4-dioxane contaminated groundwater.

Oxygen-releasing alginate beads (ORABs), a new concept of oxygen-releasing compounds (ORCs) designed to overcome some limitations regarding the fast oxygen release rate and the high pH equilibrium of ORCs, were fabricated to promote the stimulation of aerobic biodegradation in anaerobic groundwater. Slow oxygen-releasing rate and maintenance of constant pH were achieved by changing the parameters (ionic radius and valence) related to the cross-linking ions composing ORABs, and the best results were obtained for ORABs cross-linked with Al (Al-ORABs). Furthermore, the mechanism of the improved aerobic biodegradation using Al-ORABs under oxygen-limiting groundwater conditions was elucidated in batch and column studies with 1,4-dioxane and Mycrobacterium sp. PH-06 as a model contaminant and aerobic microbes, respectively. Maximum 1,4-dioxane degradations of 99% and 68.1% were achieved when Al-ORABs were applied in batch and column conditions, respectively, whereas 34.3% and 18% of 1,4-dioxane were degraded without Al-ORABs in batch and column conditions, respectively.

A novel self-assembling nanoparticle of Ag-Bi with high reactive efficiency.

A novel Ag-Bi nanoparticle has been prepared via a facile precipitation approach. The nanoparticle could achieve purification of contaminated water without supplements and exhibited much higher activity compared to other popular nanoparticles (e.g. nZVI). The excellent performance of Ag-Bi was due in part to a large production of ˙OH radicals.

Carboxymethyl cellulose coating decreases toxicity and oxidizing capacity of nanoscale zerovalent iron.

Nanoscale zerovalent iron (NZVI) with modified surface via coating with organic stabilizers has been documented with enhanced colloidal stability and dispersity. Therefore, the expanded application potential and accompanying intrinsic exposure of such nanoparticle can be anticipated. In our study, carboxymethyl cellulose (CMC)-stabilized NZVI (CNZVI) exerted minimized oxidative stress response and slower disruption of cell membrane integrity, resulting in mitigated cytotoxicity towards bacteria Agrobacterium sp. PH-08 as compared with the uncoated counterpart. The corrosive oxidation of both nanoparticles in oxygenic water provided a better understanding of coating effect. The decreased oxidative degradation of probe 4-chlorophenol with CNZVI than NZVI implicated a weaker oxidizing capacity, which might overweight massive adhesion-mediated redox damage and explain the different exposure outcome. However, enhanced evolution of iron oxide as well as the promoted production of hydrogen peroxide adversely demonstrated CMC-coating facilitated iron corrosion by oxygen, suggesting CMC was most likely to act as a radical scavenger and compete with organics or bacteria for oxidants. Moreover, XRD, XPS and TEM results showed that the spherical NZVI was oxidized to form needle-shaped iron oxide-hydroxide (γFeOOH) with no detectable oxidative stress for PH-08, alleviating worries regarding exotoxicological impact of iron nanotechnology.