Nitrogen-doped metal-free granular activated carbons as economical and easily separable catalysts for peroxymonosulfate and hydrogen peroxide activation to degrade bisphenol A.

The fabrication of low-cost, highly efficient, environmentally friendly, and easily separable metal-free heterogeneous catalysts for environmental remediation remains a challenge. In this study, granular nitrogen-doped highly developed porous carbons with a particle size of 0.25-0.30 mm were prepared by preoxidation and subsequent NH3 modification of a commercially available coconut-based activated carbon, and used to activate peroxymonosulphate (KHSO5) or hydrogen peroxide (H2O2) to degrade bisphenol A (BPA). The nitrogen-doped carbon (ACON-950) prepared by NH3 modification at 950 °C, with the addition of only 0.15 g/L could remove 100% of 50 mg/L BPA in 150 min, and more than 90% of the removed BPA was due to degradation. The removal rates of total organic carbon of ACON-950/KHSO5 and ACON-950/H2O2 systems reached 60.4% and 66.2% respectively, indicating the excellent catalytic activity of ACON-950. The reaction rate constant was significantly positively correlated with the absolute content of pyridinic N (N-6) and graphitic N (N-Q) and negatively and weakly positively correlated with pyrrolic N (N-5) and defects. Quenching experiments combined with electron paramagnetic resonance demonstrated that singlet oxygen was the dominant reactive oxidative species for BPA degradation. ACON-950 was characterized before and after the degradation reaction using N2 adsorption-desorption analyzer, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results confirmed the prominent contribution of both the N-6 and N-Q to the catalytic performance of nitrogen-doped carbons. The reusability of ACON-950 and its application in actual water bodies further demonstrated its remarkable potential for the remediation of organic pollutants in wastewater.

Mechanism and ecological environmental risk assessment of peroxymonosulfate for the treatment of heavy metals in soil.

Oxidation technologies based on peroxymonosulfate (PMS) have been effectively used for the remediation of soil organic pollutants due to their high efficiency. However, the effects of advanced PMS-based oxidation technologies on other soil pollutants, such as heavy metals, remain unknown. In this study, changes in the form of heavy metals in soil after using PMS and the risk of pollution to the ecological environment were investigated. Furthermore, two risk assessment methods, the mung bean germination toxicity test and groundwater leaching soil column test, were employed to evaluate the soil before and after PMS treatment. The results showed that PMS has a strong ability to degrade complex compounds, enabling the transformation of heavy metals, such as Cd, Pb, and Zn, from stable to active states in the soil. The risk assessments showed that PMS treatment activated heavy metals in the soil, which delayed the growth of plants, increased heavy metal content in plant tissues and the risk of groundwater pollution. These findings provide a new perspective for understanding the effects of PMS on soil, thus facilitating the sustained and reliable development of future research in the field of advanced oxidation applied to soil treatment.

Assessment of color changes and adverse effects of over-the-counter bleaching protocols: a systematic review and network meta-analysis.

OBJECTIVES: To assess color change efficacy and the adverse effects of varied over-the-counter (OTC) bleaching protocols. METHODOLOGY: The study included randomized clinical trials evaluating color changes from OTC bleaching agents. Nine databases were searched, including the partial capture of the grey literature. The RoB2 tool analyzed the individual risk of bias in the studies. Frequentist network meta-analyses compared treatments through common comparators (∆Eab* and ∆SGU color changes, and tooth sensitivity), integrating direct and indirect estimates and using the mean and risk differences as effect measures with respective 95% confidence intervals. The GRADE approach assessed the certainty of the evidence. RESULTS: Overall, 37 remaining studies constituted the qualitative analysis, and ten composed the meta-analyses. The total sample included 1,932 individuals. ∆Eab* was significantly higher in groups 6% hydrogen peroxide (HP) strips (≥ 14 h). ∆SGU was significantly higher in groups at-home 10% carbamide peroxide (CP) (≥ 14 h), followed by 6% HP strips (≥ 14 h) and 3% HP strips (≥ 14 h). At-home 10% CP (7-13 h) and placebo showed lower risks of tooth sensitivity without significant differences between these treatments. CONCLUSION: Considering the low level of evidence, OTC products presented satisfactory short-term effects on tooth bleaching compared to the placebo, with little to no impact on dentin hypersensitivity and gingival irritation. CLINICAL RELEVANCE: OTC products are proving to be practical alternatives for tooth whitening. However, patients should be advised about the possible risks of carrying out such procedures without professional supervision.

Computational model of radiation oxygen effect with Monte Carlo simulation: effects of antioxidants and peroxyl radicals.

PURPOSE: Oxygen plays a crucial role in radiation biology. Antioxidants and peroxyl radicals affect the oxygen effect greatly. This study aims to establish a computational model of the oxygen effect and explore the effect attributed to antioxidants and peroxyl radicals. MATERIALS AND METHODS: Oxygen-related reactions are added to our track-structure Monte Carlo code NASIC, including oxygen fixation, chemical repair by antioxidants and damage migration from base-derived peroxyl radicals. Then the code is used to simulate the DNA damage under various oxygen, antioxidant and damage migration rate conditions. The oxygen enhancement ratio(OER) is calculated quantifying by the number of double-strand breaks for each condition. The roles of antioxidants and peroxyl radicals are examined by manipulating the relevant parameters. RESULTS AND CONCLUSIONS: Our results indicate that antioxidants are capable of rapidly restoring DNA radicals through chemical reactions, which compete with natural and oxygen fixation processes. Additionally, antioxidants can react with peroxyl radicals derived from bases, thereby preventing the damage from migrating to DNA strands. By quantitatively accounting for the impact of peroxyl radicals and antioxidants on the OER curves, our study establishes a more precise and comprehensive model of the radiation oxygen effect.

Novel calcium oxide activated peroxymonosulfate system for methylene blue removal: Identification of key influencing factors, transformation pathway and toxicity assessment.

The activation of peroxymonosulfate (PMS) has gained significant interest in the removal of organic pollutants. However, traditional methods usually suffer from drawbacks such as secondary contamination and high energy requirements. In this study, we propose a green and cost-effective approach utilizing calcium oxide (CaO) to activate PMS, aiming to construct a simple and reliable PMS based advanced oxidation processes (AOPs). The proposed CaO/PMS system achieved fast degradation of methylene blue (MB), where the degradation rate of CaO/PMS system (0.24 min-1) was nearly 2.67 times that of PMS alone (0.09 min-1). Under the optimized condition, CaO/PMS system exhibited remarkable durability against pH changes, co-exists ions or organic matters. Furthermore, singlet oxygen (1O2) was identified as the dominant reactive oxygen species by electron paramagnetic resonance (EPR) and quenching tests. Accordingly, the degradation pathways of MB are proposed by combing the results of LC/MS analysis and density functional theory (DFT) calculations, and the predicted ecotoxicity of the generated byproducts evaluated by EOCSAR could provide systematic insights into the fates and environmental risks of MB. Overall, the study provides an eco-friendly and effective strategy for treating dyeing wastewater, which should shed light on the application of PMS based AOPs.

Coating CoFe2O4 shell on Fe particles to increase the utilization efficiencies of Fe and peroxymonosulfate for low-cost Fenton-like reactions.

Bimetallic composites (Fe@CoFe2O4) with zero-valent Fe as the core encapsulated by CoFe2O4 layers are synthesized by a coprecipitation-calcination method, which are applied to activate PMS for the degradation of bisphenol A (BPA). Enhanced activity of Fe@CoFe2O4 is achieved with very fast degradation rate (kobs = 0.5737 min-1). In the fixed-bed reactor, the catalyst lifetime (tul) of Fe@CoFe2O4 is determined to be 22 h compared to 11 h of Fe, and the deactivation rate constant (kd) for Fe@CoFe2O4 is 0.0083 mg·L-1·h-1, only ∼1/10 of Fe (0.0731). The XPS results indicate that the core-shell structure of Fe@CoFe2O4 could promote the redox cycles of Co3+/Co2+ and Fe3+/Fe2+. It is proved that the coating of CoFe2O4 shell on Fe0 can protect the Fe0 core from being oxidized by PMS to form passivation layer. The electrons of Fe0 can therefore be used effectively for activating PMS to produce ROSs via the CoFe2O4 shell. This modification method of Fe0 would decrease the cost of PMS based wastewater remediation greatly, thus should have great potential on an industrial scale.

Synergistic enhancement of redox pairs and functional groups for the removal of phenolic organic pollutants by activated PMS using silica-composited biochar: Mechanism and environmental toxicity assessment.

In present work, a novel catalyst of cobalt supported on silica-composited biochar (Co@ACFA-BC) derived from fly ash and agricultural waste was synthesized. A series of characterizations confirmed that Co3O4 and Al/Si-O compounds were successfully embedded on the surface of biochar, which triggered superior catalytic activity for PMS activation towards phenol degradation. Particularly, the Co@ACFA-BC/PMS system could completely degrade phenol in the wide pH range, and was almost unaffected by environmental factors including humic acid (HA), H2PO4-, HCO3-, Cl-, and NO3-. Further quenching experiment and EPR analysis proved that both radical (SO4·-, ·OH, O2·-) and non-radical (1O2) pathways were involved in the catalytic reaction system, and the excellent PMS activation was attributed to the electron pair cycling of Co2+/Co3+ and the active sites provided by Si-O-O and Si/Al-O bonds on the catalyst surface. Meanwhile, the carbon shell effectively inhibited the leaching of metal ions, enabling the Co@ACFA-BC catalyst to maintain excellent catalytic activity after four cycles. Finally, biological acute toxicity assay demonstrated that the toxicity of phenol could be significantly reduced after being treated by Co@ACFA-BC/PMS. Overall, this work provides a promising strategy for solid waste valorization and a feasible methodology for green and efficient treatment of refractory organic pollutants in water environment.

Remediation and resource utilization of petroleum-contaminated soil by pyrite-assisted pyrolysis as bifunctional materials to adsorb heavy metal and activate peroxymonosulfate oxidation.

Petroleum-contaminated soil (PCS) requires not only efficient remediation technology but also economically viable reuse strategy of remediated soil with vast volume. This study developed a pyrite-assisted pyrolysis to convert PCS into a bifunctional material for the adsorption of heavy metal and the activation of peroxymonosulfate (PMS) oxidation. Adsorption isotherm and kinetic model fitting by Langmuir and pseudo-second-order well clarified the adsorption capacity and behavior of carbonized soil (CS) loaded with sulfur and iron (FeS@CS) for heavy metals. The theoretic maximum adsorption capacities of Pb2+, Cu2+, Cd2+, and Zn2+ by Langmuir model were 415.40, 80.25, 61.55, and 30.90 mg/g, respectively. The main adsorption mechanism includes sulfide precipitation, co-precipitation and surface complexation by iron oxides, and complexation by oxygen-containing functional groups. When the dosage of FeS@CS and PMS were both 3 g/L, the removal rate of aniline reached 99.64 % in 6 h. After five cycles of reuse, the aniline degradation rate was still as high as 93.14 %. The non-free radical pathway dominated in CS/PMS and FeS@CS/PMS systems. The electron hole was the primary active species in the CS/PMS system, which promoted aniline degradation by accelerating direct electron transfer. In comparison with CS, the surface of FeS@CS contained more iron oxides, oxygen-containing functional groups, and oxygen vacancies, making 1O2 the primary active species in the FeS@CS/PMS system. This study proposed a new integrated strategy for the efficient remediation of PCS and value-added reutilization of remediated soil.

Impact of aerosol in-situ peroxide formations induced by metal complexes on atmospheric H2O2 budgets.

Hydrogen peroxide (H2O2), hydroxyl radicals (OH), hydroperoxyl (HO2), and superoxide (O2-) radicals interacting with aerosol particles significantly affect the atmospheric pollutant budgets. A multiphase chemical kinetic box model (PKU-MARK), including the multiphase processes of transition metal ions (TMI) and their organic complexes (TMI-OrC), was built to numerically drive H2O2 chemical behaviors in the aerosol particle liquid phase using observational data obtained from a field campaign in rural China. Instead of relying on fixed uptake coefficient values, a thorough simulation of multiphase H2O2 chemistry was performed. In the aerosol liquid phase, light-driven TMI-OrC reactions promote OH, HO2/O2-, and H2O2 recycling and spontaneous regenerations. The in-situ generated aerosol H2O2 would offset gas-phase H2O2 molecular transfer into the aerosol bulk phase and promote the gas-phase level. When combined with the multiphase loss and in-situ aerosol generation involving TMI-OrC mechanism, the HULIS-Mode significantly improves the consistency between modeled and measured gas-phase H2O2 levels. Aerosol liquid phase could be a pivotal potential source of aqueous H2O2 and influence the multiphase budgets. Our work highlights the intricate and significant effects of aerosol TMI and TMI-OrC interactions on the multiphase partitioning of H2O2 when assessing atmospheric oxidant capacity.

Assessment of Bioactive Phytochemicals and Utilization of Rosa canina Fruit Extract as a Novel Natural Antioxidant for Mayonnaise.

The oxidation of food emulsions causes rancidity, which reduces their shelf life. To prevent rancidity, synthetic antioxidants are widely used in the food industry. However, due to their potential health risks, researchers are exploring natural alternatives. This study aimed to investigate whether Rosa canina fruit extract (RCFE) could be used as a natural antioxidant to extend the shelf life of mayonnaise. Mayonnaise containing varying concentrations of RCFE [0.125% (T1), 0.25% (T2), 0.50% (T3), 0.75% (T4)] was compared to a mayonnaise control sample (C1) and a mayonnaise sample containing 0.02% BHT (C2) for 60 days of storage at 4 °C. RCFE was found to have high levels of total phenols content (52.06 ± 1.14 mg GAE g-1), total flavonoids content (26.31 ± 1.03 mg QE g-1), and free radical scavenging activity. The GC-MS analysis of RCFE revealed 39 different peaks, whereas the HPLC analysis showed the presence of 13 polyphenolic compounds in RCFE. The pH values of T2, T3, and T4 mayonnaise samples substantially declined as storage progressed; however, the reduction was less than that of C1 and C2. After 60 days, mayonnaise samples T2, T3, and T4 had greatly reduced peroxide and free fatty acid levels compared to C1 and C2. The mayonnaise enriched with RCFE (T3 and T4) had the most potent antioxidative ability and the lowest value of lipid hydroperoxides (peroxide value, POV) and the lowest value of thiobarbituric-acid-reactive substances (TBARS). The sensory evaluation revealed that the T3 sample exhibited the highest overall acceptability. In conclusion, this study recommends that RCFE could be used as a natural preservative to enhance the shelf life of functional foods.

Synthesis, Characterization, and Investigation of Novel Ionic Liquid-Based Tooth Bleaching Gels: A Step towards Safer and Cost-Effective Cosmetic Dentistry.

The objective of this study was to synthesize a novel choline hydroxide ionic liquid-based tooth bleaching gel. Ionic liquid-based gels were synthesized and characterized using FTIR along with pH testing. Tooth sample preparation was carried out in line with ISO 28399:2020. The effects of synthesized gels on tooth samples were tested. Tooth samples were stained and grouped into three experimental groups: EAI (22% choline hydroxide gel), EAII (44% choline hydroxide gel), and EB (choline citrate gel) and two control groups: CA (commercial at-home 16% carbamide peroxide gel) and CB (deionized water). The tooth color analysis, which included shade matching with the Vitapan shade guide (n = 2), and digital colorimetric analysis (n = 2) were evaluated. The surface characteristics and hardness were analyzed with 3D optical profilometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Microhardness testing (n = 3), respectively. The tooth color analysis (Vitapan shade guide) revealed that all the tooth samples treated with synthesized choline citrate gel (EB) showed an A1 shade as compared to the other four groups, giving a range of shades. An analysis of the ΔE values from digital colorimetry; EAI, EAII, CA, and CB showed ΔE values in a range that was clinically perceptible at a glance. However, EB showed the highest value of ΔE. The mean microhardness values for the five groups showed that the effects of three experimental gels i.e., 44% choline hydroxide, 22% choline hydroxide, and choline citrate, on the microhardness of the tooth samples were similar to that of the positive control, which comprised commercial at-home 16% carbamide peroxide gel. SEM with EDX of three tested subgroups was closely related in surface profile, elemental composition, and Ca/P ratio. The roughness average values from optical profilometry of four tested subgroups lie within approximately a similar range, showing a statistically insignificant difference (p > 0.05) between the tested subgroups. The synthesized novel experimental tooth bleaching gels displayed similar tooth bleaching actions without any deleterious effects on the surface characteristics and microhardness of the treated tooth samples when compared with the commercial at-home tooth bleaching gel.

The efficient degradation of diclofenac by ferrate and peroxymonosulfate: performances, mechanisms, and toxicity assessment.

In this study, the degradation efficiency and reaction mechanisms of diclofenac (DCF), a nonsteroidal anti-inflammatory drug, by the combination of ferrate (Fe(VI) and peroxymonosulfate (PMS) (Fe(VI)/PMS) were systematically investigated. The higher degradation efficiency of DCF in Fe(VI)/PMS system can be obtained than that in alone persulfate (PS), Fe(VI), PMS, or the Fe(VI)/PS process at pH 6.0. DCF was efficiently removed in Fe(VI)/PMS process within a wide range of pH values from 4.0 to 8.0, with higher degradation efficiency in acidic conditions. The increasing reaction temperature (10 to 30 ℃), Fe(VI) dose (6.25 to 100 µM), or PMS concentration (50 to 1000 µM) significantly enhanced the DCF degradation. The existences of HCO3¯, Cl¯, and humic acid (HA) obviously inhibited the DCF removal. Electron paramagnetic resonance (EPR), free radical quenching, and probing experiments confirmed the existence of sulfate radicals (SO4•¯), hydroxyl radicals (•OH), and Fe(V)/ Fe(IV), which are responsible for DCF degradation in Fe(VI)/PMS system. The variations of TOC removal ratio reveal that the adsorption of organics with ferric particles, formed in the reduction of Fe(VI), also were functioned in the removal process. Sixteen DCF transformation byproducts were identified by UPLC-QTOF/MS, and the toxicity variation was evaluated. Consequently, eight reaction pathways for DCF degradation were proposed. This study provides theoretical basis for the utilization of Fe(VI)/PMS process.

In vitro assessment of activated charcoal-based dental products.

OBJECTIVE: Assess the effects of activated charcoal-based products on whitening and changes on dental enamel surface. MATERIAL AND METHODS: Fifty-two blocks of bovine dental enamel were randomly distributed in four groups (n = 13): brushing with activated charcoal-based powder (PW); brushing with activated charcoal-based dentifrice (AC); brushing with a conventional dentifrice containing 1450 ppm of fluoride (CD); and whitening with 10% carbamide peroxide (CP). Color, microhardness, and surface alteration were analyzed at baseline and after 14 days of treatment. Three samples per group were randomly selected and examined using scanning electron microscopy (SEM) to analyze the morphology. RESULTS: PW exhibited greater color change for the ΔE00 , ΔWID, Δb* and ΔL* parameters than other groups (p < 0.05). After treatment, microhardness decreased in AC and CP groups (p < 0.05). Also, PW and AC groups showed more surface alteration than CD and CP (p < 0.001). Changes in the morphology of dental enamel were observed by SEM in PW and AC groups. CONCLUSION: Activated charcoal-based products showed a lower whitening effect than 10% carbamide peroxide. These products also influenced dental enamel microhardness, resulting in greater surface alteration. CLINICAL SIGNIFICANCE: Activated charcoal-based products promoted minimum whitening effects with significant enamel surface alteration. The 10% carbamide peroxide was more effective for whitening and caused slight enamel surface alteration.

Comparative assessment of the efficacy of low concentration bleaching agents using quantitative light induced fluorescence in removing stains: An In vitro study.

Background: Tooth discoloration has become a common esthetic problem in recent years. Removal of stains by bleaching is well-documented. Low concentration home bleaching products are available in market in different forms and concentrations. Aim: The aim of this study is to evaluate and compare the efficacy of low concentration commercially available home bleaching products (whitening strip, gel, and mouthwash) in removing stains and whitening the tooth using clinical and digital methods. Materials and Methods: Sixty permanent enamel samples mounted in an acrylic block were artificially stained and randomly divided into four groups. Negative control, 15 % Carbamide peroxide gel group, 2% Hydrogen 16 peroxide mouthwash group and 6% Hydrogen peroxide strip group respectively. The samples were bleached with respective agents according to the manufacturer's instructions. The efficacy on 7th and 14th day was evaluated clinically (SGU change), photographically (ΔE), and using quantitative light-induced fluorescence (ΔF). The data were analyzed using paired t-test and analysis of variance. Results: Postbleaching, 6% hydrogen peroxide strips and 15% carbamide peroxide gel showed maximum improvement (ΔΔF - 15.73 and 11.89, ΔE - 19.8 and 18.9, respectively) when compared to 2% hydrogen peroxide mouthwash and negative control group (ΔΔF - 9.68 and 6.59, ΔE - 15.04 and 9.44, respectively). The difference was statistically significant (P = 0.001). Conclusion: 6% hydrogen peroxide strips and 15% carbamide peroxide gel showed maximum improvement in stain removal and tooth whitening however, the strips showed better efficacy than the gel. Strips have the added advantage of lesser contact period, less salivary dilution, and no gingival contact. Therefore, strips can be a better alternative for gels and mouthwashes.

Assessment of Lipid Quality in Commercial Omega-3 Supplements Sold in the French Market.

Supplementation of omega-3 fatty acids is considered a valuable strategy to supply the low intake of these fatty acids. Thus, the safety of the supplements is an important milestone. Because of that, we analyzed 20 unflavored supplements sold in the French market for fatty acid and triglyceride composition, for EPA and DHA, and for tocol content, as well as for oxidative status. This study found that only 2.5% of the supplements did not meet their label claims for omega-3 content. TAG analysis showed high variability among the triglyceride distribution, and the same trend was also noticed for the tocol content; in fact, a high variability of the distribution of the six tocols (four tocopherols and two tocotrienols) was found among the samples. Of the tested products, all of them complied with peroxide value, p-anisidine value, and Totox values established by the Global Organization for EPA and DHA Omega-3s (GOED) and were not oxidized.

Detection of Hydrogen Peroxide in Liquid and Vapors Using Titanium(IV)-Based Test Strips and Low-Cost Hardware.

Titanium(IV) solutions are known to detect hydrogen peroxide in solutions by a colorimetric method. Xplosafe's XploSens PS commercial titanium(IV)-based peroxide detection test strips are used to detect hydrogen peroxide in liquids. The use of these test strips as gas-phase detectors for peroxides was tested using low-cost hardware. The exposure of these strips to hydrogen peroxide liquid or gas leads to the development of an intense yellow color. For liquids, a digital single-lens reflex camera was used to quantify the color change using standardized solutions containing between 50 and 500 ppm peroxide by mass. Analysis of the images with color separation can provide a more quantitative determination than visual comparison to a color chart. For hydrogen peroxide gas, an inexpensive web camera and a tungsten lamp were used to measure the reflected light intensity as a function of exposure from a test strip held in a custom cell. First-order behavior in the color change with time was observed during the exposure to peroxide vapor over a range of peroxide concentrations from 2 and 30 ppm by volume. For a 1-min measurement, the gas-phase detection limit is estimated to be 1 ppm. A 0.01 ppm detection limit can be obtained with a 1-h exposure time. Titanium(IV)-based peroxide detection test strips are sensitive enough to work as a gas-phase hydrogen peroxide detector.

A low-cost and eco-friendly powder catalyst: Iron and copper nanoparticles supported on biochar/geopolymer for activating potassium peroxymonosulfate to degrade naphthalene in water and soil.

A low-cost and environment-friendly biochar/geopolymer composite loaded with Fe and Cu nanoparticles (Fe-Cu@BC-GM) was prepared by impregnation-calcination using lignin and kaolin as precursors. SEM, FTIR and XRD analysis suggested that the Fe-Cu@BC-GM had a certain pore structure, rich functional groups and stable crystal structure. The obtained Fe-Cu@BC-GM was used as the catalyst of potassium peroxymonosulfate (PMS) for remediation of wastewater and soil polluted by naphthalene (NAP). Experimental results indicated that Fe-Cu@BC-GM exhibited outstanding catalytic performance, and the maximum degradation rate of NAP in water and soil reached 98.35% and 67.98% within 120 min, respectively. The XPS measurement confirmed the presence of successive Fe (Ⅲ)/Fe (Ⅱ) and Cu(Ⅱ)/Cu(Ⅰ) redox pairs cycles on the surface of Fe-Cu@BC-GM, which made Fe (Ⅲ) and Cu(Ⅰ) continuously generated Fe (Ⅱ) activating PMS to produce SO4·- and ·OH for the degradation of NAP. The effects of Fe-Cu@BC-GM/PMS system on plant toxicity were evaluated by analyzing the degradation intermediates and bioassay of mung bean. It was proved that the Fe-Cu@BC-GM/PMS system could degrade NAP into less toxic intermediates, and the seed germination rate, root and stem length of mung bean after soil remediation were not notably different from those of the uncontaminated soil. This work opened new prospect for the application of geopolymer in degradation of persistent organic pollutants (POPs) and provided a cost-effective option for the remediation of the persistent organic pollutants contaminated water and soil.

Assessment of the validity of the quenching method for evaluating the role of reactive species in pollutant abatement during the persulfate-based process.

Reactive species such as sulfate radicals (SO4•-), hydroxyl radicals (•OH), and/or singlet oxygen (1O2) have often been proposed as the main reactive species for pollutant abatement during the persulfate-based process, and their relative importance is conventionally assessed by the quenching method based on an implicit fundamental assumption that the added high-concentration quenchers (e.g., tert-butanol and methanol) only scavenge their target reactive species, but do not considerably affect the other reaction mechanism of the system. To examine the validity of this assumption, this study evaluated the effects of several commonly used quenchers (tert-butanol, methanol, ethanol, isopropanol, furfuryl alcohol, and L-histidine) on the mechanism of a cobalt mediated peroxymonosulfate (Co(II)/PMS) process. The results demonstrate that besides quenching target reactive species, the added high-concentration quenchers can cause many confounding effects on the Co(II)/PMS process, e.g., accelerating PMS decomposition, interfering reactive species production, and quenching of non-target reactive species. Because of these confounding effects, the quenching method can actually lead to serious misinterpretation of the role of reactive species in pollutant abatement during the persulfate-based process. The findings of this study highlight that the underlying assumption of the quenching method is usually invalid for the persulfate-based process. Therefore, it should be cautious to apply the quenching method to investigate the mechanism of the persulfate-based process, and some debatable conclusions of prior studies obtained with the quenching method may require further verification.

Efficient activation of peroxymonosulfate mediated by Co(II)-CeO2 as a novel heterogeneous catalyst for the degradation of refractory organic contaminants: Degradation pathway, mechanism and toxicity assessment.

A series of Co(II)-CeO2 mixed metal oxides were synthesized by a facile hydrothermal-calcination procedure for activating peroxymonosulfate (PMS) and degrading toxic and difficult biodegradable organics. Co(II)-CeO2 showed excellent degradation performance toward rhodamine B (RhB), toluidine blue, methylene blue and diclofenac. RhB is a refractory organic contaminant, and ecotoxicological evaluation unraveled its harmfulness to the biosphere. RhB was selected as the model pollutant to investigate catalytic mechanisms. Parameters affecting degradation performance were profoundly investigated, including Co:Ce feed ratio, initial pH, PMS dosage, catalyst dosage, RhB concentration, coexisting ions and reaction temperature. Reaction mechanisms were proposed based on density functional theory calculations and identifications of reactive oxygen species. Improvements have been achieved in seven aspects compared to previous studies, including 100% degradation ratio in both real water samples and each reuse of the catalyst, ultrafast degradation rate, cost-effectiveness of the catalyst, toxicity-attenuation provided by the developed degradation method, high degree of mineralization for the model pollutant, negligible leaching of active sites, and the enhancement of catalytic performance by utilizing trace leached cobalt, endowing the technique with broad applicability and prospect.

Fruit economic characteristics and yields of 40 superior Camellia oleifera Abel plants in the low-hot valley area of Guizhou Province, China.

In this study, we assessed 26 economic characteristics and yields of the mature fruit of 40 superior Camellia oleifera Abel plants grown at the C. oleifera germplasm resource nursery in the low-hot valley area of Southwest Zuizhou, China, using principal component analysis (PCA). Correlations among the characteristics and the variability of the plants in these characteristics were also analyzed. Out of the 26 characteristics, 16 primary economic characteristics were selected for comprehensive assessment, based on the results of which the plants were ordered to obtain excellent C. oleifera germplasms. The data were subjected to PCA, and the 16 characteristics were integrated into 6 independent comprehensive indices, which included PV1 (single-fruit weight), PV2 (pericarp thickness), PV3 (seed rate), PV4 (total unsaturated fatty acids), PV5 (iodine value) and PV6 (dry seed rate). Then, the sum of the products of the contribution rates of the components and components scores was taken as the comprehensive score of each superior plant. In C. oleifera grown in the low-hot valley area, the oil yield exhibited very significant positive correlations with the dry seed rate and kernel rate but a very significant negative correlation with the 100-seed weight. The dry seed rate exhibited very significant negative correlations with the fruit diameter and fresh seed rate. Among the 26 characteristics, the variations of the acid value, peroxide value, number of fertile seeds, 100-seed weight and single-fruit weight were great; those of the fruit diameter, fruit height, kernel yield, oleic acid and total unsaturated fatty acid were small, showing strong genetic stability. According to the obtained comprehensive scores, the top 10 plants were ordered as follows: CY-6 > CY-13 > CY-31 > CY-11 > CY-16 > CY-22 > CY-28 > CY-23 > CY-24 > CY-29. This result was basically consistent with the ranking result according to the average yield per unit crown width within five years. In the low-hot valley area of Guizhou, C. oleifera exhibits excellent performance in single-fruit weight, total unsaturated fatty acids and kernel rate, 6 characteristics, i.e., acid value, peroxide value, single-fruit weight, the number of fertile seeds, 100-seed weight and α-linolenic acid possess high breeding potentials.