PMS Concentration Research Articles

PMS coupled Mn(II) mediated electrochemistry processes (E-Mn(II)-PMS) on the efficient RB19 wastewater treatment: Focus on the regulation and reinforcement of Mn(III)/Mn(II)

Dye wastewater, represented by reactive blue 19 (RB19), severely threatens the aquatic ecological environment and human health, such that an efficient RB19 wastewater treatment technology should be urgently developed. Based on manganese ion-mediated electrochemistry, PMS was introduced to develop a novel electrocatalytic system (E-Mn(II)-PMS) that can efficiently remove and degrade RB19. The synergistic effect between E, Mn(II), and PMS was verified in this study through comparative experiments of a wide variety of systems. The removal efficiency of RB19 reached 95.1% in 50 min under reasonable power consumption (3.29 kWh/m3). Moreover, the effects exerted by different operating conditions (e.g., initial pH, current density, RB19 concentration, Mn(II) concentration, as well as PMS concentration) and water matrix on the degradation efficiency of RB19 were explored through single factor experiments. The active oxidation species (ROS) and their contribution rate for the degrading and removing RB19 were studied through quenching experiments, EPR experiments, TMT-15 metal capture experiments, as well as PP complexation experiments. The role played by non-free radicals took on critical significance in the oxidation removal of RB19, which comprised direct electro oxidation, Mn(III) oxidation, and 1O2 oxidation. The enhancement effect of free radicals (SO4·− and HO∙) was not sufficiently significant, with a low degree of contribution. The oxidation effect of the anode facilitated the conversion of Mn (II) to Mn (III), which was employed in PMS for expediting the production of 1O2. The reduction effect of the cathode blocked the production of Mn (IV) as a side reaction, such that the continuous circulation of manganese ions between divalent and trivalent was promoted. Meanwhile, the cathode reacted with PMS to generate a small part of SO4·− and HO∙. In addition, the reaction active site of RB19 was predicted, and a possible degradation pathway was proposed in accordance with the mass spectrometry results and the DFT calculation. As revealed by the results of the QSAR analysis and the plant culture experiments, the biological toxicity of RB19 was markedly reduced after the sample was administrated with E-Mn(II)-PMS. E-Mn(II)-PMS-mediated electrochemical technology displays several advantages (e.g., high efficiency, low consumption, recyclability, wide pH window, and strong applicability) while showing promising market development and utilization for treating dye wastewater.

ACTIVATION OF PEROXYMONOSULFATE BY CuCoFe LAYERED DOUBLE HYDROXIDE FOR THE DECOMPOSITION OF LEVOFLOXACIN

In this study, we synthesized CuCoFe-LDH bilayer hydroxide catalysts in different Cu:Co:Fe ratios (1:1:1; 1:2:1, and 1:3:2) by hydrothermal method and applied them to activate PMS for decomposing levofloxacin. The obtained LDH samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results showed that CuCoFe-LDH (1:3:2) has the strongest ability to activate PMS and degrade levofloxacin. After 10 minutes of reaction (catalyst content of 200 mg/L, PMS concentration of 1.629 mM, pH 7, at 30 oC), the decomposition efficiency was 64.89, 83.93, and 92.58% for LDH with ratios of 1:1:1, 1:2:1, and 1:3:2, respectively. The influence of PMS concentration and reaction temperature on levofloxacin degradation was investigated. PMS at high concentrations was beneficial for the formation of active oxygen species. The degradation rate of levofloxacin was affected by temperature and the activation energy was 34.04 kJ/mol.

Strong enhancement on acetaminophen removal in thermal-activated peroxymonosulfate with sodium metaborate: Performance, mechanism, and control of chlorinated by-products formation

This study introduced sodium metaborate (NaBO2) into thermal/PMS system to enhance acetaminophen degradation. The added NaBO2 possessed better performance than sodium tetraborate in accelerating the degradation of acetaminophen with thermal/PMS system over the wide pH range from 3.0 to 11.0. NaBO2 could be partly hydrolyzed to the strong buffer capacity of the pair of H3BO3/B(OH)4− to well keep the reaction solution pH at 9.4–9.7 regardless of the initial pH. HOOB(OH)3− and HOOBO were produced via the reactions between PMS and B(OH)4−/BO2−. 1O2 and HO• were the main ROS accountable for acetaminophen degradation in NaBO2/thermal/PMS system. 1O2 was mainly formed from the self-decomposition of PMS and the reactions between PMS and HOOB(OH)3−/HOOBO. HO• was mainly formed from the thermolysis of the O-O bonds of PMS, HOOB(OH)3− and HOOBO. Three elimination pathways of acetaminophen were proposed according to the identified nine elimination intermediates, and the reaction solution toxicity was significantly decreased in NaBO2/thermal/PMS system. Improving NaBO2 dosage, PMS concentration and reaction temperature could accelerate acetaminophen removal. Cl− and Br− significantly promoted acetaminophen removal, while humic acid had the adverse effect. NaBO2/thermal/PMS system had well anti-interference capacity for actual water constituents. Moreover, the added NaBO2 could significantly inhibit the production of chlorinated by-products via the transformation of the free chlorine to the inert product of B(OH)3OCl− in Cl−-containing water treatment with NaBO2/thermal/PMS system. This study provides an effective method for improving the thermal/PMS system oxidation capacity and suppressing the chlorinated by-products production in Cl−-containing water treatment.

A co-precipitation route for the preparation of eco-friendly Cu-Al-layered double hydroxides with efficient tetracycline degradation.

The construction of novel efficient catalysts for the treatment of organic pollutants in the aqueous environment is essential. The lamellar-like Cu-Al layered double hydroxides (CuAl-LDHs) with various mole ratios were synthesized by a simple route of co-precipitation, and the corresponding degradation characteristic was tested for the removal of tetracycline (TC) using PMS activation. The degradation efficiency of TC over CuAl-LDHs increased up to 93% within 10min for the Cu/Al mole ratio of 3:1 and almost not changed at a higher mole ratio. For further calcining the optimal catalyst at 300 ℃, the degradation efficiency of TC was found to be increased to 96%. Sulfuric radicals and singlet oxygen were analyzed to be the main reason for the change in degradation characteristics, which was proved by radical quenching experiments and electron paramagnetic resonance technique. The parameters including PMS concentration, catalyst dosage, and reaction temperature on the TC degradation as well as the degradation mechanism for PMS activation were elaborated. The best proportion of CuAl-LDHs owned splendid stability and catalytic activity after reusing, which showed enormous potential in practical application.

Construction of microwave/PMS combined dual responsive perovskite-MXene system for antibiotic degradation: Synergistic effects of thermal and non-thermal

A series of two-dimensional catalysts (LFCO/Ti3C2-x) were prepared by dispersing perovskite on layered Ti3C2 for microwave-combined PMS catalyzed degradation of ciprofloxacin (CIP). Under the optimal treatment conditions (10% Ti3C2 composite, 1.5 g·L−1 catalyst dosage, 1 mM PMS concentration and initial pH = 7.0), the catalyst achieved 96.49% CIP removal efficiency within 14 min. The addition of Ti3C2 contributed to the granulation and homogeneous dispersion of perovskite, which facilitated charge transfer and generation of active species. The catalyst characterization before and after the reaction and experiments related to the quenching of the active species confirmed that the thermal effect of MW irradiation promoted the generation of ROS. The non-thermal effect of MW enhanced the electron transfer ability of the catalytic system and accelerated the oxidation of metal sites, which indirectly promoted the generation of ROS. Combined with LC-MS and DFT calculations, the degradation pathway and mechanism of CIP were revealed. Meanwhile, the ecotoxicity of CIP intermediates calculated using ecological structure–activity relationship software indicates that they are much less harmful or not toxic. This work opens new perspectives for the application of perovskite-MXene based catalysts in the rapid and efficient catalytic activation of MW combined AOPs for antibiotic degradation.

Rational construction of visible-light-driven MIL-88A(Fe)@PMo12 heterojunction with S-scheme electron transfer pathway to activate peroxymonosulfate for degradation of organic pollutants

Coupling of photocatalysis and persulfate oxidation is a promising approach to remove refractory organic pollutants. In 2022, there are about 30 publications on this topic, and the frequency of citations for related articles has reached 1,100. But the rational design and engineering of a desirable photocatalyst is still a great challenge. Herein, a S-scheme heterojunction photocatalyst was prepared by incorporation of Keggin phosphomolybdic acid (PMo12) into MIL-88A(Fe) through a one-step hydrothermal method. The prepared catalyst was characterized by several techniques, and used as visible-light-driven photocatalyst to activate peroxymonosulfate for the degradation of pollutants. The optimal photocatalyst (MIL-88A(Fe)@PMo12-30) displayed the outstanding catalytic activity and good stability. In MIL-88A(Fe)@PMo12-30 system, the degradation rate of AR18 could be increased by 20.55 times compared pristine MIL-88A(Fe). PMS concentration, catalyst dosage, initial pH value, and dye concentration influenced AR18 degradation. The scavenging experiments and EPR analysis disclosed that reactive species (RSs), including SO4−, OH, O2−, h+, and 1O2 were generated. Basis on the band structure, reactive species, PL and electrochemical analysis, the enhanced photocatalytic performance of MIL-88A(Fe)@PMo12-30 was mainly ascribed to the intimate contact of both component and unusual S-scheme electron transfer path. This work may open new horizons to construct efficient POMOFs hybrid photocatalysts.

CuFe3O4@ZIF-2 with oxygen vacancies and multiple reactive sites to efficiently activate peroxymonosulfate for levofloxacin degradation

In this work, CuFe3O4@ZIF-X (X = 1,2,3,4 and 5) composite catalysts with oxygen vacancies and multiple reactive sites were synthesized for the first time by Cu-doped Fe3O4-supported ZIF-X and used to efficiently activate PMS for levofloxacin (LEV) degradation. Influencing factors on LEV degradation were investigated, including the amount of CuFe3O4, pH, catalyst dosage, PMS concentration, coexisting inorganic anions and natural organic matter. In the presence of 1 mM PMS and 40 mg/L CuFe3O4@ZIF-2, 98% removal of LEV (10 mg/L) and 47% mineralization could be achieved within 10 min. The rate constants of CuFe3O4@ZIF-2/PMS were 2.9 times and 4.3 times those of ZIF and Fe3O4@ZIF, respectively. Further investigation found that the introduction of Cu-doped Fe3O4 onto ZIF significantly ameliorates the problem of the reduced catalytic performance of magnetic MOFs due to the high saturation magnetization intensity and severe hindrance of the active sites. Then, the mechanism of LEV degradation, including radical and nonradical pathways, was expounded. Furthermore, the intermediates of LEV degradation were identified, and five possible degradation pathways were proposed. CuFe3O4@ZIF-2 demonstrated a decent catalytic performance even after five consecutive recycles and low metal ion leaching after LEV degradation, greatly improving the problem of secondary contamination.

The characteristic of atmospheric particulate matter and the influence factors in Xiamen for air quality management

Urbanization can drive economic growth, but it may harm the quality of the urban environment if improper actions are performed. Environmental issues resulting from urbanization can negatively impact the health of city dwellers. Therefore, studying air pollutants is crucial to urban development. In this study, we focus on Xiamen and examine the distribution patterns of urban air pollutants over an extended period of time. The goal is to enhance Xiamen’s air quality and bridge the research gap in long-term air quality studies specific to Xiamen. Based on monitoring data from 2014 to 2021 spanning 8 years, this study analyzed the trends in atmospheric particulate matter (PM: PM10, PM2.5) and their relationship with meteorological factors (such as wind speed: WS, temperature: T, dew point temperature: DPT, height of the cloud ceiling: HCC) and the concentrations of other pollutants (SO2, NO2, CO, and O3). The results indicated that (1) The high air quality in Xiamen with the lowest PM values observed during summer and the highest during winter; NO2 and SO2 concentrations showed similar trends to PM, while O3 and CO concentrations varied differently. (2) In general, the maximum daily PM concentration was observed in the evening and early morning, while the lowest value appeared at noon. The concentrations of PMs were positively correlated with other pollutants, while T, WS, HCC (cloud cover of more than 70%), and DPT were negatively correlated with PM concentrations. (3) There exists a relationship between concentrations of atmospheric particulate matter, atmospheric pollutants, and meteorological factors. The wind direction had varying effects on PM concentration, with PM2.5 and PM10 concentrations showing consistent trends and higher concentrations of PMs observed when winds blew from the west, southeast, and northeast. This study also provides a summary of strategies for addressing different air pollutant distribution characteristics. The purpose of this study is to analyze the distribution patterns of air pollutants in Xiamen and provide valuable insights for improving the city’s air quality.

Promoted peroxymonosulfate activation into ferrite sites over perovskite for sunset yellow degradation: Optimization parameters by response surface methodology

The purpose of this research is to show the potential of CeFeO3 (CFO) perovskite as photocatalysts in PMS-activated AOPs for the degradation of target molecules. CeFeO3 photocatalyst was synthesized via a simple precipitation method. The structural, morphological and optical properties of the perovskite were characterized by XRD, SEM-EDS, and UV–vis diffuse reflectance analyses. Furthermore, the degradation efficiency of sunset yellow (SY) was investigated through batch experiments under different parameters (catalyst dosage, PMS concentration and initial dye concentration) and the results were optimized by applying Box-Behnken design method. The decomposition reaction was optimized in the presence of 0.49 g/L of catalyst dosage, 4.73 mM of PMS amount and 14.02 mg/L of dye concentration, with the degradation efficiency of 91.8%. It was observed that O2•−, OH•, and SO4•– played dominant role in reaction. Furthermore, CFO particles were sufficiently incorporated with different carbon materials (graphitic carbon nitride (g-C3N4), carbon fiber (CF) and N-doped carbon quantum dots (NCQDs)), showing excellent removal efficiency. This research shows inspiration for the treatment of polluted water with CeFeO3 under the synergistic effect of PMS and photocatalysis.

Study on the performance efficiency, mechanism, power consumption and biochemical properties of E/Ce(IV)/PMS on the enhanced removal of RB19

In this study, an advanced oxidation process with E/Ce(IV) synergistic PMS (E/Ce(IV)/PMS) was established for the efficient removal of Reactive Blue 19 (RB19). The catalytic oxidation performance of different coupling systems was examined and the synergistic effect of E/Ce(IV) with PMS in the system was substantiated. The oxidative removal of RB19 in E/Ce(IV)/PMS was excellent, achieving a removal efficiency of 94.47% and a reasonable power consumption (EE/O value was 3.27 kWh·m−3). The effect of pH, current density, Ce(IV) concentration, PMS concentration, initial RB19 concentration and water matrix on the removal efficiency of RB19 were explored. Additionally, quenching and EPR experiments showed that the solution contains different radicals such as SO4·−, HO∙ and 1O2, where 1O2 and SO4·− played key roles, but HO∙ just acted a weaker role. Ce ion trapping experiment confirmed that Ce(IV) was involved in the reaction process and played a major role (29.91%). RB19 was subject to three possible degradation pathways, and the intermediate products displayed well biochemical properties. To conclude, the degradation mechanism of RB19 was explored and discussed. In the presence of current, E/Ce(IV)/PMS performed a rapid Ce(IV)/Ce(III) cycle, continuously generating strong catalytic oxidation Ce(IV), The reactive radicals derived from the decomposition of PMS, in conjunction with Ce(IV) and direct electro-oxidation, efficiently destroyed the molecular structure of RB19 and showed an efficient removal rate.

Spatio-temporal variations and socio-economic drivers of air pollution: Evidence from 332 Chinese prefecture-level cities

Air pollution is the result of a complex interaction between natural and anthropogenic environmental conditions. Recently, what's the mutual correlation between air pollutants, and how the monthly socio-economic indicators influence air pollution at the prefecture-level cities are still lack of discussion. Based on monthly air pollutants concentrations and socio-economic indicators from January 2015 to September 2020, this study systematically explored the spatial-temporal characteristics of China's air pollutants and its socio-economic drivers. Results showed that annual mean concentrations of CO, NO2, SO2, PM10 and PM2.5 fell substantially from 2015 to 2020, decreasing by 37%, 27%, 63%, 39% and 40%, respectively, whereas O3 changed slightly. Summertime O3 and NO2 pollution in North China Plain, and wintertime air pollution in China remained the seriously polluted. PMs concentrations were significantly positively correlated with SO2, CO and NO2 concentrations. The increases in GDP per capita aggravated NO2 and PMs pollution in southeast coastal areas in spring and winter. The air pollution in North China Plain were severer in spring and winter induced by the monthly retail sales of social consumer goods. In the Fenwei Plain, the growing electricity consumption per GDP contributed to O3 and PM10 mitigation in summer and autumn. It is worth noting that the improvement of socio-economic level and energy consumption level showed a trend of exacerbating CO, NO2, and O3 pollution from 2015 to 2020. The comprehensive monthly analysis provides theoretical support for fine-scale monitoring and feasible control strategy formulating for achieving China's sustainable development.

Natural manganese ores for efficient removal of organic pollutants via catalytic peroxymonosulfate‐based advanced oxidation processes

AbstractPeroxymonosulfate‐based advanced oxidation processes (PMS‐AOPs) for in situ persistent organic pollutant (POP) remediation in aqueous solutions can be a promising technology. However, this technology is constrained by its high toxicity and cost of metal oxide and non‐metal catalysts for PMS activation. Here, we investigated the catalytic performance of a widely available natural mineral, manganese ore (MO), for PMS activation. A series of natural MO samples in an aqueous solution were prepared via the Fenton‐like reaction. The samples' crystalline structure, surface morphology, textural properties, and other surface characteristics of the selected MO were systematically characterized. The effects of PMS concentration and process parameters on the degradation performance of four chosen model pollutants, that is, phenol, tetrabromobisphenol A (TBBPA), rhodamine B (RhB), and methylene blue (MB), were evaluated. The experimental results showed that natural MO increased catalytic activity and enhanced the PMS oxidation processes, with 98%, 90%, and 75% removal efficiencies on phenol, TBBPA, and RhB, respectively, within 1.5 h. The reduction in the initial pH solution from 10 to 7 and the increase in temperature from 15 to 45°C enhanced the MB degradation rate (decolorization) by 55 and 46%, respectively, within 2 h. During the PMS activation process, SO4•−, •OH, and 1O2 species were generated, but only SO4•− and •OH radicals with strong oxidative potentials contributed to the catalytic degradation. The dissolved metals from the experiments were found well within the limit of drinking water standards, verifying that the MO + PMS catalytic system is suitable for commercial applications. This work provides insights into the development potential and prospects of using natural minerals for PMS activation and POP degradation, which can accelerate their industrial applications.

Activation of Peroxymonosulfate Using Spent Li-Ion Batteries for the Efficient Degradation of Chloroquine Phosphate

Recycling and reusing spent lithium-ion batteries (LIBs) have gained a lot of attention in recent years, both ecologically and commercially. The carbon nanotube-loaded CoFe2O4 (CoFe2O4@CNTs) composite was made using a solvothermal technique utilizing wasted LIBs as the starting material and carbon nanotubes as support, and it was used as an efficient peroxymonosulfate (PMS, HSO5−) activator to degrade chloroquine phosphate (CQP). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the physical and chemical properties of the catalyst generated. The impacts of CoFe2O4@CNTs dosage, PMS concentration, reaction temperature, initial pH value, starting CQP concentration, and co-existing ions have undergone extensive experimental testing. In comparison to bare CoFe2O4, the CoFe2O4@CNTs demonstrated increased catalytic activity, which might be attributed to their super electron transport capacity and large surface area. In ideal conditions, the mineralization efficiency and removal efficiency of 10 mg/L CQP approached 33 and 98.7%, respectively. By employing external magnets, the CoFe2O4@CNTs catalyst may be simply recycled and reused several times. The potential reaction mechanism in the CoFe2O4@CNTs/PMS system was also investigated. In summary, this study indicates that CoFe2O4@CNTs generated from spent lithium-ion batteries have a high potential in PMS activation for CQP and other pollutant degradation.

Enhanced Heterogeneous Activation of Peroxymonosulfate by Nitrogen–Sulfur Co-Doped Mofs-Derived Carbon

It is important to further enhance the performance of green and efficient non-homogeneous catalysts for advanced oxidation process of Peroxymonosulfate (PMS-AOP) for green treatment of industrial wastewater. In this paper, nitrogen–sulfur co-doped MOFs-derived carbon material (CoSN@C) was prepared by one-pot synthesis followed by carbonization, and its morphological structure was characterized by XRD and SEM. After pyrolysis, the CoSN@C still maintained the dodecahedral morphology and structure of ZIF-67. The synergistic effects of S and N significantly elevated the activation of PMS. The results show that the CoSN@C + PMS system can effectively activate PMS to degrade Rhodamine B (RhB), with a rate constant (1.85 min−1) four times higher than that of the CoN@C + PMS system (0.44 min−1). The optimal catalytic process parameters of material dosage, PMS concentration, temperature, pH, and other parameters were also investigated for the activation of PMS to remove Rhodamine B. The cyclic experiment shows that the CoSN@C has excellent recyclability and the degradation rate of RhB still reached 88.9% after four cycles. Radical capture experiments and EPR tests showed that the CoSN@C + PMS system generated a large amount of SO4·− and ·OH radicals adsorbed on the catalyst surface and a certain amount of singlet oxygen, and the free radical pathway and non-radical pathway worked together to degrade RhB efficiently and rapidly. While non-radical pathway with singlet oxygen as main reactive oxygen species played a key role in the CoN@C + PMS system. This work provides a new idea for the rational design of non-homogeneous catalysts for PMS-AOP system.

Degradation of refractory organic matter in MBR effluent from treating landfill leachate by UV/PMS and UV/H2O2: a comparative study

ABSTRACT This study applied ultraviolet/peroxymonosulfate (UV/PMS) and UV/hydrogen peroxide (UV/H2O2) processes to the advanced treatment of membrane bioreactor (MBR) effluent. The degradation efficiency of refractory organic matter and the reaction mechanisms of the two processes were systematically investigated. The results showed that the degradation efficiency of the UV/PMS processes was significantly lower than that of the UV/H2O2 process when the PMS concentration was significantly lower than the H2O2 concentration, e.g. the UV254 removals under optimal conditions were 72.92% and 82.21%, respectively. Additionally, the UV/PMS process could operate over a broader pH range. The degradation efficiency of the UV/PMS process was slightly increased by HCO3 – and Cl- due to the activation of PMS, while in the UV/H2O2 process, HCO3 - and Cl- depressed the degradation efficiency by competing with organic matter to react with reactive oxygen species (ROS). After the two processes, the aromaticity, humification, condensation degree, and molecular weight of refractory organic matter in the MBR effluent were considerably decreased. Fulvic- (HA) and humic-like substances (FA) were greatly degraded by the two processes. The UV/PMS had a superior degradation efficiency for macromolecular HA in the early stage of the reaction, and the UV/H2O2 could degrade HA to protein-like substances in the latter stage of the reaction. These differences between the two processes could be attributed to the dominance of different ROS, with SO4 •- and HO• dominating in the UV/PMS, and HO• dominating in the UV/H2O2. The results of this study provide theoretical support for the application of MBR effluent treatment.

Fe-Trimesic Acid/Melamine Gel-Derived Fe/N-Doped Carbon Nanotubes as Catalyst of Peroxymonosulfate to Remove Sulfamethazine

The conventional precursor preparation of metal–organic frameworks (MOFs) for nitrogen-doping carbon materials is divided into the preparation of MOFs and the mixing of the nitrogen source, which is a complex and time-consuming step. In this study, Fe-BTC gel/nitrogen source-derived carbon materials were synthesized using one or more of the following raw ingredients: Fe(NO3)3·9H2O, FeCl3·6H2O, Fe2(SO4)3, trimesic acid, melamine and dicyandiamide. The influence of different raw ingredients on the preparation and performance of catalysts was investigated. Fe(NO3)3·9H2O can react with trimesic acid to form a gel with ethanol as solvent, and the gel helped the homogeneous dispersion of the added melamine and did not precipitate. Fe-C-N(M), synthesized from the three materials mentioned, was identified as the optimal catalyst; the removal rate of 5 mg/L sulfadimethoxine (SMZ) reached 100% at 15 min when the Fe-C-N(M) dosage was 50 mg/L, PMS concentration was 0.5 mM, and the pH was 5.78 (initial pH of the solution). The removal of SMZ was not significantly inhibited by the pH (3–9) and 0–10 mM inorganic anions (Cl−, NO3−, HCO3− and H2PO42−). Through quenching tests, electron paramagnetic resonance and probe experiments, 1O2 and a small amount of free radicals (•OH and SO4•−) bound on the catalyst surface are discovered to be the primary active ingredients that activate PMS to degrade SMZ.

Impact of dry deposition flux and dust intrusion phenomena on elemental concentrations of air particulate matter

Depositions of trace elements of air particulates in the atmosphere have gained much attention in recent times due to their environmental, climatic and health impacts. In the current study, trace elements of size-segregated rural and urban particulate matter (PM2.5 and PM2.5−10) were characterized using particle-induced X-ray emission method. Effects of dry deposition flux and Saharan dust intrusion on the elemental concentrations were determined. The mean elemental concentration in the rural fine PM ranged between 0.0002 ± 0.0002 μg m−3 (for Se) and 0.6658 ± 0.5816 μg m−3 (for S) whereas in the urban fine PM the concentration ranged between 0.0007 ± 0.0008 μg m−3 (for As) and 0.5869 ± 0.3429 μg m−3 (for Ca). In the coarse PM fraction, concentration ranged between 0.0001 ± 0.0001 μg m−3 (for Se) and 0.5886 ± 0.5343 μg m−3 (for Ca) at the rural site; and between 0.0002 ± 0.0002 μg m−3 (for Se) and 1.9201 ± 1.911 μg m−3 (for Ca) at the urban site. Mainly crustal elements (Al, Ca, Fe) and ‘pollution’ source element (S) recorded high and significant dry deposition fluxes across the two sites in both PM modes. Deposition flux was relatively higher in the coarse than in the fine PM mode. The average dry deposition flux estimated for fine and coarse PM at the rural and urban sites were 33.68 ± 57.19 μg m−2 day−1 and 47.71 ± 92.19 μg m−2 day−1; 36.66 ± 61.95 μg m−2 day−1 and 107.02 ± 237.71 μg m−2 day−1, respectively. Mainly crustal (Al, Ca, Fe) and “pollution” (S) element recorded high and significant dry deposition fluxes across the two sites and in the two PM modes. The impacts of dust on climate, air quality, and the environment in general have increased the need to better understand the dust flow system. In the current study, dust intruding the study area from the Sahara was analyzed using the NMMB/BSC dust model. The model’s output indicated that, the highest daily surface dust concentration was observed in the central and south-west of Turkey which corresponded with the peak period of Saharan dust transport to the Eastern Mediterranean in the month of March.

Allochthonous arbuscular mycorrhizal fungi promote Salix viminalis L.–mediated phytoremediation of polycyclic aromatic hydrocarbons characterized by increasing the release of organic acids and enzymes in soils

Polycyclic aromatic hydrocarbons (PAHs) are well known persistent organic pollutants that have carcinogenic, teratogenic, and mutagenic effects on humans and animals. Arbuscular mycorrhizal fungi (AMF) that can infest plant hosts and form symbioses may help plants to enhance potential rhizosphere effects, thus contributing to the rhizodegradation of PAH-contaminated soils. The present study aimed to assess the effectiveness of AMF on enhancing Salix viminalis–mediated phytoremediation of PAH-polluted soil and clarify the plant enzymatic and organic acid mechanisms induced by AMF. Natural attenuation (NA), phytoremediation (P, Salix viminalis), S. viminalis-AMF combined remediation using willow inoculated with Funneliformis mosseae (PM), Laroideoglomus etunicatum (PE), and Rhizophagus intraradices (PI) were used as strategies for the remediation of PAH-polluted soils. The results showed that AMF inoculation contributed to the dissipation of the high-molecular-weight PAH benzo (α) pyrene that had concentrations in PM, PE, and PI treatments of 40.1 %, 24.49 %, and 36.28 % of the level in the NA treatment, and 62.32 %, 38.05 %, and 56.38 % of the level in the P treatment after 90 days. The mycorrhizal treatment also improved the removal efficiency of phenanthrene and pyrene, as their concentrations were sharply decreased after 30 days compared to the NA and P treatments. The research further clarified the changes in rhizosphere substances induced by AMF. Organic acids including arachidonic acid, octadecanedioic acid, α-linolenic acid, 10,12,14-octadecarachidonic acid and 5-methoxysalicylic acid that can act as co-metabolic substrates for certain microbial species to metabolize PAHs were significantly increased in AMF-inoculated treatments. AMF inoculation also elevated the levels of polyphenol oxidase, laccase, and dehydrogenase, that played crucial roles in PAHs biodegradation. These findings provide an effective strategy for using AMF-assisted S. viminalis to remediate PAH-polluted soils, and the results have confirmed the key roles of organic acids and soil enzymes in plant-AMF combined remediation of PAHs.

Heterogeneous degradation of cefotaxime sodium with peroxymonosulfate activated by an effective and magnetically separable Ni0.5Zn0.5Fe2O4 catalyst

Magnetic Ni0.5Zn0.5Fe2O4 was fabricated by a simple solvothermal method, characterized by a variety of technologies, and used to activate PMS for the degradation of cefotaxime sodium (CFX) in water. The results indicated that Ni0.5Zn0.5Fe2O4 showed superior catalytic activity than that of ZnFe2O4 and NiFe2O4. Factors affecting the degradation of CFX were investigated, including PMS concentration, catalyst dosage, initial pH, reaction temperature and water matrices. The quenching experiments and electron paramagnetic resonance (EPR) measurements verified the generation of SO4•-, •OH and 1O2 in the Ni0.5Zn0.5Fe2O4/PMS system. Plausible mechanism on the activation of PMS was proposed according to the XPS analysis of Ni0.5Zn0.5Fe2O4 before and after reaction, showing that Ni2+ and Zn2+ were responsible for the radical generation and Fe3+ was not reactive to the activation of PMS. Additionally, the reusability experiments proved the good stability of Ni0.5Zn0.5Fe2O4. When the Ni0.5Zn0.5Fe2O4/PMS process was used to treat real river water spiked with CFX, the removal of CFX was much faster than that in deionized water. Thence, the Ni0.5Zn0.5Fe2O4/PMS system might be a candidate for removing antibiotics in environmental remediation.

Bicarbonate enhanced heterogeneous activation of peroxymonosulfate by copper ferrite nanoparticles for the efficient degradation of refractory organic contaminants in water

Nowadays, the treatment of residual refractory organic contaminants (ROCs) is a huge challenge for environmental remediation. In this study, a potential process is provided by copper ferrite catalyst (CuFe2O4) activated peroxymonosulfate (PMS, HSO5−) in the bicarbonate (HCO3−) enhanced system for efficient removal of Acid Orange 7 (AO7), 2,4-dichlorophenol, phenol and methyl orange (MO) in water. The impact of key reaction parameters, water quality components, main reactive oxygen species (ROS), probable degradation mechanism, rational degradation pathways and catalyst stability were systematically investigated. A 95.0% AO7 (C0 = 100 mg L−1) removal was achieved at initial pH (pH0) of 5.9 ± 0.1 (natural pH), CuFe2O4 dosage of 0.15 g L−1, PMS concentration of 0.98 mM, HCO3− concentration of 2 mM, and reaction time of 30 min. Both sulfate radical (SO4−•) and hydroxyl radical (•OH) on the surface of catalyst were proved as the predominant radical species through radical quenching experiments and electron paramagnetic resonance (EPR) analysis. The buffer nature of HCO3− was partially contributed for the enhanced degradation of AO7 under CuFe2O4/PMS/HCO3− system. Importantly, according to 13C nuclear magnetic resonance (NMR) and EPR analysis, the positive effect of bicarbonate may be mainly attributed to the formation of peroxymonocarbonate (HCO4−), which may enhance the generation of •OH. The magnetic CuFe2O4 particles can be well recycled and the leaching concentration of Cu was acceptable (<1 mg L−1). Considering the widespread presence of bicarbonate in water environment, this work may provide a safe, efficient, and sustainable technique for the elimination of ROCs from practical complex wastewater.