Search

In this paper, metallic copper (Cu) was supported on nanoscale zero-valent iron (nZVI) to form a nanoscale bimetallic composite (nZVI-Cu), which was used to activate persulfate (PS) to simultaneously remove the compound contaminants Cr(VI) and tetracycline hydrochloride (TCH) in simulated wastewater. nZVI, nZVI-Cu, and nZVI-Cu-activated PS (nZVI-Cu/PS) were characterized by SEM, TEM, XRD, and XPS. The effects of the bimetallic composite on Cr(VI) and TCH removal were compared in the nZVI, nZVI-activated PS (nZVI/PS), nZVI-Cu, and nZVI-Cu/PS systems. The results showed that nZVI and Cu can form a nanobimetallic system, which can create galvanic cells; thus, the galvanic corrosion of nZVI and the transfer of electrons are accelerated. For a single contaminant, the removal efficiency of Cr(VI) and TCH is the highest when nZVI is loaded with 3 wt% and 1 wt% Cu, respectively. The ratio of nZVI-Cu with 3 wt% Cu to PS is 7:1, and the removal efficiency of Cr(VI) and TCH compound contaminants is ~ 100% after 60 min under acidic conditions, which indicates that the Cr(VI) reduction and TCH oxidation were complete in the nZVI-Cu/PS system. The mechanisms of simultaneous removal of Cr(VI) and TCH in the nZVI-Cu/PS system are proposed. The removal of Cr is because of the adsorption-reduction effects of the nZVI-Cu bimetallic material. The degradation of TCH is mainly due to the action of oxidative free radicals generated by Fe2+-activated PS. The free radical capture experiments showed that SO- 4· plays a major role in the process of TCH degradation.

High-quality amino-functionalized Ti3C2Tx MXene (alk-MXene-NH2) nanosheets were successfully synthesized by a facile alkalization-grafting modification for lead adsorption. The alk-MXene-NH2 achieved the highest BET specific area among all MXene-based adsorbents, and the generated abundant -NH2, -OH and -ONa complexing groups exhibited strong interactions with lead ions, resulting in attractively high adsorption capacity.

As emerging alternatives of legacy perfluoroalkyl substances, perfluorophosphinates (PFPiAs) and perfluorophosphonates (PFPAs) are widely applied in industrial and agricultural fields and are suppo...

It is well known that microplastics (MPs) may experience weathering and aging under ultraviolet light (UV) irradiation, but it remains unclear if these processes are impacted by natural components, such as clay minerals. In this study, we systematically investigated the photodegradation behaviors of polyvinyl chloride (PVC) and poly (ethylene terephthalate) (PET), two utmost used plastics, in the presence of clay minerals (kaolinite and montmorillonite). The results demonstrated that the clay minerals, particularly kaolinite, significantly promoted the MPs photodegradation, and the aging of PET was more prominent. The photodegradation was the most distinct at pH 7.0, regardless of the presence or absence of the clay minerals. The results of electron paramagnetic resonance and inhibition experiments of reactive oxygen species indicated that the minerals, particularly kaolinite, remarkably facilitated production of •OH, which was the key species contributing to the photodegradation of MPs. Specifically, UV irradiation facilitated the photo-ionization of MPs, producing hydrated electrons and MP radical cations (MP+). The Lewis base sites prevalent on the clay siloxane surfaces could stabilize the MP radical cations and prevent their recombination with hydrated electrons, which promoted the generation of •OH under aerobic conditions, and facilitated the degradation of MP. Two-dimensional (2D) Fourier transformation infrared (FTIR) correlation spectroscopy (COS) analysis and ultra-high-performance liquid chromatography coupled to a Q Exactive Orbitrap HF mass spectrometer were used to identify the sequential changes of functional groups, and the degradation products of the MPs. This study improves our understanding on the aging of MPs in the complex natural environment.

The emergence of Zika virus (ZIKV) infection, which is an unexpectedly associated with congenital defects, has prompted the development of safe and effective vaccines. The gram-positive enhancer matrix-protein anchor (GEM-PA) display system has emerged as a versatile and highly effective platform for delivering target proteins for vaccines. In this article, we developed a bacterium-like particle vaccine ZI-{Delta}-PA-GEM based on the GEM-PA system. The fusion protein ZI-{Delta}-PA, which contains the prM-E-{Delta} protein of ZIKV (with a stem-transmembrane region deletion) and the protein anchor PA3, was expressed. The fusion protein was successfully displayed on the GEM surface, forming ZI-{Delta}-PA-GEM. Moreover, when BALB/c mice were immunized intramuscularly with ZI-{Delta}-PA-GEM combined with 201 VG and poly(I:C) adjuvants, durable ZIKV-specific IgG and protective neutralizing antibody responses were induced. Potent B cell/DC activation was also be stimulated early after immunization. Remarkably, splenocyte proliferation, the secretion of multiple cytokines, T/B cell activation and central memory T cell responses were elicited. These data indicate that ZI-{Delta}-PA-GEM is a promising bacterium-like particle vaccine candidate for ZIKV. Author summaryBecause Zika virus (ZIKV) infection is considered as an example of "disease X", the development of a safe and effective ZIKV vaccine is essential. The gram-positive enhancer matrix-protein anchor (GEM-PA) display system has been used in many vaccine studies due to its advantages. In this study, prM-E-{bigtriangleup} protein of ZIKV (with a stem-transmembrane region deletion) and the protein anchor PA3 was fusion expressed, termed ZI-{bigtriangleup}-PA. Then the fusion protein ZI-{bigtriangleup}-PA could be displayed on the surface of GEM, forming ZI-{bigtriangleup}-PA-GEM. The author evaluated the immunogenicity of ZI-{bigtriangleup}-PA-GEM with the 201 VG and poly(I:C) adjuvants. The study demonstrates that ZI-{bigtriangleup}-PA-GEM induced mice to produce neutralizing antibody and specific cellular immune responses. The author believe that the bacterium-like particle vaccine ZI-{bigtriangleup}-PA-GEM has the potential to be used as the ZIKV vaccine.

Classical chemical precipitation technology is inefficient for the removal of heavy metal-organic complexes from wastewater. In this study, a novel and green strategy of coupling bicarbonate-activated hydrogen peroxide (BHP) oxidation and alkaline precipitation was proposed for simultaneous decomplexation of Cu-ethylenediaminetetraacetic acid (Cu-EDTA) and Cu precipitation. The Cu-EDTA decomplexation efficiency reached 92.0% within 60 min of the BHP treatment, and the decomplexation process was spontaneous and endothermic. Reactive substances such as O2−, OH, and 1O2 were identified, and O2− was predominant in the Cu-EDTA decomplexation. The weak alkaline environment provided by bicarbonate favored the generation of the reactive substances and subsequent Cu-EDTA decomplexation. Relatively higher H2O2 dosage favored Cu-EDTA decomplexation, while excessive bicarbonate dosage inhibited the reaction. TOC removal efficiency and Cu removal efficiency reached 78.4% and 68.3% after 60 min treatment, respectively. The Cu O and Cu N bonds in Cu-EDTA were destroyed by the reactive substances, and a series of Cu-containing intermediates, small organic molecules such as ethanamine, ethylene glycol and butanediol, and NO3− were produced. The released Cu ions were precipitated as Cu2(OH)2CO3, CuCO3, Cu(OH)2, and CuO. Possible pathways of Cu-EDTA decomplexation in this system were proposed.

EDTA-chelated metals, which widely occur during heavy metal contaminated-soil remediation by EDTA washing, are difficult to remove by traditional chemical precipitation because of the strong complexation between EDTA and heavy metal ions. A strategy, i.e., non-thermal plasma (NTP) oxidation/alkaline precipitation, was developed to remove the EDTA-chelated metals; EDTA-chelated copper (EDTA-Cu) was used as the model pollutant and the influences of some concomitant ions on EDTA-Cu decomplexation and Cu release were evaluated. The concomitant anions Cl− and NO3− favored EDTA-Cu decomplexation, whereas CO32− disfavored this process; the concomitant positive ions Ni2+ and Fe3+ both promoted EDTA-Cu decomplexation via replacement or Fenton-like effects. These effects were also characterized by total organic carbon and Cu2+ release analysis. The contributions of O3, O, 1O2, OH, and O2− to EDTA-Cu decomplexation were quantitatively analyzed. Ethanamine, acetamide, glycolic acid, acetic acid, formamide, ethylene glycol, and butanedioic acid were monitored using gas chromatography-mass spectrometry, and a possible decomposition pathway of EDTA-Cu was proposed. Furthermore, the chemical compositions of the precipitates were diagnosed by energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal gravimetric analysis.

The application of Ag3PO4 as a commonly used photocatalyst is limited by its high recombination potency and electron–hole pairs with weak redox potential. It is significant to enhance the photocata...

Transformation of PAHs, i.e., anthracene, and production of environmentally persistent free radicals (EPFRs) on seven types of representative soils were investigated, focusing on the influences of soil characteristics and ambient conditions on these reactions. The transformation rate of anthracene exhibits the order of red earth > yellow earth > latosol ∼ fluvo-aquic soil > brown earth > chernozem > calcic brown soil, which is positively correlated with Fe content in soils. Afterwards, batch reactions on pure representatives of soil minerals, including Fe2O3, Fe3O4, FeOOH, and MnO2, demonstrate that anthracene is prone to mineral-promoted transformation. The presence of higher amount of organic carbon lower the transformation rate of anthracene, whereas the formed EPFRs can be stabilized for a longer time. Subsequent experiments associated with the influences of environmental conditions on mineral-promoted reactions suggest that both anthracene transformation and EPFRs generation readily occur under dry condition. Light irradiation not only promotes the formation of EPFRs, but also greatly accelerates the decay of EPFRs and the 1/e lifetime decreases from 5 to 20 d in dark to approximately 1 d. Meanwhile, the anoxic condition is favorable for the persistence of EPFRs. The obtained results suggested the potential environmental risks association with EPFRs in PAHs-contaminated soils.

Microcystis aeruginosa (M. aeruginosa), as the representative hazardous algae in cyanobacteria blooms, has long posed a threat to aquatic ecosystems. Here, a self-cooling dielectric barrier discharge plasma (DBDP) reactor was used to eliminate M. aeruginosa in water. The removal efficiency and mechanism of DBDP for M. aeruginosa and its toxin release during the treatment process was investigated. The results showed that over 99% of M. aeruginosa cells were removed by DBDP over 60 min under optimal conditions, and treated M. aeruginosa lost their ability to reproduce entirely. Reactive species generated in the self-cooling DBDP reactor damaged the membrane of M. aeruginosa, leading to leakage and degradation of dissolved organic matter. Increased intracellular reactive oxygen species accelerated the breakdown of protein and enzyme, and causes cell cytolysis. Eventually, M. aeruginosa was mineralized and lost its activity. The ·OH, 1O2 and ·O2- were crucial for inactivating M. aeruginosa. During the treatment process, the toxin microcystin-LR increased in the first 20 min, but declined over time: its concentration fell below 1 μg·mL-1 after 60 min. This study provides insight into M. aeruginosa’ s elimination in water by DBDP and has significant implications for developing a plasma technique to curtail cyanobacteria bloom.

A huge amount of excess sludge is inevitably produced in wastewater treatment, and it is becoming more and more urgent to realize efficient sludge reduction. Discharge plasma oxidation was used to efficiently disintegrate excess sludge for sludge reduction in this study. Approximately 18.22% sludge disintegration and 27.8% reduction of total suspended solids (TSS) were achieved by discharge plasma treatment. The water content of the filter cake decreased from 81.9% to 76.0% and the bound water content decreased from 2.66 g/g dry solid to 0.73 g/g dry solid after treatment. The large quantities of reactive oxygen species (ROS) generated by discharge plasma played important roles in sludge disintegration by destroying flocs and promoting the transformation of organic substances. Concurrent cell lysis induced by ROS oxidation released intracellular organics and water into the liquid phase. The fraction of soluble extracellular polymer substances (S-EPS) was enhanced from 16.10% to 58.51%, whereas the tightly bound fraction was reduced from 70.62% to 28.91%. Migration and decomposition of EPS were the main processes for EPS changing at a low oxidation capacity, whereas cell lysis became important at a high oxidation capacity. In summary, the plasma treatment effectively improved sludge disintegration.

Phenol-formaldehyde resin microplastic (PF-MP) is one of the major inhalable microplastics in environments released from the manufacture, processing and usage of PF materials. The associated toxicities of PF-MP might be affected by photoaging. In this study, the dynamic evolutions of the oxidative potential (OP) and redox-active species, including environmentally persistent free radicals (EPFRs), reactive oxygen species (ROS), peroxides and conjugated carbonyls, as well as the associated cytotoxicity of PF-MP were systematically investigated as a result of the simulated sunlight irradiation. As the photoaging time extended, the OP of PF-MP increased. The contents of the produced conjugated carbonyls, ROS and PF-bound EPFRs due to light irradiation increased as well, and displayed significant correlations with the OP (Spearman r > 0.6, p

Contaminated sites from pesticide industry have attracted global concern due to the characteristics of organic pollution with high concentrations and complete loss of habitat conditions. Remediation of organophosphorus pesticide polluted soil using microwave-activated persulfate (MW/PS) oxidation was investigated in this study, with parathion as the representative pesticide. Approximately 90 % of parathion was degraded after 90 min of MW/PS oxidation treatment, which was superior to those by single PS or MW treatment. Relatively greater performances for parathion degradation were obtained in a relatively larger PS dosage, higher microwave temperature, and lower organic matter content. Appropriate soil moisture favored parathion degradation in soil. SO4 −, OH, O2 −, and 1O2 generated in the MW/PS system all contributed to parathion degradation. Multiple spectroscopy analyses indicated that P O and P S bonds in parathion were destroyed after MW/PS oxidation, accompanied by generation of hydroxylated and carbonylated byproducts. The soil safety after parathion degradation was assessed via model prediction. Furthermore, MW/PS oxidation also exhibited great performance for degradation of other organophosphorus pesticides, including ethion, phorate, and terbufos.

As emerging alternatives of legacy perfluoroalkyl substances, 6:2 fluorotelomer sulfonate (6:2 FTS), 6:2 chlorinated polyfluoroalkyl ether sulfonates (6:2 Cl-PFESA), and perfluorophosphinates (C6/C6 and C8/C8 PFPiAs) are supposed to be partitioned to soil and highly persistent in the environment. The uptake of novel per- and polyfluoroalkyl substances (PFASs) by plants represents a potential pathway for their transfer in the food chain. In this study, the bioavailability of these four novel PFASs in soil and the bioaccumulation characteristics in greenhouse-grown wheat (

Background Growing studies have focused on the role of microRNA-21 (miR-21) in glioma, thus our objective was to discuss the effect of M2 bone marrow-derived macrophage (BMDM)-derived exosomes (BMDM-Exos) shuffle miR-21 on biological functions of glioma cells by regulating paternally expressed gene 3 (PEG3). Methods Seventy-one cases of human glioma tissues and 30 cases of non-tumor normal brain tissues were collected and stored in liquid nitrogen. PEG3 and miR-21 expression in glioma tissues was tested. The fasting venous blood of glioma patients and healthy control was collected and centrifuged, and then the supernatant was stored at − 80 °C refrigerator. The contents of interferon (IFN)-γ and transforming growth factor-β1 (TGF-β1) in serum were tested by ELISA. Glioma cells and normal glial cells were cultured to screen the target cells for further in vitro experiments. BMDM-Exos was obtained by ultra-high speed centrifugation and then was identified. BMDM-Exos was co-cultured with U87 cells to detect the biological functions. The fasting venous blood of glioma patients was extracted and treated with ethylene diamine tetraacetic acid-K2 anti-freezing, and then CD8+T cells were isolated. CD8+T cells were co-cultured with U87 cells to detect the CD8+T proliferation, cell cytotoxic activity, U87 cell activity, as well as IFN-γ and TGF-β1 levels. Moreover, BALB/c-nu/nu mice was taken, and the human-nude mouse glioma orthotopic transplantation model was established with U87 cells, and then mice were grouped to test the trends in tumor growth. The brain of mice (fixed by 10% formaldehyde) was sliced to detect the expression of Ki67 and proliferating cell nuclear antigen (PCNA). The spleen of mice was taken to prepare single-cell suspension, and the percentage of T lymphocytes in spleen to CD8+T cells was detected. Results PEG3 expression was decreased and miR-21 expression was increased in glioma cells and tissues. Depleting miR-21 or restoring PEG3 suppressed growth, migration and invasion as well as accelerated apoptosis of glioma cells, also raised CD8+T proliferation, cell cytotoxic activity, and IFN-γ level as well as decreased U87 cell activity and TGF-β1 level. BMDM-Exos shuttle miR-21 promoted migration, proliferation and invasion as well as suppressed apoptosis of glioma cells by reducing PEG3. Exosomes enhanced the volume of tumor, Ki67 and PCNA expression, reduced the percentage of CD8+T cells in glioma mice. Conclusion BMDM-Exos shuffle miR-21 to facilitate invasion, proliferation and migration as well as inhibit apoptosis of glioma cells via inhibiting PEG3, furthermore, promoting immune escape of glioma cells.

A large number of plastic products potentially become smaller particles, including nanoplastics, under multiple actions in the environment. The interactions between nanoplastic particles and constituents in the environment, such as minerals, would greatly affect the transport, fate and toxic effects of nanoplastics. In this study, the interactions of polystyrene nanoplastic (PSNP) with four typical minerals, including goethite, magnetite, kaolinite and montmorillonite, in aqueous phase were investigated. The stability of PSNP colloidal suspension decreased in the presence of the positively charged goethite or magnetite, while it was not affected by the negatively charged montmorillonite and kaolinite, suggesting that there was a strong electrostatic attraction between PSNP and the two iron oxides. Incubation of PSNP with other three metal oxides with different surface charges, MnO2, Al2O3 and SiO2, confirmed the importance of electrostatic interaction in the stability of PSNP suspension. The transmission electron microscopy (TEM) analysis and batch adsorption experiments indicated that PSNP was effectively adsorbed on goethite or magnetite due to the strong electrostatic attraction between them. The Fourier transform infrared spectra (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analyses indicated that there was strong hydrogen bonding between the –OH (γ-FeOOH) of goethite and PSNP, contributing to the higher adsorption of PSNP on goethite than magnetite. These findings shed light on the interactions of PSNP with mineral surfaces, and potential fate of PSNP under natural conditions in the water environment.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are global environmental pollutants and pose significant threats to environmental safety and human health. Defluorination of PFOA and PFOS was investigated theoretically and practically in a mesoporous plasma system in this study. Rapid and highly efficient defluorination was realized, and 98% and 65% defluorination rate for PFOA and PFOS, respectively, were obtained within 60 min of treatment. Electrons generated in the mesoporous plasma system played a decisive role in PFOA and PFOS defluorination; other species, including 1O2 and ·OH, also contributed to defluorination. C-F, C-C, and C-S bonds were broken by plasma oxidation; various shorter-chain perfluorocarboxylic acids, polyfluoroalkyl substances, and alcohols were produced. PFOA and PFOS decomposition mechanisms involved electron transfer, defluorination, decarboxylation, and hydroxylation reactions. Desulfonation reactions were also involved in PFOS decomposition. Density functional theory calculations identified sites susceptible to be attacked and the main degradation pathways. Effective defluorination of PFOA and PFOS reduced their toxicities. Furthermore, its potential for actual surface water treatment was also determined.

As an emerging alternative legacy perfluoroalkyl substance, C6/C6 PFPiA (perfluoroalkyl phosphinic acids) has been detected in aquatic environments and causes potential risks to human health. The degradation mechanisms of C6/C6 PFPiA in a dielectric barrier discharge (DBD) plasma system were explored using validated experimental data and density functional theory (DFT) calculations. Approximately 94.5% of C6/C6 PFPiA was degraded by plasma treatment within 15 min at 18 kV. A relatively higher discharge voltage and alkaline conditions favored its degradation. C6/C6 PFPiA degradation was attributed to attacks of •OH, •O2−, and 1O2. Besides PFHxPA and C2 −C6 shorter-chain perfluorocarboxylic acids, several other major intermediates including C4/C6 PFPiA, C4/C4 PFPiA, and C3/C3 PFPiA were identified. According to DFT calculations, the potential energy surface was proposed for possible reactions during C6/C6 PFPiA degradation in the discharge plasma system. Integrating the identified intermediates and DFT results, C6/C6 PFPiA degradation was deduced to occur by stepwise losing CF2, free radical polymerization, and C-C bond cleavage. Furthermore, the DBD plasma treatment process decreased the toxicity of C6/C6 PFPiA to some extent. This study provides a comprehensive understanding of C6/C6 PFPiA degradation by plasma advanced oxidation.

Polycyclic aromatic hydrocarbons (PAHs) are important mutagen prevalent in the contaminated sites, bringing potential risks to human health. Iron oxides are important natural components in soils. Pyrene removal in soil using persulfate (PS) oxidation activated by microwave (MW) and magnetite (Fe3O4) was investigated. Fe3O4 significantly promoted pyrene removal in the soil; 91.7 % of pyrene was degraded within 45 min treatment. Pyrene removal rate in the Fe3O4/MW/PS system was 5.18 and 3.00 times higher than that in the Fe3O4/PS and MW/PS systems. Increasing in Fe3O4 dosage, PS concentration, MW temperature, and soil moisture content in the selected range were conducive for pyrene degradation. SO4•−, •OH, O2•−, and 1O2 were responsible for pyrene degradation, and the conversion of Fe (Ⅱ) in the Fe3O4 to Fe (Ⅲ) contributed to the formation of O2•− and 1O2. Characteristic bands of pyrene were more obviously destroyed by the Fe3O4/MW/PS oxidation, in comparison with MW/PS oxidation. Ring hydroxylation and ring-opening reactions were the main degradation pathways of pyrene. The toxicities of the formed byproducts were significantly reduced after treatment. This study provided a promising option for pyrene contaminated soil remediation.

Per- and polyfluoroalkyl substances (PFASs) have been found to be widely present in soil. Dissolved organic matter (DOM) in soil are supposed to greatly affect the bioavailability of PFASs in soil. Herein, hydroponic experiments were conducted to understand the impacts of two kinds of typical DOM, bovine serum albumin (BSA) and humic acid (HA), on the uptake and translocation of legacy PFASs and their emerging alternatives, perfluorooctane sulfonic acid (PFOS), perfluorooctane acid (PFOA), perfluorohexane sulfonic (PFHxS) and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) in wheat (Triticum aestivum L.). The results indicated that both HA and BSA significantly inhibited the bioaccumulation and translocation of PFASs in the roots and shoots of wheat, and the impacts of BSA were greater than HA. This difference was explained by the greater binding affinities of the four PFASs with BSA than with HA, as evidenced by the equilibrium dialysis and isothermal titration calorimetry (ITC) analyses. It was noting that inhibition impacts of the BSA-HA mixture (1:1) were lower than BSA alone. The results of Fourier transform infrared (FT-IR) spectroscopy and excitation-emission matrix (EEM) fluorescence spectroscopy suggested that HA could bind with the fluorescent tryptophan residues in BSA greatly, competing the binding sites with PFASs and forming a cover on the surface of BSA. As a result, the binding of PFASs with BSA-HA complex was much lower than that with BSA, but close to HA. The results of this study shed light on the impacts of DOM in soil on the bioaccumulation and translocation of PFASs in plants.

The presence of viruses in water is a major risk for human and animal health due to their high resistance to disinfection. Pulsed corona discharge plasma (PCDP) efficiently inactivates bacteria by causing damage to biological macromolecules, but its effect on waterborne virus has not been reported. This study evaluated the inactivation efficacy of PCDP to viruses using spring viremia of carp virus (SVCV) as a model. The results showed that 4-log10 reduction of SVCV infectivity in cells was reached after 120 s treatment, and there was no significant difference in survival of fish infected with SVCV inactivated by PCDP for 240 s or more longer compared to the control fish without virus challenge, thus confirming the feasibility of PCDP to waterborne virus inactivation. Moreover, the high input energy density caused by voltage significantly improved the inactivation efficiency. The further research indicated that reactive species (RS) generated by pulsed corona discharge firstly reacted with phosphoprotein (P) and polymerase complex proteins (L) through penetration into the SVCV virions, and then caused the loss of viral infectivity by damage to genome and other structural proteins. This study has significant implications for waterborne virus removal and development of novel disinfection technologies.

Microplastics (MPs) have attracted considerable attention due to its worldwide distribution, environmental persistence, and ecological risks. In this work, the photodegradation of MPs mediated by five different types of soils were investigated. The results showed: after 20 d of xenon lamp irradiation, significant degradation of MP was observed on Harbin (S1), Huainan (S2), Jiangxi (S3), Shaanxi (S4) and Hainan (S5). The order of photodegradation rate of MP was S2 > S5 > S4 > S1 > S3. The components of the soil have some correlations with MPs photodegradation. The photodegradation of MP mediated by soil components (specifically, the clay, the iron oxides and MnO2) displayed positive effect, while the photodegradation of MPs mediated by organic carbon showed inhibition trend. It is worth noting that electrostatic interaction may be the dominant factor affecting the interaction between MPs photodegradation rate and different soils surfaces. This study is helpful to deepen the understanding of the photochemical behavior of MP in soil, and is of great significance to evaluate the environmental fate and mechanism mediated by MP in soil.

Decomplexation is an effective approach and key step for heavy metal–organic complex removal because conventional chemical precipitation is ineffective. In this study, a novel strategy of coupling discharge plasma and iron internal microelectrolysis (“plasma + iron”) was developed for decomplexation of Cu-ethylenediaminetetraacetic acid (Cu-EDTA). There were distinct synergistic effects on Cu-EDTA decomplexation in the “plasma + iron” system, resulting from Fenton reaction, Fe(III) displacement, and flocculation. Cu-EDTA decomplexation efficiency and energy efficiency were 1.53 and 2.31 times as those in single plasma system. Iron powder accelerated H2O2 decomposition and ·OH formation, especially ·OH production on the surface of iron, which mitigated the negative effects of radical quenchers. Moreover, co-precipitation with polymeric iron further promoted the removal of Cu ions released. Some small organic acids, amides, amines, alcohols, and NO3– were identified as a result of the effective Cu-EDTA decomplexation by the “plasma + iron” strategy. The synergetic decomplexation pathways of Cu-EDTA were then further proposed.

The heavy metal-organic complexes and heavy metal ions pose great threats to human health, and their elimination from water environment is quite urgent. Simultaneous decomplexation of heavy metal complex Cu-EDTA and reduction of Cr(VI) was performed in a persulfate (PS)/formate (FA) system. Oxidizing species and reductive species were simultaneously produced in this PS/FA system, which realized 96.6% of Cu-EDTA decomplexation and 100% of Cr(VI) reduction within 90 min treatment under the solution pH 3.60. Higher solution temperature and acidic conditions favored Cu-EDTA decomplexation and Cr(VI) reduction. There existed an appropriate molar ratio of FA and PS to simultaneously realize high-efficient Cu-EDTA decomplexation and Cr(VI) reduction. SO4•-, •OH, and 1O2 drove the Cu-EDTA decomplexation, which destroyed the chelating sites of Cu and EDTA, and finally it was oxidized to small molecular alcohols, organic acids, and Cu2+. Reductive species CO2•− was produced by the reaction of SO4•− and FA, as well as •OH and FA, which dominated the reduction of Cr(VI) to Cr3+. Carbonates, hydroxides, and oxides including Cu(OH)2, CuCO3, Cu2CO3(OH)2, CuO, Cr(OH)3, and Cr2O3 were the main composites in precipitates after Cu2+ and Cr3+ were precipitated. Furthermore, Cu-EDTA decomplexation and Cr(VI) reduction processes induced by PS/FA were put forward.

Non-thermal plasma technology can inactivate microorganisms that maybe used in the food processing industry. This study mainly aims to evaluate the effect of a gas-phase surface discharge plasma system with a spray reactor on yeasts (Zygosaccharomyces rouxii LB and 1130) in apple juice. This method avoids the limitation of liquid penetration depths in plasma treatment, expanding the processing capacity. Owing to this advantage, this approach can be used to industrialize liquid food sterilization. Experimental results showed that the number of Z. rouxii LB and 1130 cells decreased by about 6.58 and 6.82 log reductions, respectively, in apple juice after discharge plasma treatment for 30 min. The treatment used a voltage of 21.3 kV and inactivation followed the downward concave Weibull kinetics. Longer plasma exposure times with higher discharge voltages and regulated volume flow rate for both gas and liquid phases resulted in greater inactivation rates. Scanning electron microscopy revealed that the structures of plasma-treated cells were severely damaged during the discharge plasma process. Plasma-generated compounds in liquid, such as hydrogen peroxide and ozone in the liquid phase, are generally responsible for the inactivation of microorganisms.

Phthalates, as additives in the plastic production process, were able to enter the soil, causing huge risks to soil environment and human health. The potential of phthalates elimination in soil using dielectric barrier discharge (DBD) plasma was evaluated, with dimethyl phthalate (DMP) as a model pollutant. The experimental results demonstrated that DMP in soil could be decomposed by the DBD plasma oxidation. DMP concentration was reduced from 200 mg kg−1 to 87 mg kg−1 after 60 min’s DBD plasma oxidation, and its decomposition process fitted well with the first-order kinetics. Soil moisture was an important parameter affecting DMP decomposition in soil. Lower initial concentration was beneficial for DMP degradation. Analysis on types and action ranges of reactive oxygen species participating in DMP decomposition demonstrated that oxygen-containing species and electron played crucial roles. DMP molecular structure was destroyed in the DBD plasma processing, and phthalic acid monomethyl ester, phthalic acid, acetic acid, and oxalic acid were detected as the main intermediates. DBD plasma oxidation decreased the toxicity of DMP to seed germination and growth. Germination rate of wheat seed and activity of root system both increased, while free radical damage to cell membrane was significantly alleviated after 60 min’s DBD plasma oxidation.

Carbon spheres (CS) were synthesized from monosaccharides (glucose), disaccharides (β-cyclodextrin), and polysaccharides (sucrose) using surfactants, and then by hydrothermal treatment with g-C3N4 ...

In this study, pulsed corona discharge plasma coupled with natural soil particles (PCDP/SPs) were used to remove tetracycline hydrochloride (TCH) from wastewater. The differences among three typical and natural soil particles (SPs, black soil (BS) of Jilin, loess soil (LS) of Shaanxi, and red soil (RS) of Hunan in China) for TCH removal were compared by the PCDP/SPs system. The energy yields upon TCH removal and synergistic effects between the pulsed corona discharge plasma (PCDP) and SPs were analyzed. The effects of various factors on removal efficiency of TCH were investigated. The results indicated that the removal efficiency of TCH and the energy yield of PCDP were obviously improved in the PCDP/SPs system. Different SPs types had significant effects on the TCH removal. The removal efficiencies of TCH in the PCDP/SPs system with LS and BS were higher than that in the PCDP/SPs system with RS. The removal efficiency of TCH increased with an increase in the pulsed peak voltage, pulsed frequency, and SPs weight and a decrease in the SPs size. The removal efficiency of TCH decreased upon increasing the initial concentration of TCH and solution conductivity. The recycling experiment showed that the removal efficiency of TCH still maintained a high level after four cycles in the PCDP/LS system; however, a decrease in the removal efficiency of TCH was also observed. The consumption of active species in solution demonstrated that OH and O3 play key roles in TCH degradation. Intermediates in the process of TCH degradation for the PCDP/SPs system with LS were identified by GC–MS, and a possible degradation pathway was also proposed.

Phthalates, as additives in the plastic production process, were able to enter the water environment, causing huge risks to ecological environment and human health. The potential of phthalates elimination in aqueous using sodium percarbonate (SPC) activated by discharge plasma (marked as “SPC + plasma”) was evaluated, with dimethyl phthalate (DMP) as a model pollutant. Experimental results showed that about 92.1% of DMP was eliminated in the “SPC + plasma” system with the treatment time of 30 min, which was 30.7% higher than that in sole plasma system, and the synergetic intensity for DMP elimination reached up to 127.0; and the energy yield was also raised by 131%. H2O2 and OH radicals formation were promoted but ozone concentration decreased in the “SPC + plasma” system. Appropriate SPC dosage benefited DMP elimination, and the synergetic intensity increased from 2.0 to 127.0 as the SPC dosage increased from 0.06 mmol L−1 to 0.12 mmol L−1. OH radicals, O2·−, 1O2, and CO3·− played crucial roles in DMP elimination, and the roles of O2·− and 1O2 were strengthened in the “SPC + plasma” system. Ultraviolet–visible spectroscopy measurement, total content of organic carbon, atomic force microscopy and three-dimensional fluorescence analysis demonstrated that DMP molecular structure was destroyed during treatment, and some smaller molecular fractions were generated. The main intermediates included phthalic acid monomethyl ester, phthalic acid, o-phthalic anhydride, acetic acid, formic acid, and oxalic acid. The possible enhancement mechanisms for DMP elimination in the “SPC + plasma” system were proposed.

Heavy metals accumulate in active sludge, and their fate and environmental risks might change during disintegration, which is essential for the subsequent treatment of the active sludge. In this study, the distribution of heavy metals (Zn, Cr, Cd, Ni, and Pb), transformation of their speciation fractions and leaching potentials were explored. Meanwhile, to explore the reasons for the changes, the evolution in morphology of sludge flocs and extracellular polymer substances (EPS) were also examined. The results showed that accompanied by the destruction of sludge flocs and the release of inner organic materials, large numbers of wrapped heavy metals were released from the solid phase into the liquid phase under discharge plasma treatment, especially for those organic bounded metals. As a consequence, the ratio of oxidizable fractions (F3) gradually decreased. The contamination degree and environmental risks of heavy metals were evaluated based on the fraction contents, and it was concluded that discharge plasma treatment could be in favor of reducing the contamination degree and environmental risks. In addition, the leaching contents of Cr decreased after plasma oxidation, while Pb, Zn, Ni and Cd contents increased; but were far below the limit values.

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), which are commonly detected in waters, are emerging environmental contaminants with strong pathogenicity. Simultaneous removal of ARB and ARGs in water by mesoporous plasma was explored in this study, focusing on evaluating the impacts of common inorganic ions on ARB inactivation, antibiotic resistance reduction, and change in ARGs profiles. The antibiotic-resistant Escherichia coli (AR E. coli) was selected as the model ARB. The experimental results demonstrated that the presence of NO3−, Cu2+, and Fe2+ all promoted AR E. coli inactivation and ARGs elimination, reduced its antibiotic resistance, and also inhibited horizontal gene transfer of ARGs; whereas CO32− inhibited these processes, and SO42− did not have distinct effect. During the plasma treatment process, Fe2+ significant enhancement on OH formation via reactions with H2O, the highest performance was observed in the presence of Fe2+. The membrane structure, disruption of biological processes, dissolution of intracellular components, and DNA. These finding shed light on the potential effects of inorganic ions on ARB and ARGs elimination induced by the mesoporous plasma.

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), as emerging environmental pollutants, are commonly detected in waters. Surface plasma was developed to simultaneously inactivate antibiotic resistant Escherichia coli (AR E. coli) and remove its associated ARGs in water. 7.0 log AR E. coli was inactivated after 10 min surface plasma treatment; minimal inhibitory concentration (MIC) representing antibiotic resistance profiles decreased by 96.9%, 96.9%, and 98.4% for the tested tetracycline, amoxicillin, and gentamicin, respectively. The ARGs (TetC, TetW, blaTEM-1, and aac(3)-II) and integron gene (intI1, indicator of horizontal gene transfer) also decreased by 1.04, 0.61, 1.84, 2.2, and 2.3 log copies within 10 min, respectively. Oxidizing substances in the surface plasma including OH, 1O2, H2O2, O3, NO2−, and NO3− contributed to AR E. coli inactivation, resulting in membrane damage, biological process disruption, protein structure changes, and DNA damage. As a result, horizontal gene transfer of ARGs was inhibited by 63% after plasma treatment. Overall, surface plasma could be an effective technique to control ARB and ARGs in water.

Heavy metal–organic complexes are difficult to remove by classic precipitation methods. In this study, MIL-53(Fe) photocatalyst was successfully synthesized and its photocatalytic activity for the decomplexation of heavy metal–organic complex was explored. Ethylenediaminetetraacetic acid complexed copper (Cu-EDTA) was chosen as the target. Experimental results showed that approximately 91% of Cu-EDTA was decomposed within 60 min under ultraviolet irradiation (UV), and 64% was mineralized within 120 min. Cu-EDTA decomplexation was mainly driven by the production of h+, HO• and 1O2 from the MIL-53(Fe). Fe(III) released from the MIL-53(Fe) was reduced by the photogenerated electrons and Cu(I) to form Fe(Ⅱ), which inhibited the recombination of photogenerated electrons and h+. More importantly, Fenton-like reactions and coprecipitation derived from the released Fe(III) promoted the decomplexation of Cu-EDTA. As a result, some small molecular compounds, including glycine, acetic acid, nitrilotriacetic acid, oxalic acid, oxamic acid, and NO3–, were generated. The possible decomplexation pathways of Cu-EDTA by MIL-53(Fe) photocatalysis were proposed. Effects of coexisting inorganic ions and organic matter on Cu-EDTA decomplexation were evaluated. Furthermore, the photocatalytic degradation potentials for other heavy metal complexes were also explored.

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs) are emerging environmental pollutants that pose great threats to human health. In this study, a novel strategy using plasma was developed to simultaneously remove antibiotic-resistant Escherichia coli (AR bio-56954 E. coli) and its ARGs, aiming to inhibit gene transfer by conjugation. Approximately 6.6 log AR bio-56954 E. coli was inactivated within 10 min plasma treatment, and the antibiotic resistance to tested antibiotics (tetracycline, gentamicin, and amoxicillin) significantly decreased. Reactive oxygen and nitrogen species (RONS) including •OH, 1O2, O2•−, NO2−, and NO3− contributed to ARB and ARGs elimination; their attacks led to destruction of cell membrane, accumulation of excessive intracellular reactive oxygen substances, deterioration of conformational structures of proteins, and destroy of nucleotide bases of DNA. As a result, the ARGs (tet(C), tet(W), blaTEM-1, aac(3)-II), and integron gene intI1), and conjugative transfer frequency of ARGs significantly decreased after plasma treatment. The results demonstrated that plasma has great prospective application in removing ARB and ARGs in water, inhibiting gene transfer by conjugation.

Antibiotic resistant bacteria (ARB) and resistance genes (ARGs) are emerging environmental pollutants with strong pathogenicity. In this study, surface plasma was developed to inactivate the donor ARB with Escherichia coli (AR E. coli) as a model, eliminate ARGs, and inhibit conjugative transfer of ARGs in water, highlighting the influences of concomitant inorganic ions. Surface plasma oxidation significantly inactivated AR E. coli, eliminated ARGs, and inhibited conjugative transfer of ARGs, and the presence of NO3-, Cu2+, and Fe2+ all promoted these processes, and SO42- did not have distinct effect. Approximately 4.5log AR E. coli was inactivated within 10 min treatment, and it increased to 7.4log AR E. coli after adding Fe2+. Integrons intI1 decreased by 3.10log (without Fe2+) and 4.43log (adding Fe2+); the addition of Fe2+ in the surface plasma induced 99.8% decline in the conjugative transfer frequency. The inhibition effects on the conjugative transfer of ARGs were mainly attributed to the reduced reactive oxygen species levels, decreased DNA damage-induced response, decreased intercellular contact, and down-regulated expression of plasmid transfer genes. This study disclosed underlying mechanisms for inhibiting ARGs transfer, and supplied a prospective technique for ARGs control.

It is difficult to remove heavy metal-organic complexes from water by chemical precipitation because of the strong complexation ability between heavy metal ions and organics. In this study, the removal of the Cu-ethylenediaminetetraacetic acid (Cu-EDTA) complex using autocatalytic persulfate (PS) oxidation was investigated. The Cu-EDTA removal efficiency reached up to 96.57% after 90 min of treatment by PS oxidation. A higher PS concentration favored Cu-EDTA removal; An increase in the initial concentration of Cu-EDTA benefited PS activation, and a greater removal performance was obtained at a lower Cu-EDTA initial concentration (0.1 mmol L−1). Excessive Cu2+ accelerated Cu-EDTA removal, while superfluous EDTA suppressed it. Relatively lower initial solution pH value favored Cu-EDTA removal. SO4•-, •OH, and 1O2 displayed significant roles in the Cu-EDTA removal process, as they destroyed the chelating sites of the Cu(II) and EDTA molecules; finally small molecular organic acids, alcohols, and NO3− were produced. The released Cu(II) existed in the precipitates in the forms of Cu-based carbonates, Cu-based hydroxides, and copper oxide. A possible decomposition pathway of Cu-EDTA was proposed. Overall, multipathway activation of PS induced by heavy metal complexes could be an effective technique for the removal of the heavy metal complexes.

Chitosan is widely used in antibacterial, hypolipidemic, and anticancer fields, and the preparation of low molecular weight chitosan with excellent solubility and hydrophilicity is beneficial for its application. In this study, simultaneous production of low molecular weight chitosan and reducing sugars via chitosan depolymerization by surface discharge plasma was developed. More than 95% of the chitosan with an initial molecular weight of 682.5 kDa was depolymerized after 60 min of treatment, with the reducing sugar yield of 23.7%. ·OH, O2·-, and 1O2 played important roles in chitosan depolymerization; they preferentially attacked the amorphous structure of chitosan, resulting in breakage of the intra- and intermolecular hydrogen bonds and β-(1,4) glycosidic bonds, thereby forming low molecular weight chitosan. More electrons and hydrogen atoms would be provided by prepared low molecular weight chitosan due to the decreased intra- and intermolecular hydrogen bonds, and a high biological activity was finally attained. Overall, discharge plasma could be used as an effective technique for chitosan depolymerization, which widens its potential applications.

Polycyclic aromatic hydrocarbons (PAHs) contaminated sites have attracted worldwide concern due to their carcinogenic, mutagenic, and teratogenic natures. Crystallographic manganese oxides (MnxOy) are ubiquitous in soils. In this study, MnxOy enhanced PAHs contaminated soil remediation in a microwave activated persulfate (MW/PS) system was conducted, and pyrene was selected as a target pollutant. Significant enhancement performance on pyrene removal was observed after adding MnxOy, which ranked as β-MnO2 > α-MnO2 > γ-MnO2 > Mn2O3. Pyrene removal efficiency was enhanced from 65.7% to 85.6% within 15 min of treatment when β-MnO2 dosage increased from 0 to 0.1 g. MnxOy in the MW/PS system improved the production of active substances and converted radical process into non-radical process via conversion of Mn(IV) to Mn(III) and Mn-O-Mn to Mn-O-X. 1O2 played significant roles in pyrene degradation, whereas the presence of β-MnO2 alleviated the shielding effects of SO4 − and OH scavengers. Pyrene molecular structures were destroyed, and some ring-opening and/or lower ring byproducts were generated. Residual toxicity of pyrene and its degradation byproducts was predicted. This work provided a potential pathway to promote PAHs contaminated soil remediation via MnxOy enhanced MW/PS oxidation, and highlighted new insights into the mechanism of PS activation by metal oxides.

The reactivity of oxidizing materials is highly related to the exposed crystal facets. Herein, δ-MnO2 with different exposure facets were synthesized and the oxidative activities of the as-prepared materials were evaluated by degrading phenol in water without light. The degradation rate of phenol by δ-MnO2-{−111} was significantly higher than that by δ-MnO2-{001}. δ-MnO2-{−111} also displayed high degradation efficiency to a variety of other organic pollutants, such as ciprofloxacin, bisphenol A, 3-chlorophenol and sulfadiazine. Comprehensive characterization and theoretical calculation verified that the {−111} facet had high density of Mn3+, thus displaying enhanced direct oxidative capacity to degrade organic pollutants. In addition, the dominant {−111} facet promoted adsorption/activation of O2, thus favored the generation of superoxide radical (O2•−), which actively participated in the degradation of pollutants. The phenol degradation kinetics could be divided into two distinct phases: the rapid phase (k1obs = 0.468 min−1) induced by Mn3+ and the slower phase (k2obs = 0.048 min−1) dominated by O2•−. The synergistically promoted non-radical and radical based reactions resulted in greatly enhanced the oxidative activity of the δ-MnO2-{−111}. These findings deepen the understanding of facet-dependent oxidative performance of materials and provided valuable insights into the possible practical application of δ-MnO2 for water purification.

Atmospheric dielectric barrier discharge (DBD) was attempted to improve the resistance of wheat seed to drought stress. Effects of DBD plasma on wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation, reactive oxygen species (ROS), antioxidant enzyme activity, abscisic acid, and drought resistant related genes expression under drought stress were investigated. The changes of the wheat seed coat before and after the DBD plasma treatment were explored. Experimental results showed that the DBD plasma treatment could alleviate the adverse effects of drought stress on wheat seed germination and seedling growth; the germination potential and germination rate increased by 27.2% and 27.6%, and the root length and shoot length of the wheat seedlings also increased. Proline and soluble sugar levels under drought stress were improved after the DBD plasma treatment, whereas the malondialdehyde content decreased. ROS contents under drought stress were reduced after the DBD plasma treatment, whereas the activities of superoxide dismutase, catalase, and peroxidase were promoted. DBD plasma treatment promoted abscisic acid generation in wheat seedlings, and it also regulated functional gene LEA1 and stimulated regulation genes SnRK2 and P5CS to resist drought stress. Etching effect and surface modification occurred on the seed coat after the DBD plasma treatment.

Humic acid (HA), a predominant type of natural organic matter in surface water, had several potential environmental and health risks. A gas phase surface discharge plasma system was employed to eliminate HA from micro-polluted surface water, and the effects of some concomitant inorganic ions on HA removal were evaluated. The experimental results showed that approximately 89.4% of HA could be smoothly eliminated after 40 min of the discharge plasma treatment, and the HA removal process could be fitted well by the first-order kinetic model. The presence of anions such as CO32− and Cl− in the natural water were adverse for the HA removal due to their competition for the active species, whereas the effects of NO3− and SO42− on the HA removal could be neglected; this deduction was also confirmed via the evolution of fluorescence spectra intensity of OH radicals. Although Cu2+ could react with H2O2 via Fenton-like reaction, its presence was still adverse for the HA removal due to the complexing effect of Cu2+ with HA molecules. In addition, the HA removal processes were characterized by UV–Vis spectrum, DOC removal, specific absorbance parameters, and three-dimensional fluorescence spectrum analysis.

An activated carbon fiber supported nanoscale zero-valent iron (ACF-nZVI) composite for Cr(VI) removal from groundwater was synthesized according to the liquid phase reduction method. The techniques of N2 adsorption/desorption, FESEM, EDX, XRD and XPS were used to characterize the ACF-nZVI composite and the interaction between the ACF-nZVI composite and Cr(VI) ions. Batch experiments were conducted to evaluate the effects of several factors, including the amount of nZVI on activated carbon fiber (ACF), pH value, initial Cr(VI) concentration, and co-existing ions on Cr(VI) removal. The results indicate that presence of ACF can inhibit the aggregation of nanoscale zero-valent iron (nZVI) particles and increase its reactivity, and the Cr(VI) removal efficiency increases with increasing amounts of nZVI on ACF and a decrease in the initial Cr(VI) concentration. In acidic conditions, almost 100% of Cr(VI) in solution can be removed after 60 min of reaction, and the removal efficiency decreases with increasing initial pH values. The Cr(VI) removal is also dependent on the co-existing ions. Reusability experiments on ACF-nZVI demonstrate that the ACF-nZVI composite can keep a high reactivity after five successive reduction cycles. The removal mechanisms are proposed as a two-step interaction including the physical adsorption of Cr(VI) on the surface or inner layers of the ACF-nZVI composite and the subsequent reduction of Cr(VI) to Cr(III) by nZVI.

Air atmospheric dielectric barrier discharge plasma (DBD) was attempted to pretreat wheat seed to improve its germination and growth in this study. The effects of the DBD plasma treatment on the wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation level, and antioxidant enzymes activity were investigated. The experimental results showed that the DBD plasma treatment with an appropriate time scale could promote the wheat seed germination and seedling growth. The germination potential, germination rate, germination index, and vigor index increased by 26.7, 9.1, 16.9, and 46.9% after 7 min’s DBD plasma treatment, respectively; the root length, shoot length, fresh weight, and dry weight of the seedlings also increased after the DBD plasma treatment. The osmotic-adjustment products, proline and soluble sugar contents, in the wheat seedlings were significantly enhanced after the DBD plasma treatment with an appropriate time scale, while the malondialdehyde content decreased. Moreover, the activities of superoxide dismutase and peroxidase also increased after the DBD plasma treatment. The DBD plasma treatment led to etching effect on the wheat seed coat, resulting in the improvement of its water absorption capacity.

Humic acid (HA) was a predominant natural organic matter in ground water and surface waters. The removal of HA from micro-polluted source water using a gas phase surface discharge plasma at different grounding modes was studied, and three kinds of grounding modes (iron wire mesh, aluminized paper, and water) were selected. The experimental results illustrated that approximately 95.3% of HA in water was removed within 30 min’s discharge plasma treatment in the iron wire mesh electrode system, and it was 89.5% and 84.6% in the aluminized paper electrode system and water electrode system, respectively; although the strongest streamer discharge and the highest ozone equivalent concentration were both observed in the iron wire mesh electrode system. The discharge plasma treatment resulted in a relatively more homogeneous surface topography in the HA molecules as analyzed by scanning electron microscope (SEM), especially in the iron wire mesh electrode system and in the aluminized paper electrode system. The decomposition process of HA at different grounding modes was analyzed and compared via the evolution of the UV–Vis spectrum, dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA) and UV absorption ratios with treatment time. In addition, the HA removal efficacy in this study was comparable with those of some other techniques.

To enhance the photocatalytic activity of TiO2, reduced graphene oxide–TiO2 (RGO–TiO2) composites with sandwich-like structure were synthesized using a simple solvothermal method. The morphology, crystalline information, and structural property of the photocatalyst were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transmission infrared spectroscopy. The photocatalytic performances of the RGO–TiO2 composites were evaluated by the degradation of orange II (AO7) in water under UV light irradiation. The results showed that the RGO–TiO2 composites exhibited much higher photocatalytic activity than TiO2 and that the removal efficiency of AO7 could reach above 95% only after 20 min of UV light irradiation under the optimum condition. The improved photocatalytic activity might be attributed to the improved charge transfer and significant separation of the photoinduced electrons and holes in the presence of a two-dimensional graphene network. The results of recycling experiments show that RGO–TiO2 composites have a high photostability, which is expected in the practical application. Radical trapping experiments indicated that ·OH plays a crucial role in the process of AO7 degradation.

The influences of non-thermal discharge plasma treatment on wheat seed germination and seedling growth were investigated using a dielectric barrier discharge (DBD) plasma system at atmospheric pressure and room temperature. DBD plasma with various gas sources (oxygen, air, argon, and nitrogen) was employed in this study. Germination characteristics, seedling growth parameters, surface changes of the seed coat, permeability, and soluble protein of the seedlings were measured after the DBD plasma treatments. The experimental results showed that moderate-intensity DBD plasma had active impacts on wheat seed germination and seedling growth. Germination potential significantly increased by 24.0, 28.0, and 35.5% after 4 min of the air plasma, nitrogen plasma, and argon plasma treatments, respectively, compared with the control; and the shoot and root length also increased; however, no enhancement was observed after the oxygen plasma treatment. Scanning electron microscope analysis showed that etching effects on the seed coat occurred after the air plasma, nitrogen plasma, and argon plasma treatments, which affected the hygroscopicity and permeability of the wheat seed. In addition, moderate-intensity DBD plasma could also activate several physiological reactions in wheat seed, resulting in the increase of soluble protein production in wheat seedlings.

Glyphosate was one of the most widely used herbicides in the world. Remediation of glyphosate-contaminated soil was conducted using atmospheric pressure dielectric barrier discharge (DBD) plasma. The feasibility of glyphosate degradation in soil was explored, and the soil leachate toxicity after remediation was assessed via a seed germination test. The experimental results showed that approximately 93.9% of glyphosate was degraded within 45 min of DBD plasma treatment with an energy yield of 0.47 g kWh⿿1, and the degradation process fitted the first-order kinetic model. Increasing the discharge voltage and decreasing the organic matter content of the soil were both found to facilitate glyphosate degradation. There existed appropriate soil moisture to realize high glyphosate degradation efficiency. Glyphosate mineralization was confirmed by changes of total organic carbon (TOC), chemical oxygen demand (COD), PO43⿿ and NO3⿿. The degradation intermediates including glycine, aminomethylphosphonic acid, acetic acid, formic acid, PO43⿿ and NO3⿿, CO2 and CO were observed. A possible pathway for glyphosate degradation in the soil using this system was proposed. Based on the soil leachate toxicity test using wheat seed germination, the soil did not exhibit any hazardous effects following high-efficiency glyphosate degradation.

Microplastics (MPs) are presumed to be inert during aging under ambient conditions. In this study, four types of virgin MPs, including polystyrene (PS), phenol-formaldehyde resin (PF), polyethylene (PE), and polyvinyl chloride (PVC), were aged under simulated solar light irradiation. Surprisingly, several environmentally persistent free radicals (EPFRs), which are considered to be a type of emerging contaminant, were detected on the irradiated PS and PF, rather than PE and PVC, by electron paramagnetic resonance (EPR) spectroscopy. Depending on the photoaging duration time, the characteristic g-factors of the EPFRs produced on PS and PF were 2.0044-2.0049 and 2.0043-2.0044, respectively. The generated EPFRs on PS and PF decayed rapidly at the initial stage and then slowly disappeared with the elapsed aging time. Analyses by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) suggested that MPs might experience chemical chain scission, O2/H2O addition, and EPFR formation under the light irradiation. Accompanying with the formation of EPFRs, reactive oxygen species, such as O2•- and •OH, were also observed. The findings provide a novel insight to evaluate the potential hazards of MPs to organisms and ecosystems.