Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory a...Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory and cardiovascular diseases.In this study,we assessed the oxidative potential(OP)of fresh and O_(3)-aged PM_(2.5)particles from various urban and rural emission sources using the dithiothreitol(DTT)method.Our results revealed variations in the OP of fresh PM_(2.5)among different emission sources,with biomass burning sources exhibiting the highest OP,followed by industrial areas,vehicular emissions,cooking emissions,and suburban areas,respectively.Water-soluble organics and transition metals might potentially exert significant influence on particle OP.O_(3)aging notably decreased the OP of PM_(2.5)particles,possibly due to the oxidation of highly DTT-active components into low redox-active small molecules.Moreover,the evolution of OP in different PM_(2.5)components,including methanol-soluble and insoluble fractions,exhibited distinct responses to O_(3)aging for source-oriented PM_(2.5).Additionally,differences in chemical composition between fresh and aged PM_(2.5)were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions.This study systematically delineates variances in the toxic potential of fresh and O_(3)-aged PM_(2.5)from various anthropogenic sources.The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM_(2.5),as well as for formulating human health protection policies.展开更多
The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition ...The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition as a promising catalyst material for the CO_(2)ER to formate.The performance of Bi catalysts(named as Bi-V)can be significantly improved when they possess single metal atom vacancy.However,creating larger-sized metal atom vacancies within Bi catalysts remains a significant challenge.In this work,Bi nanosheets with dual V0 Bi vacancy(Bi-DV)were synthesized utilizing in situ electrochemical transformation,using BiOBr nanosheets with triple vacancy associates(V■_(Bi)V··_(O)V■_(Bi),V■_(Bi)and V··_(O)denote the Bi^(3+)and O_(2)−vacancy,respectively)as a template.The obtained Bi-DV achieved higher CO_(2)ER activity than Bi-V,showing Faradaic efficiency for formate production of>92%from-0.9 to-1.2 VRHE in an H-type cell,and the partial current density of formate reached up to 755 mA/cm^(2)in a flow cell.The comprehensive characterizations coupled with density functional theory calculations demonstrate that the dual V^(0)_(Bi)vacancy on the surface of Bi-DV expedite the reaction kinetics toward CO_(2)ER,by reducing the thermodynamic barrier of^(∗)OCHO intermediate formation.This research provides critical insights into the potential of large atom vacancies to enhance electrocatalysis performance.展开更多
The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and h...The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.展开更多
Nitrate renoxification significantly influences atmospheric nitrogen cycling and global OH budgets.Although numerous nitrite acid(HONO)formation pathways from nitrate photolysis have been widely reported,the influence...Nitrate renoxification significantly influences atmospheric nitrogen cycling and global OH budgets.Although numerous nitrite acid(HONO)formation pathways from nitrate photolysis have been widely reported,the influence of various environmental factors and aerosol properties on reactive nitrogen production remains largely unclear.In this work,we employed NaNO_(3)/humic acid(HA)as a model nitrate photosensitization system to investigate the crucial roles of aerosol acidity,organic fraction,and dissolved oxygen in the production of HONO,NO_(2),and NO_(2)^(-).The presence of HA at 10 mg/L resulted in a remarkable increase in HONO production rates by approximately 2–3 times and NO_(2)^(-) concentration by 3–6 times across a pH range of 5.2 to 2.0.Meanwhile,the molar fraction of gaseous HONO in total N(Ⅲ)production increased from4%to 69%as bulk-phase pH decreased from 5.2 to 2.0.The higher organic fraction(i.e.,20 and 50 mg/L HA concentration)instead inhibited HONO and NO_(2) release.The presence of dissolved oxygen was found to be adverse for reactive nitrogen production.This suggests that the HA photosensitizer promoted the secondary conversion of NO_(2) to HONO mainly via reduced ketyl radical intermediates,while superoxide radical formation might exert a negative effect.Our findings provide comprehensive insights into reactive nitrogen production from photosensitized nitrate photolysis mediated by various external and internal factors,potentially accounting for discrepancies between field observations and model simulations.展开更多
To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summ...To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.展开更多
Recently,heterogeneous activation of peroxymonosulfate(PMS) to oxidatively degrade organic pollutants has been a hotspot.In the present work,copper ferrite-graphite oxide hybrid(CuFe2 O4@GO)was prepared and used as ca...Recently,heterogeneous activation of peroxymonosulfate(PMS) to oxidatively degrade organic pollutants has been a hotspot.In the present work,copper ferrite-graphite oxide hybrid(CuFe2 O4@GO)was prepared and used as catalyst to activate PMS for degradation of methylene blue(MB) in aqueous solution.A high degradation efficiency(93.3%) was achieved at the experimental conditions of20 mg/L MB,200 mg/L CuFe2 O4@GO,0.8 mmol/L PMS,and 25℃temperature.Moreover,CuFe2 O4@GO showed an excellent reusability and stability.The effects of various operational parameters including pollutant type,solution pH,catalyst dosage,PMS dosage,pollutant concentration,temperature,natural organic matter(NOM),and inorganic anions on the catalytic degradation process were comprehensively investigated and elucidated.The further mechanistic study revealed the Cu(Ⅱ)/Cu(Ⅰ) redox couple on CuFe2 O4@GO played the dominant role in PMS activation,where both hydroxyl and sulfate radicals were generated and proceeded the degradation of pollutants.In general,CuFe2 O4@GO is a promising heterocatalyst for PMS-based advanced oxidation processes(AOPs) in wastewater treatment.展开更多
La-EDTA-Fe3O4 was prepared by a chemical co-precipitation method. The magnetic composite was characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD） and Fourier transform infrared spectros...La-EDTA-Fe3O4 was prepared by a chemical co-precipitation method. The magnetic composite was characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. Furthermore, the adsorption properties of La-EDTA-Fe3O4 toward phosphate in water were investigated. The uptake rate of phosphate in water by La-EDTA-Fe3O4 was 3-1000 times than that of EDTA-Fe3O4, and reached 97.8% at 7 hr. The adsorption process agreed well with the Freundlich model and kinetics studies showed that the adsorption of phosphate proceeds according to pseudo second-order adsorption kinetics. The maximum removal rate was achieved at pH 6.0-7.0. The La-EDTA-Fe3O4 had good adsorption properties and could be separated well from aqueous solution by a permanent magnet. Therefore, this nanomaterial has potential application for the removal of phosphate from large water bodies.展开更多
Adansonia digitata L.(Malvaceae) is commonly known as baobab tree native to Africa.Baobab is a multi-purpose tree which offers protection and provides food,clothing and medicine as well as raw material for many useful...Adansonia digitata L.(Malvaceae) is commonly known as baobab tree native to Africa.Baobab is a multi-purpose tree which offers protection and provides food,clothing and medicine as well as raw material for many useful items.The fruit pulp,seeds,leaves,flowers.roots,and bark of baobab are edible and they have been studied by scientists for their useful properties.The fruit pulp have very high vitamin C.calcium,phosphorus,carbohydrates,fibers,potassium,proteins and lipids content,which can be used in seasoning as an appetizer and also make juices.Seeds contain appreciable quantities of phosphorus,magnesium,zinc,sodium,iron,manganese,whereas they have high levels of lysine,thiamine,calcium and iron.Baobab has numerous biological properties including antimicrobial,anti-malarial,diarrhoea,anaemia,asthma,antiviral,anti-oxidant and anti-inflammatory activities amongst others.Phytochemical investigation revealed the presence of flavonoids.phytosterols.amino acids,fatty acids,vitamins and minerals.The review summarizes the information on various aspects of traditional information,taxonomic description,medicinal properties and importantly nutritional value.展开更多
Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several appro...Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.展开更多
The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most he...The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest China,during the most polluted season(winter).Our results show that the mass concentrations of PM_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter 2020.The mass concentrations of organic matter(OM),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,respectively.The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile sources.The contribution of OM and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of pollution.Four sources of PM_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary aerosols.Secondary aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter 2020.By contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,OM and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.展开更多
As a secondary pollutant of photochemical pollution,peroxyacetyl nitrate(PAN)has attracted a close attention.A four-month campaign was conducted at a rural site in North China Plain(NCP)including the measurement of PA...As a secondary pollutant of photochemical pollution,peroxyacetyl nitrate(PAN)has attracted a close attention.A four-month campaign was conducted at a rural site in North China Plain(NCP)including the measurement of PAN,O_(3),NO_(x),PM_(2.5),oxygenated volatile organic compounds(OVOCs),photolysis rate constants of NO_(2)and O_(3)and meteorological parameters to investigate the wintertime characterization of photochemistry from November 2018 to February 2019.The results showed that the maximum and mean values of PAN were 4.38 and 0.93±0.67 ppbv during the campaign,respectively.The PAN under different PM_(2.5)concentrations from below 75μg/m^(3)up to 250μg/m^(3),showed different diurnal variation and formation rate.In the PM_(2.5)concentration range of above 250μg/m^(3),PAN had the largest daily mean value of 0.64 ppbv and the fastest production rate of 0.33 ppbv/hr.From the perspective of PAN’s production mechanism,the light intensity and precursors concentrations under different PM_(2.5)pollution levels indicated that there were sufficient light intensity and high volatile organic compounds(VOCs)and NO_(x)precursors concentration even under severe pollution level to generate a large amount of PAN.Moreover,the bimodal staggering phenomenon of PAN and PM_(2.5)provided a basis that PAN might aggravate haze through secondary organic aerosols(SOA)formation.展开更多
Tunnel displays a typical semi-closed environment, and multitudes of the pollutants tend to accumulate. The samples of gaseous pollutants and particulate matter （PM） were collected from the Xiangyin tunnel at Shangh...Tunnel displays a typical semi-closed environment, and multitudes of the pollutants tend to accumulate. The samples of gaseous pollutants and particulate matter （PM） were collected from the Xiangyin tunnel at Shanghai to investigate the characteristics of the pollutant emissions. The results indicated that both gaseous pollutants and PM exhibited much higher concentrations during the rush hours in the morning and at night due to vehicle emission. Two peaks of the PM concentration were observed in the scope of 0.7-1.1 and 3.3-4.7 μm, accounting for 14.6% and 20.3% of the total concentrations, respectively. Organic matter （OM）, EC, and many water-soluble ions were markedly higher at the rush hours in the morning than those at night, implicating comprehensive effects of vehicle types and traffic volume. The particle number concentrations exhibited two peaks at Aitken mode （25 nm and 100 rim） and accumulation mode （600 nm）, while the particle volume concentration displayed high values at the accumulation mode （100-500 nm） and coarse mode （2.5-4.0 μm）. The peak around 100 nm was detected in the morning rush hours, but it diminished with the decrease of the traffic volume. Individual-particle analysis revealed that main particles in the tunnel were Fe-rich particles, K-rich particles, mineral particles, Ca-S rich particles and A1-Si particles. The particles collected at the rush hours displayed marked different morphologies, element concentrations and particle sizes compared to the ones collected at the non-rush period. The data presented herein could shed a light on the feature of vehicle emissions.展开更多
In this work,the characterizations of Cu-SSZ-13 after hydrothermal aging(HTA)and thermal aging(TA)at different temperatures(750,800,and 850°C)are compared,and the differences between those two serious aged sample...In this work,the characterizations of Cu-SSZ-13 after hydrothermal aging(HTA)and thermal aging(TA)at different temperatures(750,800,and 850°C)are compared,and the differences between those two serious aged samples are analyzed.With this data,the effect of steam on catalysts deactivation during hydrothermal aging is analyzed.The TA at 750 and 800°C causes the dealumination and the agglomeration of Cu^(2+)ions to Cu O,resulting in the activity loss of Cu-SSZ-13.The presence of steam upon HTA at750 and 800°C aggravates the catalyst deactivation by increasing the Al detachment and the Cu^(2+)agglomeration.The structure and cupric state are almost the same in the Cu-SSZ-13 after TA and HTA at 850°C,respectively,indicating that the steam has little influence on the deactivation.The formation of CuAl_(2)O_(4) spinel is the primary reason for the deactivation after both HTA and TA at 850°C,probably attributed to the strong interaction between Cu^(2+)ions and framework Al sites at high temperatures.展开更多
A water-stable bimetallic Fe/Zrmetal-organic framework[UiO-66(Fe/Zr)]for exceptional decontamination of arsenic in water was fabricated through a facile one-step strategy.The batch adsorption experiments revealed the ...A water-stable bimetallic Fe/Zrmetal-organic framework[UiO-66(Fe/Zr)]for exceptional decontamination of arsenic in water was fabricated through a facile one-step strategy.The batch adsorption experiments revealed the excellent performances with ultrafast adsorption kinetics due to the synergistic effects of two functional centers and large surface area(498.33 m^(2)/g).The absorption capacity of UiO-66(Fe/Zr)for arsenate[As(V)]and arsenite[As(III)]reached as high as 204.1 mg/g and 101.7 mg/g,respectively.Langmuir model was suitable to describe the adsorption behaviors of arsenic on UiO-66(Fe/Zr).The fast kinetics(adsorption equilibrium in 30min,10mg/L As)and pseudo-second-ordermodel implied the strong chemisorption between arsenic ions and UiO-66(Fe/Zr),which was further confirmed by DFT theoretical calculations.The results of FT-IR,XPS analysis and TCLP test demonstrated that arsenic was immobilized on the surface of UiO-66(Fe/Zr)through Fe/Zr-O-As bonds,and the leaching rates of the adsorbed As(III)and As(V)from the spent adsorbent were only 5.6%and 1.4%,respectively.UiO-66(Fe/Zr)can be regenerated for five cycles without obvious removal efficiency decrease.The original arsenic(1.0mg/L)in lake and tapwater was effectively removed in 2.0 hr[99.0%of As(III)and 99.8%of As(V)].The bimetallic UiO-66(Fe/Zr)has great potentials in water deep purification of arsenic with fast kinetics and high capacity.展开更多
The distribution and chemical speciation of arsenic(As)in different sized atmospheric particulate matters(PMs),including total suspended particles(TSP),PM_(10),and PM_(2.5),collected from Baoding,China were analyzed.T...The distribution and chemical speciation of arsenic(As)in different sized atmospheric particulate matters(PMs),including total suspended particles(TSP),PM_(10),and PM_(2.5),collected from Baoding,China were analyzed.The average total mass concentrations of As in TSP,PM_(10),and PM_(2.5)were 31.5,35.3,and 54.1μg/g,respectively,with an order of PM_(2.5)>PM_(10)>TSP,revealing that As is prone to accumulate on fine particles.Due to the divergent toxicities of different As species,speciation analysis of As in PMs is further conducted.Most of previous studies mainly focused on inorganic arsenite(iAs^(Ⅲ)),inorganic arsenate(iAs^(Ⅴ)),monomethylarsonate(MMA),and dimethylarsinate(DMA)in PMs,while the identification and sensitive quantification of trimethylarsine oxide(TMAO)were rarely reported.In this study,a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs.An anion exchange column was used to separate MMA,DMA and iAs^(Ⅴ),while a cation exchange column to separate TMAO and iAs^(Ⅲ).Results showed that iAs^(Ⅴ) was the dominate component in all the samples,corresponding to a portion of 79.2%±9.3%of the total extractable species,while iAs^(Ⅲ),TMAO and DMA made up the remaining 21%.Our study demonstrated that iAs^(Ⅲ) accounted for about 14.4%±11.4%of the total extracted species,with an average concentration of 1.7±1.6 ng/m^(3).It is worth noting that TMAO was widely present in the samples(84 out of 97 samples),which supported the assumption that TMAO was ubiquitous in atmospheric particles.展开更多
The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green metho...The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green method for the preparation of silver nanoparti-cle/reduced graphene oxide(AgNP/rGO)composites was successfully developed through the combination of phytosynthesis,continuous flow synthesis and microwave-assistance.Oriental persimmon(Diospyros kaki Thunb.)extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites.The experimental param-eters were optimized and the morphologies of the prepared materials were investigated.The characterization results reveal that spherical AgNPs were quickly synthesized and uni-formly dispersed on rGO sheets using the proposed online system.Fourier transform in-frared spectroscopy analysis confirmed that phenols,flavonoids,and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites.Using sodium borohydride(NaBH4)degradation of p-nitrophenol(4-NP)as a model,the catalytic activity of the prepared AgNP/rGO materials was evaluated.The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials,and the compos-ite had a much better catalytic activity than the bare AgNPs and rGO had.Compared with the conventional chemical method,our online method is facile,fast,cost-efficient,and en-vironmentally friendly.展开更多
Atmospheric pollutants including SO_2, NO_2, CO, O_3 and inhalable particulate matter（PM2.5 and PM10） were monitored continuously from March 2014 to February 2015 to investigate characteristics of air pollution at L...Atmospheric pollutants including SO_2, NO_2, CO, O_3 and inhalable particulate matter（PM2.5 and PM10） were monitored continuously from March 2014 to February 2015 to investigate characteristics of air pollution at Lhasa, Tibetan Plateau. Species exhibited similar seasonal variations except O_3, with the peaks in winter but low valleys in summer. The maximum O_3 concentration was observed in spring, followed by summer, autumn, and winter. The positive correlation between O_3 and PM10 in spring indicated similar sources of them, and was assumed to be turbulent transport. Temperature was the dominant meteorological factor for most species in spring. High temperature accelerates O_3 photochemistry, and favors air disturbance which is conductive to dust resuspension in spring. Relative humidity（RH） and atmospheric pressure were the main meteorological factors in summer. RH showed negative correlations with species, while atmospheric pressure posed opposite situation. Wind speed（WS） was the dominant meteorological factor in autumn, the negative correlations between WS and species indicated diffusion by wind. Most species showed non-significant correlations with meteorological factors in winter, indicating the dependence of pollution on source emission rather than restriction by meteorology. Pollution weather character indicated that emissions were from biomass burning and dust suspension, and meteorological factors also played an important role. Air stream injection from the stratosphere was observed during O_3 pollution period. Air parcels from Southwest Asia were observed during air pollution period in winter. An enhancement in air pollutants such as O_3 would be expected in the future, more attention should be given to countermeasures for prevention of air pollution in the future.展开更多
In this study,ultrasonic field was applied during potassium hydroxide(KOH) pretreatment of wheat straw(WS).Three concentrations of KOH(2%,4%,and 6%) were tested during pretreatment.The results showed that there was a ...In this study,ultrasonic field was applied during potassium hydroxide(KOH) pretreatment of wheat straw(WS).Three concentrations of KOH(2%,4%,and 6%) were tested during pretreatment.The results showed that there was a significant influence of the ultrasonic assisted KOH pretreatment(KOH(Upt)) on physiochemical characteristics of WS during pretreatment as well as on digester performance.The pretreatment time was optimized to 36 h for all KOH concentrations.The highest total volatile fatty acid(TVFA) productions(3189 mg·L^-1) from 6%KOHupt samples were observed.Similarly,the SEM analysis and FTIR observation revealed that KOH(Upt) effectively disrupted the physical morphology of WS and successful breaking of lignin and hemicellulose linkage between carboxyl groups.Moreover,the highest biogasification(555 ml·(g VS(loaded))^-1) and biomethane productions(282 ml·(g VS(loaded))^-1) from 4%KOH(Upt) digesters,with 69% of biodegradability,indicated significant availability of organic matter from KOH(Upt).The R^2 values(0.993-0.998) in Modified Gompertz Model indicated that the model was feasible to predict methane yield for this study.Similarly,the Bo values for 4%KOH(Upt)(283.30±2.74 ml·(gVS(loaded))^-1) were also in agreement to the experimental methane yield.These results suggested that ultrasonic addition during KOH pretreatment of WS can effectively increase the organic yield during pretreatment.Moreover,the increase in methane production from 4% KOH(Upt) suggested that digester performance can be improved with lower KOH concentrations using this pretreatment.展开更多
Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other meth...Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other methods used for testing atmospheric aerosols particles,the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte.The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings.The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate,which can improve the accuracy for detecting atmospheric aerosol particles.Combined with Raman mapping,the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually.The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition,mixing state,and other related physicochemical properties.展开更多
Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex(Fe(III)-Ox).The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(III)-...Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex(Fe(III)-Ox).The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(III)-Ox under solar irradiation.Although the photolysis mechanisms of Fe(III)-Ox have been investigated extensively,information about the oxidation of volatile organic compounds(VOC),specifically the potential for Secondary Organic Aerosol(SOA)formation in the Fe(III)-Ox system,is lacking.In this study,a ubiquitous VOC methacrolein(MACR)is chosen as a model VOC,and the oxidation of MACR with Fe(III)-Ox is investigated under typical atmospheric water conditions.The effects of oxalate concentration,Fe(III)concentration,MACR concentration,and pH on the oxidation of MACR are studied in detail.Results show that the oxidation rate of MACR greatly accelerates in the presence of oxalate when compared with only Fe(III).The oxidation rate of MACR also accelerates with increasing concentration of oxalate.The effect of Fe(III)is found to be more complicated.The oxidation rate of MACR first increases and then decreases with increasing Fe(III)concentration.The oxidation rate of MACR increases monotonically with decreasing pH in the common atmospheric water pH range or with decreasing MACR concentration.The production of ferrous and hydrogen peroxide,pH,and aqueous absorbance are monitored throughout the reaction process.The quenching experiments verify that·OH and O_(2)^(+)are both responsible for the oxidation of MACR.MACR is found to rapidly oxidize into small organic acids with higher boiling points and oligomers with higher molecular weight,which contributes to the yield of SOA.These results suggest that Fe(III)-Ox plays an important role in atmospheric oxidation.展开更多
基金supported by the National Natural Science Foundation of China(No.42305109)Quzhou Municipal Science and Technology Bureau(No.2023K222).
文摘Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory and cardiovascular diseases.In this study,we assessed the oxidative potential(OP)of fresh and O_(3)-aged PM_(2.5)particles from various urban and rural emission sources using the dithiothreitol(DTT)method.Our results revealed variations in the OP of fresh PM_(2.5)among different emission sources,with biomass burning sources exhibiting the highest OP,followed by industrial areas,vehicular emissions,cooking emissions,and suburban areas,respectively.Water-soluble organics and transition metals might potentially exert significant influence on particle OP.O_(3)aging notably decreased the OP of PM_(2.5)particles,possibly due to the oxidation of highly DTT-active components into low redox-active small molecules.Moreover,the evolution of OP in different PM_(2.5)components,including methanol-soluble and insoluble fractions,exhibited distinct responses to O_(3)aging for source-oriented PM_(2.5).Additionally,differences in chemical composition between fresh and aged PM_(2.5)were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions.This study systematically delineates variances in the toxic potential of fresh and O_(3)-aged PM_(2.5)from various anthropogenic sources.The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM_(2.5),as well as for formulating human health protection policies.
基金supported by the National Natural Science Foundation of China(Nos.22276064 and 22278168)the Open Research Fund of Academy of Advanced Carbon Conversion Technology of Huaqiao University(No.AACCT0003)the Science and Technology Project of Fujian province(No.2022Y3007).
文摘The electrocatalytic reduction of carbon dioxide(CO_(2)ER)into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO_(2).Bismuth(Bi)has been gaining recognition as a promising catalyst material for the CO_(2)ER to formate.The performance of Bi catalysts(named as Bi-V)can be significantly improved when they possess single metal atom vacancy.However,creating larger-sized metal atom vacancies within Bi catalysts remains a significant challenge.In this work,Bi nanosheets with dual V0 Bi vacancy(Bi-DV)were synthesized utilizing in situ electrochemical transformation,using BiOBr nanosheets with triple vacancy associates(V■_(Bi)V··_(O)V■_(Bi),V■_(Bi)and V··_(O)denote the Bi^(3+)and O_(2)−vacancy,respectively)as a template.The obtained Bi-DV achieved higher CO_(2)ER activity than Bi-V,showing Faradaic efficiency for formate production of>92%from-0.9 to-1.2 VRHE in an H-type cell,and the partial current density of formate reached up to 755 mA/cm^(2)in a flow cell.The comprehensive characterizations coupled with density functional theory calculations demonstrate that the dual V^(0)_(Bi)vacancy on the surface of Bi-DV expedite the reaction kinetics toward CO_(2)ER,by reducing the thermodynamic barrier of^(∗)OCHO intermediate formation.This research provides critical insights into the potential of large atom vacancies to enhance electrocatalysis performance.
基金supported by the National Natural Science Foundation of China(No.22276064)the Youth Innovation Grant of Xiamen,Fujian Province(No.3502Z20206006)+1 种基金the MOE Key Laboratory of Resources and Environmental System Optimization(No.KLRE-KF202205)Fujian Science and Technology Project(No.2022Y3007).
文摘The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.
基金supported by the National Key R&D Program of China(No.2022YFC3701102)the National Natural Science Foundation of China(Nos.22376029,22176038,91744205 and 21777025)the Natural Science Foundation of Shanghai City(No.22ZR1404700).
文摘Nitrate renoxification significantly influences atmospheric nitrogen cycling and global OH budgets.Although numerous nitrite acid(HONO)formation pathways from nitrate photolysis have been widely reported,the influence of various environmental factors and aerosol properties on reactive nitrogen production remains largely unclear.In this work,we employed NaNO_(3)/humic acid(HA)as a model nitrate photosensitization system to investigate the crucial roles of aerosol acidity,organic fraction,and dissolved oxygen in the production of HONO,NO_(2),and NO_(2)^(-).The presence of HA at 10 mg/L resulted in a remarkable increase in HONO production rates by approximately 2–3 times and NO_(2)^(-) concentration by 3–6 times across a pH range of 5.2 to 2.0.Meanwhile,the molar fraction of gaseous HONO in total N(Ⅲ)production increased from4%to 69%as bulk-phase pH decreased from 5.2 to 2.0.The higher organic fraction(i.e.,20 and 50 mg/L HA concentration)instead inhibited HONO and NO_(2) release.The presence of dissolved oxygen was found to be adverse for reactive nitrogen production.This suggests that the HA photosensitizer promoted the secondary conversion of NO_(2) to HONO mainly via reduced ketyl radical intermediates,while superoxide radical formation might exert a negative effect.Our findings provide comprehensive insights into reactive nitrogen production from photosensitized nitrate photolysis mediated by various external and internal factors,potentially accounting for discrepancies between field observations and model simulations.
基金supported by the Basic Research Cultivation Support Plan of Southwest Jiaotong University(No.2682023ZTPY016)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0982)the National Natural Science Foundation of China(Nos.U23A2030,42205100,and 41805095).
文摘To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.
基金the Collaborative Innovation Plan of Hubei Province for Key Technologies in the Eco-Ramie Industryfinancially supported by the Natural Science Foundation of Hubei Province,China (No.2018CFB515)the financial support from the National Natural Science Foundation of China (No.41701541)
文摘Recently,heterogeneous activation of peroxymonosulfate(PMS) to oxidatively degrade organic pollutants has been a hotspot.In the present work,copper ferrite-graphite oxide hybrid(CuFe2 O4@GO)was prepared and used as catalyst to activate PMS for degradation of methylene blue(MB) in aqueous solution.A high degradation efficiency(93.3%) was achieved at the experimental conditions of20 mg/L MB,200 mg/L CuFe2 O4@GO,0.8 mmol/L PMS,and 25℃temperature.Moreover,CuFe2 O4@GO showed an excellent reusability and stability.The effects of various operational parameters including pollutant type,solution pH,catalyst dosage,PMS dosage,pollutant concentration,temperature,natural organic matter(NOM),and inorganic anions on the catalytic degradation process were comprehensively investigated and elucidated.The further mechanistic study revealed the Cu(Ⅱ)/Cu(Ⅰ) redox couple on CuFe2 O4@GO played the dominant role in PMS activation,where both hydroxyl and sulfate radicals were generated and proceeded the degradation of pollutants.In general,CuFe2 O4@GO is a promising heterocatalyst for PMS-based advanced oxidation processes(AOPs) in wastewater treatment.
基金supported by the National Natural Science Foundation of China (No.21007014, 21107024)the Start Foundation of Hunan Agricultural University (No.10YJ01)+2 种基金the National Science and Technology Major Projects (No.2009ZX07212-001-05)the National Environmental Protection Public Welfare Program (No.201009047)the Scientific Research Fund of Hunan Provincial Education Department (No.11C0650)
文摘La-EDTA-Fe3O4 was prepared by a chemical co-precipitation method. The magnetic composite was characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR）. Furthermore, the adsorption properties of La-EDTA-Fe3O4 toward phosphate in water were investigated. The uptake rate of phosphate in water by La-EDTA-Fe3O4 was 3-1000 times than that of EDTA-Fe3O4, and reached 97.8% at 7 hr. The adsorption process agreed well with the Freundlich model and kinetics studies showed that the adsorption of phosphate proceeds according to pseudo second-order adsorption kinetics. The maximum removal rate was achieved at pH 6.0-7.0. The La-EDTA-Fe3O4 had good adsorption properties and could be separated well from aqueous solution by a permanent magnet. Therefore, this nanomaterial has potential application for the removal of phosphate from large water bodies.
基金Supported by University Grant Commission,New Delhi,India[Grant No.F.14-2(SC)/2010(SA-Ⅲ)]
文摘Adansonia digitata L.(Malvaceae) is commonly known as baobab tree native to Africa.Baobab is a multi-purpose tree which offers protection and provides food,clothing and medicine as well as raw material for many useful items.The fruit pulp,seeds,leaves,flowers.roots,and bark of baobab are edible and they have been studied by scientists for their useful properties.The fruit pulp have very high vitamin C.calcium,phosphorus,carbohydrates,fibers,potassium,proteins and lipids content,which can be used in seasoning as an appetizer and also make juices.Seeds contain appreciable quantities of phosphorus,magnesium,zinc,sodium,iron,manganese,whereas they have high levels of lysine,thiamine,calcium and iron.Baobab has numerous biological properties including antimicrobial,anti-malarial,diarrhoea,anaemia,asthma,antiviral,anti-oxidant and anti-inflammatory activities amongst others.Phytochemical investigation revealed the presence of flavonoids.phytosterols.amino acids,fatty acids,vitamins and minerals.The review summarizes the information on various aspects of traditional information,taxonomic description,medicinal properties and importantly nutritional value.
基金financial support from Ministry of Science and Technology of the People’s Republic of China (Nos.2016YFE0112200 and 2016YFC0202700)National Natural Science Foundation of China (Nos.21507011,21677037 and 21607027)Natural Science Foundation of Shanghai (Nos. 19ZR1471200,17ZR1440200)
文摘Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.
基金supported by the National Natural Science Foundation of China(Nos.42205100 and 41805095)the Sichuan Science and Technology Program(Nos.2019YFS0476and 2022NSFSC0982)support from the Sichuan comprehensive monitoring station for environmental air quality。
文摘The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of PM_(2.5)have also changed.We studied the interannual variation of PM_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest China,during the most polluted season(winter).Our results show that the mass concentrations of PM_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter 2020.The mass concentrations of organic matter(OM),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,respectively.The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile sources.The contribution of OM and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of pollution.Four sources of PM_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary aerosols.Secondary aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter 2020.By contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,OM and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.
基金supported by the National Natural Science Foundation of China(Nos.91843301,91743202,41805091)Ministry of Science and Technology of China(No.2016YFC0202700)+1 种基金National research program for key issues in air pollution control(Nos.DQGG0103,DQGG0102)Marie Sk?odowska-Curie Actions(No.690958-MARSU-RISE-2015)
文摘As a secondary pollutant of photochemical pollution,peroxyacetyl nitrate(PAN)has attracted a close attention.A four-month campaign was conducted at a rural site in North China Plain(NCP)including the measurement of PAN,O_(3),NO_(x),PM_(2.5),oxygenated volatile organic compounds(OVOCs),photolysis rate constants of NO_(2)and O_(3)and meteorological parameters to investigate the wintertime characterization of photochemistry from November 2018 to February 2019.The results showed that the maximum and mean values of PAN were 4.38 and 0.93±0.67 ppbv during the campaign,respectively.The PAN under different PM_(2.5)concentrations from below 75μg/m^(3)up to 250μg/m^(3),showed different diurnal variation and formation rate.In the PM_(2.5)concentration range of above 250μg/m^(3),PAN had the largest daily mean value of 0.64 ppbv and the fastest production rate of 0.33 ppbv/hr.From the perspective of PAN’s production mechanism,the light intensity and precursors concentrations under different PM_(2.5)pollution levels indicated that there were sufficient light intensity and high volatile organic compounds(VOCs)and NO_(x)precursors concentration even under severe pollution level to generate a large amount of PAN.Moreover,the bimodal staggering phenomenon of PAN and PM_(2.5)provided a basis that PAN might aggravate haze through secondary organic aerosols(SOA)formation.
基金supported by the National Key R&D Program of China(2016YFC0202700)Ministry of Science and Technology of China(2016YFE0112200)+2 种基金National Natural Science Foundation of China(Nos.21777025,21577022,21190053,40975074)the Marie Sklodowska-Curie Actions(690958-MARSU-RISE2015)the International Cooperation project of Shanghai municipal government(15520711200)
文摘Tunnel displays a typical semi-closed environment, and multitudes of the pollutants tend to accumulate. The samples of gaseous pollutants and particulate matter （PM） were collected from the Xiangyin tunnel at Shanghai to investigate the characteristics of the pollutant emissions. The results indicated that both gaseous pollutants and PM exhibited much higher concentrations during the rush hours in the morning and at night due to vehicle emission. Two peaks of the PM concentration were observed in the scope of 0.7-1.1 and 3.3-4.7 μm, accounting for 14.6% and 20.3% of the total concentrations, respectively. Organic matter （OM）, EC, and many water-soluble ions were markedly higher at the rush hours in the morning than those at night, implicating comprehensive effects of vehicle types and traffic volume. The particle number concentrations exhibited two peaks at Aitken mode （25 nm and 100 rim） and accumulation mode （600 nm）, while the particle volume concentration displayed high values at the accumulation mode （100-500 nm） and coarse mode （2.5-4.0 μm）. The peak around 100 nm was detected in the morning rush hours, but it diminished with the decrease of the traffic volume. Individual-particle analysis revealed that main particles in the tunnel were Fe-rich particles, K-rich particles, mineral particles, Ca-S rich particles and A1-Si particles. The particles collected at the rush hours displayed marked different morphologies, element concentrations and particle sizes compared to the ones collected at the non-rush period. The data presented herein could shed a light on the feature of vehicle emissions.
基金supported by the National Key Research and Development Program of China (2018YFC0214103)the National Natural Science Foundation of China (22006044)the Scientific Research Funds of Huaqiao University (605-50Y200270001)。
文摘In this work,the characterizations of Cu-SSZ-13 after hydrothermal aging(HTA)and thermal aging(TA)at different temperatures(750,800,and 850°C)are compared,and the differences between those two serious aged samples are analyzed.With this data,the effect of steam on catalysts deactivation during hydrothermal aging is analyzed.The TA at 750 and 800°C causes the dealumination and the agglomeration of Cu^(2+)ions to Cu O,resulting in the activity loss of Cu-SSZ-13.The presence of steam upon HTA at750 and 800°C aggravates the catalyst deactivation by increasing the Al detachment and the Cu^(2+)agglomeration.The structure and cupric state are almost the same in the Cu-SSZ-13 after TA and HTA at 850°C,respectively,indicating that the steam has little influence on the deactivation.The formation of CuAl_(2)O_(4) spinel is the primary reason for the deactivation after both HTA and TA at 850°C,probably attributed to the strong interaction between Cu^(2+)ions and framework Al sites at high temperatures.
基金This work was supported by the National Natural Science Foundation of China(No.21777040)the Beijing Natural Science Foundation(No.8182051)the Fundamental Research Funds for the Central Universities(No.2017ZZD07).
文摘A water-stable bimetallic Fe/Zrmetal-organic framework[UiO-66(Fe/Zr)]for exceptional decontamination of arsenic in water was fabricated through a facile one-step strategy.The batch adsorption experiments revealed the excellent performances with ultrafast adsorption kinetics due to the synergistic effects of two functional centers and large surface area(498.33 m^(2)/g).The absorption capacity of UiO-66(Fe/Zr)for arsenate[As(V)]and arsenite[As(III)]reached as high as 204.1 mg/g and 101.7 mg/g,respectively.Langmuir model was suitable to describe the adsorption behaviors of arsenic on UiO-66(Fe/Zr).The fast kinetics(adsorption equilibrium in 30min,10mg/L As)and pseudo-second-ordermodel implied the strong chemisorption between arsenic ions and UiO-66(Fe/Zr),which was further confirmed by DFT theoretical calculations.The results of FT-IR,XPS analysis and TCLP test demonstrated that arsenic was immobilized on the surface of UiO-66(Fe/Zr)through Fe/Zr-O-As bonds,and the leaching rates of the adsorbed As(III)and As(V)from the spent adsorbent were only 5.6%and 1.4%,respectively.UiO-66(Fe/Zr)can be regenerated for five cycles without obvious removal efficiency decrease.The original arsenic(1.0mg/L)in lake and tapwater was effectively removed in 2.0 hr[99.0%of As(III)and 99.8%of As(V)].The bimetallic UiO-66(Fe/Zr)has great potentials in water deep purification of arsenic with fast kinetics and high capacity.
基金funded by the National Key R&D Program of China(No.2018YFB0605101)the National Natural Science Foundation of China(Nos.22076198 and 91543107)the Fundamental Research Funds for the Central Universities(No.2017ZZD07)。
文摘The distribution and chemical speciation of arsenic(As)in different sized atmospheric particulate matters(PMs),including total suspended particles(TSP),PM_(10),and PM_(2.5),collected from Baoding,China were analyzed.The average total mass concentrations of As in TSP,PM_(10),and PM_(2.5)were 31.5,35.3,and 54.1μg/g,respectively,with an order of PM_(2.5)>PM_(10)>TSP,revealing that As is prone to accumulate on fine particles.Due to the divergent toxicities of different As species,speciation analysis of As in PMs is further conducted.Most of previous studies mainly focused on inorganic arsenite(iAs^(Ⅲ)),inorganic arsenate(iAs^(Ⅴ)),monomethylarsonate(MMA),and dimethylarsinate(DMA)in PMs,while the identification and sensitive quantification of trimethylarsine oxide(TMAO)were rarely reported.In this study,a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs.An anion exchange column was used to separate MMA,DMA and iAs^(Ⅴ),while a cation exchange column to separate TMAO and iAs^(Ⅲ).Results showed that iAs^(Ⅴ) was the dominate component in all the samples,corresponding to a portion of 79.2%±9.3%of the total extractable species,while iAs^(Ⅲ),TMAO and DMA made up the remaining 21%.Our study demonstrated that iAs^(Ⅲ) accounted for about 14.4%±11.4%of the total extracted species,with an average concentration of 1.7±1.6 ng/m^(3).It is worth noting that TMAO was widely present in the samples(84 out of 97 samples),which supported the assumption that TMAO was ubiquitous in atmospheric particles.
基金This study was supported by the National Natural Science Foundation of China(Nos.21620102008,and 21777040)the Beijing Natural Science Foundation(No.8182051)the Fundamental Research Funds for the Central Universities(No.2017ZZD07).
文摘The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green method for the preparation of silver nanoparti-cle/reduced graphene oxide(AgNP/rGO)composites was successfully developed through the combination of phytosynthesis,continuous flow synthesis and microwave-assistance.Oriental persimmon(Diospyros kaki Thunb.)extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites.The experimental param-eters were optimized and the morphologies of the prepared materials were investigated.The characterization results reveal that spherical AgNPs were quickly synthesized and uni-formly dispersed on rGO sheets using the proposed online system.Fourier transform in-frared spectroscopy analysis confirmed that phenols,flavonoids,and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites.Using sodium borohydride(NaBH4)degradation of p-nitrophenol(4-NP)as a model,the catalytic activity of the prepared AgNP/rGO materials was evaluated.The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials,and the compos-ite had a much better catalytic activity than the bare AgNPs and rGO had.Compared with the conventional chemical method,our online method is facile,fast,cost-efficient,and en-vironmentally friendly.
基金supported by the National Natural Science Foundation of China(Nos.21577022,21190053,40975074)Ministry of Science and Technology of China(2016YFC0203700)
文摘Atmospheric pollutants including SO_2, NO_2, CO, O_3 and inhalable particulate matter（PM2.5 and PM10） were monitored continuously from March 2014 to February 2015 to investigate characteristics of air pollution at Lhasa, Tibetan Plateau. Species exhibited similar seasonal variations except O_3, with the peaks in winter but low valleys in summer. The maximum O_3 concentration was observed in spring, followed by summer, autumn, and winter. The positive correlation between O_3 and PM10 in spring indicated similar sources of them, and was assumed to be turbulent transport. Temperature was the dominant meteorological factor for most species in spring. High temperature accelerates O_3 photochemistry, and favors air disturbance which is conductive to dust resuspension in spring. Relative humidity（RH） and atmospheric pressure were the main meteorological factors in summer. RH showed negative correlations with species, while atmospheric pressure posed opposite situation. Wind speed（WS） was the dominant meteorological factor in autumn, the negative correlations between WS and species indicated diffusion by wind. Most species showed non-significant correlations with meteorological factors in winter, indicating the dependence of pollution on source emission rather than restriction by meteorology. Pollution weather character indicated that emissions were from biomass burning and dust suspension, and meteorological factors also played an important role. Air stream injection from the stratosphere was observed during O_3 pollution period. Air parcels from Southwest Asia were observed during air pollution period in winter. An enhancement in air pollutants such as O_3 would be expected in the future, more attention should be given to countermeasures for prevention of air pollution in the future.
基金supported by Yuan Yi Biomass S&T Company of China(No.H2015198)。
文摘In this study,ultrasonic field was applied during potassium hydroxide(KOH) pretreatment of wheat straw(WS).Three concentrations of KOH(2%,4%,and 6%) were tested during pretreatment.The results showed that there was a significant influence of the ultrasonic assisted KOH pretreatment(KOH(Upt)) on physiochemical characteristics of WS during pretreatment as well as on digester performance.The pretreatment time was optimized to 36 h for all KOH concentrations.The highest total volatile fatty acid(TVFA) productions(3189 mg·L^-1) from 6%KOHupt samples were observed.Similarly,the SEM analysis and FTIR observation revealed that KOH(Upt) effectively disrupted the physical morphology of WS and successful breaking of lignin and hemicellulose linkage between carboxyl groups.Moreover,the highest biogasification(555 ml·(g VS(loaded))^-1) and biomethane productions(282 ml·(g VS(loaded))^-1) from 4%KOH(Upt) digesters,with 69% of biodegradability,indicated significant availability of organic matter from KOH(Upt).The R^2 values(0.993-0.998) in Modified Gompertz Model indicated that the model was feasible to predict methane yield for this study.Similarly,the Bo values for 4%KOH(Upt)(283.30±2.74 ml·(gVS(loaded))^-1) were also in agreement to the experimental methane yield.These results suggested that ultrasonic addition during KOH pretreatment of WS can effectively increase the organic yield during pretreatment.Moreover,the increase in methane production from 4% KOH(Upt) suggested that digester performance can be improved with lower KOH concentrations using this pretreatment.
基金the National Natural Science Foundation of China(No.21976030 and No.21677037)the Natural Science Foundation of Shanghai(No.19ZR1471200 and No.17ZR1440200)。
文摘Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other methods used for testing atmospheric aerosols particles,the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte.The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings.The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate,which can improve the accuracy for detecting atmospheric aerosol particles.Combined with Raman mapping,the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually.The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition,mixing state,and other related physicochemical properties.
基金The authors gratefully acknowledge financial support from the Ministry of Science and Technology of the People’s Republic of China(Grant Nos.2017YFC0210005 and 2016YFE0112200).
文摘Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex(Fe(III)-Ox).The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(III)-Ox under solar irradiation.Although the photolysis mechanisms of Fe(III)-Ox have been investigated extensively,information about the oxidation of volatile organic compounds(VOC),specifically the potential for Secondary Organic Aerosol(SOA)formation in the Fe(III)-Ox system,is lacking.In this study,a ubiquitous VOC methacrolein(MACR)is chosen as a model VOC,and the oxidation of MACR with Fe(III)-Ox is investigated under typical atmospheric water conditions.The effects of oxalate concentration,Fe(III)concentration,MACR concentration,and pH on the oxidation of MACR are studied in detail.Results show that the oxidation rate of MACR greatly accelerates in the presence of oxalate when compared with only Fe(III).The oxidation rate of MACR also accelerates with increasing concentration of oxalate.The effect of Fe(III)is found to be more complicated.The oxidation rate of MACR first increases and then decreases with increasing Fe(III)concentration.The oxidation rate of MACR increases monotonically with decreasing pH in the common atmospheric water pH range or with decreasing MACR concentration.The production of ferrous and hydrogen peroxide,pH,and aqueous absorbance are monitored throughout the reaction process.The quenching experiments verify that·OH and O_(2)^(+)are both responsible for the oxidation of MACR.MACR is found to rapidly oxidize into small organic acids with higher boiling points and oligomers with higher molecular weight,which contributes to the yield of SOA.These results suggest that Fe(III)-Ox plays an important role in atmospheric oxidation.
