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1.
Se Pu ; 40(1): 88-99, 2022 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-34985220

RESUMO

Submicron nonporous silica (NPS) materials feature small particle sizes, smooth surfaces, and regular shapes. They also exhibit excellent performance as a stationary phase; however, their use is limited by their low specific surface area and low phase ratio. Therefore, a novel surface modification strategy tailored for NPS microspheres was designed, involving a multi-step reaction. 3-Glycidyloxypropyltrimethoxysilane (GPTS) was first grafted onto NPS particles as a silane coupling agent. Polyethyleneimine (PEI), a high-molecular-weight polymer, was then coated onto the particles, providing numerous amino reaction sites. In the final step, an acylation reaction was initiated between stearoyl chloride and the amino groups to obtain the final product, designated as C18-NH2-GPTS-SiO2. Elemental analysis, FT-IR spectroscopy, Zeta potential analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed to investigate the success of the chemical modifications at each step. The carbon content increased from 0.55% to higher than 8.29%. Thus, it solved the low carbon loading capacity problem when modifying NPS microspheres with traditional C18 reversed phase (e. g., octadecyl chlorosilane modification). Meanwhile, the reasons for the considerable differences between NPS and porous silica (PS) microspheres in terms of the reactivity to surface modification were investigated in detail. The BET method was employed to compare the pore structures. FT-IR and 29Si solid-state NMR spectroscopy were employed to analyze the differences in the structure and quantity of silanol groups on the surfaces of the NPS and PS microspheres. Differences were observed not only in the pore size and surface area, but also in the types of silanol groups. FT-IR analysis indicated that the NPS and PS microspheres had different υSi-OH band positions, which shifted from 955 to 975 cm-1, respectively. 29Si solid-state NMR analysis further highlighted the differences in structural information for Si atom environments. Results revealed that 16% of silicon atoms in the PS microspheres had one hydroxyl group (isolated silanols, Q3, δ 100), while 19% had two hydroxyl groups (geminal silanols, Q2, δ 90). On the other hand, the NPS microspheres possessed no geminal silanols, and only 30% of the Si atoms were in the Q3 state. Therefore, the NPS microspheres had a lower density of silanol groups and lacked geminal silanol groups, compared to the PS microspheres. Geminal silanol groups have already been confirmed in previous studies to offer far higher reactivity than isolated silanols. These factors together explained the low reactivity of NPS microspheres toward surface modification. Further, the low specific surface area of the microspheres arising from their nonporous nature made it challenging to obtain a high carbon content through a simple one-step reaction. Hydrophobic substances such as hydrocarbons from the benzene series and polycyclic aromatic hydrocarbons (PAHs) were selected to study the chromatographic performance. The hydrophobic mechanism was revealed by the separation of PAHs using different ratios of acetonitrile. Separation was achieved with a C18-NH2-GPTS-SiO2 column, following which a hydrophobic phenomenon occurred. The presence of the amino coating led to the inversion of the electroosmotic flow (EOF) of the silica microspheres on the pressurized capillary electrochromatography (pCEC) platform. It also enhanced the linear velocity in the pCEC platform when the pH was selected to be low. The effects of the applied voltage on the separation ability of the 720 nm C18-NH2-GPTS-SiO2 column were examined to determine optimal conditions. Rapid and effective separation was achieved in a relatively short time. Therefore, the C18-NH2-GPTS-SiO2 stationary phase is promising for practical use with a higher phase ratio, demonstrating superiority for use in reversed-phase pCEC separation, and thus, providing a new strategy and valuable reference for the future application of submicron NPS microspheres.


Assuntos
Eletrocromatografia Capilar , Carbono , Tamanho da Partícula , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Huan Jing Ke Xue ; 43(1): 521-529, 2022 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-34989537

RESUMO

Long-term fertilization has an important effect on soil fertility and soil microbial activity. In order to explore the effects of long-term fertilization on soil extracellular enzyme activities and nutrient characteristics in a terrace on the Loess Plateau, we based our investigation on the long-term nutrient localization plot of Ansai Soil and Water Conservation Experimental Station, Chinese Academy of Sciences. We measured the soil physicochemical properties, microbial biomass, and extracellular enzyme activities of six fertilization treatments, which included no fertilization (CK); manure and nitrogen fertilization (MN); manure and phosphate fertilization (MP); manure, nitrogen, and phosphate fertilization (MNP); manure (M); and nitrogen and phosphate fertilization (NP). The results showed that all fertilization treatments significantly increased soil nutrient content and soil extracellular enzyme activities compared with that in CK. Correlation analysis showed that extracellular enzyme activity and soil physicochemical properties had an extremely significant correlation. The redundancy analysis indicated that soil nutrient and soil microbial biomass could explain 79.66% and 74.87% of the variation in soil extracellular enzyme activity and its stoichiometric ratio, respectively. Thus, the effects of fertilization on soil fertility were primarily through influencing soil extracellular enzyme activities indirectly. M, MN, MP, and MNP significantly improved soil organic carbon (SOC); soil total nitrogen (STN); and carbon (C), nitrogen (N), and phosphorus (P) source enzyme content; however, MNP changed the soil pH, which had an inhibitory effect on microbial activities. Vector analysis showed that the microbial communities of all treatments were in the condition of P limitation. Although MNP could alleviate the extent of P limitation, there was no significant difference between M and MP. Our study indicated that long-term application of manure[7500 kg·(hm2·a)-1]could meet the nutrient requirements of dryland crop growth, and long-term application of manure combined with phosphorus fertilization could alleviate the resource constraints faced by microorganisms. Consequently, our results provide a new insight into improving regional nitrogen excess.


Assuntos
Fertilizantes , Solo , Agricultura , Carbono , Fertilização , Fertilizantes/análise , Esterco , Nitrogênio/análise , Nutrientes , Fósforo , Microbiologia do Solo
3.
Huan Jing Ke Xue ; 43(1): 550-559, 2022 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-34989540

RESUMO

Clarifying the characteristics of soil microbial nutrient limitation and its driving mechanisms during vegetation restoration after farmland abandonment has important implications for revealing soil nutrient cycling and maintaining ecosystem stability. To determine the limitation of soil microbial nutrients and its relationship with soil properties along a chronosequence of abandoned farmland in the middle of the Qinling Mountains, the soil physicochemical properties and five enzyme activities (ß-1,4-glucosidase (BG), cellobiohydrolase (CBH), ß-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP)) were measured, and models of extracellular enzymatic activity were applied. The results showed that the activities of BG, CBH, NAG, LAP, and AP were significantly increased following farmland abandonment. With the increasing years of abandonment, the ratios of (BG+CBH)/(NAG+LAP) and (BG+CBH)/AP significantly decreased, whereas the ratio of (NAG+LAP)/AP increased. Correlation analysis showed that most soil physicochemical properties were significantly correlated with extracellular enzyme activities and extracellular enzymatic stoichiometry. The vector length of extracellular enzymatic stoichiometry decreased with the increase in abandonment years, indicating that the limitation of soil microorganisms on carbon (C) was reduced. Moreover, the vector angles (>45°) showed a decreasing trend, indicating that microbial metabolisms were limited by phosphorus (P) and gradually decreased. Regression analysis showed that the C and P limitations were significantly related to total nutrients, available nutrients, nutrient ratio, and soil physical properties. Partial least squares path modeling (PLS-PM) revealed that the C and P limitations were directly regulated by nutrient ratio. PLS-PM further showed that soil total nutrients indirectly affected soil microbial C and P limitations by affecting nutrient ratio, and nutrient ratio affected the soil metabolism limitation via available nutrients and pH. Our study suggests that the characteristics of microbial metabolism during the vegetation restoration process reflect the mechanism of microorganism-mediated soil nutrient cycling, which provides a theoretical basis for revealing the community dynamics and stability during the vegetation restoration process and maintaining the regional ecological environment security in the Qinling Mountains.


Assuntos
Ecossistema , Microbiologia do Solo , Carbono/análise , China , Nitrogênio/análise , Fósforo/análise , Solo
4.
Huan Jing Ke Xue ; 43(1): 569-576, 2022 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-34989542

RESUMO

The net greenhouse gas emissions from upland soils, as indicated by global warming potential (GWP), mainly depend on the soil carbon sequestration and nitrous oxide (N2O) emissions. The annual changes in surface (0-20 cm) soil organic carbon (SOC) content from 2010 to 2017 and the N2O emissions from 2014 to 2017 were measured within a long-term fertilization experiment. The objective was to quantify the effect of stalk incorporation on the soil carbon sequestration, annual N2O emissions, and GWP of a winter wheat-summer maize field in the Guanzhong Plain. The field experiment included three treatments:conventional fertilization (CF), conventional fertilization plus maize stalks (CFS), and an unfertilized control (CK). The CF and CFS treatments received the same amount of urea per year, with nitrogen (N) input at 165 kg·hm-2 and 188 kg·hm-2 in the winter wheat season and summer maize season, respectively. The CF treatment retained the stubbles (about 10 cm above ground) when harvesting the winter wheat and summer maize crops. The CFS treatment retained the same wheat stubbles and all maize stalks (containing approximately 40 kg·hm-2 of N). The CK treatment was unfertilized throughout the year, with the stubble management the same as that in the CF treatment. The results showed that the CK treatment displayed few changes in SOC content and low N2O emissions, with GWP varying from 0.04 to 0.11 t·(hm2·a)-1. The SOC contents in the CF and CFS treatments increased linearly with the fertilization years (P<0.001), and their SOC sequestration rates were 0.69 t·(hm2·a)-1 and 0.97 t·(hm2·a)-1, respectively. The N2O emissions from the CF and CFS treatments varied from 1.65 to 5.36 kg·(hm2·a)-1 and from 3.08 to 7.73 kg·(hm2·a)-1, respectively. The annual N2O emissions from the CFS treatment were 43%-94% higher than those from the CF treatment, whereas the difference was only significant between 2015 and 2016 (P<0.05). The GWP of the CF and CFS treatments varied from -1.95 to -0.28 t·(hm2·a)-1 and from -2.59 to -0.35 t·(hm2·a)-1, respectively. The cumulative GWP of the CFS treatment was 42% lower than that of the CF treatment between 2014 and 2017. In summary, the studied winter wheat-summer maize field acted as a sink of greenhouse gases under the conventional fertilization regime. The stalk incorporation further favored greenhouse gas mitigation despite the trade-offs between SOC sequestration and N2O emissions.


Assuntos
Óxido Nitroso , Solo , Agricultura , Carbono , Sequestro de Carbono , China , Fertilizantes/análise , Aquecimento Global , Óxido Nitroso/análise , Estações do Ano , Triticum , Zea mays
5.
Environ Int ; 158: 106990, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34991251

RESUMO

INTRODUCTION: Epidemiological evidence suggests that motorized vehicle users have a higher air pollutant exposure (especially from vehicle exhaust) than active (walking or cycling) transport users. However, studies often relied on insufficiently diverse sample and ignored that minute ventilation has an effect on individuals' inhaled dose. This study examined commuters' breathing zone concentration and inhaled doses of black carbon (BC) when travelling by different transport modes in the Grand Paris region. METHODS: Personal exposure to BC was continuously measured with MicroAethalometer (MicroAeth AE51) portable monitors strapped on participants' shoulder with tube inlet at the level of the neck (breathing zone), and inhaled doses were derived from several methods estimating ventilation [based on metabolic equivalents from accelerometry [METs], heart rate, and breathing rate]. Trip stages and transport modes were assessed from GPS and mobility survey data. Breathing zone concentrations and inhaled doses of BC were compared across transport modes at the trip stage level (n = 7495 for 283 participants) using linear mixed effect models with a random intercept at individual level. RESULTS: Trip stages involving public transport and private motorized transport were associated with a 2.20 µg/m3 (95% CI: 1.99, 2.41) and 2.29 µg/m3 (95% CI: 2.10, 2.48) higher breathing zone concentration to BC than walking, respectively. Trip stages with other active modes had a 0.41 µg (95% CI: 0.25, 0.57) higher inhaled dose, while those involving public transport and private motorized transport had a 0.25 µg (95% CI: -0.35, -0.15) and 0.19 µg (95 %CI: -0.28, -0.10) lower inhaled dose of BC per 30 min than walking. CONCLUSION: The ranking of transport modes in terms of personal exposure was markedly different when breathing zone concentrations and inhaled doses were considered. Future studies should take both into account to explore the relationship of air pollutants in transport microenvironments with physiological response.


Assuntos
Poluentes Atmosféricos , Exposição Ambiental , Poluentes Atmosféricos/análise , Carbono , Exposição Ambiental/análise , Monitoramento Ambiental , Humanos , Exposição por Inalação , Material Particulado/análise , Fuligem/análise , Emissões de Veículos/análise
6.
Cancer Lett ; 524: 172-181, 2022 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-34688844

RESUMO

The influence of high-linear energy transfer (LET) particle radiation on the functionalities of mesenchymal stromal cells (MSCs) is largely unknown. Here, we analyzed the effects of proton (1H), helium (4He), carbon (12C) and oxygen (16O) ions on human bone marrow-MSCs. Cell cycle distribution and apoptosis induction were examined by flow cytometry, and DNA damage was quantified using γH2AX immunofluorescence and Western blots. Relative biological effectiveness values of MSCs amounted to 1.0-1.1 for 1H, 1.7-2.3 for 4He, 2.9-3.4 for 12C and 2.6-3.3 for 16O. Particle radiation did not alter the MSCs' characteristic surface marker pattern, and MSCs maintained their multi-lineage differentiation capabilities. Apoptosis rates ranged low for all radiation modalities. At 24 h after irradiation, particle radiation-induced ATM and CHK2 phosphorylation as well as γH2AX foci numbers returned to baseline levels. The resistance of human MSCs to high-LET irradiation suggests that MSCs remain functional after exposure to moderate doses of particle radiation as seen in normal tissues after particle radiotherapy or during manned space flights. In the future, in vivo models focusing on long-term consequences of particle irradiation on the bone marrow niche and MSCs are needed.


Assuntos
Proteínas Mutadas de Ataxia Telangiectasia/genética , Quinase do Ponto de Checagem 2/genética , Histonas/genética , Células-Tronco Mesenquimais/efeitos da radiação , Células-Tronco/efeitos da radiação , Medicina Aeroespacial , Apoptose/genética , Apoptose/efeitos da radiação , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Células da Medula Óssea/efeitos da radiação , Carbono/efeitos adversos , Ciclo Celular/genética , Ciclo Celular/efeitos da radiação , Linhagem da Célula/genética , Linhagem da Célula/efeitos da radiação , Citometria de Fluxo , Regulação da Expressão Gênica/efeitos da radiação , Hélio/efeitos adversos , Humanos , Células-Tronco Mesenquimais/metabolismo , Oxigênio/efeitos adversos , Prótons/efeitos adversos , Voo Espacial , Células-Tronco/metabolismo
7.
J Environ Sci (China) ; 115: 10-24, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34969440

RESUMO

This study reports for the first time a comprehensive analysis of nitrogenous and carbonaceous aerosols in simultaneously collected PM2.5 and TSP during pre-monsoon (March-May 2018) from a highly polluted urban Kathmandu Valley (KV) of the Himalayan foothills. The mean mass concentration of PM2.5 (129.8 µg/m3) was only ~25% of TSP mass (558.7 µg/ m3) indicating the dominance of coarser mode aerosols. However, the mean concentration as well as fractional contributions of water-soluble total nitrogen (WSTN) and carbonaceous species reveal their predominance in find-mode aerosols. The mean mass concentration of WSTN was 17.43±4.70 µg/m3 (14%) in PM2.5 and 24.64±8.07 µg/m3 (5%) in TSP. Moreover, the fractional contribution of total carbonaceous aerosols (TCA) is much higher in PM2.5 (~34%) than that in TSP (~20%). The relatively low OC/EC ratio in PM2.5 (3.03 ± 1.47) and TSP (4.64 ± 1.73) suggests fossil fuel combustion as the major sources of carbonaceous aerosols with contributions from secondary organic aerosols. Five-day air mass back trajectories simulated with the HYSPLIT model, together with MODIS fire counts indicate the influence of local emissions as well as transported pollutants from the Indo-Gangetic Plain region to the south of the Himalayan foothills. Principal component analysis (PCA) also suggests a mixed contribution from other local anthropogenic, biomass burning, and crustal sources. Our results highlight that it is necessary to control local emissions as well as regional transport while designing mitigation measures to reduce the KV's air pollution.


Assuntos
Poluentes Atmosféricos , Incêndios , Aerossóis/análise , Poluentes Atmosféricos/análise , Carbono/análise , Monitoramento Ambiental , Nitrogênio , Material Particulado/análise , Estações do Ano
8.
J Environ Sci (China) ; 115: 330-340, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34969460

RESUMO

Nonradical reaction driven by peroxymonosulfate (PMS) based advanced oxidation processes has drawn widespread attention in water treatment due to their inherent advantages, but the degradation behavior and mechanism of organic pollutants are still unclear. In this study, the performance, intermediates, mechanism and toxicity of tetracycline (TC) degradation were thoroughly examined in the constructed magnetic nitrogen-doped porous carbon/peroxymonosulfate (Co-N/C-PMS) system. The results showed that 85.4% of TC could be removed within 15 min when Co-N/C and PMS was simultaneously added and the degradation rate was enhanced by 3.4 and 14.7 folds compared with Co-N/C or PMS alone, respectively. Moreover, the performance of Co-N/C was superior to that of most previously reported catalysts. Many lines of evidence indicated that Co-N/C-PMS system was a singlet oxygen-dominated nonradical reaction, which was less interfered by pH and water components, and displayed high adaptability to actual water bodies. Subsequently, the degradation process was elaborated on the basis of three-dimensional excitation-emission matrix spectra and liquid chromatography-mass spectrometry. At last, the toxicity of treated TC was greatly reduced by using microalgae Coelastrella sp. as ecological indicator. This study provides a promising approach based on singlet oxygen-dominated nonradical reaction for eliminating TC in water treatment.


Assuntos
Carbono , Oxigênio Singlete , Fenômenos Magnéticos , Nitrogênio , Peróxidos , Porosidade , Tetraciclina
9.
Environ Res ; 204(Pt A): 111946, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34453896

RESUMO

This study aims to compare the effects of different carbon sources on sulfur-oxidizing denitrifying microorganisms by using glucose, ethanol, and acetate as carbon sources. Under the same chemical oxygen demand Cr (CODCr), nitrate, and sulfide concentrations, the removal rate of nitrate and total organic carbon, and the yield of elemental sulfur in a static experiment and a continuous flow reactor with glucose as the carbon source were lower than those with ethanol and acetic acid as the carbon source. The core sulfur-oxidizing denitrifying bacteria that use glucose as the carbon source were Azoarcus, Geoalkalibacter, and Mangroviflexus; those that use ethanol as the carbon source were Arcobacter, Pseudomonas, and Thauera; those that use acetate as the carbon source were Pseudomonas and Azoarcus. The metabolic activity of microorganisms that use different carbon sources was explained by functional gene detection. The fluctuation of gltA, a functional gene indicating heterotrophic metabolism of microorganisms, was small in three reactors, but that of the sulfur oxidation gene, Sqr, in the reactor with acetic acid as the carbon source was larger. Our results suggest that acetate is a more suitable carbon source for denitrification-desulfurization systems.


Assuntos
Reatores Biológicos , Desnitrificação , Carbono , Nitratos , Oxirredução , Enxofre
10.
Environ Res ; 204(Pt A): 111991, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34478723

RESUMO

Based on the recent concern on the pollution of water bodies with herbicides, adsorptive removal of typical herbicides with similar chemical structures, e. g. clofibric acid (CLFA), methylchlorophenoxypropionic acid or mecoprop (MCPP) and 2,4-dichlorophenoxyacetic acid (2,4-D) from water was studied using a porous nitrogen-enriched carbon. To prepare the nitrogen-enriched carbon, pyrolysis of a melamine (MLM) incorporated metal-azolate framework-6 (MLM(x)@MAF6; x = 0-50 M % of the ligand 2-ethylimidazole for MAF6), that was prepared for the first time via an in situ method, was carried out. The MLM(x)@MAF6-derived carbons (MDC6M(x)s) were characterized and used in the removal of CLFA, MCPP and 2,4-D from water. We found that the MDC6M(25), obtained from MLM(25)@MAF6 with 25% MLM (as the optimum precursor composition), showed the highest maximum adsorption capacity (Q0) of 1031 mg/g for CLFA, compared with any reported adsorbents, so far. The physicochemical properties of CLFA, as well as adsorbents and adsorptions under wide pH conditions, were employed to propose a plausible adsorption mechanism including hydrogen bonding. Remarkably, the porous carbon with enriched nitrogen, derived from MAF6 loaded MLM via in situ method, was very competitive in herbicides adsorption because of the contribution of well-dispersed nitrogen sties on the adsorbent. Finally, MDC6M(25) was suggested as a potential adsorbent for the removal of herbcides, including CLFA, MCPP and 2,4-D, from water, which is highly attractive to mitigate the environmental issue, especially, water pollution by various herbicides.


Assuntos
Herbicidas , Poluentes Químicos da Água , Purificação da Água , Adsorção , Carbono , Cinética , Nitrogênio , Triazinas , Água , Poluentes Químicos da Água/análise
11.
Environ Res ; 204(Pt A): 111938, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34478726

RESUMO

Agricultural microplastic pollution has become a growing concern. Unfortunately, the impacts of microplastics (MPs) on agricultural soil carbon and nitrogen dynamics have not been sufficiently reported. In an attempt to remedy this, we conducted a 105-day out-door mesocosm experiment in a soil-plant system using sandy soils amended with two types of MPs, low-density polyethylene (LDPE-MPs) and biodegradable (Bio-MPs), at concentrations of 0.0% (control), 0.5%, 1.0%, 1.5%, 2.0% and 2.5% (w/w, weight ratio of microplastics to air-dry soil). Soil organic matter (SOM), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), available nitrogen (AN) of N-NH4+ and N-NO3-, and dissolved organic nitrogen (DON) were measured on day 46 (D46) and 105 (D105) of the experiment. SOM was also measured after microplastics were mixed into soils (D0). For LDPE-MPs treatments, SOM on D0, D46 and D105 showed no significant differences, while for Bio-MPs treatments, SOM significantly (p < 0.05) decreased from D0 to D46. Compared to the control, soil POXC was significantly (p = 0.001) lowered by 0.5%, 1.0% and 2.5% LDPE-MPs and ≥ 1.0% Bio-MPs on D105. LDPE-MPs showed no significant effects on soil DOC and nitrogen cycling. 2.0% and 2.5% Bio-MPs showed significantly higher (p < 0.001) DOC and DON (on D46 and D105) and ≥1.5% Bio-MPs showed significantly lower (p = 0.02) AN (on D46). Overall, Bio-MPs exerted stronger effects on the dynamics of soil carbon and nitrogen cycling. In conclusion, microplastics might pose serious threats to agroecosystems and further research is needed.


Assuntos
Microplásticos , Solo , Carbono , Nitrogênio , Plásticos , Polímeros
12.
Environ Res ; 204(Pt A): 111856, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34389349

RESUMO

In agro-areas, linuron (LNR) and amino-triazole (ATZ) are the widely used herbicides to protect crops, but their widespread use pollutes the environment, especially when these are mixed with water or soil. In efforts to address these environmental issues and to detect trace quantities of the herbicides, a graphitic carbon nitride (g-C3N4) with cetyltrimethylammonium bromide (CTAB) modified carbon paste electrode (g-C3N4-CTAB/CPE) was developed and used for the detection of LNR and ATZ. Materials were characterized by XRD, TEM and AFM techniques. The effect of pH on electro-oxidation (under optimized conditions) showed the maximum peak current at pH of 4.2 for AMT and pH 6.0 for LNR. The electro-kinetic and thermodynamic parameters of LNR and ATZ were determined. Additional experiments were performed for the trace level detection of ATZ and LNR using the square wave voltammetric technique. Concentrations were varied linearly in the range of 3.0 × 10-7 M to 4.5 × 10-5 M for ATZ with a detection limit of 6.41 × 10-8 M, and 1.2 × 10-7 M to 3.0 × 10-4 M for LNR with a detection limit of 2.47 × 10-8 M. The developed novel sensor was effective for trace level detection of LNR and ATZ in water and soil samples.


Assuntos
Herbicidas , Linurona , Carbono , Cetrimônio , Eletrodos , Grafite , Compostos de Nitrogênio , Triazóis
13.
Environ Res ; 204(Pt A): 111854, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34437850

RESUMO

Fluorescent carbon dots (CDs) are prepared from a natural resource Carica Papaya Leaves, by sand bath method. The as-synthesized CDs optical and structural properties were characterized by UltraViolet-Visible, FT- IR, and fluorescence spectroscopy. Also the size, shape, and particle size distribution was studied using Transmission electron microscopy technique. These CDs were examined for biomedical applications like free radical scavenging activity using DPPH assay, antioxidant activity using phosphomolybdate assay, and in vitro anti-inflammatory activity using membrane stabilization protocol. The CDs exhibited excellent biological activities at lower concentrations and showed notable half-maximal effective concentration (EC50). The EC50 of free radical scavenging activity (27.6 µg/mL), antioxidant activity (23.00 µg/mL), and in vitro anti-inflammatory activity (15.52 µg/mL) signifies that CDs can be potential therapeutic agents.


Assuntos
Carica , Pontos Quânticos , Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Carbono , Corantes Fluorescentes , Folhas de Planta
14.
J Hazard Mater ; 425: 128037, 2022 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-34906873

RESUMO

High contents of heavy metals and Cl are major challenges for incineration residue disposal. Classification by the Chinese government and the coronavirus disease 2019 pandemic have changed the characteristics of incineration residues, thereby increasing the difficulty of disposal. In this study, medical waste incineration fly ash (MWI FA) was proposed as an additive to promote chlorination volatilization of heavy metals from municipal solid waste incineration fly ash (MSWI FA) and medical waste incineration slag (MWI S). When the mixing ratio of MWI FA to MSWI FA was 1:3, the chlorination volatilization efficiencies of Cu, Zn, Pb, and Cd at 1000 °C for 60 min were 50.2%, 99.4%, 99.7%, and 97.9%, respectively. When MWI FA was mixed with MWI S at a ratio of 1:1, the chlorination volatilization efficiencies of Cu, Zn, Pb, and Cd at 1200 °C for 40 min were 88.9%, 99.7%, 97.3%, and 100%, respectively. Adding MWI FA can replenish Cl in MSWI FA and MWI S while increasing the surface area and forming pore structures by sublimation of NaCl and decomposition of CaSO4, or can reduce the melting point and viscosity by Na2O destroying the glass matrix. Therefore, MWI FA can be co-disposed with MSWI FA and MWI S respectively to enhance the chlorination volatilization of heavy metals.


Assuntos
COVID-19 , Resíduos de Serviços de Saúde , Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Halogenação , Humanos , Incineração , Metais Pesados/análise , Material Particulado , SARS-CoV-2 , Resíduos Sólidos , Volatilização
15.
J Environ Sci (China) ; 113: 132-140, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34963523

RESUMO

The concentration variation of C3-C11 non-methane hydrocarbons (NMHCs) collected in several types of commercial flexible bags and adsorption tubes was systematically investigated using a gas chromatography-flame ionization detector (GC-FID) system. The percentage loss of each NMHC in the polyvinyl fluoride (PVF) bags was less than 5% during a 7-hr storage period; significant NMHCs loss was detected in aluminum foil composite film and fluorinated ethylene propylene bags. The thermal desorption efficiency of NMHCs for adsorption tubes filled Carbopack B and Carboxen1000 sorbents was greater than 95% at 300℃, and the loss of NMHCs in the adsorption tubes during 20-days storage at 4℃ was less than 8%. The thermal desorption efficiency for C11 NMHCs in the adsorption tube filled with Carbograph 1 and Carbosieve SⅢ absorbents was less than 40% at 300℃, and pyrolysis of the absorbents at 330℃ interfered significantly with the measurements of some alkenes. The loss of alkenes was significant when NMHCs were sampled by cryo-enrichment at -90℃ in the presence of O3 for the online NMHC measurements, and negligible for enrichment using adsorption tubes at 25℃. Although O3 scrubbers have been widely used to eliminate the influence of O3 on NMHC measurements, the loss of NMHCs with carbon numbers greater than 8 was more than 10%. Therefore, PVF bags and adsorption tubes filled Carbopack B and Carboxen1000 sorbents were recommended for the sampling of atmospheric NMHCs.


Assuntos
Poluentes Atmosféricos , Metano , Adsorção , Poluentes Atmosféricos/análise , Carbono , Cromatografia Gasosa , Monitoramento Ambiental , Hidrocarbonetos/análise
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 268: 120661, 2022 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-34896678

RESUMO

The folic acid (FA) level in human body can be used as an indicator for body's normal physiological activities and offer insight into the growth and reproduction of the body's cells. But the abnormal level of FA can cause some diseases. Herein, we designed a simple and convenient approach to prepare fluorescent N-doped carbon dots (N-CDs) for the FA detection. These N-CDs have excellent hydrophilicity, high photostability, and outstanding biocompatibility, as well as excitation-independent emission behavior with typical excitation/emission peaks at 295 nm/412 nm. Upon the existence of FA, the fluorescence emission spectrum of N-CDs was significantly quenched through the synergy of static quenching mechanism and internal filtering effect (IFE). Under optimal conditions, the limit of detection was 28.0 nM (S/N = 3) within the FA concentration range of 0-200.0 µM. In addition, N-CDs were successfully employed to detect FA in real samples such as urine and fetal bovine serum (FBS), with a recovery rate of 99.6%-100.7% for quantitative addition. Furthermore, cell experiments confirmed the low toxicity and the cell imaging performance of these N-CDs, indicating that the obtained N-CDs could be served as a credible quantitative probe for FA analysis in the field of biosensing.


Assuntos
Carbono , Pontos Quânticos , Corantes Fluorescentes , Ácido Fólico , Humanos , Nitrogênio , Pontos Quânticos/toxicidade
17.
J Colloid Interface Sci ; 609: 249-259, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34906910

RESUMO

Poor conductivity is an obstacle that restricts the development of the electrochemistry performance of Fe3O4. In this work, a novel carbon and nitrogen co-doped ultrafine Fe3O4 nanoparticles (CN-Fe3O4) have been synthesized by triethylamine (TEA) induction and subsequent calcination. The addition of TEA could not only regulate the size of Fe3O4 nanoparticles, but also promote the formation of amorphous carbon layer. Well-designed CN-Fe3O4 heterostructures provide a highly interconnected porous conductive network, large heterogeneous interface area, large specific surface area and a large number of active sites, which greatly improve conductivity and promote electron transfer and electrolyte diffusion. The prepared CN-Fe3O4 electrode exhibits a high specific capacitance of 399.3 mF cm-2 and good cycling stability. Meanwhile, CN-Fe3O4 catalyst exhibits excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities, with overpotentials of 136 and 281 mV at the current density of 10 mA cm-2, respectively. This work provides a promising approach for the design of high-performance anode materials for supercapacitors and provides profound implications for the development of catalysts with bifunctional catalytic activity.


Assuntos
Carbono , Nanopartículas , Catálise , Eletrodos , Etilaminas
18.
J Environ Sci (China) ; 113: 385-393, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34963546

RESUMO

Atmospheric nanoparticles (PM < 0.1 µm) are a major cause of environmental problems and also affect health risk. To control and reduce these problems, sources identification of atmospheric particulates is necessary. Combustion of bituminous coal and biomass including rubber wood, palm kernel, palm fiber, rice stubble, rice straw, maize residue, sugarcane leaves and sugarcane bagasse, which are considered as sources of air quality problems in many countries, was performed. Emissions of particle-bound chemical components including organic carbon (OC), elemental carbon (EC), water-soluble ions (NH4+, Cl-, NO3-, SO42-), elements (Ca, K, Mg, Na) and heavy metals (Cd, Cr, Ni, Pb) were investigated. The results revealed that PM < 0.1 µm from all samples was dominated by the OC component (>50%) with minor contribution from EC (3%-12%). The higher fraction of carbonaceous components was found in the particulates with smaller sizes, and lignin content may relate to concentration of pyrolyzed organic carbon (PyOC) resulting in the differences of OC/EC values. PM emitted from burning palm fiber and rice stubble showed high values of OC/EC and also high PyOC. Non-carbonaceous components such as Cl-, Cr, Ca, Cd, Ni, Na and Mg may be useful as source indicators, but they did not show any correlation with the size of PM.


Assuntos
Poluentes Atmosféricos , Material Particulado , Aerossóis , Poluentes Atmosféricos/análise , Biomassa , Carbono/análise , China , Monitoramento Ambiental , Tamanho da Partícula , Material Particulado/análise
19.
J Environ Manage ; 301: 113803, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34626944

RESUMO

Invasive species alter hydrologic processes at watershed scales, with impacts to biodiversity and the supporting ecosystem services. This effect is aggravated by climate change. Here, we integrated modelled hydrologic data, remote sensing products, climate data, and linear mixed integer optimization (MIP) to identify stewardship actions across space and time that can reduce the impact of invasive species. The study area is the windward coast of Hawai'i Island (USA) across which non-native strawberry guava occurrence varies from extremely dense stands in lower watershed reaches, to low densities in upper watershed forests. We focused on the removal of strawberry guava, an invader that exerts significant impacts on watershed condition. MIP analyses spatially optimized the assignment of effective management actions to increase water yield, generate revenue from enhanced freshwater services, and income from removed biomass. The hydrological benefit of removing guava, often marginal when considered in isolation, was financially quantified, and single- and multiobjective MIP formulations were then developed over a 10-year planning horizon. Optimization resulted in $2.27 million USD benefit over the planning horizon using a payment-for-ecosystem-services scheme. That value jumped to $4.67 million when allowing work schedules with overnight camping to reduce costs. Pareto frontiers of weighted pairs of management goals showed the benefit of clustering treatments over space and time to improve financial efficiency. Values of improved land-water natural capital using payment-for-ecosystem-services schemes are provided for several combinations of spatial, temporal, economical, and ecosystem services flows.


Assuntos
Ecossistema , Espécies Introduzidas , Carbono , Conservação dos Recursos Naturais , Florestas , Água
20.
J Environ Manage ; 301: 113856, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34626948

RESUMO

The conventional sintering process of municipal solid waste incineration (MSWI) fly ash is always energy intensive. The process forms a cracked structure because of the difficulty in forming the liquid phase to enhance the mass transfer process. Therefore, exploring a new disposal method to simultaneously decrease the sintering temperature and improve the mechanical and heavy metal leaching properties of sintered samples is necessary. In this study, a pressure-assisted sintering treatment was introduced to dispose fly ash by varying the chemical composition and mechanical pressure at relatively low temperatures (300-500 °C). The results revealed that the compressive strength of treated samples increased with the CaO/SiO2 molar ratio increasing from 0.5 to 1.0, and a maximum value of 238.28 ± 8.50 MPa was obtained. The heavy metal leaching concentration results demonstrated a low risk of contamination in the treated samples. Microstructure analyses suggested that the densification process was enhanced with increased mechanical pressure, and the formed calcium silicates and aluminosilicates positively affected the compressive strength. Moreover, smaller crystal lattices were observed during aggregation formation, suggesting the restraint of anomalous crystal growth, which accelerated the densification process and increased the compressive strength. Moreover, the mass transfer process during the pressure-assisted sintering process was enhanced compared with the conventional thermal process, which was reflected by the transformation of elements from homogeneous to heterogeneous distribution. Therefore, the improved mechanical properties and leaching behavior of heavy metals were attributed to the densified microstructure, formation of new minerals, and enhanced driving force during the pressure-assisted sintering process. These findings suggest that pressure-assisted sintering is a promising method for maximizing the reutilization and minimizing the energy consumption simultaneously to dispose fly ash.


Assuntos
Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Incineração , Metais Pesados/análise , Material Particulado , Dióxido de Silício , Resíduos Sólidos/análise
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