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1.
Environ Sci Technol ; 58(39): 17475-17484, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39283811

RESUMO

Synergistic catalytic removal of multipollutants (e.g., volatile organic compound (VOC) oxidation and nitrogen oxide (NOx) reduction) is highly demanded due to the increasingly strict emission standards. The prevention of the key reactive intermediate species nitrite excessive oxidation over the supported noble-metal catalysts, rather than the traditional low-efficiency transition metal oxide catalysts, remains a great challenge. Herein, a sound strategy of Pd single atoms saturated with acidic transition element ligands is proposed. The coexistence of Pd and V dual single atoms strengthens the adsorption of reactants, while synergistic interaction between dual atoms and surface oxygen weakens activation of lattice oxygen, thus significantly reducing the overoxidation of nitrite. Meanwhile, the neutralization of the active Pd and inert V sites results in a rational decrease in the redox property of Pd and an obvious increase in that of V. The Pd1V1/CeO2 dual single-atom catalyst achieves 90% conversion of NOx and toluene at 238 and 230 °C and has a large temperature window (>150 °C) for NOx reduction. This research makes a breakthrough in the development of efficient supported noble-/transition-metal dual single-atom catalysts for VOC and NOx simultaneous purification.


Assuntos
Óxidos de Nitrogênio , Oxirredução , Oxigênio , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/química , Óxidos de Nitrogênio/química , Oxigênio/química , Catálise
2.
J Am Chem Soc ; 145(20): 11110-11120, 2023 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-37191364

RESUMO

Improving the product selectivity meanwhile restraining deep oxidation still remains a great challenge over the supported Pd-based catalysts. Herein, we demonstrate a universal strategy where the surface strong oxidative Pd sites are partially covered by the transition metal (e. g., Cu, Co, Ni, and Mn) oxide through thermal treatment of alloys. It could effectively inhibit the deep oxidation of isopropanol and achieve the ultrahigh selectivity (>98%) to the target product acetone in a wide temperature range of 50-200 °C, even at 150-200 °C with almost 100% isopropanol conversion over PdCu1.2/Al2O3, while an obvious decline in acetone selectivity is observed from 150 °C over Pd/Al2O3. Furthermore, it greatly improves the low-temperature catalytic activity (acetone formation rate at 110 °C over PdCu1.2/Al2O3, 34.1 times higher than that over Pd/Al2O3). The decrease of surface Pd site exposure weakens the cleavage for the C-C bond, while the introduction of proper CuO shifts the d-band center (εd) of Pd upward and strengthens the adsorption and activation of reactants, providing more reactive oxygen species, especially the key super oxygen species (O2-) for selective oxidation, and significantly reducing the barrier of O-H and ß-C-H bond scission. The molecular-level understanding of the C-H and C-C bond scission mechanism will guide the regulation of strong oxidative noble metal sites with relatively inert metal oxide for the other selective catalytic oxidation reactions.

3.
J Environ Sci (China) ; 126: 459-469, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36503772

RESUMO

A novel La-Co-O-C (LC-C) composites were prepared via a facile co-hydrothermal route with oxides and glycerol and further optimized for methane catalytic activity and thermal stability via component regulation. It was demonstrated that Co3O4 phase was the main component in regulation. The combined results of X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of oxygen (O2-TPD), temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of ammonia/carbon dioxide (NH3/CO2-TPD) revealed that component regulation led to more oxygen vacancies and exposure of surface Co2+, lower surface basicity and optimized acidity, which were beneficial for adsorption of active oxygen species and activation of methane molecules, resulting in the excellent catalytic oxidation performance. Especially, the (3.5)LC-C (3.5 is Co-to-La molar ratio) showed the optimum activity and the T50 and T90 (the temperature at which the CH4 conversion rate was 50% and 90%, respectively) were 318 and 367°C, respectively. Using theoretical calculations and in situ diffuse reflection infrared Fourier transform spectroscopy characterization, it was also found that the catalytic mechanism changes from the "Rideal-Eley" mechanism to the "Two-term" mechanism depending on the temperature windows in which the reaction takes place. Besides, the use of the "Flynn-Wall-Ozawa" model in thermoanalytical kinetics revealed that component regulation simultaneously optimized the decomposition activation energy, further expanding the application scope of carbon-containing composites.


Assuntos
Hidrogênio , Metano , Oxirredução , Catálise , Oxigênio
4.
Environ Sci Technol ; 56(12): 8722-8732, 2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35579250

RESUMO

Photothermal synergistic catalytic oxidation of toluene over single-atom Pt catalysts was investigated. Compared with the conventional thermocatalytic oxidation in the dark, toluene conversion and CO2 yield over 0.39Pt1/CuO-CeO2 under simulated solar irradiation (λ = 320-2500 nm, optical power density = 200 mW cm-2) at 180 °C could be increased about 48%. An amount of CuO was added to CeO2 to disperse single-atom Pt with a maximal Pt loading of 0.83 wt %. The synergistic effect between photo- and thermocatalysis is very important for the development of new pollutant treatment technology with high efficiency and low energy consumption. Both light and heat played an important role in the present photothermal synergistic catalytic oxidation. 0.39Pt1/CuO-CeO2 showed good redox performance and excellent optical properties and utilized the full-spectrum solar energy. Light illumination induced the generation of reactive oxygen species (•OH and •O2-), which accelerated the transformation of intermediates, promoted the release of active sites on the catalyst surface, and improved the oxidation reaction.

5.
Angew Chem Int Ed Engl ; 61(27): e202203827, 2022 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-35419926

RESUMO

The controlled oxidation of alcohols to the corresponding ketones or aldehydes via selective cleavage of the ß-C-H bond of alcohols under mild conditions still remains a significant challenge. Although the metal/oxide interface is highly active and selective, the interfacial sites fall far behind the demand, due to the large and thick support. Herein, we successfully develop a unique Au-CuO Janus structure (average particle size=3.8 nm) with an ultrathin CuO layer (0.5 nm thickness) via a bimetal in situ activation and separation strategy. The resulting Au-CuO interfacial sites prominently enhance isopropanol adsorption and decrease the energy barrier of ß-C-H bond scission from 1.44 to 0.01 eV due to the strong affinity between the O atom of CuO and the H atom of isopropanol, compared with Au sites alone, thereby achieving ultrahigh acetone selectivity (99.3 %) over 1.1 wt % AuCu0.75 /Al2 O3 at 100 °C and atmospheric pressure with 97.5 % isopropanol conversion. Furthermore, Au-CuO Janus structures supported on SiO2 , TiO2 or CeO2 exhibit remarkable catalytic performance, and great promotion in activity and acetone selectivity is achieved as well for other reducible oxides derived from Fe, Co, Ni and Mn. This study should help to develop strategies for maximized interfacial site construction and structure optimization for efficient ß-C-H bond activation.

6.
J Environ Sci (China) ; 99: 281-295, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183708

RESUMO

CO2 capture and utilization (CCU) is an effective strategy to mitigate global warming. Absorption, adsorption and membranes are methods used for CO2 separation and capture, and various catalytic pathways have also been developed for CO2 utilization. Although widely researched and used in industry, these processes are energy-intensive and this challenge needs to be overcome. To realize further optimization, novel materials and processes are continuously being developed. New generation materials such as ionic liquids (ILs) have shown promising potential for cost-effective CO2 capture and utilization. This study reviews the current status of ILs-based solvents, adsorbents, membranes, catalysts and their hybrid processes for CO2 capture and utilization. The special properties of ILs are integrated into new materials through hybridization, which significantly improves the performance in the process of CCU.


Assuntos
Líquidos Iônicos , Adsorção , Dióxido de Carbono , Catálise , Solventes
7.
J Environ Sci (China) ; 88: 260-272, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31862067

RESUMO

In order to study their synergistic catalytic effects in toluene degradation, CuMn2O4/HTS-1 (HTS-1 was a titanium silicon molecular sieve), Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1 catalysts were prepared by the impregnation method. The textural properties, redox properties and acidity of the catalysts were characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), frustrated total internal reflection (FT-IR), ammonium temperature-programmed desorption (NH3-TPD) and pyridine adsorption internal reflection (Py-IR) measurements. The potential roles of Lewis acid sites (activating dioxygen) were discussed, and the experimental results indicated that the most efficient route for toluene degradation over Cu0.7Mn2Ce0.3Ox/HTS-1 (toluene conversion rate of 90% (T99)=295°C) was ascribed to regulation of the synergistic effects of redox properties (activating molecular toluene) and Lewis acid sites (activating dioxygen). The Mars-Van-Krevelen (MVK) model was adopted to describe the reaction process of toluene oxidation, which gave an in-depth view into the toluene degradation over CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1. In addition, the synergistic effects between redox properties and Lewis acid sites were studied in detail.


Assuntos
Modelos Químicos , Tolueno/química , Catálise , Cobre/química , Manganês/química , Oxirredução , Espectroscopia de Infravermelho com Transformada de Fourier , Titânio
8.
J Environ Sci (China) ; 97: 25-34, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32933737

RESUMO

Shijiazhuang, the city with the worst air quality in China, is suffering from severe ozone pollution in summer. As the key precursors of ozone generation, it is necessary to control the Volatile Organic Compounds (VOCs) pollution. To have a better understanding of the pollution status and source contribution, the concentrations of 117 ambient VOCs were analyzed from April to August 2018 in an urban site in Shijiazhuang. Results showed that the monthly average concentration of total VOCs was 66.27 ppbv, in which, the oxygenated VOCs (37.89%), alkanes (33.89%), and halogenated hydrocarbons (13.31%) were the main composite on. Eight major sources were identified using Positive Matrix Factorization modeling with an accurate VOCs emission inventory as inter-complementary methods revealed that the petrochemical industry (26.24%), other industrial sources (15.19%), and traffic source (12.24%) were the major sources for ambient VOCs in Shijiazhuang. The spatial distributions of major industrial activities emissions were identified by using geographic information statistics system, which illustrated the VOCs was mainly from the north and southeast of Shijiazhuang. The inverse trajectory analysis using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and Potential Source Contribution Function (PSCF) clearly demonstrated the features of pollutant transport to Shijiazhuang. These findings can provide references for local governments regarding control strategies to reduce VOCs emissions.


Assuntos
Poluentes Atmosféricos/análise , Compostos Orgânicos Voláteis/análise , China , Cidades , Monitoramento Ambiental , Emissões de Veículos/análise
10.
J Air Waste Manag Assoc ; 65(2): 165-70, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25947052

RESUMO

The SO2removal ability (including adsorption and oxidation ability) of activated carbon produced from oxytetracycline bacterial residue and impregnated with copper was investigated. The activated carbon produced from oxytetracycline bacterial residue and modified with copper was characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of the catalysts, SO2concentration, weight hourly space velocity, and temperature on the SO2adsorption and oxidation activity were evaluated. Activated carbon produced from oxytetracycline bacterial residue and used as catalyst supports for copper oxide catalysts provided high catalytic activity for the adsorbing and oxidizing of SO2from flue gases.


Assuntos
Poluentes Atmosféricos/química , Carvão Vegetal/química , Cobre/química , Recuperação e Remediação Ambiental/métodos , Resíduos Perigosos/análise , Oxitetraciclina/química , Dióxido de Enxofre/química , Adsorção , Microscopia Eletrônica de Varredura , Oxirredução , Espectrometria por Raios X , Difração de Raios X
11.
Sci Total Environ ; 933: 173235, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38750751

RESUMO

Treatment of naphthenic acids (NAs) in wastewater is necessary due to its high toxicity and difficult degradation. In the heterogeneous Fenton-like advanced oxidation of organic pollutant system, the insufficient accessibility of oxidizing agent and NAs greatly hamper the reaction efficiency. CO2-responsive phase transfer materials derived from polyethylene glycol (PEG)-based deep eutectic solvents were specific targeted at the immiscible-binary phase system. The NAs oxidative degradation process was optimized including the kinds of catalyst (Molecular weight of PEG, constitute of DESs, and dosage.), temperature, flow rate of CO2, et al. With the help of fluorescence properties of catalyst, the hydrophilic-hydrophobic interaction was visual-monitored and further studied. The amphipathic property of PEG-200/Sodium persulfate/Polyether amine 230 (PEA230) greatly reduced the aqueous/organic phase transfer barrier between sodium persulfate and NAs (up to 84 %), thus accreting oxidation rate. The surface tension decreased from 35.364 mN/m to 28.595 mN/m. To control the reaction rate, the CO2 respond structure of amido played an important role. In addition, the interfacial transfer intermediates and oxidation pathways were also explored by nuclear magnetic resonance, flourier transform infrared spectroscopy, surface tension, and radical inhibition experiments. The mechanism of advanced oxidation of NAs catalyzed by CO2-responsive phase transfer catalyst was proposed, which would made up for the deficiency of the system theory of heterogeneous chemical oxidation of organic pollutants.

12.
J Colloid Interface Sci ; 675: 935-946, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39002243

RESUMO

Generally, sulfur poisoning is considered to be one of the main factors contributing to the deactivation of selective catalytic reduction of NOx by CO (CO-SCR) catalysts, while the promotional effect of SO2 on NO reduction over Ir/SiO2 is observed which is an interesting scientific phenomenon. After the introduction of 20 ppm SO2, NOx conversion increased from âˆ¼ 40 % to âˆ¼ 90 % at 275 °C, and N2 selectivity increased from âˆ¼ 80 % to 100 % at 200 âˆ¼ 300 °C. Furthermore, the promoting effect could remain unchanged after 24 h of continuous reaction. However, the temperature point for achieving complete conversion of CO increased from 225 °C to 275 °C after the introduction of SO2. Experimental characterization and theoretical calculation jointly proved that the inhibition of CO oxidation by the generation of sulfate was the main reason for promoting NO reduction. Under the coexistence of O2 and SO2, SO2 was firstly oxidized to SO3 on the iridium surface and generated sulfate species on surface hydroxyl groups of SiO2. Some active sites for O2 adsorption were covered by the generated surface sulfate, and adsorbed CO was hard to react with adsorbed O2, resulting in Langmuir-Hinshelwood (L-H) reaction pathways for CO oxidation being inhibited. Therefore, unoxidized CO reacted with NO adsorbed species and generated N2O to generate N2 and CO2, improving NO reduction. This new insight has implications for understanding the promotional effect of SO2 on NO reduction with CO in the presence of O2.

13.
Nanoscale ; 15(29): 12157-12174, 2023 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-37431630

RESUMO

Chlorinated benzene-containing compounds (CBCs) refer to volatile organic compounds which simultaneously contain benzene rings and Cl atoms. It has been widely believed to cause serious harm to human health and the natural environment due to high toxicity, high persistence, and refractory degradation, thus, it is urgent to develop CBC abatement technology. In this review, several CBCs control techniques are compared, and the catalytic oxidation technology stands out for its good low-temperature activity and chlorine resistance of metal oxide catalysts. Then, the common and individual reaction pathways and water impact mechanisms of CBC catalytic oxidation on transition metal catalysts are concluded. Subsequently, three typical metal oxides (namely, VOx, MnOx, and CeO2-based catalysts) are introduced in the catalytic degradation of CBCs, whose catalytic activity influence factors are also proposed on active components, support properties, surface acidity, and nanostructure (crystal, morphology, etc.). Furthermore, the effective strategies to enhance the REDOX cycle and surface acidic sites are summarized by the doping of metals, the modification of support or/and acidic groups, and the construction of nanostructures. Finally, the key points for efficient catalyst design are speculated. This review may provide ideas for the breakthroughs of activity-enhanced strategies, the design of efficient catalysts, and research on reaction-promoted mechanisms.

14.
Sci Total Environ ; 905: 167448, 2023 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-37777121

RESUMO

With the increase of urban building height, people pay more and more attention to the characteristics of pollutants in urban canopy height. This study combined the generalized additive model (GAM) and the observation-based model (OBM) to explore the vertical characteristics and drivers of ozone (O3) based on meteorology tower (200 m) data to quantify the effects of factors and photochemical reactions on O3 formation at different heights. The F values of GAM reflect the importance of each factor, indicating that NO (F is 33.99 in the peak season, 36.72 in the non-peak season) was the dominant driver of O3 and was more important in the lower layer (20-116 m). Temperature (F is 35.42) was the main contributor to O3 pollution in the peak season, especially for O3 in the upper layer (116-200 m). The net O3 production rate in the peak season was 1.47 times that in the non-peak season due to strong photochemical reactions and meteorological conditions. And the net O3 production rate decreased sharply with increasing height in the two seasons. Less net O3 production in the upper layer was accompanied by a higher O3 mixing ratio, which indicated that there was more background O3 in the upper layer. OBM model results showed that the reaction between hydroperoxyl radical (HO2) and NO was the primary contribution pathway, accounting for 54.00 % and 57.50 % in the peak and non-peak seasons, respectively. O3 formation was highly sensitive to VOCs, while NOx reduction could have positive or negative effects on O3 depending on the levels of hydroxyl radical (OH). The understanding of the formation mechanism of O3 and the influence of NO on O3 provides insights into the importance of anthropogenic activities at urban canopy heights in shaping the vertical structure of O3.

15.
Chemosphere ; 329: 138651, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37059204

RESUMO

Trichloroethylene is carcinogenic and poorly degraded by microorganisms in the environment. Advanced Oxidation Technology is considered to be an effective treatment technology for TCE degradation. In this study, a double dielectric barrier discharge (DDBD) reactor was established to decompose TCE. The influence of different condition parameters on DDBD treatment of TCE was investigated to determine the appropriate working conditions. The chemical composition and biotoxicity of TCE degradation products were also investigated. Results showed that when SIE was 300 J L-1, the removal efficiency could reach more than 90%. The energy yield could reach 72.99 g kWh-1 at low SIE and gradually decreased with the increase of SIE. The k of the Non-thermal plasma (NTP) treatment of TCE was about 0.01 L J-1. DDBD degradation products were mainly polychlorinated organic compounds and produced more than 373 mg m-3 ozone. Moreover, a plausible TCE degradation mechanism in the DDBD reactors was proposed. Lastly, the ecological safety and biotoxicity were evaluated, indicating that the generation of chlorinated organic products was the main cause of elevated acute biotoxicity.


Assuntos
Ozônio , Tricloroetileno , Poluentes Químicos da Água , Tricloroetileno/química , Ozônio/química , Oxirredução , Poluentes Químicos da Água/análise
16.
Environ Pollut ; 323: 121293, 2023 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-36804559

RESUMO

One of the major pollutants influencing urban air quality in China is O3. O3 is the second most important pollutant affecting air quality in Shijiazhuang, which is the third largest city in the Beijing-Tianjin-Hebei area and the provincial capital of Hebei province. To fully understand the characteristics of O3 and volatile organic compounds (VOCs), which are O3 precursors, and the role of VOCs to ozone formation, we measured the hourly concentrations of O3 and 85 VOCs in Shijiazhuang continuously from January to November 2020, and the concentration characteristics of both together with the chemical reactivity and sources of VOCs were analyzed from a seasonal perspective. The O3 concentration in Shijiazhuang showed a phenomenon of high summer and low winter, and the VOCs showed a phenomenon of high winter and low spring. In the summer when the O3 exceedance rate is the highest, the time-domain variation characteristics of O3 were analyzed by wavelet analysis model, and the main periods controlling the O3 concentration variation in Shijiazhuang in summer 2020 were 52 days, 32 days, 19 days and 12 days. The maximum incremental reactivity (MIR) and propylene equivalence method indicated ethene, propylene and 1-pentene were common substances in the top five species of each season. The T/B, Iso-p/N-p, Iso-p/E, N-p/E, and positive matrix factorization (PMF) model showed that industrial source (18.62%-22.03%) and vehicle emission (13.20%-17.69%) were the major VOCs sources in Shijiazhuang. Therefore, to control the O3 concentration in Shijiazhuang, it is necessary to decrease alkenes emissions as well as VOCs from industrial source and vehicle emission.


Assuntos
Poluentes Atmosféricos , Ozônio , Compostos Orgânicos Voláteis , Pequim , Emissões de Veículos/análise , Poluentes Atmosféricos/análise , Compostos Orgânicos Voláteis/análise , Estações do Ano , Urbanização , China , Ozônio/análise , Monitoramento Ambiental
17.
Int J Biol Macromol ; 242(Pt 2): 124829, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37210053

RESUMO

Deep eutectic solvents (DESs) composed by amino acids (L-arginine, L-proline, L-alanine) as the hydrogen bond acceptors (HBAs) and carboxylic acids (formic acid, acetic acid, lactic acid, levulinic acid) as hydrogen bond donors (HBDs) were prepared and used for the dissolution of dealkaline lignin (DAL). The mechanism of lignin dissolution in DESs was explored at molecular level by combining the analysis of Kamlet-Taft (K-T) solvatochromic parameters, FTIR spectrum and density functional theory (DFT) calculations of DESs. Firstly, it was found that the formation of new hydrogen bonds between lignin and DESs mainly drove the dissolution of lignin, which were accompanied by the erosion of hydrogen bond networks in both lignin and DESs. The nature of hydrogen bond network within DESs was fundamentally determined by the type and number of functional groups in both HBA and HBD, which affected its ability to form hydrogen bond with lignin. One hydroxyl group and carboxyl group in HBDs provided active protons, which facilitated proton-catalyzed cleavage of ß-O-4, thus enhancing the dissolution of DESs. The superfluous functional group resulted in more extensive and stronger hydrogen bond network in the DESs, thus decreasing the lignin dissolving ability. Moreover, it was found that lignin solubility had a closed positive correlation with the subtraction value of α and ß (net hydrogen donating ability) of DESs. Among all the investigated DESs, L-alanine/formic acid (1:3) with the strong hydrogen-bond donating ability (acidity), weak hydrogen-bond accepting ability (basicity) and small steric-hindrance effect showed the best lignin dissolving ability (23.99 wt%, 60 °C). On top of that, the value of α and ß of L-proline/carboxylic acids DESs showed some positive correlation with the global electrostatic potential (ESP) maxima and minima of the corresponding DESs respectively, indicating the analysis of ESP quantitative distributions of DESs could be an effective tool for DESs screening and design for lignin dissolution as well as other applications.


Assuntos
Solventes Eutéticos Profundos , Lignina , Lignina/química , Solubilidade , Aminoácidos , Solventes/química , Biomassa , Alanina , Prolina , Ácidos Carboxílicos
18.
Sci Total Environ ; 885: 163773, 2023 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-37146826

RESUMO

With the development of the petrochemical industry, a large amount of naphthenic acids in petrochemical wastewater was accumulated in the environment, causing serious environmental pollution. Most of the commonly used methods for the determination of naphthenic acids have the characteristics of high energy consumption, complicated pretreatment, long detection cycle, and the need to send samples to analytical laboratories. Therefore, it is essential to develop an efficient and low-cost field analytical method for rapidly naphthenic acids quantify. In this study, nitrogen-rich carbon quantum dots (N-CQDs) based on natural deep eutectic solvents (NADESs) was successfully synthesized by a one-step solvothermal method. The fluorescence property of carbon quantum dots was used to achieve the quantitative detection of naphthenic acids in wastewater. The prepared N-CQDs showed excellent fluorescence and stability, showed a good response to naphthenic acids and a linear relationship in the concentration range of naphthenic acids from 0.03 to 0.09 mol‧L-1. The effect of common interferents in petrochemical wastewater on the detection of naphthenic acids by N-CQDs was investigated. The results showed that N-CQDs had good specificity for the detection of naphthenic acids. N-CQDs was applied to the naphthenic acids wastewater, and the concentration of naphthenic acids in the wastewater was successfully calculated according to the fitting equation.

19.
Environ Sci Pollut Res Int ; 30(8): 21313-21325, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36269475

RESUMO

To control the spread of COVID-19, Shijiazhuang implemented two lockdowns of different magnitudes in 2020 (lockdown I) and 2021 (lockdown II). We analyzed the changes in air quality index (AQI), PM2.5, O3, and VOCs during the two lockdowns and the same period in 2019 and quantified the effects of anthropogenic sources during the lockdowns. The results show that AQI decreased by 13.2% and 32.4%, and PM2.5 concentrations decreased by 12.9% and 42.4% during lockdown I and lockdown II, respectively, due to the decrease in urban traffic mobility and industrial activity levels. However, the sudden and unreasonable emission reductions led to an increase in O3 concentrations by 160.6% and 108.4%, respectively, during the lockdown period. To explore the causes of the O3 surge, the major precursors NOx and VOCs were studied separately, and the main VOCs species affecting ozone formation during the lockdown period and the source variation of VOCs were identified, and it is important to note that the relationship between diurnal variation characteristics of VOCs and cooking became apparent during the lockdown period. These findings suggest that regional air quality can be improved by limiting production, but attention should be paid to the surge of O3 caused by unreasonable emission reductions, clarifying the control priorities for urban O3 management.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , COVID-19 , Humanos , Poluentes Atmosféricos/análise , Material Particulado/análise , Monitoramento Ambiental , Controle de Doenças Transmissíveis , Poluição do Ar/análise , China
20.
J Air Waste Manag Assoc ; 62(12): 1394-402, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23362758

RESUMO

UNLABELLED: The oxytetracycline bacterial residue-activated carbon (OBR-AC) prepared from oxytetracycline bacterial residue with K2CO3 under chemical activation was studied. The effects of activation temperature, activation time, and activation ratio on the specific surface area (SSA) and methylene blue adsorption (MBA) were studied. Characterization of the optimum OBR-AC was performed by using scanning electron microscopy (SEM), pore structure (PS,) and Fourier-transform infrared spectroscopy (FT-IR). The optimum parameters were as follows: 800 degrees C activation temperature, 3 hr activation time, and 1:3 activation ratio. The SSA and MBA under optimum conditions were 1593.09 m2/g and 117.0 mg/g, respectively. Adsorption equilibrium and kinetics data were determined for the adsorption of phenol from the synthetically prepared phenol solution. The results showed that the Langmuir model gave the best fit for equilibrium isotherm, whereas the kinetics data were well fitted by the pseudo-second order model. IMPLICATIONS: In the past, the bacterial residues have been used for feed additives in China. Unfortunately, doubts of its suitability as a feedstock have been raised because of the small amount of antibiotics, a large number of the fermentation by-products and metabolic products and by-products remaining in the bacterial residues. So Oxytetracycline Bacterial Residue (OBR) is one of hazardous wastes in China. In order to solve the problem of OBR, the preparation of OBR-AC is studied, and OBR-AC under optimum operation parameters is characterized by Scanning Eldctron Microscopy (SEM), Pore Structure (PS) and Fourier Transfer-Infra Red (FT-IR). Moreover, the phenol adsorption isotherms and kinetics models for OBR-AC under optimum operation parameters are studied.


Assuntos
Bactérias/química , Bactérias/metabolismo , Indústria Farmacêutica , Resíduos Industriais/análise , Oxitetraciclina/química , Fenóis/química , Adsorção , Antibacterianos/química , Antibacterianos/metabolismo , Carbono/química , Eliminação de Resíduos/métodos , Temperatura , Fatores de Tempo
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