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1.
J Environ Sci (China) ; 125: 603-615, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36375942

RESUMO

Wuhan Tianhe International Airport (WUH) was suspended to contain the spread of COVID-19, while Shanghai Hongqiao International Airport (SHA) saw a tremendous flight reduction. Closure of a major international airport is extremely rare and thus represents a unique opportunity to straightforwardly observe the impact of airport emissions on local air quality. In this study, a series of statistical tools were applied to analyze the variations in air pollutant levels in the vicinity of WUH and SHA. The results of bivariate polar plots show that airport SHA and WUH are a major source of nitrogen oxides. NOx, NO2 and NO diminished by 55.8%, 44.1%, 76.9%, and 40.4%, 33.3% and 59.4% during the COVID-19 lockdown compared to those in the same period of 2018 and 2019, under a reduction in aircraft activities by 58.6% and 61.4%. The concentration of NO2, SO2 and PM2.5 decreased by 77.3%, 8.2%, 29.5%, right after the closure of airport WUH on 23 January 2020. The average concentrations of NO, NO2 and NOx scatter plots at downwind of SHA after the lockdown were 78.0%, 47.9%, 57.4% and 62.3%, 34.8%, 41.8% lower than those during the same period in 2018 and 2019. However, a significant increase in O3 levels by 50.0% and 25.9% at WUH and SHA was observed, respectively. These results evidently show decreased nitrogen oxides concentrations in the airport vicinity due to reduced aircraft activities, while amplified O3 pollution due to a lower titration by NO under strong reduction in NOx emissions.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , COVID-19 , Humanos , Aeroportos , Emissões de Veículos/análise , Dióxido de Nitrogênio/análise , COVID-19/epidemiologia , China , Controle de Doenças Transmissíveis , Poluição do Ar/análise , Poluentes Atmosféricos/análise , Aeronaves , Óxidos de Nitrogênio/análise , Monitoramento Ambiental/métodos , Material Particulado/análise
2.
Sensors (Basel) ; 22(14)2022 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-35890877

RESUMO

The ship exhaust sniffing unmanned aerial vehicle (UAV) system can be applied to monitor vessel emissions in emission control areas (ECAs) to improve the efficiency of maritime law enforcement and reduce ship pollution. To solve the problems of large size, heavy weight and high cost of ship exhaust sniffing sensors, in this paper, a unique diffused mini-sniffing sensor was designed, which provides a low-cost, lightweight, and highly adaptable solution for ship exhaust sniffing UAV. To verify the measurement accuracy of the system, a large number of on-site tests were performed based in the mouth of the Yangtze River, and some cases of violation of the fuel sulfur content (FSC) were verified and punished. Maritime law enforcement officers boarded the ship to take oil samples from eight suspected ships and sent them to the laboratory for testing. The results showed that the FSCs of the eight ships in chemical inspection were all greater than the regulatory limit 0.5% (m/m) of the International Maritime Organization (IMO). The system enables authorities to monitor emissions using rotary UAVs equipped with diffused mini-sniffing sensors to measure the FSC of navigating ships, which couple hardware and operational software with a dedicated lab service to produce highly reliable measurement results. The system offers an effective tool for screening vessel compliance.


Assuntos
Poluentes Atmosféricos , Navios , Poluentes Atmosféricos/análise , Difusão , Monitoramento Ambiental/métodos , Material Particulado/análise , Rios , Enxofre/análise , Emissões de Veículos/análise
3.
Water Sci Technol ; 82(11): 2296-2303, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33339785

RESUMO

In this study, the removal effect of free and immobilized bacteria on crude oil was determined. Sodium alginate and polyvinyl alcohol were used as embedding agent, and ramie was modified as an adsorbent to immobilize free bacteria. The conditions for preparing immobilized pellets were optimized using the response surface method, and the best combination was simulated and obtained by Design-Expert 8.0. The best degradation rate of immobilized bacteria was 75.52%. The degradation by free bacteria and immobilized bacteria showed that the selected microorganisms had a good degradation effect on petroleum hydrocarbons.


Assuntos
Poluição por Petróleo , Petróleo , Bactérias , Biodegradação Ambiental , Hidrocarbonetos
4.
Molecules ; 24(19)2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31547594

RESUMO

Boswellic acids (BAs), as the main components of frankincense, exhibit notable anti-inflammatory properties. However, their pharmaceutical development has been severely limited by their poor oral bioavailability. Traditional Chinese medicinal processing, called Pao Zhi, is believed to improve bioavailability, yet the mechanism is still completely unclear. Previous research suggested that the bioavailability of a drug can be influenced by physical properties. This paper was designed to investigate the physical properties of frankincense and processed frankincense, including the surface morphology, particle size, polydispersity index (PDI), zeta potential (ZP), specific surface area, porosity, and viscosity. The differences in the intestinal absorption characteristics and equilibrium solubilities between frankincense and processed frankincense were determined by an ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UHPLC-TQ-MS) analysis method. The results showed that vinegar processing can alter the surface morphology, decrease the particle size and PDI, raise the absolute values of the ZP, specific surface area and porosity, and drop the viscosity of frankincense. Meanwhile, the rates of absorption and dissolution of the main BAs were increased after the processing of frankincense. The present study proves that the physical properties were changed after processing, in which case the bioavailability of frankincense was enhanced.


Assuntos
Medicamentos de Ervas Chinesas/química , Franquincenso/química , Extratos Vegetais/química , Triterpenos/química , Cromatografia Líquida de Alta Pressão , Absorção Intestinal , Espectrometria de Massas em Tandem , Viscosidade
5.
Zhongguo Zhong Yao Za Zhi ; 44(20): 4467-4475, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31872634

RESUMO

Scutellariae Radix is one of the commonly used heat-clearing and damp-drying drugs in clinical practice. Establishment of the quality evaluation system for Scutellariae Radix is of great significance to ensure safety and effectiveness of clinical drug use.Scutellariae Radix pieces were prepared under different processing conditions with 3 softening methods: boiling,atmospheric steaming and pressurized steaming. High performance liquid chromatography( HPLC) method was used to determine the content of five flavonoids in Scutellariae Radix,and L*,a*,b*values representing color chromaticity of Scutellariae Radix powder were measured by colorimeter,then total color value E*was calculated. Simple correlation and canonical correlation analysis was used to explore the correlation between color of Scutellariae Radix powder and content of five flavonoids. The results showed that the contents of baicalin and wogonoside were significantly positively correlated with L*,b*and E*values,but negatively correlated with a*value. The contents of wogonin,apigenin,and melaleuca A were positively correlated with a*value,but negatively correlated with L*,b*,and E*values( P<0. 01). There was a significant negative correlation between the content of flavonoid glycosides and flavonoid aglycones( P<0. 01).All of these indicated that the color of Scutellariae Radix powder was significantly correlated with content of five flavonoids. The experiment results proved that when color difference between Huangqin pieces and medicinal materials was kept at ΔL*<6,Δb*<3,ΔE*<6,the total amount of the two glycosides in the pieces was about ±1. 5% of the medicinal materials; in this case,the total amount of the two glycosides was relatively high and stable,indicating that the color of Huangqin decoction pieces is a concrete manifestation of its intrinsic quality,and the chromaticity value detected by colorimeter can be used as a means to quickly evaluate the quality of Scutellariae Radix pieces. The results provide a new detection index for the characteristic quality evaluation system of Scutellariae Radix pieces.


Assuntos
Medicamentos de Ervas Chinesas , Scutellaria baicalensis , Cromatografia Líquida de Alta Pressão , Flavonoides
6.
Water Sci Technol ; 78(12): 2626-2638, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30767927

RESUMO

The aim of this study was to isolate hydrocarbons-degrading bacteria for treatment of oily wastewater from long-standing petroleum-polluted sediments in Bohai Bay, China. Six hydrocarbons-degrading bacteria were screened and identified as Pseudomonas sp. and Bacillus sp. A new approach using a combination of various bacterial species in petroleum biodegradation was proposed and evaluated for its degradation characteristics. Gas chromatography-flame ionization detection (GC-FID) analysis showed that mixed bacterial agents (YJ01) degraded 80.64% of crude oil and 76.30% of crude oil alkanes, exhibiting good biodegradation effect. Besides, after 14 days of culture, the biodegradation assessment markers, pristane and phytane, showed significant degradation rates of 46.75% and 78.23%, respectively. Kinetic analysis indicated that the degradation trends followed a single first-order kinetics model and the degradation half-life (t1/2) of 15 g/L crude oil was significantly shorter (5.48 days). These results indicated that YJ01 could degrade a wider range of hydrocarbons as well as some recalcitrant hydrocarbon components, and can be applied for bioremediation and treatment of oil-contaminated environment.


Assuntos
Biodegradação Ambiental , Petróleo/metabolismo , Águas Residuárias/microbiologia , Poluentes Químicos da Água/metabolismo , Bactérias/metabolismo , China , Hidrocarbonetos , Cinética , Petróleo/análise , Águas Residuárias/química , Microbiologia da Água , Poluentes Químicos da Água/análise
7.
Environ Pollut ; 350: 124053, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38677458

RESUMO

Dust pollution from storage and handling of materials in dry bulk ports seriously affects air quality and public health in coastal cities. Accurate prediction of dust pollution helps identify risks early and take preventive measures. However, there remain challenges in solving non-stationary time series and selecting relevant features. Besides, existing studies rarely consider impacts of port operations on dust pollution. Therefore, a hybrid approach based on data decomposition and deep learning is proposed to predict dust pollution from dry bulk ports. Port operational data is specially integrated into input features. A secondary decomposition and recombination (SDR) strategy is presented to reduce data non-stationarity. A dual-stage attention-based sequence-to-sequence (DA-Seq2Seq) model is employed to adaptively select the most relevant features at each time step, as well as capture long-term temporal dependencies. This approach is compared with baseline models on a dataset from a dry bulk port in northern China. The results reveal the advantages of SDR strategy and integrating operational data and show that this approach has higher accuracy than baseline models. The proposed approach can mitigate adverse effects of dust pollution from dry bulk ports on urban residents and help port authorities control dust pollution.


Assuntos
Poluentes Atmosféricos , Cidades , Aprendizado Profundo , Poeira , Monitoramento Ambiental , Poeira/análise , Monitoramento Ambiental/métodos , China , Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos
8.
Environ Pollut ; 356: 124292, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38823545

RESUMO

Oceans are ultimately a sink of plastic waste. Complex artificial coastlines pose remarkable challenges for coastal plastic waste monitoring. With the development of machine learning methods, high detection accuracy can be achieved; however, many false positives have been noted in various network models used for plastic waste investigation. In this study, extensive surveys of artificial coastlines were conducted using drones along the Dongjiang Port artificial coastline in the Binhai District, Tianjin, China. The deep learning model YOLOv8 was enhanced by integrating the InceptionNeXt and LSK modules into the network to improve its detection accuracy for plastic waste and reduce instances of tourists being misidentified as plastic. In total, 553 high-resolution coastline images with 3488 items of detected plastic waste were compared using the original and improved YOLOv8 models. The improved YOLOv8s-IL model achieved a detection rate of 64.9%, a notable increase of 11.5% compared with that of the original model. The number of false positives in the improved YOLOv8s-IL model was reduced to 32.3%, the multi-class F-score reached 76.5%, and the average detection time per image was only 2.7 s. The findings of this study provide technical support for future large-scale monitoring of plastic waste on artificial coastlines.

9.
Artigo em Inglês | MEDLINE | ID: mdl-35805613

RESUMO

In order to evaluate the pollution characterization of PM2.5 (particles with aerodynamic diameters less than or equal to 2.5 µm) and secondary aerosol formation under the different photochemical activity levels, CO was used as a tracer for primary aerosol, and hourly maximum of O3 (O3,max) was used as an index for photochemical activity. Results showed that under the different photochemical activity levels of L, M, LH and H, the mass concentration of PM2.5 were 29.8 ± 17.4, 32.9 ± 20.4, 39.4 ± 19.1 and 42.2 ± 18.9 µg/m3, respectively. The diurnal patterns of PM2.5 were similar under the photochemical activity and they increased along with the strengthening of photochemical activity. Especially, the ratios of estimated secondary aerosol to the observed PM2.5 were more than 58.6% at any hour under the photochemical activity levels of LH and H. The measured chemical composition included water soluble inorganic ions, organic carbon (OC), and element carbon (EC), which accounted for 73.5 ± 14.9%, 70.3 ± 24.9%, 72.0 ± 21.9%, and 65.8 ± 21.2% in PM2.5 under the photochemical activities of L, M, LH, and H, respectively. Furthermore, the sulfate (SO42-) and nitrate (NO3-) were nearly neutralized by ammonium (NH4+) with the regression slope of 0.71, 0.77, 0.77, and 0.75 between [NH4+] and 2[SO42-] + [NO3-]. The chemical composition of PM2.5 was mainly composed of SO42-, NO3-, NH4+ and secondary organic carbon (SOC), indicating that the formation of secondary aerosols significantly contributed to the increase in PM2.5. The formation mechanism of sulfate in PM2.5 was the gas-phase oxidation of SO2 to H2SO4. Photochemical production of nitric acid was intense during daytime, but particulate nitrate concentration was low in the afternoon due to high temperature.


Assuntos
Poluentes Atmosféricos , Material Particulado , Aerossóis/análise , Poluentes Atmosféricos/análise , Carbono , China , Monitoramento Ambiental , Nitratos , Compostos Orgânicos , Material Particulado/análise , Estações do Ano , Sulfatos/análise
10.
Phytomedicine ; 98: 153931, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35104761

RESUMO

BACKGROUND: Boswellic acids in Olibanum (known as frankincense) are potent anti-inflammatory properties in treating ulcerative colitis (UC), but its low bioavailability limited drug development. Evidence accumulated that vinegar processing of frankincense exerts positive effects on improving absorption of compositions. The underlying mechanism is unknown. In recent decades, spectacular growth and multidisciplinary integration of metabolic application were witnessed. The relationship between drug absorption and curative effect has been more or less established. However, it remains a knowledge gap in the field between drug absorption and endocrine metabolism. PURPOSE: To investigate the enhancement mechanism of vinegar processing in the absorption of boswellic acids via the aspect of bile acid metabolism. METHODS: The effects of raw frankincense (RF) and processed frankincense (PF) were compared by the UC model of rats. The plasma concentration of boswellic acids and the hepatic and colonic bile acids contents were quantified by UPLC-TQ-MS. The levels of mRNA and protein associated with bile acid metabolism were also compared. RESULTS: The results showed that PF exhibited re-markable mitigating effects on UC with the elevated plasma level of boswellic acid and upregulated expression of the absorption-related protein multidrug resistance-associated protein 2 (MRP2) and organic anion transporting polypeptide 1B3 (OATP1B3) in the liver and colon. It improved colonic lithocholic acid (LCA), which promoted the expression of bile acid nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR), resulting in the upregulation of MRP2 and OATP1B3. CONCLUSION: This paper revealed the mechanisms behind the absorption promotion effects of processing. Bile acids metabolism exhibits potential status in pharmaceutical development. The results shed light on the interdisciplinary collaboration between the metabolism and drug absorption fields.

11.
Bioresour Technol ; 324: 124639, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33434875

RESUMO

In this study, a laboratory-scale sequencing batch reactor (SBR) equipped with aerobic granular sludge (AGS) technology was continuously operated for 220 days to remove ammonium from an existing landfill leachate. The ammonium removal was characterized by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) technology. This method helped to analyze the long-term community structural stability of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and denitrifying bacteria (DB) throughout the experiment. Simultaneously, 16S rRNA gene cloning and sequencing analysis identified the dominant species of different microbial species. Experimental results confirmed that ammonium removal was inhibited at the high nitrogen loading rate (NLR) stage while the low NLR stage achieved satisfactory ammonium removal. Moreover, the findings demonstrated that functionally stable wastewater treatment bioreactors facilitated the occurrence of stable microbial community structures.


Assuntos
Compostos de Amônio , Poluentes Químicos da Água , Reatores Biológicos , Nitrogênio , RNA Ribossômico 16S/genética , Esgotos
12.
Front Physiol ; 12: 705588, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34483960

RESUMO

The presence of hypertension (HTN) in type 2 diabetes mellitus (DM) is a common phenomenon in more than half of the diabetic patients. Since HTN constitutes a predictor of vascular complications and cardiovascular disease in type 2 DM patients, it is of significance to understand the molecular and cellular mechanisms of type 2 DM binding to HTN. This review attempts to understand the mechanism via the perspective of the metabolites. It reviewed the metabolic perturbations, the biological function of perturbated metabolites in two diseases, and the mechanism underlying metabolic perturbation that contributed to the connection of type 2 DM and HTN. DM-associated metabolic perturbations may be involved in the pathogenesis of HTN potentially in insulin, angiotensin II, sympathetic nervous system, and the energy reprogramming to address how perturbated metabolites in type 2 DM affect the pathogenesis of HTN. The recent integration of the metabolism field with microbiology and immunology may provide a wider perspective. Metabolism affects immune function and supports immune cell differentiation by the switch of energy. The diverse metabolites produced by bacteria modified the biological process in the inflammatory response of chronic metabolic diseases either. The rapidly evolving metabolomics has enabled to have a better understanding of the process of diseases, which is an important tool for providing some insight into the investigation of diseases mechanism. Metabolites served as direct modulators of biological processes were believed to assess the pathological mechanisms involved in diseases.

13.
Bull Environ Contam Toxicol ; 84(4): 482-7, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20306170

RESUMO

Characteristics of the spatial and temporal distributions of selected heavy metals (Cu, Zn, Cd, Pb and Hg) in Bohai Bay, north China was examined. Surface sediment samples from 15 sites were collected and analyzed for the selected metals with atomic absorption spectrometry (AAS) from the year of 1997-2007. Mean concentrations of metals in the 11-year period showed that Hg and Zn concentrations slightly fluctuated, while Cu, Cd and Pb concentrations in sediments varied with time. High levels of heavy metals occurred not only along the shoreline but also at some site in the inner part of the bay, suggesting the contamination sources of heavy metals from both terrestrial inputs and the atmospheric deposition. Compared with the environmental background values of selected heavy metals it indicated that anthropogenic activities influenced the sediment quality. The contamination factor C(fi), which is used to evaluate the pollution of the environment, showed that the contamination by selected heavy metals was moderate. Cd, Zn and Pb were the main polluting elements in this area.


Assuntos
Sedimentos Geológicos/análise , Metais Pesados/análise , China , Água do Mar/análise , Poluentes Químicos da Água/análise
14.
Chemosphere ; 249: 126194, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32086065

RESUMO

Polycyclic aromatic hydrocarbons (PAHs), nitro- (NPAHs) and oxy-derivatives (OPAHs) are of considerable concern due to their toxicity and carcinogenic hazards. Ships are recognized as an important emission source of these compounds. Marine diesel oil (MDO) and heavy fuel oil (HFO) are the two most commonly used fuels. The emission characteristics and toxicities of PM2.5-bound PAHs, NPAHs and OPAHs due to HFO and MDO combustion in atypical ocean-going vessel were investigated. The EF variability of polycyclic aromatic compounds (PACs) varied considerably with the fuel formulation (HFO and MDO) and engine loading (20%-100%). The concentration of ΣPACs was 0.63 mg/kWh for MDO and ranged from 2.14 to 9.80 mg/kWh for HFO. Compared to HFO-20%, the EFs of ΣPAHs, ΣNPAHs and ΣOPAHs from MDO-20% were reduced by 97%, 77% and 73%, respectively. As identified through the coefficient of divergence, the profile of HFO-20% was notably different from those under the other three engine loadings for HFO. In addition, the emissions of ΣPAHs and ΣOPAHs showed a significant correlation with PM2.5, while they were relatively weak for ΣNPAHs. However, the CO and PAC emissions were not highly correlated. Furthermore, the BaPeq-ΣPAHs values were 0.010 mg/g for MDO and ranged from 0.092 mg/g to 0.306 mg/g for HFO, and the reduction ranged from 89% to 97% by substituting MDO for HFO. These data highlight the importance of improving fuel quality in close proximity to port areas and are useful for enhancing relevant databases.


Assuntos
Poluentes Atmosféricos/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Emissões de Veículos/análise , Poluição do Ar/estatística & dados numéricos , Aeronaves , Monitoramento Ambiental , Óleos Combustíveis , Gasolina , Oceanos e Mares , Material Particulado/análise , Compostos Policíclicos , Navios/estatística & dados numéricos
15.
Bull Environ Contam Toxicol ; 83(3): 416-21, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19290458

RESUMO

The spatio-temporal varying characteristics of dissolved inorganic nitrogen, reactive phosphate (RP), chemical oxygen demand (COD), and dissolving oxygen (DO) in Tianjin coastal seawater were investigated based on observation from May 1996 to October 2006. The concentrations of dissolved inorganic nitrogen (DIN), RP and COD ascended gradually and their varying ranges were 0.103-2.432, 0.009-0.12, and 0.8-2.9 mg L(-1), respectively. While DO in seawater decreased from 8.9 to 6.1 mg L(-1) gradually. Those indicated that human-induced eutrophication occurred and the seawater quality deteriorated. The spatial distributions of DIN, RP and COD were largely uniform, where isopleths generally descended from estuarine zones and bays to the central areas and from northern area to southern area, indicating that continental input is the dominant source of those pollutants. Especially, peak zones of those pollutants usually appeared near estuaries, Tianjin harbors, and dumping site of dredged sediment, which indicates that the urban and industrial sewage, shipping waste, dredged soil were the main sources for those contaminants in seawater.


Assuntos
Nitrogênio/análise , Fósforo/análise , Água do Mar/análise , China , Eutrofização , Estudos Longitudinais , Oxigênio/análise , Estações do Ano , Poluentes Químicos da Água/análise , Poluição Química da Água/análise
16.
Bull Environ Contam Toxicol ; 83(6): 907-12, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19684998

RESUMO

Characteristics of the spatial and temporal distributions of selected dissolved heavy metals (Cu, Zn, Pb, Hg and Cd) in Bohai Bay, north China was investigated. Water samples from 22 sites were collected and analyzed for the selected metals with atomic absorption spectrometry from the year of 1996 to 2005. Relatively high concentrations of Cu, Zn, Pb and Hg were detected, with maximum concentrations in the 10-year period of 16.30, 422.00, 40.40, 0.23 µg/L respectively. The concentrations of Cd in all samples were quite low, with maximum level of 0.89 µg/L. The spatial distribution of dissolved Cu, Zn and Pb was analogous, where their average concentrations generally descended from the coastline to the central areas of the bay. Differently, for Hg and Cd, relatively high concentrations occurred not only in inshore but also in offshore areas. Measured data of heavy metals were compared with sea water quality standard of China (SWQSC). Cd concentrations in all samples were below SWQSC Grade-I. The percentages of Cu, Zn, Pb, and Hg at Grade-III levels in Bohai Bay were 2.67%, 30.00%, 30.43% and 0.36%, respectively, suggesting the severe contamination of Zn and Pb in this area. Terrestrial inputs via different rivers and sewages may be the important source for the heavy metals contamination.


Assuntos
Metais Pesados/análise , Água do Mar/química , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Poluição Química da Água/estatística & dados numéricos
17.
Artigo em Inglês | MEDLINE | ID: mdl-29757213

RESUMO

A new kind of hydrophobic and oil sorbent based on jute fiber was successfully prepared by the integration of silica onto a fiber surface via the sol-gel method and subsequent hydrophobic modification with octadecyltrichlorosilane (OTS). Compared with the hydrophilic raw fiber, the modified fiber had a water contact angle (CA) of 136.2°, suggesting that the material has good hydrophobicity. Furthermore, the ability of oil in the oil/water system (taking diesel for example) to absorb was revealed by the kinetics, the isotherm equation, and the thermodynamic parameters. Adsorption behavior was kinetically investigated using pseudo first-order and pseudo second-order models. The data mostly correlated with the pseudo first-order model. The equilibrium adsorption at 298 K was assessed by using the Langmuir and Freundlich isotherm models. The Freundlich model had greater consistency with the experimental data. The obtained thermodynamic parameters demonstrate that the adsorption of diesel is spontaneous, favorable, and exothermic.


Assuntos
Celulose/química , Recuperação e Remediação Ambiental/métodos , Gasolina , Interações Hidrofóbicas e Hidrofílicas , Poluição por Petróleo , Silanos/química , Dióxido de Silício/química , Adsorção , Cinética , Transição de Fase , Termodinâmica
18.
RSC Adv ; 8(53): 30257-30264, 2018 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-35546839

RESUMO

A superhydrophobic and superoleophilic oil sorbent was prepared by attaching SiO2 particles onto a cotton fiber surface by a sol-gel method and subsequent octadecyltrichlorosilane modification. The surface formation was confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, and an observation of the water behavior on the cotton surface. The sorption capacity of the modified cotton in pure oil and in an oil/water mixture, the oil adsorption and the reusability were investigated. Compared with raw cotton, the as-prepared cotton absorbed different oils rapidly up to in excess of 25-75 g g-1 its own weight, and the water adsorption was nearly 0 g g-1. The modified cotton fiber could separate oil/water mixtures efficiently through a flowing system. After 10 cycles, the as-prepared cotton was still highly hydrophobic with a 6-times greater adsorption than raw cotton. By a simple modification, a low-cost, high-adsorption and environmentally friendly modified cotton could be prepared that can be considered a promising alternative to organic synthetic fibers to clean up oil spills.

19.
Artigo em Inglês | MEDLINE | ID: mdl-30261691

RESUMO

Speciation variation and comprehensive risk assessment of metal(loid)s (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) were investigated in surface sediments from the intertidal zones of the Yellow River Delta, China. Results showed that only the concentrations of As, Cd and Pb were significantly different between April and September (p < 0.01). In April, the residual fraction (F4) was predominant for As, Cr, Cu, Ni and Zn. However, the exchangeable and carbonate-associated fraction (F1) was dominant for Cd averaging 49.14% indicating a high environmental risk. In September, the F4 fraction was predominant and the F1 fraction was very low for most metal(loid)s except Cd and Mn. The geo-accumulation index (Igeo), the F1 fraction and potential ecological risk index (PERI) of most metal(loid)s were relatively low in surface sediments for both seasons. But Pb, As and Ni were between the threshold effect level (TEL)and the probable effect level (PEL) for 66.67%, 83.33% and 91.67% in April and As and Ni were between TEL and PEL for 41.67% and 91.67%, which indicated that the concentration of them was likely to occasionally exhibit adverse effects on the ecosystem. Although the Igeo, the F1 fraction or PERI of Cd in both seasons was higher at some sites, the results of sediment quality guidelines (SQGs) indicated that the biological effects of Cd were rarely observed in the studied area.


Assuntos
Biodiversidade , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Rios/química , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , China , Medição de Risco , Estações do Ano
20.
Mar Pollut Bull ; 122(1-2): 129-138, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28666592

RESUMO

Silica aerogel, with mesoporous structure and high hydrophobicity, is a promising adsorbent for oil spill clean-up. To make it economic and environmental-friendly, hydrocarbon desorption and silica aerogel regeneration were investigated. After hydrocarbon desorption at 80°C, silica aerogel maintained its hydrophobicity. After toluene, petrol, and diesel desorption, shrinkage of mesopores (from 19.9 to 16.8, 13.5, and 13.4nm) of silica aerogels occurred, causing decreased adsorption capacities (from 12.4, 11.2, and 13.6 to 12.0, 6.5, and 2.3g/g). Low surface tension of petrol caused high stress on mesopores during its desorption, resulting in significant pore shrinkage. For diesel, its incomplete desorption and oxidation further hindered the regeneration. Therefore, diesel desorption was also conducted at 200°C. Severe diesel oxidation occurred under aerobic condition and destroyed the mesopores. Under anaerobic condition, no diesel oxidation occurred and the decreases in pore size (to 13.2nm) and adsorption efficiency (to 10.0g/g) of regenerated silica aerogels were much less, compared with under aerobic condition. This study provided new insights on silica aerogel regeneration for oil spill clean-up.


Assuntos
Hidrocarbonetos , Poluição por Petróleo/prevenção & controle , Dióxido de Silício , Adsorção , Interações Hidrofóbicas e Hidrofílicas
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