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1.
Water Res ; 170: 115367, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31838365

RESUMO

Solar-driven evaporation has been proposed as an efficient way to harvest solar energy for water treatment and desalination. However, the complex preparation process and the degradation of photothermal absorbers restrict their practical applications in solar thermal technology. Herein, a solar-assisted fabrication of three-dimensional dimpled MoS2 membrane (DMM-SA) with an open macroporous (1-2 µm) network is fabricated by folding and overlapping nanosheets under solar illumination. DMM-SA exhibits superior water permeability (334-461 LMH/bar) and extraordinary chemical and structural stability. Compared to the 1T and mixed-phase DMM-SA samples, 2H-DMM-SA floating on the water surface generates high heat localization and achieves high evaporation efficiencies of 83.8 ± 0.8% and 91.5 ± 1.1% at 1 and 3 sun illumination, respectively. After multiple illumination and regeneration cycles, 2H-DMM-SA presents high water evaporation and salt rejection performance. After desalination, the salinity level of permeate water is far below the World Health Organization (WHO) standard. Numerical simulations verify that the inner spaces between two nanosheets and the nanochannels contribute to the high bulk water and vapor fluxes during desalination. The facile and efficient design of 3D 2H-DMM-SA provides a novel avenue for seawater utilization by harvesting solar energy.


Assuntos
Energia Solar , Purificação da Água , Molibdênio , Luz Solar , Água
3.
An Bras Dermatol ; 94(5): 532-541, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31777353

RESUMO

BACKGROUND: The knowledge of general practitioners about photoprotection is unknown. OBJECTIVES: To develop and validate an instrument to evaluate the knowledge of general practitioners and pediatricians about photoprotection, gauging the knowledge of these professionals. METHODS: The study followed the steps: (1) Literature identification and item elaboration related to the theme; (2) Content validation; (3) Apparent validation; (4) Construct validation: internal consistency analysis and discriminatory analysis; (5) Reliability analysis. In Step 4, the instrument was applied to 217 general practitioners and pediatricians who worked in the host city of the study; the scores were compared with dermatologists scores. RESULTS: The final instrument had 41 items and showed satisfactory internal consistency (Cronbach's alpha=0.780), satisfactory reproducibility and good test-retest reliability (good-to-excellent kappa statistic in more than 60% of items). The discriminatory analysis registered a mean score of 54.1 points for dermatologists and 31.1 points for generalists and pediatricians, from a total of 82 possible points, representing a statistically significant difference (p<0.001). Generalists and pediatricians demonstrated an understanding of the relationship between excessive sun exposure and skin cancer, but they revealed lack of technical information necessary for their professional practice. STUDY LIMITATIONS: The instrument evaluates only knowledge, without evaluating the conduct of the participants. CONCLUSION: The results show that the instrument has good internal consistency and good reproducibility. It could be useful in the identification of general practitioners and pediatricians knowledge gaps on the subject, for the subsequent development of training and educational strategies.


Assuntos
Clínicos Gerais/estatística & dados numéricos , Conhecimentos, Atitudes e Prática em Saúde , Pediatras/estatística & dados numéricos , Proteção Radiológica/métodos , Energia Solar , Inquéritos e Questionários/normas , Raios Ultravioleta/efeitos adversos , Adulto , Brasil , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Exposição à Radiação/prevenção & controle , Reprodutibilidade dos Testes , Neoplasias Cutâneas/prevenção & controle , Estatísticas não Paramétricas , Protetores Solares/uso terapêutico
4.
J Phys Chem Lett ; 10(23): 7383-7390, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31714789

RESUMO

Photosynthetic organisms use networks of chromophores to absorb and deliver solar energy to reaction centers. We present a detailed model of the light-harvesting complexes in purple bacteria, including explicit interaction with sunlight, radiative and nonradiative energy loss, and dephasing and thermalizing effects of coupling to a vibrational bath. We capture the effect of slow vibrations by introducing time-dependent disorder. Our model describes the experimentally observed high efficiency of light harvesting, despite the absence of long-range quantum coherence. The one-exciton part of the quantum state fluctuates continuously but remains highly mixed at all times. These results suggest a relatively minor role for structure in determining efficiency. We build hypothetical models with randomly arranged chromophores but still observe high efficiency when nearest-neighbor distances are comparable to those in nature. This helps explain the high transport efficiency in organisms with widely differing antenna structures and suggests new design criteria for artificial light-harvesting devices.


Assuntos
Complexos de Proteínas Captadores de Luz/química , Fotossíntese , Proteobactérias/metabolismo , Complexos de Proteínas Captadores de Luz/metabolismo , Modelos Biológicos , Teoria Quântica , Energia Solar
5.
Sci Total Environ ; 688: 1069-1080, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726538

RESUMO

Belowground interspecific facilitation and complementarity contribute to the phosphorus (P) uptake advantages in the cereal-legume intercropping system. However, the root morphological and physiological plasticity and, subsequently, the P uptake capability response to light conditions in intercropping systems remain unclear. Soybean was grown under two levels of P application rates in sole and intercropping systems (maize/soybean relay strip intercropping) from 2016 to 2018 in Renshou, southwest of China. As a supplement to the field experiment, soybean was also grown in L-S (simulating the light conditions of sole cropping in the field: light first and then shading) and S-L (simulating the light conditions of intercropping in the field: shading first and then light) light conditions with two levels of P application in 2018 in a pot experiment. After maize harvest (approximately 3/4 of the soybean growth period), light capture in intercropping was higher than sole (ameliorated light conditions in intercropping system), which resulted in an advantage of P uptake in intercropped soybean. Both low P supply and more light capture increased the total root length and root APase activity. The genes GmEXPB2 (which is associated with root growth) and GmACP1 (which is associated with exudation of APase) were highly expressed in plants that captured more light under both P-sufficient and P-deficient conditions. Additionally, more light capture increased the production of lateral roots and the proportion of in the upper 15 cm soil layer roots at the reproductive stage in the field. Across the field and pot experiments, increased root morphological and physiological plasticity were associated with lower P concentrations in the leaves and greater allocation of photosynthates to roots as sucrose. It is suggested that ameliorated light conditions can regulate soybean root growth plasticity and, consequently, P uptake in maize/soybean relay strip intercropping systems, especially in the areas with low solar radiation.


Assuntos
Agricultura/métodos , Luz , Fósforo/metabolismo , Soja/fisiologia , China , Produtos Agrícolas/crescimento & desenvolvimento , Raízes de Plantas , Energia Solar
6.
Environ Monit Assess ; 191(12): 764, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31745665

RESUMO

Solar energy generated by grid-connected photovoltaic (GCPV) systems is considered an important alternative electric energy source because of its clean energy production system, easy installation, and low operating and maintenance costs. This has led to it becoming more popular compared with other resources. However, finding optimal sites for the construction of solar farms is a complex task with many factors to be taken into account (environmental, social, legal and political, technical-economic, etc.), which classic site selection models do not address efficiently. There are few studies on the criteria that should be used when identifying sites for solar energy installations (large grid-connected photovoltaic systems which have more than 100 kWp of installed capacity). It is therefore essential to change the way site selection processes are approached and to seek new methodologies for location analysis. A geographic information system (GIS) is a tool which can provide an effective solution to this problem. Here, we combine legal, political, and environmental criteria, which include solar radiation intensity, local physical terrain, environment, and climate, as well as location criteria such as the distance from roads and the nearest power substations. Additionally, we use GIS data (time series of solar radiation, digital elevation models (DEM), land cover, and temperature) as further input parameters. Each individual site is assessed using a unique and cohesive approach to select the most appropriate locations for solar farm development in the Valencian Community, a Spanish region in the east of Spain.


Assuntos
Monitoramento Ambiental , Sistemas de Informação Geográfica , Energia Solar , Desenvolvimento Sustentável , Agricultura , Eletricidade , Espanha , Temperatura Ambiente
7.
Nat Commun ; 10(1): 4282, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537786

RESUMO

Microbial biophotovoltaics (BPV) offers a biological solution for renewable energy production by using photosynthetic microorganisms as light absorbers. Although abiotic engineering approaches, e.g., electrode modification and device optimization, can enhance the electrochemical communication between living cells and electrodes, the power densities of BPV are still low due to the weak exoelectrogenic activity of photosynthetic microorganisms. Here, we develop a BPV based on a D-lactate mediated microbial consortium consisting of photosynthetic cyanobacteria and exoelectrogenic Shewanella. By directing solar energy from photons to D-lactate, then to electricity, this BPV generates a power density of over 150 mW·m-2 in a temporal separation setup. Furthermore, a spatial-temporal separation setup with medium replenishment enables stable operation for over 40 days with an average power density of 135 mW·m-2. These results demonstrate the electron flow constrained microbial consortium can facilitate electron export from photosynthetic cells and achieve an efficient and durable power output.


Assuntos
Fontes de Energia Bioelétrica/microbiologia , Eletricidade , Energia Renovável , Shewanella/metabolismo , Synechococcus/metabolismo , Técnicas Eletroquímicas , Ácido Láctico/metabolismo , Fótons , Shewanella/genética , Energia Solar , Synechococcus/genética
8.
Environ Sci Pollut Res Int ; 26(32): 33236-33259, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31515770

RESUMO

Renewable sources are relevant in a country's energy planning because they are linked to the creation of opportunities for technological, economic, and productive development guided by the principles of sustainability. Thus, the aim of this study was to investigate the relation between electric generation capacity by renewable and non-renewable energies and Brazilian socioeconomic variables. The analysis of the interrelationships between electricity generation capacity and economic growth in Brazil, from April 2009 to March 2017, was carried out by the vector autoregressive and autoregressive distributed lag methodologies. It was verified that the variance of employment is explained by renewable sources: hydroelectric in 7.71%, biomass in 1.99%, wind energy in 3.13%, and solar energy in 10.58%. While, the GDP variance is explained in 3.15% by hydroelectric energy, 0.06% by biomass, 1.70% by wind energy, and 17.38% by solar energy. The export variance is explained by renewable sources: hydroelectric 2.48%, biomass 0.39%, wind energy 2.34%, and solar energy 17.58%. Finally, the variance of the minimum wage is explained by hydroelectric energy in 1.48%, biomass in 5.09%, wind energy in 9.09%, and solar energy in 10.67%. An ARDL (1, 1, 2, 0, 0, 0, 3, 2, 0, 2, 0, 2) model was also adjusted for natural gas, with AIC (13.082) and BIC (13.739), and the ARDL (1, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 4) model adjusted for hydroelectric power, with AIC (13.633) and BIC (14.189), considering the variables' order cited above. Through the adjustment of the ARDL model, it was verified that there is a long-term influence of socioeconomic variables on electricity production variables, both renewable and non-renewable ones. The analysis of the impulse response function and the variance decomposition allowed us to verify that the installed capacity for production of electric energy exerts influence on Brazilian socioeconomic variables considered in this study.


Assuntos
Desenvolvimento Econômico , Energia Renovável , Biomassa , Brasil , Dióxido de Carbono/análise , Eletricidade , Gás Natural , Energia Solar , Vento
9.
Environ Sci Pollut Res Int ; 26(30): 31478-31490, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31478170

RESUMO

Degradation of photovoltaic system's power due to dust deposition is one of the important concerns of photovoltaic investors, especially the PV modules which are installed in the hot and dry parts of a country. This issue requires to be more understood and quantify its impact on the PV module performance in installation site. This study experimentally studied the dust deposition using several glasses which were fixed in the wooden frames at different tilt angles and directions in the southeast of Iran. The dust deposition on the glasses, solar energy reduction of the dusty glasses, and PV power reduction due to dust deposition were measured in all months of the year. The results showed that the average dust deposition on the glasses is 4.6 × 10-3 gr/m2day during the year. In case of no rain precipitation and no cleaning, this value reached 2.74 × 10-2gr/m2day. The percentage of solar energy reduction due to dust deposition was varied between 2 and 16% during the year. A correlation for prediction of the solar energy transmittance reduction based on the settled dust on the glass samples was developed in the studied region using 1-year data collection. The average solar energy reduction was obtained 7% during the year, and this value reached 44% in case of no rain precipitation and no glass cleaning. Results showed that in the most months of the year the wind direction and the direction of the glasses with the maximum dust deposition were coincided with each other. Furthermore, the experimental measurement showed that the calculated optimum monthly tilt angle in some months of the year is not the same with the measured tilt angle due to dust deposition. The difference between the calculated and measured tilt angles in these months was 15°.


Assuntos
Poeira/análise , Monitoramento Ambiental , Energia Solar , Irã (Geográfico) , Vento
10.
J Environ Manage ; 248: 109309, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31394476

RESUMO

Heavy dependence on fossil fuels among rural households contributes to GHG emissions and air pollution while increasing landfill loads in Poland. This study examines benefits from the renewable energy utilization support program that subsidized household purchase and installation of thermal solar panels. This review of synergy between energy, climate, and air quality policies focuses on solar panel subsidies funded through the European Union and county governments in Mazowieckie Voivodship in Poland. County government offices, using the unpublished list of households receiving subsidies for thermal solar panel installation, mediated in the implementation of the survey and collected 123 completed questionnaires in May and June 2015. The heteroscedasticity-corrected OLS estimates two equations identifying and quantifying factors influencing the purchase price of solar panels and rural household monthly energy bill savings after installation using the gathered data. Among sociodemographic variables, increasing age was associated with an increasing price paid for the panels, but education was associated with paying a lower price for solar panels and lower self-reported energy bill savings. Panel purchase price increased if the respondent was a farmer, viewed subsidies as important, and preferred domestically manufactured panels. Location of household increased the price as compared to the reference county. Savings on monthly energy bills increased if respondent had a positive view of solar energy, expected a decrease in the bill following the purchase of panels, and heated large areas in the house. Subsidy programs have been important in increased household solar energy utilization, especially among farm households, while self-reported energy bill savings increased with positive attitudes towards renewable energy and the larger heated areas in rural residences.


Assuntos
Poluição do Ar , Energia Solar , Clima , Humanos , Investimentos em Saúde , Polônia , Energia Renovável
11.
Environ Sci Pollut Res Int ; 26(30): 31119-31132, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31456146

RESUMO

One of the most critical challenges is bird dropping deposition (soiling) on a glass surface of the photovoltaic (PV) module in an open environment of Western Rajasthan. This paper has been now exclusively emphasized to focus on effects of the bird dropping phenomenon on the performance of PV systems. The presented study includes the impact of the seasonal bird dropping effect on the reduction in energy yield with various tilt angle configurations. Considering this, the highest level of reduction in power loss was observed at the end of winter (March) and minimum during rainfall (August) every year. The sitting/walking tendency of birds with the plate inclination directly affects the PV output, which is demonstrated by optical study of glass samples (bird dropping patterns). Consequently, the studies of optical transmittance conclude the effect of dropping with different tilt regions I (ß < 25°), II (25° ≤ ß ≤ 60°), and III (60° ≤ ß ≤ 90°), i.e., explained by bird movement onto the module surface. The result also showed that optimal inclination ß (40°) has a smaller soiling effect in tilt region II (25-60°) correspondingly.


Assuntos
Aves , Fezes/química , Energia Solar , Animais , Índia , Chuva , Difração de Raios X
12.
Environ Sci Pollut Res Int ; 26(29): 30286-30302, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432370

RESUMO

Pakistan has an abundant solar power potential which can be effectively utilized for the electricity generation. There are various sites across the country which have sufficient solar irradiation across the year, and thus, suitable for the installation of solar photovoltaic (PV) power projects. This study, therefore, aims to undertake research on the establishment of solar power project site selection in Pakistan. In this context, 14 promising cities of Pakistan are considered as alternatives and studied in terms of economic, environmental, social, location, climate, and orography criteria and further supplemented with 20 sub-criteria. Initially, the analytical hierarchy process (AHP) method has been used to prioritize each of the main criteria and sub-criteria. Later, fuzzy VlseKriterijuska Optimizacija I Komoromisno Resenje (F-VIKOR) method has been employed to prioritize the 14 alternatives. The present investigation reveals that Khuzdar (C2), Badin (C3), and Mastung (C7) are the most suitable cities for the installation of solar PV power projects in Pakistan. Finally, the outcome of the sensitivity analysis revealed that obtained results are reliable and robust for the installation of solar PV power projects in Pakistan. This study shall assist government, energy planners, and policymakers in making cities sustainable by establishing solar power projects in Pakistan.


Assuntos
Conservação de Recursos Energéticos/métodos , Tomada de Decisões , Energia Solar/economia , Desenvolvimento Sustentável , Cidades , Conservação de Recursos Energéticos/economia , Pesquisa Empírica , Lógica Fuzzy , Paquistão , Fatores Socioeconômicos
13.
J Environ Manage ; 248: 109337, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31386989

RESUMO

This is the first study to assess the current status of solar photovoltaic (PV) adoption across a range of wastewater treatment plant sizes, and to identify the opportunities for solar PV in the wastewater sector. It quantifies solar PV contributions to the energy demand of the wastewater treatment plants and improves knowledge of sector-specific factors influencing PV uptake. California was used as a case study due to its high commitment to solar power and the high data availability. The study compiled and examined data on multiple wastewater treatment plant attributes from 105 Californian plants, representing 78% of total state flows. The analysis focused on the effect of three sector-specific influencing factors: size of wastewater treatment plant, presence/absence of anaerobic digestion and geographical location (urban vs rural). Solar PV adoption was observed to vary significantly with the size of the wastewater treatment plants. Of the 105 plants analysed, 41 installed a solar PV system. Of these 41, 39 were installed in wastewater treatment plants with a flow rate below 50 mega gallons day-1 (MGD). Only two plants with flow above 50 MGD had solar PV installed. In wastewater treatment plants with a flow rate above 5 MGD, solar PV was primarily installed in hybrid configurations with anaerobic digestion. In these plants, biogas contributed 25-65% to the overall energy demand, while solar provided 8-30%. In wastewater treatment plants with a flow rates below 5 MGD, solar PV often represented the only source of renewable energy, producing 30-100% of the energy demand of these plants. Across all the plants analysed, 1 MW was the most adopted solar installation size and solar PV installations were mostly found in wastewater treatment plants in rural settings. While acknowledging multiple other factors of potential influence, these results demonstrate the role of solar PV in wastewater treatment plants under three sector-specific influencing factors. The results will support the sector in making informed decisions over solar PV investments, helping wastewater utilities to transition towards sustainable management practices.


Assuntos
Energia Solar , Águas Residuárias , Biocombustíveis , California
14.
Chem Soc Rev ; 48(19): 4966-4978, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31368460

RESUMO

The recent advances in the micro/nanomotor field have shown great progress in the propulsion of such devices by fuel-free mechanisms. Light, as an abundant and natural source, has been demonstrated to be a promising external field to wirelessly induce the motion of these tiny micro/nanomachines, without the need of any toxic fuel or complex system set-up. This tutorial review covers the most representative examples of light-driven micro/nanomotors developed so far, which self-propelled exclusively under fuel-free conditions. Their different swimming behaviors triggered by light stimuli, divided into four main categories (schooling, phototaxis, gravitaxis and directional motion), are discussed along with their similarities with the motion modes of microorganisms. Moreover, the main parameters that influence the motion of light-driven photocatalytic-based micro/nanomotors as well as alternative strategies to develop more efficient systems are also discussed.


Assuntos
Materiais Biomiméticos/química , Luz , Nanotecnologia , Catálise , Nanoestruturas/química , Energia Solar
15.
Nanoscale ; 11(32): 15083-15090, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31380538

RESUMO

The solar-to-electric conversion efficiency of mesoscopic solar cells is highly dependent on electron extraction under solar irradiation and determines the charge recombination processes within devices. Boosting charge transfer via building energy level alignment has been proved to be a promising method to enhance the output power of solar cells. In the current work, we present the successful fabrication of functional biomass-converted carbon quantum dots with graded energy levels by doping nitrogen or sulphur atoms from lotus root powder. When employed as light absorbers for mesoscopic solar cells, light harvesting and electron extraction can be markedly increased arising from the band alignment of graded carbon quantum dots, yielding maximal power conversion efficiencies of 0.158% and 0.208% for bi- and tri-cascaded photovoltaics, respectively. The primary results demonstrate that the employment of an energy-graded architecture is a promising strategy to optimize the device output. Following this line of thought, we further fabricate a co-sensitized device by integrating graded carbon quantum dots with N719 dyes to enhance the electron extraction capability. The final device yields an efficiency as high as 9.04%, showing the potential application of carbon quantum dots in high-performance solar cells.


Assuntos
Carbono/química , Pontos Quânticos/química , Energia Solar , Biomassa , Fontes de Energia Elétrica , Teoria Quântica
16.
Environ Pollut ; 253: 365-376, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31325881

RESUMO

Enormous research interest is devoted to fabricating three-dimensional graphene-based gels (3D GBGs) toward improved conversion of solar energy by virtue of the intrinsic properties of single graphene and 3D porous structure characteristics. Here, this concise minireview is primarily focused on the recent progress on applications of 3D GBGs, including aerogels and hydrogels, in photocatalytic degradation of pollutants from water and air, such as organic pollutants, heavy metal ions, bacteria and gaseous pollutants. In particular, the preponderances of 3D GBG photocatalysts for environmental pollutants degradation have been elaborated. Furthermore, in addition to discussing opportunities offered by 3D GBG composite photocatalysts, we also describe the existing problems and the future direction of 3D GBG materials in this burgeoning research area. It is hoped that this review could spur multidisciplinary research interest for advancing the rational utilization of 3D GBGs for practical applications in environmental remediation.


Assuntos
Poluentes Ambientais/química , Recuperação e Remediação Ambiental/métodos , Grafite/química , Gases , Géis , Metais Pesados , Energia Solar , Luz Solar , Água/química
17.
J Photochem Photobiol B ; 197: 111555, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31326844

RESUMO

A series of heterocyclic donor-acceptor systems were synthesized and well characterized by using 1H, 13C NMR, FT-IR, and elemental analysis. They were designed to investigate the effect of thiophene and cyanoacrylic acid number units on the thermal, optical, electrochemical and finally photovoltaic properties of dye-sensitized solar cells prepared with the selected compounds. The effect of chemical structure on their properties was demonstrated. They showed the beginning of thermal decomposition between 230 and 270 °C. The compounds absorbed the radiation in the range of 300-500 nm or 200-400 nm. They were electrochemically active and varied in energy band gap from 3.40 to 1.58 eV. Additionally, their optimized geometry, HOMO-LUMO levels, ionization potential, and electron affinity were evaluated using density functional theory. The photovoltaic devices based on TiO2 sensitized with the obtained molecules exhibited low power conversion efficiency, which was the highest for the device containing the symmetrical molecule with bithiophene structure. Under co-sensitization, the cell made of the same compound gave significant enhancement of efficiency of 6.3% being higher to that of the individual device prepared from dye N719 (5.75%). Moreover, the effects of immersion time of TiO2 electrode in the dye solution and co-sensitization methods were tested. The surface morphology of photoanode was investigated using atomic force microscopy.


Assuntos
Corantes/química , Cianoacrilatos/química , Energia Solar , Cianoacrilatos/síntese química , Teoria da Densidade Funcional , Fontes de Energia Elétrica , Microscopia de Força Atômica , Oxirredução , Titânio/química
18.
Chemosphere ; 236: 124366, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31344624

RESUMO

In this work, for the first time, the nonionic surfactant polyoxyethylene-(20)-sorbitan monooleate (Tween 80, C64H124O26) aided soil washing effluent was treated by enhanced activation of persulfate (PS) using Fe(III)-EDDS (EDDS: ethylenediamine-N, N-disuccinic acid) complexes under simulated solar light irradiation. The performance of this system was followed via the production and reactivity of radical species (SO4-, HO, Cl2-) and degradation of phenanthrene (PHE) used as a model pollutant in soils. Different physico-chemical parameters such as the concentration of reactive species and pH were investigated through the PHE degradation efficiency. The second-order rate constants of the reactions for generated radicals with PHE and Tween 80 in solution were identified through competitive reaction experiments under steady-state conditions and application of nanosecond laser flash photolysis (LFP) as well. A kinetic approach was applied to assess the selectivity and reactivity of photo-generated radicals in aqueous medium in order to explain the observed degradation trends. This work proposes an innovative technology of management of soil washing solutions using Fe(III)-EDDS complexes and solar light for the activation of persulfate.


Assuntos
Compostos Férricos/química , Fenantrenos/química , Solo/química , Energia Solar
19.
Environ Sci Technol ; 53(15): 8854-8861, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31313923

RESUMO

Ferrihydrite commonly occurs in soils and sediments, especially in acid mine drainage (AMD). Solar irradiation may affect Fe(II)-catalyzed transformation of metastable ferrihydrite to more stable iron oxides on AMD surface. We investigated the Fe(II)-catalyzed transformation process and mechanism of ferrihydrite under light irradiation. In nitrogen atmosphere, Fe2+aq could be oxidized to goethite and lepidocrocite by hydroxyl radical (OH•), superoxide radical (O2•-) and hole (hvb+) generated from ferrihydrite under ultraviolet (UV) irradiation (300-400 nm) at pH 6.0, and O2•- and hvb+ were mainly responsible for Fe2+aq oxidation. In addition, the ligand-to-metal charge-transfer (LMCT) process between Fe(II) and ferrihydrite could be promoted by UV irradiation. Goethite proportion increased with increasing Fe2+aq concentration. Both visible (vis) and solar irradiation could also lead to the oxidation of Fe2+aq to goethite and lepidocrocite, and the proportion of lepidocrocite increased with increasing light intensity. Fe2+aq was photochemically oxidized to schwertmannite at pH 3.0 and 4.5, and the oxidation rate was higher than that under dark conditions in air. The photochemical oxidation rate of Fe2+aq decreased in the presence of humic acid. This study facilitates a better understanding of the formation and transformation of iron oxides in natural environments and ancient Earth.


Assuntos
Ferro , Energia Solar , Compostos Férricos , Oxirredução , Água
20.
Environ Pollut ; 253: 130-140, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31306820

RESUMO

Skin cancer is the most common type of cancer in the United States, the majority of which is caused by overexposure to ultraviolet (UV) irradiance, which is one component of sunlight. National Environmental Public Health Tracking Program at CDC has collaborated with partners to develop and disseminate county-level daily UV irradiance (2005-2015) and total solar irradiance (1991-2012) data for the contiguous United States. UV irradiance dataset was derived from the Ozone Monitoring Instrument (OMI), and solar irradiance was extracted from National Solar Radiation Data Base (NSRDB) and SolarAnywhere data. Firstly, we produced daily population-weighted UV and solar irradiance datasets at the county level. Then the spatial distributions and long-term trends of UV irradiance, solar irradiance and the ratio of UV irradiance to solar irradiance were analyzed. The national average values across all years are 4300 Wh/m2, 2700 J/m2 and 130 mW/m2 for global horizontal irradiance (GHI), erythemally weighted daily dose of UV irradiance (EDD) and erythemally weighted UV irradiance at local solar noon time (EDR), respectively. Solar, UV irradiances and the ratio of UV to solar irradiance all increased toward the South and in some areas with high altitude, suggesting that using solar irradiance as indicator of UV irradiance in studies covering large geographic regions may bias the true pattern of UV exposure. National annual average daily solar and UV irradiances increased significantly over the years by about 0.3% and 0.5% per year, respectively. Both datasets are available to the public through CDC's Tracking network. The UV irradiance dataset is currently the only publicly-available, spatially-resolved, and long-term UV irradiance dataset covering the contiguous United States. These datasets help us understand the spatial distributions and temporal trends of solar and UV irradiances, and allow for improved characterization of UV and sunlight exposure in future studies.


Assuntos
Energia Solar , Raios Ultravioleta , Exposição Ambiental , Humanos , Ozônio/análise , Neoplasias Cutâneas , Análise Espaço-Temporal , Luz Solar , Estados Unidos
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