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Quantum yields pollutants

Heming Zhang, Xiaoxuan Wei, Xuedan Song, Shaheen Shah, Jingwen Chen, Jianhui Liu, Ce Hao, Zhongfang Chen
For organic pollutants, photodegradation, as a major abiotic elimination process and of great importance to the environmental fate and risk, involves rather complicated physical and chemical processes of excited molecules. Herein, we systematically studied the photophysical and photochemical processes of a widely used antibiotic, namely sulfapyridine. By means of density functional theory (DFT) computations, we examined the rate constants and the competition of both photophysical and photochemical processes, elucidated the photochemical reaction mechanism, calculated reaction quantum yield (Φ) based on both photophysical and photochemical processes, and subsequently estimated the photodegradation rate constant...
October 7, 2017: Chemosphere
Vanessa Hörmann, Klaus-Reinhard Brenske, Christian Ulrichs
Three common plant species (Dieffenbachia maculata, Spathiphyllum wallisii, and Asparagus densiflorus) were tested against their capacity to remove the air pollutants toluene (20.0 mg m(-3)) and 2-ethylhexanol (14.6 mg m(-3)) under light or under dark in chamber experiments of 48-h duration. Results revealed only limited pollutant filtration capabilities and indicate that aerial plant parts of the tested species are only of limited value for indoor air quality improvement. The removal rate constant ranged for toluene from 3...
October 18, 2017: Environmental Science and Pollution Research International
Li Ling, Heather Tugaoen, Jonathon Brame, Shahnawaz Sinha, Chuanhao Li, Jared Schoepf, Kiril Hristovski, Jae-Hong Kim, Chii Shang, Paul Westerhoff
A photocatalyst-coated optical fiber was coupled with a 318 nm ultraviolet-A light emitting diode, which activated the photocatalysts by interfacial photon-electron excitation while minimizing photonic energy losses due to conventional photocatalytic barriers. The light delivery mechanism was explored via modeling of evanescent wave energy produced upon total internal reflection and photon refraction into the TiO2 surface coating. This work explores aqueous phase LED-irradiated optical fibers for treating organic pollutants and for the first time proposes a dual-mechanistic approach to light delivery and photocatalytic performance...
November 2, 2017: Environmental Science & Technology
Jiliang Ci, Ye Tian, Shigenori Kuga, Zhongwei Niu, Min Wu, Yong Huang
The doping of nitrogen into carbon quantum dots is vitally important for improved fluorescence performance. However, the synthesis of nitrogen-doped carbon quantum dots (N-CQDs) is usually conducted under strong acid and high temperature, which results in environmental pollution and energy consumption. Herein, the N-CQDs were prepared by a mild one-pot hydrothermal process. The hydrothermal reaction temperature was adjusted to control the particle size, nitrogen/carbon atomic ratio, and quantum yield. The products were water soluble with a narrow particle size distribution and good dispersion stability over a wide pH range...
September 21, 2017: Chemistry, An Asian Journal
Tsung-Rong Kuo, Shih-Ting Hung, Yen-Ting Lin, Tzu-Lin Chou, Ming-Cheng Kuo, Ya-Pei Kuo, Chia-Chun Chen
Quantum dot light-emitting diodes (QD-LEDs) have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency, and cost efficiency. For the practical applications, the development of heavy-metal-free QD-LEDs from environment-friendly materials is the most important issue to reduce the impacts on human health and environmental pollution. In this work, heavy-metal-free InP/ZnS core/shell QDs with different fluorescence were prepared by green synthesis method with low cost, safe, and environment-friendly precursors...
September 19, 2017: Nanoscale Research Letters
Bijoli Mondal, Asok Adak, Pallab Datta
This work investigates the degradation kinetics of a recalcitrant organic pollutant, cetyltrimethylammonium bromide (CTAB), using direct UV and UV-H2O2 advanced oxidation processes. Direct photolysis at 253.7 nm showed only 55% degradation upto fluence dose of 40.65 J/cm(2) for initial CTAB concentration of 100 mg/L. The apparent fluence-based pseudo-first order rate constant and quantum yield were 2.29(±0.325)×10(-5) cm(2)/mJ and 0.305(±0.043) mol/Einstein respectively. In case of UV-H2O2, > 99% degradation was observed upto fluence dose of 0...
August 9, 2017: Environmental Technology
Andrew J McCabe, William A Arnold
Dissolved organic matter (DOM) quantity and composition control the rate of formation (Rf,T) of triplet excited states of dissolved natural organic matter ((3)DOM*) and the efficiency of (3)DOM* formation (the apparent quantum yield, AQYT). Here, the reactivity of (3)DOM* in stormflow samples collected from watersheds with variable land covers is examined. Stormflow DOM reflects variability in DOM quantity and composition as a function of land cover and may be important in controlling the fate of cotransported pollutants...
August 16, 2017: Environmental Science & Technology
Alexandra A P Mansur, Herman S Mansur, Anderson J Caires, Rafael L Mansur, Luiz C Oliveira
Quantum dots (QDs) are colloidal semiconductor nanocrystals with unique properties that can be engineered by controlling the nanoparticle size and chemical composition by doping and alloying strategies. However, due to their potential toxicity, augmenting their biocompatibility is yet a challenge for expanding to several biomedical and environmentally friendly applications. Thus, the main goal of this study was to develop composition-tunable and biocompatible Zn x Cd1 - x S QDs using carboxymethylcellulose polysaccharide as direct capping ligand via green colloidal aqueous route at neutral pH and at room temperature for potential biomedical and environmental applications...
December 2017: Nanoscale Research Letters
Marcela Prado Silva, Arlen Mabel Lastre-Acosta, Simón Mostafa, Garrett McKay, Karl G Linden, Fernando L Rosario-Ortiz, Antonio Carlos Silva Costa Teixeira
Singlet oxygen ((1)O2), hydroxyl radicals ((•)OH), and excited triplet states of organic matter ((3)OM(*)) play a key role in the degradation of pollutants in aquatic environments. The formation rates and quantum yields (Φ) of these reactive intermediates (RI) through photosensitized reactions of dissolved organic matter (DOM) have been reported in the literature for decades. Urban biowaste-derived substances (UW-BOS), a form of organic matter derived from vegetative and urban waste, have recently been shown to be efficient sensitizers in the photo-degradation of different contaminants...
June 23, 2017: Environmental Science and Pollution Research International
Lu Tian, Yangfan Li, Tingting Ren, Yaoli Tong, Binsheng Yang, Yingqi Li
We herein opened up a facile and green strategy for the fabrication of bright orange-fluorescent gold-silver nanoclusters (AuAgNCs@ew, GSNCs) by a one-pot synthesis at a vital molar ratio of Au/Ag precursors in the egg white protein matrix using microwave-assisted method. The prepared GSNCs exhibited enhanced fluorescence with fluorescent quantum yield of 5.4%, which is dependent on gold and silver synergies. Due to the advantageous superiority of low-toxicity, excellent stability and satisfactory fluorescence, the as-prepared GSNCs has been successfully used in cell imaging and temperature sensing...
August 1, 2017: Talanta
Horst Kisch
Photocatalysis at semiconductor surfaces is a growing field of general photocatalysis because of its importance for the chemical utilization of solar energy. By analogy with photoelectrochemistry the basic mechanism of semiconductor photocatalysis can be broken down into three steps: photogenerated formation of surface redox centers (electron-hole pairs), interfacial electron transfer from and to substrates (often coupled with proton-transfer), and conversion of primary redox intermediates into the products...
April 5, 2017: Accounts of Chemical Research
Ai-Yong Zhang, Yuan-Yi He, Tan Lin, Nai-Hui Huang, Qiao Xu, Jing-Wei Feng
Visible-light-driven photocatalysis is a promising technology for advanced water treatment, but it usually exhibits a low efficiency. Cu2O is a low-cost semiconductor with narrow band gap, high absorption coefficient and suitable conduction band, but suffers from low charge mobility, poor quantum yield and weak catalytic performance. Herein, the Cu2O catalytic capacity for refractory pollutants degradation is drastically improved by a simple and effective strategy. By virtue of the synergistic effects between photocatalysis and Fenton, a novel and efficient photocatalysis-driven Fenton system, PFC, is originally proposed and experimentally validated using Cu2O/Nano-C hybrids...
January 29, 2017: Journal of Hazardous Materials
Guocheng Zhu, Jun Yin
Natural organic matter is an important component of the aquatic environments, which has attracted wide attention to its influence of interaction with other pollutants. The present work aimed to investigate its fluorescence quenching (FQ) by coated metallic silver particles (AgNPs). In this work, using fluorescence spectroscopy in conjunction with UV-Vis spectroscopy and dynamic light scattering, the effect of coated AgNPs on fluorescence quenching intensity (FQI) of humic acid (HA) was assessed. In addition, the influence of electrolytes (NaCl, NaNO3 and CaNO3) in the FQI was observed...
July 2017: Journal of Fluorescence
S A Nsibande, P B C Forbes
High pesticide use, especially in agriculture, can lead to environmental pollution and potentially adverse health effects. As result, pesticide residues end up in different media, including water and food products, which may serve as direct routes for human exposure. There is thus a continuous drive to develop analytical methods for screening and quantification of these compounds in the different environmental media in which they may occur. Development of quantum dot (QD) based sensors for monitoring pesticides has gained momentum in recent years...
November 16, 2016: Analytica Chimica Acta
Alicia Gomis-Berenguer, Leticia F Velasco, Inmaculada Velo-Gala, Conchi O Ania
The interest in the use of nanoporous carbon materials in applications related to energy conversion and storage, either as catalysts or additives, has grown over recent decades in various disciplines. Since the early studies reporting the benefits of the use of nanoporous carbons as inert supports of semiconductors and as electron acceptors that enhance the splitting of the photogenerated excitons, many researchers have investigated the key role of carbon matrices coupled to all types of photoactive materials...
March 15, 2017: Journal of Colloid and Interface Science
Mengkai Li, Chen Wang, Miaoling Yau, James R Bolton, Zhimin Qiang
A mini-fluidic VUV/UV photoreaction system (MVPS) was developed in our previous study, and it was demonstrated as a powerful tool for studies on pollutant degradation by the VUV/UV process. In this study, we investigated the VUV/UV photodegradation of sulfamethazine (SMN), one of the most frequently detected antibiotics in the environment. The determination methods of photochemical kinetic parameters (e.g., photon fluence-based rate constant and quantum yield) were developed based on the MVPS. The photon fluence-based reaction rate constants for SMN degradation by UV alone and VUV/UV processes were determined as 0...
January 1, 2017: Water Research
Yunxiang Li, Shuxin Ouyang, Hua Xu, Xin Wang, Yingpu Bi, Yuanfang Zhang, Jinhua Ye
Efficient generation of active oxygen-related radicals plays an essential role in boosting advanced oxidation process. To promote photocatalytic oxidation for gaseous pollutant over g-C3N4, a solid-gas interfacial Fenton reaction is coupled into alkalinized g-C3N4-based photocatalyst to effectively convert photocatalytic generation of H2O2 into oxygen-related radicals. This system includes light energy as power, alkalinized g-C3N4-based photocatalyst as an in situ and robust H2O2 generator, and surface-decorated Fe(3+) as a trigger of H2O2 conversion, which attains highly efficient and universal activity for photodegradation of volatile organic compounds (VOCs)...
October 3, 2016: Journal of the American Chemical Society
Xi Chen, Wen-Yao Liu, Liang Song, Su Li, Yi Wu, Xian-Meng Shi, Jun-Biao Huang, Chuan-Sheng Wu
Atmospheric depositions pose significant threats to biodiversity and ecosystem function. However, the underlying physiological mechanisms are not well understood, and few studies have considered the combined effects and interactions of multiple pollutants. This in situ study explored the physiological responses of two epiphytic bryophytes to combined addition of nitrogen, phosphorus and sulfur. We investigated the electrical conductivity (EC), total chlorophyll concentration (Chl), nutrient stoichiometry and chlorophyll fluorescence signals in a subtropical montane cloud forest in south-west China...
2016: PloS One
F Jentzsch, O Olsson, J Westphal, M Reich, C Leder, K Kümmerer
To prevent water shortages in the future and to reduce domestic water consumption, decentralized grey water (GW) reuse has become increasingly important. This water has, however, to be free of pollutants. Conventional treatment of GW does not fully eliminate micropollutants such as the UV filter substance ethylhexyl methoxycinnamate (EHMC). EHMC, which is commonly used in sunscreens and personal care products, is an endocrine disruptor and shows potential to bioaccumulation, which is also reflected in its low water solubility...
December 1, 2016: Science of the Total Environment
Izaskun Llagostera, Daniel Cervantes, Neus Sanmartí, Javier Romero, Marta Pérez
Seagrasses form some of the most important coastal habitats. They may be negatively affected by trace metal contamination in certain coastal areas. In this study we experimentally assessed selected morphological and physiological traits of the seagrass Cymodocea nodosa, with increasing concentrations of copper (Cu) under controlled laboratory conditions. Short term (21 days) sub-lethal effects such as decreased maximum quantum yield, increased leaf necrosis and decreased shoot growth and shoot recruitment were clearly observed at the highest Cu exposure (5 mg L(-1)), while the effects were weaker at the intermediate concentration (2...
September 2016: Bulletin of Environmental Contamination and Toxicology
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