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https://www.readbyqxmd.com/read/29247911/degradation-of-perfluorinated-compounds-by-sulfate-radicals-new-mechanistic-aspects-and-economical-considerations
#1
Holger V Lutze, Julia Brekenfeld, Sergej Naumov, Clemens von Sonntag, Torsten C Schmidt
Perfluorinated organic compounds (PFC) are an important group of pollutants, which are difficult to be degraded in conventional water treatment. Even hydroxyl radical based processes are not capable to degrade these compounds. Sulfate radicals can oxidize a group of PFC, i.e., perfluorinated carboxylic (PFCAs) acids. However, information in literature on kinetics and reaction mechanism is largely based on model simulations which are prone to errors. The present study provides mechanistic insights based on product formation, material balances, competition kinetics experiments and quantum chemical calculations...
October 30, 2017: Water Research
https://www.readbyqxmd.com/read/29237126/impact-of-ultra-small-platinum-nanoparticles-coating-on-different-morphologies-of-gold-nanostructures-for-multiple-one-pot-photo-catalytic-environment-protection-reactions
#2
Dinesh Kumar, Sang Bong Lee, Chan Hee Park, Cheol Sang Kim
Here, we report preparation of various morphologies of core-satellite hybrid plasmonic nanomaterials of gold and platinum viz., the coating of platinum nanoparticles on gold nanostars (Pt@AuNSs), nanospheres (Pt@AuNPs) and nanorods (Pt@AuNRs) for visible-NIR-sun light illuminated highly efficient photo-conversion of CO2 to HCOOH and visible light mediated degradation of various organic dyes (methylene blue, methyl orange and methyl red) in a single step at room temperature. In comparison, Pt@AuNSs shows higher conversion efficiency for CO2 photoconversion to HCOOH with 1...
December 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29223821/germination-physiological-and-biochemical-responses-of-acacia-seedlings-acacia-raddiana-and-acacia-tortilis-to-petroleum-contaminated-soils
#3
Thanh Hoai Tran, Einav Mayzlish Gati, Amram Eshel, Gidon Winters
Along the arid Arava, southern Israel, acacia trees (Acacia raddiana and Acacia tortilis) are considered keystone species. Yet they are threatened by the ongoing aquifer depletion for agriculture, the conversion of natural land to agricultural land, seed infestation by bruchid beetles, and the reduction in precipitation level in the region. In the acacia dominated Evrona reserve (southern Arava), adding to these threats are recurrent oil spills from an underground pipeline. We report here a study of the effects of contaminated soils, from a recent (December 2014) and a much older (1975) oil spills...
December 7, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29207354/biomonitoring-chromium-iii-or-vi-soluble-pollution-by-moss-chlorophyll-fluorescence
#4
Yang-Er Chen, Hao-Tian Mao, Jie Ma, Nan Wu, Chao-Ming Zhang, Yan-Qiu Su, Zhong-Wei Zhang, Ming Yuan, Huai-Yu Zhang, Xian-Yin Zeng, Shu Yuan
We systematically compared the impacts of four Cr salts (chromic chloride, chromic nitrate, potassium chromate and potassium bichromate) on physiological parameters and chlorophyll fluorescence in indigenous moss Taxiphyllum taxirameum. Among the four Cr salts, K2Cr2O7 treatment resulted in the most significant decrease in photosynthetic efficiency and antioxidant enzymes, increase in reactive oxygen species (ROS), and obvious cell death. Different form the higher plants, although hexavalent Cr(VI) salt treatments resulted in higher accumulation levels of Cr and were more toxic than Cr(III) salts, Cr(III) also induced significant changes in moss physiological parameters and chlorophyll fluorescence...
December 1, 2017: Chemosphere
https://www.readbyqxmd.com/read/29145130/photophysical-and-photochemical-insights-into-the-photodegradation-of-sulfapyridine-in-water-a-joint-experimental-and-theoretical-study
#5
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
https://www.readbyqxmd.com/read/29043589/assessment-of-filtration-efficiency-and-physiological-responses-of-selected-plant-species-to-indoor-air-pollutants-toluene-and-2-ethylhexanol-under-chamber-conditions
#6
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
https://www.readbyqxmd.com/read/29028332/coupling-light-emitting-diodes-with-photocatalyst-coated-optical-fibers-improves-quantum-yield-of-pollutant-oxidation
#7
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
https://www.readbyqxmd.com/read/28941048/one-pot-green-synthesis-of-nitrogen-doped-carbon-quantum-dots-for-cell-nucleus-labeling-and-copper-ii-detection
#8
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
https://www.readbyqxmd.com/read/28929358/green-synthesis-of-inp-zns-core-shell-quantum-dots-for-application-in-heavy-metal-free-light-emitting-diodes
#9
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
https://www.readbyqxmd.com/read/28791921/effect-of-operating-conditions-and-interfering-substances-on-photochemical-degradation-of-a-cationic-surfactant
#10
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
https://www.readbyqxmd.com/read/28745895/reactivity-of-triplet-excited-states-of-dissolved-natural-organic-matter-in-stormflow-from-mixed-use-watersheds
#11
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
https://www.readbyqxmd.com/read/28683540/composition-tunable-optical-properties-of-zn-x-cd-1%C3%A2-%C3%A2-x-s-quantum-dot-carboxymethylcellulose-conjugates-towards-one-pot-green-synthesis-of-multifunctional-nanoplatforms-for-biomedical-and-environmental-applications
#12
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
https://www.readbyqxmd.com/read/28646308/photochemical-generation-of-reactive-intermediates-from-urban-waste-bio-organic-substances-under-uv-and-solar-irradiation
#13
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
https://www.readbyqxmd.com/read/28501207/novel-bimetallic-gold-silver-nanoclusters-with-synergy-enhanced-fluorescence-for-cyanide-sensing-cell-imaging-and-temperature-sensing
#14
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
https://www.readbyqxmd.com/read/28378591/semiconductor-photocatalysis-for-chemoselective-radical-coupling-reactions
#15
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
https://www.readbyqxmd.com/read/28208094/a-simple-strategy-to-refine-cu2o-photocatalytic-capacity-for-refractory-pollutants-removal-roles-of-oxygen-reduction-and-fe-ii-chemistry
#16
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
https://www.readbyqxmd.com/read/28035517/fluorescence-quenching-of-humic-acid-by-coated-metallic-silver-particles
#17
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
https://www.readbyqxmd.com/read/27968720/fluorescence-detection-of-pesticides-using-quantum-dot-materials-a-review
#18
REVIEW
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
https://www.readbyqxmd.com/read/27914582/photochemistry-of-nanoporous-carbons-perspectives-in-energy-conversion-and-environmental-remediation
#19
REVIEW
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
https://www.readbyqxmd.com/read/27847148/sulfamethazine-degradation-in-water-by-the-vuv-uv-process-kinetics-mechanism-and-antibacterial-activity-determination-based-on-a-mini-fluidic-vuv-uv-photoreaction-system
#20
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
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