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Quantum yields pollutants

Chao Tai, Shaodong Zhang, Yongguang Yin, Zhifeng Dai, Yanbin Li, Guibin Jiang, Yong Cai, Chunhua Huang, Jianbo Shi
Herein, we report on a simple, clean, and efficient method for generating hydroxyl radicals using a nitrocellulose membrane (NCM) under light of wavelengths greater than 280 nm. Hydroxyl radicals formed on the NCM surface, diffusing into the bulk solution under irradiation. Radical generation was shown to be dependent on the nature of the NCM and light, and independent of the properties of the bulk solution. The quantum yield for hydroxyl radical of the NCM was 1.72 × 10-4, approximately 2.46 times that of TiO2...
February 8, 2018: ChemSusChem
Poushali Das, Sayan Ganguly, Priti Prasanna Maity, Madhuparna Bose, Subhadip Mondal, Santanu Dhara, Amit Kumar Das, Susanta Banerjee, Narayan Ch Das
Proper waste disposal from household and restaurants is becoming an important and recurring waste-management concern. Herein, a method of upcycling of waste kitchen chimney oil has been adopted to prepare fluorescent multifunctional carbon quantum dots. These nanodots showed superior biocompatibility, excellent optical properties, water solubility and high yield. Preparation of C-dots from highly abundant carbon source of waste refusals is highly effective in commercial aspect as well as in reducing the immense environmental pollution...
January 30, 2018: Journal of Photochemistry and Photobiology. B, Biology
M S Swapna, S Sankararaman
The present work describes a solution for the effective use of the hazardous particulate matter (diesel soot) from the internal combustion engines (ICEs) as a potential material emitting white light for white light emitting diodes (WLEDs). The washed soot samples are subjected to Field Emission Scanning Electron Microscopy (FESEM), High- Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive Spectroscopy (EDS), UV-Visible, Photoluminescent (PL) Spectroscopy and quantum yield measurements. The CIE plot and Correlated Color Temperature (CCT) reveals the white fluorescence on photoexcitation...
February 5, 2018: Journal of Fluorescence
Jingjing Chu, Fan Zhu, Xiaoyong Chen, Huizi Liang, Renjie Wang, Xuxu Wang, Xinhao Huang
Contamination by heavy metals has become a serious environmental pollution issue today due to its potential threat to plant, wildlife, and human health. Photosynthesis, a process in which light energy is used to produce sugar and other organic compounds, is sensitive to heavy metals. In the present study, the response of photosynthetic process and carbon assimilation of Schima superba was investigated under cadmium (Cd) stress. Three Cd concentrations (0, 300, and 600 mg kg-1) were used designated as control (CK), low Cd (L1), and high Cd treatment (L2) of plants...
February 1, 2018: Environmental Science and Pollution Research International
Manuvesh Sangwan, Lei Zhu
Methyl-substituted 2-nitrophenols are important components of "brown carbon" from biomass burning. Photolysis is their major gas-phase degradation pathway. To determine the extent of light absorptions by 4-methyl-2-nitrophenol and 5-methyl-2-nitrophenol, we obtained their absorption cross-sections in the 295-400 nm region by using cavity ring-down spectroscopy. Cross-section values for 4-methyl-2-nitrophenol were (1.01±0.07)×10-18, (5.72±0.39)×10-18, and (1.80±0.17)×10-20 cm2/molecule at 295, 345, and 400 nm, where errors quoted represent 1σ measurement uncertainty...
January 27, 2018: Journal of Physical Chemistry. A
Pengchao Xie, Siyang Yue, Jiaqi Ding, Ying Wan, Xuchun Li, Jun Ma, Zongping Wang
Vacuum-Ultraviolet (VUV), an efficient and green method to produce hydroxyl radical (•OH), is effective in degrading numerous organic contaminants in aqueous solution. Here, we proposed an effective and simple kinetic model to describe the degradation of organic pollutants in VUV system, by taking the •OH scavenging effects of formed organic intermediates as co-existing organic matter in whole. Using benzoic acid (BA) as a •OH probe, •OH was regarded vital for pollutant degradation in VUV system, and the thus developed model successfully predicted its degradation kinetics under different conditions...
January 9, 2018: Water Research
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
Dinesh Kumar, Sang Bong Lee, Chan Hee Park, Cheol Sang Kim
Here, we report the 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-sunlight illuminated highly efficient photoconversion 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...
January 10, 2018: ACS Applied Materials & Interfaces
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...
March 2018: Environmental Pollution
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, K2 Cr2 O7 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...
March 2018: Chemosphere
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...
January 2018: 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...
August 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
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