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51.
The weatherability of three types of enhanced photodegradable polyethylene films and corresponding control films were studied under outdoor and marine floating conditions at two exposure sites. Progress of weathering was monitored using tensile elongation at break. In general, both the enhanced-degradable plastics and the corresponding controls degraded slower in marine exposure than in outdoor exposure. This is attributed to the lower sample temperatures (compared to samples exposed outdoors) and to shielding from light afforded by surface fouling in samples exposed floating in sea water. Enhanced-photodegradable polyethylenes disintegrated faster than the control samples in the case of both outdoor and marine exposures. The improvement obtained in marine exposures was greater than that for outdoor exposure of corresponding sample types. This is due to the extremely slow rates of disintegration of control films under marine floating conditions. 相似文献
52.
水环境中邻苯二甲酸酯的迁移转化研究 总被引:7,自引:1,他引:7
邻苯二甲酸酯(PAEs)是一类普遍使用的化学工业品,并广泛存在于环境中.已有研究表明,PAEs环境内分泌干扰物,对人类和自然环境有非常大的危害.总结了PAEs在地表水中的分布和在水体中迁移转化的主要途径,如水解、光降解、与颗粒物(沉积物或悬浮颗粒物)的作用以及生物转化作用,并指出对它们进一步研究的重要性和今后主要的研究方向. 相似文献
53.
Phototransformation of fibrate drugs in aqueous media 总被引:1,自引:1,他引:1
M. Cermola M. DellaGreca M.R. Iesce L. Previtera M. Rubino F. Temussi M. Brigante 《Environmental Chemistry Letters》2005,3(1):43-47
The photochemical conversion of bezafibrate, gemfibrozil, fenofibrate and fenofibric acid has been examined in aqueous media. Irradiation with a solar simulator in distilled water caused about 10% degradation for the first three drugs after 200 hr, while fenofibric acid was completely degraded after 100 hr. Experiments have also been performed in the presence of nitrates or humic acids, considered as environmental photosensitizers, and only for gemfibrozil a reduction of degradation has been observed. Photoproducts have been characterized and the mechanistic pathways discussed on the basis of experimental and literature data. 相似文献
54.
Nowadays,widespread researches have been focused on the development of effective photocatalysts to remove pollutants of the aquatic system.In accordance with the universal studies,two new sets of UiO-66@metal oxide(including ZnO and TiO_2)/graphene oxide heterojunctions were synthesized for photodegradation of aromatic(tetracycline)and nonaromatic(malathion) pollutants which are challenging cases in the environment.The dosage of the photocatalyst,pH of the solution,the type of metal oxide,and the presence of various scavengers are assayed parameters in this work.In the optimum condition,maximum photodegradation efficiency is achieved in 90 min for tetracycline(81%) and malathion(100%) by the UiO-66@ZnO/graphene oxide.The superior separation of charge carriers by Z-scheme mechanism,excellent electron mobility on layers of graphene oxide and high surface area are factors that enhanced the efficiency.Furthermore,in comparison with pure UiO-66,the band gaps belong to heterojunctions revealed a red shift in the absorption edge,which can be responsible for more expand adsorption of the solar spectrum.Total organic carbon analysis verified the decontamination of these pollutants in the solution.The produced main intermediates during the photocatalytic process were identified and the possible degradation pathway proposed.In general,the superior photocatalytic activity suggests that these designed photocatalysts can be a promising choice for having a clean future. 相似文献
55.
Xinyi Liu Caichao Wan Xianjun Li Song Wei Luyu Zhang Wenyan Tian Ken-Tye Yong Yiqiang Wu Jian Li 《Frontiers of Environmental Science & Engineering》2021,15(4):54
56.
57.
Nitrate-induced photodegradation of atenolol in aqueous solution: kinetics, toxicity and degradation pathways 总被引:2,自引:0,他引:2
The extensive utilization of β-blockers worldwide led to frequent detection in natural water. In this study the photolysis behavior of atenolol (ATL) and toxicity of its photodegradation products were investigated in the presence of nitrate ions. The results showed that ATL photodegradation followed pseudo-first-order kinetics upon simulated solar irradiation. The photodegradation was found to be dependent on nitrate concentration and increasing the nitrate from 0.5 mM L−1 to 10 mM L−1 led to the enhancement of rate constant from 0.00101 min−1 to 0.00716 min−1. Hydroxyl radical was determined to play a key role in the photolysis process by using isopropanol as molecular probe. Increasing the solution pH from 4.8 to 10.4, the photodegradation rate slightly decreased from 0.00246 min−1 to 0.00195 min−1, probably due to pH-dependent effect of nitrate-induced OH formation. Bicarbonate decreased the photodegradation of ATL in the presence of nitrate ions mainly through pH effect, while humic substance inhibited the photodegradation via both attenuating light and competing radicals. Upon irradiation for 240 min, only 10% reduction of total organic carbon (TOC) can be achieved in spite of 72% transformation rate of ATL, implying a majority of ATL transformed into intermediate products rather than complete mineralization. The main photoproducts of ATL were identified by using solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) techniques and possible nitrate-induced photodegradation pathways were proposed. The toxicity of the phototransformation products was evaluated using aquatic species Daphnia magna, and the results revealed that photodegradation was an effective mechanism for ATL toxicity reduction in natural waters. 相似文献
58.
Large volumes of wastewater with a high organic load are generated by the pulp and paper industry that negatively affect the quality of receiving waters. The main waste products in the pulp mill effluents are lignin derived macromolecular compounds, which are similar to natural humic substances and very resistant to wastewater treatments. Fulvic acids (FA) represent the higher percentage of these humic substances and it was observed that solar irradiation modify their properties. Several analytic tools, namely, UV–Visible, molecular fluorescence and FTIR spectroscopies, were used to assess the effect of solar exposition on fulvic acids from a kraft pulp mill effluent. It may be concluded that sun irradiation may alter to a high extent the physicochemical properties of macromolecular organic matter, namely fulvic acids, released by kraft pulp mill effluents. After solar exposition, the aromaticity decreases, the aliphatic structures become more oxygenated, and the fulvic acids from the pulp mill effluent remaining in solution are more similar to aquatic fulvic acids from non polluted sites. 相似文献
59.
Hongrui M Linke Ge Shengkai Cao Crispin Halsall Junfeng Niu Dongxiao Bai Guangkai He Peng Zhang 《环境科学学报(英文版)》2023,35(2):139-145
The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry.Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs,2-hydroxyfluorene (2-OHFL) and 9-hydroxyfluorene (9-OHFL),which are newly recognized contaminants in the wider environment including colder regions.Interestingly,their photodegradation kinetics were clearly influenced by whether they reside in ice or water.Under the same simulated s... 相似文献
60.
Polythene sheeting is a major litter component on estuarine beaches and river banks. Sanitary towel backing strips, which
are one of the commonest items of sewage related debris found on beaches, enter the riverine system via combined sewer overflows.
Investigations on these items, positioned at natural riverine stranding levels, showed that after an initial rapid breakdown
little further loss of tensile strength occurred. Experiments carried out on backing strips, buried in the bank suspended
from a tree and tethered to the bank, showed significant change. Buried samples retained the greatest tensile strength retention,
dropping no lower than 90 %, the other samples showed similar retention rates at 80%. The difference is probably due to photodegradation
as biodegradation effects were minimal. Probably, the longevity of such plastics is a major reason for their abundance and
widespread distribution both on river banks and beaches. 相似文献