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641.
Sorption of tylosin and sulfamethazine on solid humic acid 总被引:3,自引:0,他引:3
Tylosin(TYL) and sulfamethazine(SMT) are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid(HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions(pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H(2.0–7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~+/SMT~+ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared(FT-IR) and ~13C-nuclear magnetic resonance(NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions. 相似文献
642.
Changzhou Xu Rongjun Qu Shasha Li Changmei Sun Ying Zhang Jingjing Gao Yuzhong Niu Qianli Ma Xiquan Song Shuangcheng Wang Chunxia Li 《Journal of Polymers and the Environment》2016,24(3):206-220
A series of nanaoscale aramid-based adsorbents were prepared by the functionalization of poly (p-phenylene terephthalamide) (PPTA) with different content of ethylenediamine (EDA). Their structures were characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. Metal ions, including Hg2+, Pb2+, Ag+, Cu2+, Cd2+, and Ni2+ were chosen as the models to explore the binding behaviors of PPTA–ECH–EDA in aqueous medium. Results showed that PPTA–ECH–EDA exhibited higher adsorption capacity for Hg2+ due to their nanoscale structures. In particular, the adsorption rate was so high that equilibrium was achieved within 15 min for Hg2+. The adsorption of Hg2+ on PPTA–ECH–EDA followed the pseudo second-order model well. Langmuir and Freundlich models were employed to fit the isothermal adsorption, and the results revealed that Freundlich isotherm was a better model to predict the experimental data. The adsorption mechanism was revealed by X-ray photoelectron spectroscopy. It is preconceived that PPTA–ECH–EDA could be used as an effective adsorbent for fast removal of heavy ions from wastewater. 相似文献
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645.
Sang-Keun Song Zang-Ho Shon Ki-Hyun Kim 《Atmospheric environment (Oxford, England : 1994)》2009,43(18):3015-3023
The photochemical oxidation and dispersion of reduced sulfur compounds (RSCs: H2S, CH3SH, DMS, CS2, and DMDS) emitted from anthropogenic (A) and natural (N) sources were evaluated based on a numerical modeling approach. The anthropogenic emission concentrations of RSCs were measured from several sampling sites at the Donghae landfill (D-LF) (i.e., source type A) in South Korea during a series of field campaigns (May through December 2004). The emissions of natural RSCs in a coastal study area near the D-LF (i.e., source type N) were estimated from sea surface DMS concentrations and transfer velocity during the same study period. These emission data were then used as input to the CALPUFF dispersion model, revised with 34 chemical reactions for RSCs. A significant fraction of sulfur dioxide (SO2) was produced photochemically during the summer (about 34% of total SO2 concentrations) followed by fall (21%), spring (15%), and winter (5%). Photochemical production of SO2 was dominated by H2S (about 55% of total contributions) and DMS (24%). The largest impact of RSCs from source type A on SO2 concentrations occurred around the D-LF during summer. The total SO2 concentrations produced from source type N around the D-LF during the summer (a mean SO2 concentration of 7.4 ppbv) were significantly higher than those (≤0.3 ppbv) during the other seasons. This may be because of the high RSC and SO2 emissions and their photochemistry along with the wind convergence. 相似文献
646.
国内近年来在建筑施工中经常发生土方坍塌事故,给人民生命财产造成了巨大损失。为此我们必须认真分析事故原因,总结经验教训,采取有效改进措施,才能防止类似事故重复发生。 相似文献
647.
Wang Da Yu Yan Zhang Zhipeng Fang Huiying Chen Jianmeng He Zhiqiao Song Shuang 《Environmental science and pollution research international》2016,23(18):18369-18378
Environmental Science and Pollution Research - The conversion of CO2 into useful raw materials for fuels and chemicals by solar energy is described using a plasmonic photocatalyst comprised of Ag... 相似文献
648.
本文针对传统基于时差的声发射定位方法精度及稳定性不足且易受检测环境影响的问题,提出了一种基于收敛算法的声发射源定位方法,经过循环迭代不断优化声发射信号的到达时刻计算方式,使得定位计算重构的定位源稳定收敛在近似同一区域,从而提高声发射源的定位准确度。 相似文献
649.
Jin-Do Chung Jae-Hyuk Hyun Jang-Heon Song 《Journal of Material Cycles and Waste Management》2016,18(3):455-459
The incineration of food waste water in conjunction with the domestic waste is getting attention as a food waste water treatment method, due to its low treatment cost and high efficiency. Many studies verified that the ammonia in the food waste water served as a reducing agent to suppress the generation of NOx when the food waste water was injected and incinerated. However, they have not revealed the correlation between the change in the concentration of the CO and NOx by the influence of the solid matters contained in the food waste water on the incineration of the wastes. The purpose of this study is to determine the optimum amount of the food waste water injected through four nozzles in the primary and secondary incineration chambers and to assess the correlation between the concentration of CO and NOx in accordance with the food waste water injection in each chamber of the incinerator. For the study, four food waste water injection nozzles were installed; two (A and B) at the top of the primary incineration chamber and the other two (C and D) in the secondary incineration chamber. The correlation between the change in the concentration of CO and NOx was studied adjusting the amount of the food waste water injected through the nozzles. From the result, Case II showed the concentration of CO and NOx as 1.8–10 and 14–26 ppm, respectively, while Case I showed that of CO and NOx as 15–30 and 9–18 ppm, respectively. Those levels are well below the Korean emission criteria, 50 ppm for CO and 80 ppm for NOx. Based on the results, it is evident there is a certain trade-off between emission of CO and NOx, and Case II which has relatively low concentration of CO is easier and cheaper to control. 相似文献
650.
Long Zhou Thomas Woodfin Tian Chen Kun Song 《Journal of Environmental Planning and Management》2018,61(3):430-450
A city's spatial footprint is covered by extensive impervious building roofs and paved surfaces, which contribute to greater storm-water runoff, more surface pollutants, and less carbon sequestration, hence, worse ecosystem services. This research conducts an empirical study on the ecological and economic impacts of a citywide adoption of green roofs and permeable pavements in Corvallis, OR. The effects on ecosystem services of using green roofs and pervious pavements for a low impact development are modelled using Integrated Value of Ecosystem Services Trade-offs and compared to those from the City's current conventional development without green roofs and pervious pavements. The differences are analysed for ecological impact by storm-water yield, storm-water purification, and carbon sequestration and economic impact by a cost-benefit comparison. The results indicate that low impact development, especially intensive green roofs on commercial/industrial buildings and permeable pavements for parking lots, plays a significant role, even with a higher initial implementation cost, for long-term urban sustainability. 相似文献