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11.
苯酚、苯在水/阴离子有机膨润土界面的环境行为研究 总被引:8,自引:0,他引:8
研究了苯酚在水/阴离子有机膨润土界面的吸附行为,初步探讨了阴离子有机膨润土对苯酚、苯的吸附性能、机理及影响因素。结果表明,阴离子表面活性剂改性后,膨润土中有机碳含量增加了10~38倍,对苯酚、苯的吸附能力大大提高。水中苯酚、苯在水/阴离子有机膨润土界面的吸附行为主要分配作用所致,其吸附等温线呈线性。 相似文献
12.
季铵盐改性土壤对水中苯酚的吸附及机理研究 总被引:6,自引:0,他引:6
采用十六烷基三甲基溴化铵(HDTMA)对土壤进行了改性。结果表明,改必一时最适温度为50 ̄55℃,最适PH为中性最适HDTMA浓度为1%,又考察了PH、改性土壤用量及振荡时间对吸附效果的影响,通过测定吸附等温线探讨了吸附机理。结果表明,PH=3 ̄10时,酚捐附去除率基本不变,当PH〉10时,吸附效率随PH增大而提高。随着改性土壤用量的增加和振荡时间的延长。酚的去除率升高。改性土壤对苯酚的等温吸附规 相似文献
13.
Johan Axelman Dag Broman Carina Näf Harald Pettersen 《Environmental science and pollution research international》1995,2(1):33-36
Linear relatinships between log bioconcentration factor (BCF) and log Kow for a variety of compounds have been reported many times in the literature. Analysis of the thermodynamics of the two partition
processes has, however, shown that they are not analogous and that linear relationships can be expected to have different
slopes for structurally unrelated compounds. In this study a set of literature lipid normalized BCF (BCFL) values of chlorbenzenes (CBs) for rainbow trout and polycyclic aromatic hydrocarbons (PAHs) forDaphnia was put together with literature Kow values. The slopes of the regression lines for log BCFL versus log Kow for the two groups of compounds proved to differ significantly in a statistical test using analysis of variance (ANOVA).
The difference, which is of significance for estimates of BCFs in environmental modelling of these types of compounds, is
explained by the differences in chemical structure of the two groups of compounds. 相似文献
14.
在疏散过程中,出口利用不均现象时有发生,距离最短路径并不一定是最快的路径。提出了大规模人群分区疏散优化算法,该算法以疏散时间最短为目标,综合考虑了人群分布、出口位置、出口宽度等因素,通过迭代计算,求解每个行人的最优出口选择,从而得到优化疏散分区结果。以具有多个出口的某大型步行商业街区疏散为例,利用经典的无后退有偏随机行走模型进行模拟计算,对是否采用优化分区的疏散时间进行了比较分析。结果表明:采用优化分区疏散时,部分人员放弃路径最短的疏散出口,而被导向选择宽度较宽和附近人员密度较低的出口,从而提高整体疏散效率。该算法解决了以距离最短为目标的疏散分区方式导致的出口利用不均和不充分的现象,有效提高了疏散效率,对于区域分区疏散策略的制定具有一定指导意义。 相似文献
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16.
S. RATURI K. R. ISLAM M. J. CAROLL R. L. HILL 《Journal of environmental science and health. Part. B》2013,48(5):697-710
Thatch development in intensively managed turf sites may cause environmental concerns for greater sorption or leaching of applied chemicals in terrestrial ecosystems. To determine the adsorption potential of Carbaryl (1-Napthyl N-methylcarbamate), 2,4-D (2,4-dichloro-phenoxyacetic acid), and Triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) in turf ecosystems, composite thatch and underlying soil samples from three- and six-year-old stands of cool-season Southshore creeping bentgrass (Agrostis palustris Huds.) and warm-season Meyer zoysiagrass (Zoysia japonica Steud.) were collected. The samples were processed and analyzed for total organic carbon (COrg); extractable (CExt), humic (CHA) and fulvic acid (CFA); anthrone reactive nonhumic carbon (ARC) fractions; and CHA and CFA associated iron (Fe) contents. Pesticide adsorption capacity (K f ) and intensity (1/n), organic carbon partition coefficient (K OC ) and Gibbs free energy change (Δ G) were calculated for thatch materials and the underlying soils using a modified batch/flow technique. Both bentgrass (BT) and zoysiagrass thatch (ZT) contained a greater concentration of CExt, CFA, CHA, and ARC than the respective soils (BS and ZS). The CExt, CFA, CHA, and ARC concentration was higher in BT compared with ZT. The BT contained a greater concentration of bound Fe in both CFA and CHA fractions than in BS, whereas ZT had more bound Fe in CHA fraction than in ZS. On average, the BT had a greater concentration of bound Fe in CExt, CFA, and CHA fractions than in the ZT. Among the pesticides, Carbaryl had higher K f and 1/n values than 2,4-D and Triclopyr for both thatch and soil. Although the K OC and Δ G values of Carbaryl were higher in both BT and ZT than in the underlying soils, the K OC and Δ G values of 2,4-D were significantly higher in BS and ZS than in the overlying thatch materials. The 2,4-D and Triclopyr had higher leaching indices (LI) than Carbaryl for both BT and ZT materials than the respective soils. The Carbaryl, however, had a higher LI for soils than for thatch materials. Averaged across thatch materials and soils, COrg accounted for 96, 85, and 84% variations in Carbaryl, 2,4-D, and Triclopyr adsorption, respectively. Among the COrg fractions, lignin followed by CFA and CHA accounted for greater adsorption of pesticides, especially Carbaryl. The concentration of CHA and CFA bound Fe did not correlate with K f and 1/n values of pesticides. 相似文献
17.
Partitioning of polycyclic aromatic hydrocarbons to solid-sorbed nonionic surfactants 总被引:1,自引:0,他引:1
The partition of hydrophobic organic compounds (HOCs) into solid-sorbed surfactant has a crucial role in describing and predicting the distribution of HOCs in solid-water-surfactant systems. The experimental results of this study indicated that the partition coefficients of polycyclic aromatic hydrocarbons (PAHs) into the solid-sorbed surfactant (Ksm) increased with an increase in the sorption amount of surfactants onto solid and reached a stable maximum value (Km sm) at the sorption of surfactants in saturation state, at which the solid surface was completely covered with the surface micelle (or admicelle). The fitted Km sm values for PAHs with different surfactants were found to have a good linear relationship with the corresponding partition coefficient of PAHs to surfactant micelles in solution (Kmc), and then a model was developed to describe and predict the distribution of PAHs in solid-water-surfactant systems. These results are of practical interest for developing effective and safe surfactant-enhanced remediation technologies. 相似文献
18.
The migration and transformation of dissolved organic matter during the freezing processes of water 总被引:1,自引:0,他引:1
This study investigated the partitioning behavior of dissolved organic matter (DOM) in liquid and ice phases, as well as the changes in the optical properties and chlorine reactivity of DOM during the freezing processes of water. DOM was rejected from the ice phase and accumulated in the remaining liquid phase during water freezing. Moreover, the decrease in freezing temperature, as well as the increase in dissolved organic carbon (DOC) concentration of feed water, caused an increase in DOM captured in the ice phase. The ultraviolet-absorbing compounds, trihalomethane precursors, as well as fulvic acid- and humic acid-like fluorescent materials, were more liable to be to be rejected from the ice phase and were more easily retained in the unfrozen liquid phase during water freezing, as compared with organics (on average) that comprise DOC. In addition, it was also found a higher accumulation of these organics in the unfrozen liquid phase during water freezing at higher temperature. The freeze/thaw processes altered the quantity, optical properties, and chlorine reactivity of DOM. The decrease in ultraviolet light at 254 nm as well as the production of aromatic protein- and soluble microbial byproduct-like fluorescent materials in DOM due to freeze/thaw were consistently observed. On the other hand, the changes in DOC, trihalomethane formation potential, and fulvic acid- and humic acid-like fluorescence caused by freeze/thaw varied significantly between samples. 相似文献
19.
Wenping Zhang Changsheng Guo Jiapei Lv Xu Li Jian Xu 《Frontiers of Environmental Science & Engineering》2022,16(3):30
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