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291.
涂铁砂吸附镉的动力学研究 总被引:1,自引:0,他引:1
研究了10℃,20℃,40℃的温度下,涂铁砂(Iron oxide coated sand,简称IOCS)对镉的吸附动力学。镉在IOCS表面的吸附可分为两个阶段,吸附反应的前60min为快速吸附阶段,60min后,吸附速率明显变慢。温度升高加快了镉在IOCS表面的吸附速率。用Elovich动力学模型,准一级反应模型,准二级反应模型,二级反应模型和粒内扩散动力学模型对实验数据进行回归分析,准二级反应模型能更好地描述镉在IOCS表面的吸附,各吸附模型的模拟优劣顺序为:准二级模型>二级模型>Elovich模型>准一级模型>粒内扩散模型。 相似文献
292.
Climatology,Trend Analysis and Prediction of Sandstorms and their Associated Dustfall in China 总被引:2,自引:0,他引:2
Sun Leng Zhou Xukai Lu Juntian Kim Yong-Pyo Chung Yong-Seung 《Water, Air, & Soil Pollution: Focus》2003,3(2):41-50
Based on statistical data about Sand and Dust Storms (SDS) and their associated dustfall, features of temporal and spatialdistribution were studied first in this article. SDS and associateddustfalls occurred most often in northern China, especiallynorthwestern China. However, in the last two years, they have atendency to occur on the central and western parts of the Inner Mongolia Autonomous Region. As a result, Beijing is now among the impact areas, and the Chinese government is paying greaterattention to the matter. The changing trends of SDS and associated dustfalls were subsequently analyzed. Occurrences were seen to be decreasing with the feature of fluctuation duringthe period of 1954–2001, but they have slightly increased since 2000. Also, climate factors related to SDS and associated dustfalls were discussed. Finally, it was recommended that methods to predict SDS in China be further studied in the future. 相似文献
293.
Amanda B. White Praveen Kumar Patricia M. Saco Bruce L. Rhoads Ben C. Yen 《Journal of the American Water Resources Association》2003,39(6):1547-1560
ABSTRACT: The objective of this work is to determine the effects of extension of a stream network through land drainage activities during the late 1800s on the hydrologic response of a watershed. The Mackinaw River Basin in Central Illinois was chosen as the focus and the pre‐land and post‐land drainage activity hydrologic responses were obtained through convolution of the hill slope and channel responses and compared. The hill slope response was computed using the kinematic wave model and the channel response was determined using the geomorphologic instantaneous unit hydrograph method. Our hypothesis was that the hydrologic response of the basin would exhibit the characteristic effects of settlement (i.e., increases in peak discharges and decreases in times to peak). This, indeed, is what occurred; however, the increase in peak discharges diminishes as scale increases, leaving only the decrease in times to peak. At larger scales, the dispersive effects of the longer hill slope lengths in the pre‐settlement scenario seem to balance the depressive effects of the longer path lengths in the post‐settlement scenario, thus the pre‐settlement and post‐settlement peak discharges are approximately equivalent. At small scales, the dispersion caused by the hill slope is larger in the pre‐settlement case; thus, the post‐settlement peak discharges are greater than the pre‐settlement. 相似文献
294.
295.
在研发矸石山自燃预警技术中着重了解煤矸石山自燃机理,同时对煤矸石堆积中矸石内部的动态的要素探索,达到阻断煤矸石自燃的目的,矸石山自燃区的准确定位和自燃的早期临界温度监控很重要,所以,很有必要针对矸石山自燃预警系统的研发来确保煤矿生产安全,促进恢复矸石山生态环境着手于基础工作。 相似文献
296.
表面活性剂去除土壤和地下水中LNAPLs作用机制研究 总被引:5,自引:2,他引:3
去除多孔介质中滞留的LNAPLs,表面活性剂对LNAPLs的增溶和降低界面张力是关键.在实验测得不同浓度Triton X-100溶液对正十六烷的增溶以及它们之间界面张力的基础上,通过平衡清洗实验和砂柱冲洗实验分析了不同形态正十六烷的产生规律和机制.结果表明,正十六烷溶解能力与Triton X-100浓度成正比,当Triton X-100浓度大于临界胶束浓度CMC时,计算得摩尔增溶比MSR=1.680 4,胶束相/水相分配系数对数值lgKmc=1.715 8;正十六烷-Triton X-100溶液之间界面张力与Triton X-100浓度成反比,其变化规律符合高斯模型(R2=0.996 4);溶解态正十六烷和自由态正十六烷与增溶和降低界面张力分别有较好的对应关系,表明增溶和降低界面张力都对多孔介质中正十六烷去除有影响,其中降低界面张力可以有效增加多孔介质中正十六烷的流动性,在正十六烷去除过程中起主要作用. 相似文献
297.
298.
Evaluation of the adsorption potential of titanium dioxide nanoparticles
for arsenic removal 总被引:1,自引:1,他引:0
The adsorption potential of titanium dioxide (TiO2) nanoparticles for removing arsenic from drinking water was evaluated. Pure and iron-doped TiO2 particles are synthesized via sol-gel method. The synthesized TiO2 nanoparticles were then immobilized on ordinary sand for adsorption studies. Adsorption isotherms were conducted on the synthesized nanoparticles as well as the sand coated with TiO2 nanoparticles under varying conditions of air and light, namely, the air-sunlight (A-SL), air-light (AL), air-dark (AD) and nitrogen-dark (ND). X-Ray diffraction (XRD) analysis showed that the pure and the iron-doped TiO2 nanoparticles were in 100% anatase crystalline phase with crystal sizes of 108 and 65 nm, respectively.Adsorption of arsenic on the three adsorbents was non-linear that could be described by the Freundlich and Langmuir adsorption models. Iron doping enhanced the adsorption capacity of TiO2 nanoparticle by arresting its grain growth and making it visible light responsive resulting in a higher affinity for arsenic. Similarly, the arsenic removal by adsorption on the sand coated with TiO2 nanoparticles was the highest among the three types of sand used. In all cases, As(V) adsorbed more compared with As(III). Solution pH appeared to be the most important factor in controlling the amount of arsenic adsorbed. 相似文献
299.
以北京2002年的ρ(PM10)日平均值和气象要素观测资料为例,根据小波分析的原理,利用Matlab小波分析工具,对逐日ρ(PM10)时间序列进行分解和重构,分析了该地区ρ(PM10)的年变化规律和突变特征.结果表明:2002年北京PM10污染季节性变化强,春季最严重,冬季次之,夏、秋季节较好;全年共有4个突变点,均出现在沙尘暴或强沙尘暴期间,并指出沙尘天气是北京ρ(PM10)发生突变的主要影响因素.在此基础上,根据形成原因及气象资料分析,将2002年PM10重污染天气过程分为沙尘型和排放累积型2类,并阐述了形成各类PM10重污染天气的气象原因. 相似文献
300.
针对神东矿区大柳塔煤矿52304工作面通过风积沙较厚区域时强烈的矿压显现现象,通过理论分析与物理相似模型以及现场测试等方法,建立工作面过风积沙区域时的力学模型,分析风积沙厚度对大采高工作面矿压显现规律的影响,对风积沙厚度对工作面关键层力学稳定性做出分析,并通过数值模拟对影响性进行研究。研究结果表明:风积沙厚度较大的开采区域,作用在覆岩主关键层结构上的载荷较大,造成主关键层破断块体的结构回转变形失稳,造成工作面矿压显现极强烈;大采高和风积沙厚度较大条件下距煤层较远的主关键层破断运动也会对工作面矿压显现产生影响,且采高、厚风积沙因素缺少其中一个时,主关键层均不会对工作面矿压产生明显影响。 相似文献