排序方式: 共有37条查询结果,搜索用时 15 毫秒
11.
The adsorption/desorption behavior of copper and cadmium on soils was investigated in this study. The adsorption isotherm of copper and cadmium conformed to Langmuir equation better than Freundlich equation. The effect of ionic strength, pH, and organic acid, including ethylenediamine tetraacetic disodium acid salt (EDTA), citric acid, oxalic acid and tartaric acid, on the desorption of copper and cadmium was studied. The desorption of copper and cadmium increased with the increase of ionic strength, while the desorption decreased with the rise of pH. The desorption of copper and cadmium enhanced by organic acids was influenced by pH. EDTA showed excellent enhancement on the desorption of both copper and cadmium; citric acid demonstrated great enhancement on the desorption of copper but negligible enhancement on the desorption of cadmium; oxalic acid enhanced the desorption of copper only at pH around 6.4 and enhanced the desorption of cadmium in the pH range from 6.4 to 10.7; tartaric acid slightly enhanced the desorption of copper but negligibly enhanced the desorption of cadmium. The desorption mechanism in the presence of organic acids were explained as the competition of complexation, adsorption and precipitation. The net effect determined the desorption efficiency. This study provided guidance for the selection of organic acids to enhance the electrokinetic (EK) remediation of copper and cadmium from contaminated soils. 相似文献
12.
工业机器也属职业事故的重要危险源之一。在其设计时 ,有效地进行安全性分析是消除和控制工业机器中存在的固有危险的最佳途径。为此 ,推荐了一种用于工业机器的安全分析模式 ;并对已有的安全分析方法进行了重点选择 ,将供设计人员使用的安全分析方法从百余种减少到 11种 ;还对这些方法进行了分类 ,可供设计人员在设计工业机器时 ,较方便地选择和系统地应用。 相似文献
13.
The adsorption and desorption characteristics of Al3+ to/from humic acids at di erent pH, ionic strength, and temperature were
studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount (Qmax) and
adsorption constant (k) increased, whereas, the absolute value of standard thermodynamic molar free energy change ( G0
m) decreased
with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0.15 mol/L, Qmax and k
increased and the absolute value of G0
m decreased at constant pH and temperature. High temperature was unfavorable for the adsorption
reaction, as indicated by the dramatic decrease of Qmax and the absolute value of G0
m with an increase in temperature. The standard
thermodynamic molar free energy change ( G0
m) and the standard thermodynamic enthalpy change ( H0m
) of the adsorption reaction
were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-Al3+ complex
accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al3+
from humic acids. These results demonstrated that the Al3+ adsorption reaction was a “biphase” reaction, and adsorption occurred at
both the interior and exterior adsorption sites of humic acids. 相似文献
14.
概述了水体沉积物中磷的存在形态以及磷素释放的影响因素。主要讨论了溶解氧、温度、pH值、水体扰动、沉积物组成、生物作用和光照对沉积物磷释放的影响,并提出了目前存在的问题和未来发展的方向,为水体富营养化的研究提供了科学的理论依据。 相似文献
15.
重庆市不同材质路面径流污染特征分析 总被引:3,自引:3,他引:0
通过采集和监测2010年雨季重庆市同一区域的2条不同材质公路的3次降雨径流过程水样,研究了沥青路面和水泥路面径流的污染特征和差异.结果表明,2种材质路面径流中化学需氧量(COD)、总氮(TN)和总磷(TP)的次降雨平均浓度(EMC)均超过国家地表水环境质量V类水质标准(GB 3838—2002);沥青路面径流中总悬浮物(TSS)、COD和TP的浓度明显高于水泥路面,分别为水泥路面的2.05、1.35和1.27倍;沥青路面污染物的初始浓度普遍高于水泥路面,TSS和TP浓度最大值的出现时间滞后于水泥路面.在2010年6月19日、7月4日和7月9日的3场降雨事件中,沥青路面30%径流量与此时径流污染物浓度之比的平均值(FF30)分别为水泥路面的1.26、1.07和1.32倍.沥青路面坑槽较多和成分复杂是导致其表现出不同于水泥路面的径流污染特征的重要原因. 相似文献
16.
超高效液相色谱-串联质谱法同时测定环境水样中的15种抗生素 总被引:2,自引:0,他引:2
采用固相萃取/超高效液相色谱-串联质谱法,建立了水样中磺胺类、四环素类、氟喹诺酮类、大环内酯类和氯霉素类15种抗生素的同时测定方法.水样经HLB固相萃取柱富集,ACQUITY UPLC BEH C_(18)色谱柱分离,以乙腈和5 mmol·L~(-1)乙酸铵溶液(含0.1%甲酸)为流动相梯度洗脱,电喷雾离子源-串联质谱多反应监测模式检测.结果表明,同时测定15种抗生素的线性范围为5—100μg·L~(-1)(相关系数均大于0.997),检出限为2.1—22.0 ng·L~(-1),定量限为6.9—71.8 ng·L~(-1);空白水样在加标水平为5、10、20μg·L~(-1)时,抗生素的回收率为50.1%—109.0%,相对标准偏差为0.4%—8.5%(n=7).用本文建立的方法检测某农业小流域环境水样,发现5类抗生素可被不同程度检出,浓度范围为0.1—106.2 ng·L~(-1). 相似文献
17.
Tong Juxiu Yang Jinzhong Hu Bill X. Sun Huaiwei 《Environmental science and pollution research international》2016,23(20):20378-20387
Environmental Science and Pollution Research - Prevention of chemical transfer from soil to surface runoff, under condition of irrigation and subsurface drainage, would improve surface water... 相似文献
18.
Jinzhong Li Xueju Li Shujuan Sun Xuegong Liu Suiliang Huang 《Frontiers of Environmental Science & Engineering in China》2011,5(4):573-584
A modularized and air adjustable constructed submerged plant bed (CSPB) which can be used to restore the eutrophic water is
introduced in this paper. This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth,
impaired water transparency, algae bloom and substantial duckweed in summer, which are not naturally suitable for growing
hydrophyte. This pilot study in Waihuan River of Tianjin, China, revealed that reduction of Chemical Oxygen Demand (COD),
Total Nitrogen (TN) and Total Phosphorus (TP) by the use of CSPB could be reached 30%–35%, 35%–40%, 30%–40% respectively in
the growing season (from March to October) and 5%–10%, 5%–15%, 7%–20% respectively in the winter (from November to February)
when the detention time was 6 d. The relationships between the concentration of COD, TN, TP and the detention time fit the
first-order kinetic equation well and the coefficients of determination (R
2) were all above 0.9. The attenuation coefficients k of the kinetic equation were a function of the water temperature. When
the water temperature was quite low or quite high, k was not significantly changed with increasing or decreasing water temperature. While when the temperature was in a moderate
range, an increase or decrease of water temperature would lead to a rapid increase or decrease in k. 相似文献
19.
20.
浅析胶莱盆地边缘层间滑动断层构造及其控矿机制 总被引:1,自引:0,他引:1
层间滑动断层构造产出于胶莱拉分盆地边部莱阳组砾岩与下伏下元古界荆山群变质岩系的不整合面上 ,是胶莱盆地东北缘蓬家夼和发云夼层间滑动角砾岩型金矿化的主要部位。层间滑动断层是在中生代白垩纪期间中国东部古板块和郯庐断裂构造活动造成的区域大地构造背景下 ,在胶莱走滑拉分盆地的形成过程中产生的。在层间滑动断层由张性应力环境向挤压应力环境过渡过程中 ,源于地壳深部的金矿成矿流体 ,与大气降水混合形成工业金矿体 ,金矿化主要发生在构造角砾岩及碎裂岩的胶结物内 ,金矿化类型和强度具有明显的对称性。层间滑动断层以其产出于特定的部位、产状、成因及控矿机制的不同与其它伸展作用形成的断裂构造相区别。 相似文献