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461.
机械工业废水中重金属离子的处理工艺研究 总被引:4,自引:0,他引:4
研究了过氧化钙处理剂对机械工业废水中重金属离子锰、铜、锌、铬的处理工艺,以及过滤方法对重金属离子去除率的影响。处理的最佳条件为:过氧化钙用量0.1%~0.2%,处理时间30min,处理温度为室温,处理过程中不需调整pH。 相似文献
462.
Metal complexation by natural ligands is important for metal transport and distribution in surface and ground water. The goal of the work was to study the ligand exchange rate for two important metal ions in natural aquatic systems (Al, Fe) was determined using EDTA and natural organic matter (NOM) of humic type as ligands. After adding EDTA to a solution containing metal-NOM complexes, these complexes dissociated and metal-EDTA complexes were formed. Metal-NOM complexes were separated from metal-EDTA complexes with the help of size-exclusion chromatography and detected by on-line inductively coupled plasma-mass spectrometry (ICP-MS). Injecting the samples into the system over time after addition of EDTA allowed us to measure the rate of the exchange of NOM by EDTA. The experiments could be well described with a first-order rate law assuming that the dissociation of the metal-NOM complexes is the rate-determining step. The exchange rate of Fe was found to be faster than that of Al. This corresponds well with the exchange rate of water molecules from the coordination sphere of the metal ions, which is also faster for Fe than for Al. Furthermore, the UV and the fluorescence signal of the chromatograms were measured. The results indicate that no disaggregation of NOM molecules took place, although about 75-85% of the aggregate-forming metal ions exchanged NOM by EDTA in their coordination sphere. This suggests clearly the fundamental role of NOM in colloidal transport of metals and in their bioavailability. 相似文献
463.
Pesavento M Biesuz R Profumo A Soldi T 《Environmental science and pollution research international》2003,10(5):317-320
SCOPE: The detection and investigation of metal ions bound in strong complexes in natural waters is a difficult task, due to low concentration of the metal ions themselves, and also of the strong ligands, which, moreover, are often not of a well-defined composition. Here, a method is proposed for the investigation of the speciation of metal ions in natural waters. OBJECTIVE AND METHOD: It is based on the sorption of metal ions on strongly sorbing ion exchange resins, i.e. complexing resins. For this reason the method is called Resin Titration. It has been shown in previous investigations that the concentration of metal ion totally sorbed by a particular resin, and its reaction coefficient in the solution phase in the presence of the resin, can be determined from the sorption data using a simple relationship. Here, a data treatment (the Ruzic linearization method) is proposed for also determining the concentration of the ligands responsible for the complex in equilibrium with the resin. RESULTS: The method was applied to data obtained by Resin Titration of a freshwater and a seawater. Copper(II) and aluminium(III) were considered, using Chelex 100 as a titrant, due to its strong sorbing properties towards these metal ions. The results were: the total metal concentration in equilibrium with the resin, the side reaction coefficients, and the concentration of ligands. In all these cases the ligands forming very strong complexes were found to be at concentration lower than that of the metals. CONCLUSION: The Ruzic linearization method allows the determination of the concentration of the ligands forming very strong complexes in equilibrium with Chelex 100. The reaction coefficient was better determined by the calculation method previously proposed for RT. The ligands responsible for the strong complexes were found to be at low concentration, often lower than that of the metal ions considered. The metal in the original sample is partly bound to these ligands, since the complexes are very strong. Only a part of the metal is linked to weaker ligands, or free. 相似文献
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Seasonal Fluctuation in Heavy Metal Pollution in Iran´s Siahroud River - A Preliminary Study (7 pp) 总被引:1,自引:0,他引:1
Charkhabi AH Sakizadeh M Rafiee G 《Environmental science and pollution research international》2005,12(5):264-270
Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality
of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The
scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and
municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed
into the various water systems supported by the river, including the water system for Rasht City.
Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe,
and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic
Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed
by IR gas measurement.
Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels
as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial
land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly
from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour
of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic
sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster
analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In
addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This
observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly
different.
Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution
levels of Pb, Cd, Mn and Fe. 相似文献
468.
东京根霉对重金属Cr^3+、Mn^2+和Zn^2+的吸附研究 总被引:5,自引:0,他引:5
张建梅 《环境污染治理技术与设备》2006,7(8):64-68
利用固定化发酵中产生的废菌体——东京根霉(Rhizopustonkinesis)去除废水中Cr^3+、Mn^2+和Zn^2+,研究了预处理、pH、温度、金属离子初始浓度、吸附时间等条件对吸附量的影响。结果表明,用NaOH浸泡4—6h、在pH=5—6,温度25-35℃时吸附效果最好,用Langmuir、Freundlich和Temkin方程对其吸附等温线进行拟合,相关性都比较好;用不同的吸附动力学方程描述东京根霉吸附金属离子的最优和最次模型分别为Elovich方程和一级扩散方程,双常数方程和抛物线扩散方程拟合介于前二者之间。 相似文献
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以双氯芬酸为目标有机药物污染物,探究其在以锰矿石为填料并接种了异化金属还原菌(Geobactermetallireducens,简称GS-15细菌)的垂直流人工湿地中的去除过程.结果表明,双氯芬酸在锰矿石人工湿地中的平均去除率最高为23.56%.采用XRD和XRF对反应前后的锰矿石进行物相和元素相对含量分析,得出锰(Mn)是参与降解双氯芬酸的关键响应元素.GS-15细菌利用锰矿石发生异化还原对双氯芬酸的氧化降解是锰矿石人工湿地对双氯芬酸的主要去除途径.此外,利用液质联用技术(LC-MS/MS)对降解产物进行鉴定,发现双氯芬酸被降解生成了5-羟基双氯芬酸、双氯芬酸-2,5-亚氨基琨和1,3-二氯苯三种降解产物,该研究成果对有机药物废水的深度处理提供新的方法和理论指导. 相似文献