脂肪磺酸基阳离子交换树脂对Cr~(3+)的吸附和解吸性能

研究了脂肪磺酸基阳离子交换树脂(简称树脂)对Cr3+的吸附和解吸性能。在溶液初始Cr3+质量浓度为250mg/L、吸附温度为25℃、溶液pH为5的条件下,树脂对Cr3+的吸附量最大。Cr3+质量浓度在实验范围内,等温吸附过程均符合Langmuir和Freundlich方程,最大吸附量为18.6208mg/g。树脂对Cr3+的吸附在吸附时间为180min时趋于平衡,且吸附为液膜扩散控制。随吸附温度的升高(10～55℃),树脂对Cr3+的吸附量略有增加。用质量分数为5%的HCl溶液可将吸附在树脂上的Cr3+解吸,解吸率近100%,且重复5次吸附和解吸过程,树脂对Cr3+的吸附量基本保持不变。     

Pesticide adsorption on a calcareous soil modified with sewage sludge and quaternary alkyl-ammonium cationic surfactants

BACKGROUND, AIM AND SCOPE: Pesticides are often found in soil as a result of their application to control pests. They can be transported on soil particles to surface waters or they can lixiviate and reach other environmental compartments. Soil modification with amendments, such as sewage sludge, and with surfactants, h been proposed to reduce pesticide environmental fate. METHODS: The sorption of atrazine, methidathion and diazinon using the batch technique has been studied on non-modified soil and soil modified with sewage sludge and cationic surfactants, as well as the effect of their addition on soil properties such as organic carbon (OC) content and exchange cations. RESULTS AND DISCUSSION: The OC content of the surfactant modified soils was the highest with the surfactant with the longest hydrocarbon chain (hexadecyltrimethyl ammonium bromide, HDTMA). The results of the OC content run in parallel with the increase in pesticide retention. When the sorption was n malized to soil OC content, the retention induced by addition of HDTMA was still the highest, which is an indication that the organic matter derived from the organic cations is a more effective medium to retain dissolved contaminants, than organic matter from native soil. The addition of sewage sludge to the soil did only result in a slight increase of the soil CEC and, hence, moderately affected the ability of the cationic surfactant to retain the pesticides. CONCLUSIONS: The addition of cationic surfactants to soil would possibly reduce the movement to groundwater of atrazine, methidathion and diazinon. In the case of HDTMA, the decrease in sorption at high surfactant loadings was very slow, being that the surfactant was able to retain the pesticides at concentration values which clearly exceeded the monolayer coverage. RECOMMENDATIONS AND PERSPECTIVES: Contamination by pesticides, which are present in the soil due to their direct input in this medium or to spills or illegal tipping, may be hindered from migration to groundwater by application of a cationic surfactant.     

流动注射分光光度法研究离子强度对活性炭吸附阴、阳离子染料的影响

运用流动注射分光光度法,考察了不同离子强度(NaCl)下,在水溶液中表面带负电的活性炭分别吸附阴、阳离子染料的动力学行为。实验结果表明,对于所考察的2种阳离子染料和3种阴离子染料,活性炭的表观吸附速率常数均随着离子强度的增大而增大。这种加速吸附效应的出现,主要是因为离子强度的增大促进了活性炭表面与染料之间的非静电力作用。     

不同晶型锰氧化物去除水中亚甲基蓝染料的研究

利用溶液法和固态合成法制备α、β、γ和δ晶型粉末二氧化锰,借助等电点测定技术、颗粒计数仪、傅立叶-红外光谱、X射线衍射光谱和原子力显微镜对其性质进行了表征;并通过静态吸附平衡实验考察了上述物质对水溶液中阳离子染料亚甲基蓝的去除效能.结果表明,δ二氧化锰去除染料的能力相对最强,试验条件下染料去除率达99.0%,脱色能力受pH变化的影响也最小;其脱色机理可能是染料中的N原子与二氧化锰表面羟基形成的氢键作用,以及静电吸引的叠加,其中氢键去除占主导地位.其它晶型的二氧化锰只在强酸性时存在表面羟基;故只在强酸性时有良好的脱色能力.pH值是影响去除染料能力的关键因素,脱色能力随pH值的变化规律因晶型而异,体系温度和颗粒分布也对去除能力有一定影响.     

浮选法处理阳离子染料结晶紫废水的研究

采用浮选方法,以结晶紫作为阳离子染料模型,以十二烷基苯磺酸钠做捕集剂,对水溶液中染料进行去除处理.研究了十二烷基苯磺酸钠的用量、染料浓度、浮选时间、pH值等对浮选效率的影响,优化了浮选条件,并对方法的机理进行了初步的探讨.该法所用装置简单,试剂价廉,操作简便,去除率高,在染料废水的处理方面有良好的应用前景.     

黄铁矿催化类Fenton反应处理阳离子红X-GRL废水

基于对天然矿物黄铁矿进行SEM、EDS表征的基础上,以黄铁矿为非均相类Fenton催化剂,以偶氮染料阳离子红X-GRL为目标污染物,考察了催化剂双氧水用量、溶液初始pH值、阳离子红X-GRL初始浓度、反应时间等因素对染料脱色效果的影响.结果表明,在H2O2浓度为26.6mg/L、矿用量1g/L、溶液初始pH值6.4左右的条件下,反应2min后,染料脱色率达95%左右.进行了黄铁矿在水溶液中的酸性氧化实验并且考察了Fe2+、SO42-浓度及溶液pH随矿重复利用次数的变化规律.初次使用的黄铁矿具有很强的酸性氧化特性,反应过程中伴随着大量Fe2+、SO42-及H+的溶出.染料的快速脱色主要是均相Fenton反应作用的结果.黄铁矿作为一种新的催化剂大大提高了类Fenton反应的催化活性,而且该新型类Fenton反应能克服传统Fenton反应适用pH范围小的局限性,拓展了Fenton反应在废水处理中的应用.     

Cationic organobismuth complex as an effective catalyst for conversion of CO2 into cyclic carbonates

In order to achieve high-efficiency conversion of CO₂ into valuable chemicals, and to exploit new applications of organobismuth compounds, cationic organobismuth complex with 5,6,7,12-tetrahydrodibenz[c,f][1,5] azabismocine framework was examined for the first time for the coupling of CO₂ into cyclic carbonates, using terminal epoxides as substrates and tetrabutylammonium halide as co-catalyst in a solvent-free environment under mild conditions. It is shown that the catalyst exhibited high activity and selectivity for the coupling reaction of CO₂ with a wide range of terminal epoxide. The selectivity of propylene carbonates could reach 100%, and the maximum turnover frequency was up to 10740 h⁻¹ at 120°C and 3 MPa CO₂ pressure when tetrabutylammonium iodide was used as co-catalyst. Moreover, the catalyst is environment friendly, resistant to air and water, and can be readily reused and recycled without any loss of activity, demonstrating a potential in industrial application.     

阳离子絮凝剂P(AM-DAC)的合成、表征及应用

以丙烯酰胺(AM)和丙烯酰氧乙基三甲基氯化铵(DAC)为单体,过硫酸钾(KPS)为引发剂,通过水溶液聚合的方法合成了阳离子絮凝剂P(AM-DAC)。探讨了单体配比、单体浓度、引发剂用量、反应时间、反应温度等因素对阳离子聚丙烯酰胺(CPAM)主要性能的影响。实验得出了较佳的反应条件:聚合温度为70℃,引发剂用量为0.16%,单体配比m(AM):m(DAC)=1:8,总单体浓度为20%,反应时间3 h。在上述条件下,所得阳离子聚丙烯酰胺絮凝剂的特性黏数为18.692 4 dL/g,在其加入量为0.003%的条件下处理巡司河污水,上层清液透光率达90.7%,污泥脱水率达89.2%。并对该聚合物絮凝剂的结构和热行为进行了表征。     

有机颜料废水的混凝预处理研究

利用絮凝剂阳离子聚丙烯酰胺(CPAM)和混凝剂聚合氯化铝(PAC)对有机颜料废水进行混凝处理,考察了单独使用CPAM、PAC及两者联合使用的处理效果,探讨了初始pH值、混凝剂投加量对处理效果的影响.结果表明,CPAM与PAC复配处理该废水时效果较好,水样pH值为7.0;CPAM与PAC的投药量分别为10mg/L和150mg/L时,浊度去除率可达97.56％.     

粉末凹凸棒石对水溶性阳离子染料废水的脱色研究

本文研究了凹凸棒石粘土处理阳离子染料废水的吸附脱色规律。结果表明,粉末凹凸棒石对水溶性阳离子染料具有优良的脱色效果。例如,染料初始浓度１００ｍｇ·ｌ＾－１（色度相当于２２００￣４０００倍）,粘土投加量０．５％,七种被研究的阳离子染料废水平均脱色率近９９％,吸附机理主要是离子交换。