Catalytic dechlorination of chlorobenzene in water by Pd/Fe bimetallic system

IntroductionChlorinatedorganiccompoundshavebeenusedonalargescaleinthechemical,petrochemical,andelectronicindustries.Inrecentyears ,worldwideattentionhasbeengiventotheenvironmentalandhealthimpactofthemasaclassofcontaminants .Severalareknowntocauseozonedepletion ,whileothersproduceadverseeffectsonthehumancentralnervoussystemandhavebeenlinkedtodiseasessuchascancer.Almostallofthechlorinatedaromaticcompoundsaretoxicandthermallystable .Oncereleasedintoenvironment,theywillaccumulateinthesurroundings…     

四氨基酞菁钯/γ-Al_2O_3可见光催化降解罗丹明B

采用浸渍法制备了四氨基酞菁钯(PdTAPc)/γ-Al_2O_3负载型光催化剂,采用UV-Vis,FTIR,XRD,SEM技术对其进行了表征,并将其用于罗丹明B的可见光催化降解,考察了光催化剂加入量、溶液pH、H_2O_2加入量、反应温度对罗丹明B降解效果的影响,并对光催化剂的稳定性进行了测试。表征结果显示,PdTAPc以圆片状负载于γ-Al_2O_3上,二者的结构均未发生明显变化。实验结果表明:在光催化剂加入量1.6 g/L、溶液pH 7.0、H_2O_2加入量12 mmol/L、反应温度20℃的优化条件下反应120 min,罗丹明B(质量浓度0.05 g/L)的降解率高达95%;光催化剂具有较高的稳定性,使用4次后罗丹明B的降解率仍高于85%。     

Determination of Au(III) and Pd(II) ions by flame atomic absorption spectrometry in some environmental samples after solid phase extraction

A simple and sensitive solid phase extraction method was developed for simultaneous separation and preconcentration of gold and palladium ions with N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridine-4-yl-4H-1,2,4-triazol-3-yl)thio]acetyl}hydrazine carbo thioamide complex on Amberlite XAD-1180 resin before their determination by flame atomic absorption spectrometry. Some analytical parameters such as HNO₃ concentration of the sample solution, amount of complexing agent, sample volume, eluent type and volume, effects of foreign ions and adsorption capacity of the resin were investigated for quantitative recovery of gold and palladium ions. The effects of some anions and cations were also examined. Under optimum conditions, the detection limits for gold and palladium ions were found to be 0.29 and 0.19 μg L^?1, respectively. The preconcentration factor for gold and palladium was 250. After being validated by standard addition and analysis of standard reference material, the procedure was successfully applied to the analysis of sea and stream water, anodic slime, gold ore, soil and electronic waste.     

堇青石负载Pd和过渡金属氧化物催化剂的表征及其对CO的催化氧化活性

以堇青石蜂窝陶瓷(CC)为载体,采用浸渍法制备了堇青石负载Pd和过渡金属混合氧化物催化剂,记作Pd-M-Mn(M=Cu,Co,Fe,Ni)/CC。实验结果表明:Pd-Co-Mn/CC催化剂的催化活性最高;随着Pd负载量的增加,CO转化率提高;当Pd负载量为1.00%时,反应温度为150℃时CO转化率达到98%,200℃时CO转化率达到100%;在反应温度150℃条件下,Pd-Co-Mn/CC催化剂(Pd负载量1.00%)的CO转化率在前30h内小幅度下降,随后稳定在90%以上,反应100h后,催化剂表面颜色由黑色变为棕褐色。     

钛负载纳米Pd粒子电极的电化学催化性能研究

采用电化学沉积法将纳米钯粒子负载在钛板上,制备钛负载纳米钯粒子的NanoPd/Ti电极.利用循环伏安法和线性扫描伏安法对比研究NanoPd/Ti电极与Ti电极的电化学性能,以及分别对氯苯和硝基苯模拟废水电化学催化性能,表明NanoPd/Ti电极循环伏安过程出现新的氧化峰和还原峰,反应电位明显正移,反应过程峰电流也明显增大.通过降解实验,NanoPd/Ti电极可以在更低电压,更短时间内达到更好CODcr去除效果.     

Significance of platinum group metals emitted from automobile exhaust gas converters for the biosphere

Intention, Goal, Scope, Background  Following the introduction of automobile catalytic converters the platinum group metals (PGM) platinum (Pt), palladium (Pd) and rhodium (Rh) gain on increasing interest in environmental research as these metals are emitted with exhaust fumes into the environment. Consequently, elevated PGM levels were found in different environmental matrices uch as road dusts, soils along heavily frequented roads, sediments of urban rivers etc. Accordingly, the effects of increasing PGM emissions on the biosphere are controversially discussed. Objective  This paper summarizes the present knowledge on the biological availability of PGM to plants and animals. As biological availability is one of the most decisive factors determining the toxicologi-cal potential of xenobiotics, this information is very important to evaluate the possible threat of the noble metals to ecosystems. Results and Discussion  The availability of soluble as well as particle bound PGM to terrestrial plants was demonstrated in several studies. Experimental investigations revealed uptake of Pt, Pd and Rh also by aquatic plants. Additionally, the biological availability of the noble metals for animals has been verified in experimental studies using soluble metal salts, catalytic converter model substances, sediments of urban rivers, road dust or tunnel dust as metal sources. These studies refer mainly to aquatic animals. Beside of free living organisms, in particular worms parasitizing fish demonstrated a high potential to accumulate PGM. This could be of great interest in respect of biomonitoring purposes. Generally, for plants as well as for animals Pd turns out to be the best available metal among the PGM. Compared to other heavy metals, the biological availability of PGM from road dust to zebra mussels(Dreissena polymorpha) ranged between that of Cd and Pb. Conclusion  Especially chronic effects of PGM on the biosphere can not be excluded due to (1) their cumulative increase in the environment, (2) their unexpected high biological availability and bioaccumulation and (3) their unknown toxicological and ecotoxicological potential. However, it appears that acute effects on ecosystems due to anthropogenic PGM emission are not likely. Recommendation and Outlook  Research on environmental PGM contamination of the biosphere, especially the fauna, and on long-term toxiciry of low PGM concentrations is highly appreciated. These studies require very sensitive analytical techniques to determine PGM even in low sample amounts. Research has to be done in particular on reliable determination of (ultra) trace levels of Pd and Rh as the lack of data on these two metals is mainly due to analytical problems.     

城市环境铂族金属分布特性及生态健康风险研究进展

随着铂族金属铂（Pt）、钯（Pd）、铑（Rh）被广泛应用于汽车尾气催化净化器中,这三种金属在自然界中的含量逐渐升高。越来越多的研究表明,这几种曾被认为对环境影响较小的金属的确会带来潜在的生态健康风险。本文概括了国内外城市各种环境介质的含量分布,重点分析了铂族金属的源解析方法、粒径分布特性、影响其排放的因素和其潜在的生态健康风险。就全世界的城市来看,灰尘、空气、土壤、沉积物等各种环境介质中铂族金属的含量均有显著提高,主要来源于汽车三元催化净化器。这三种金属倾向于富集在细颗粒中,行车模式是影响其排放量的重要因素,自然界的共存物质可增强它们的溶解性和迁移性,从而使它们的生物可利用性大大提高。生物体吸收这类金属后,可与体内的物质发生反应,形态发生变化,毒性增强。在以后的研究中,除了持续跟踪调查这三种金属在环境中的含量水平以外,还应加强研究这三种金属在环境中的颗粒分布、迁移转化、形态变换、生物可利用性以及生物毒性等,使我们能够更好地评估其生态健康风险,并为与之相关的应用研发、防范措施、政策制订提供引导和支持。     

负载型纳米Fe-Pd降解水溶性偶氮染料

采用阳离子交换树脂表面为载体,合成了负载型纳米Fe-Pd二元复合金属材料,采用扫描电子显微镜(SEM)和能谱分析对该材料进行表征,研究了其对一些水溶性偶氮染料的降解效果.实验表明,该材料对0.05 g.L-1甲基橙、日落黄、酸性橙8、金橙G和活性红2等偶氮染料有较好的降解效果,纳米双金属中Pd含量的增加有利于染料的降解;反应体系初始pH值对染料的降解率影响较大,本研究中,pH 4酸性条件下降解效果最佳;制备的材料在第10次活化后,仍有较好的降解效果;为环境中偶氮染料的降解提供了一种有效的方法.     

钯离子液相催化氧化低浓度磷化氢

采用Pd^2＋液相催化氧化低浓度PH3,考察了Pd^2＋浓度、O2体积分数、PH3质量浓度、混合气流量、反应温度等因素对Pd^2＋吸收液去除低浓度PH3效果的影响。实验结果表明,采用10mL Pd^2＋浓度为0．112mol／L的水溶液作为吸收液净化含低浓度PH3的混合气,在反应温度22℃、O2体积分数5％、PH3质量浓度850mg／m^3、混合气流量190mL／min的条件下,印min之内PH3去除率保持在90％以上。Pd^2＋浓度越高、O2体积分数越大、反应温度越高,PH3去除率越高;混合气流量越大,PH3去除率越低;反应温度越低、O2体积分数越大,PH3去除率的下降速率越小。     

制备方法对MgAl水滑石衍生氧化物负载钯催化剂丙烷完全氧化活性的影响

以沉积沉淀法(DP)、浸渍法(IM)和共沉淀法(CP)制备MgAl水滑石衍生氧化物负载钯催化剂,用ICP、XRD、SEM、TEM、EDS、TPR以及比表面测定等手段对催化剂进行了表征.ICP和XRD数据表明用上述3种方法均可成功制备水滑石为前体载钯催化剂.SEM、TEM、EDS数据表明不同方法制备的样品具有不同的形貌以及钯在其中的分散度.综合各类表征数据可知Pd在催化剂中暴露的活性位是影响其活性的主要因素.