Preparation of Thin Palladium Composite Membranes and Application to Hydrogen/Nitrogen Separation

Thin palladium composite membranes were prepared by modified electroless plating method on a-alumina supports and a dense Pd/α-Al2O3 composite membrane with high hydrogen flux, good selectivity for hydrogen was obtained. It was tested in a single gas permeation system for hydrogen permeance and hydrogen selectivity over mtrogen. The hydrogen permeance of the corresponding membrane was ashigh as 2.45×10^-6mol·m^-2·s^-1.Pa^-1 and H2/N2 selectivityover700 at 623K and a pressure difference of 0.1MPa. The-main resistance of the composite membrane to H2 permeation lies in the aluminum ceramic support rather than the thin Pd layer.

On-line Separation and Preconcentration for Histamine Determination in Fish Meal Using Cation-Exchanger Resin

FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier stream through the injection valve. The merged streams were passed through a quartz flow cell in a spectrophotometer connected to recorder. Under the optimum conditions, the calibration curve was linear in the range 0.02-1.5 μg mL^-1 of histamine using the peak height as an analytical signal, while the detection limit was 0.01 μg mL^-1. The precision and accuracy of the method were studied depending upon the values of the relative standard deviation and relative error percentage. The selectivity of the method was investigated by studying the effect of interference from other species accompanied with histamine in fish meal. Under the optimum conditions, the system was used for on line separation, preconcentration of histamine. The proposed method was applied for the determination of histamine in fish meal. The results were compared with the standard method and a good agreement between the results was obtained.

Octa-<i>O</i>-Methoxy Resorcin [4] Arene Amberlite XAD-4 Polymeric Chelating Resin for Solid Phase Extraction, Preconcentration, Separation and Trace Determination of Ni(II), Cu(II), Zn(II) and Cd(II) Ions

Synthetic resin, Amberlite XAD-4 was linked covalently with the third generation supramolecule, octa-O-methoxy resorcin [4] arene through -N=N-group to form chelating resin, which has been characterized and effectively used for the separation and preconcentration of metal ions such as Ni(II), Cu(II), Zn(II) and Cd(II). Critical parameters such as pH, flow rate, sorption capacity, breakthrough studies, distribution coefficient, preconcentration factor, concentration of eluting agents responsible for quantitative extraction of metal ions were optimized. The synthesized resin showed good binding affinity towards Ni(II), Cu(II), Zn(II) and Cd(II) under selective pH conditions. Good breakthrough capacity and fast exchange kinetics of the resin lead to effective separation of metal ions from their binary and ternary mixture by column method on the basis of pH and eluting agents. The resin could be reused for about 8 -10 cycles. The proposed method having the analytical data with the relative standard deviation (RSD) 2% and with recoveries of analytes higher than 98%, reflects upon the reproducibility and reliability of the method which has been successfully applied in the separation and determination of Ni(II), Cu(II), Zn(II) and Cd(II) ions in synthetic, natural and ground water samples.

Preparation of a zeolite-palladium composite membrane for hydrogen separation:Influence of zeolite film on membrane stability

With the development of hydrogen energy,palladium-based membranes have been widely used in hydrogen separation and purification.However,the poor chemical stability of palladium composite membranes limits their commercial applications.In this study,a zeolite-palladium composite membrane with a sandwich-like structure was obtained by using a TS-1 zeolite film grown on the surface of palladium membrane.The membrane microstructure was characterized by SEM and EDX.The effects of the TS-1 film on the hydrogen permeability and stability of palladium composite membrane were investigated in details.Benefited from the protection of the TS-1 zeolite film,the stability of palladium composite membrane was enhanced.The results indicate that the TS-1-Pd composite membrane was stable after eight cycles of the temperature exchange cycles between 773 K and 623 K.Especially,the loss of hydrogen permeance for TS-1-Pd composite membrane was much smaller than that of the pure palladium membrane when the membrane was tested in the presence of C3H6atmosphere.It indicated that the TS-1-Pd composite membrane had better chemical stability in comparison with pure palladium membrane,owing to its sandwich-like structure.This work provides an efficient way for the deposition of zeolite film on palladium membrane to enhance the membrane stability.

Separation,preconcentration and determination of Pb(Ⅱ) in water samples using microcrystalline triphenylmethane loaded with quinolin-8-olate

This paper described a novel method for the preconcentration of Pb（II） using microcrystalline triphenylmethane loaded with quinolin-8-olate prior to the determination by flame atomic absorption spectrometry. Pb（II） could be enriched by controlling appropriate condition. The preconcentration factor could reach to 200 and the detection limit of Pb（II） was 0.074 μg/L. The recovery was in a range of 93.5-103% with relative standard deviation of 1.0-2.2%. The proposed method had been successfully applied to the determination of trace Pb（U） in various water samples with satisfactory result.

Effects of Sn residue on the high temperature stability of the H_2-permeable palladium membranes prepared by electroless plating on Al_2O_3 substrate after SnCl_2–PdCl_2 process: A case study

The stability of composite palladium membranes is of key importance for their application in hydrogen energy systems. Most of these membranes are prepared by electroless plating, and beforehand the substrate surface is activated by a SnCl_2–PdCl_2 process, but this process leads to a residue of Sn, which has been reported to be harmful to the membrane stability. In this work, the Pd/Al_2O_3 membranes were prepared by electroless plating after the SnCl_2–PdCl_2 process. The amount of Sn residue was adjusted by the SnCl_2 concentration, activation times and additional Sn(OH)_2coating. The surface morphology, cross-sectional structure and elemental composition were analyzed by scanning electron microscopy(SEM), metallography and energy dispersive spectroscopy(EDS), respectively. Hydrogen permeation stability of the prepared palladium membranes were tested at450–600 °C for 400 h. It was found that the higher SnCl_2 concentration and activation times enlarged the Sn residue amount and led to a lower initial selectivity but a better membrane stability. Moreover, the additional Sn(OH)_2coating on the Al_2O_3 substrate surface also greatly improved the membrane selectivity and stability.Therefore, it can be concluded that the Sn residue from the SnCl_2–PdCl_2 process cannot be a main factor for the stability of the composite palladium membranes at high temperatures.

Study on Physical and Chemical Behaviors of Rare Earths in Preparing Ceramic Tube Supported Palladium Film by Electroless Plating

The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10 ~ 20℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.

Preconcentration and separation of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridyl-azo)-resorcinol

This paper reports a simple and highly selective method for preconcentrating and separating of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridylazo)-resorcinol (ABPR·SG). ABPR·SG is stable in solution from 6 mol/L HCl to pH 7.0 and in common organic solvents. The maximum adsorptive capacity of Pd(II) on ABPRSG is 362 μmol/g. After preconcentrating and separation by using ABPR·SG column, Pd(II) and Pt(IV) of μg/L level in artificial water samples can be measured reliably by common spectrophotometer. The maximum concentration factors of Pd(II) and Pt(IV) on ABPR·SG column are 143 and 125 respectively. The chromatographic column packed with ABPR·SG can be reused. The method is simple and efficient.

Sorption Separation of Pairs of Elements with Similar Properties Pd(Ⅱ)-Pt(Ⅳ) and Pd(Ⅱ)-Cu(Ⅱ) Using Chemically Modified Silica Containing Sulfide Sulfur

The adsorption of Pd(Ⅱ), Pt(IV) and Cu(Ⅱ) in static and dynamic conditions on chemically modified silica containing sulfide sulfur (number of grafted functional groups of the sorbent was 0.2 (CMS-S 0.2) and 0 3 mmol/g (CMS-S 0.3)) was studied. It is established that an increase in the acidity of the sorption of Pd(Ⅱ) and Pt(Ⅳ) decreases, whereas the Cu(Ⅱ) does not change. Time to reach the constant values of the sorption is 15 min. In equal conditions, the sorption decreases in the number of Pd(Ⅱ)>Pt(IV)>Cu(Ⅱ). Based on retrieved data suggested that the sorption of Pd(Ⅱ) proceeds according the coordination mechanism. In the case of sorption from solutions with a high palladium content can be polymerization of adsorbed complexes in the sorbent phase. Worked out the optimal conditions for the separation of pairs of Pd(Ⅱ)-Pt(Ⅳ) and Pd(Ⅱ)-Cu(Ⅱ) under dynamic conditions with the extraction of palladium(Ⅱ) in the eluate is above 95%.

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply andrapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrateand separate of trace amount of Au(III), Pt(IV), Pd(IV) and Ir(IV) ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0 mL/minat pH 2, and can also be desorbed with 15 mL of 4 mol/L HCl+3% thiourea from the fiber column withrecoveries of 96.5%-100%. The chelating fiber can be reused for ten times, the recoveries of theseions are still over 92%, and hundred to thousand times of excess of Fe(III), Al(III), Ca(II),Mg(II), Ni(II), Mn(II), Cu(II), Zn(II), and Cd(II) cause no interference on the determination of theanalyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The staticsaturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80 mmol/g.The relative standard deviations for the determination of 20.0 ng/mL each of Au(III), Pt(IV),Pd(IV) and Ir(IV) are in the range of 0.7%-3.0%. The recoveries for test from standard additions toreal solution samples are between 96% and 100%. The concentration of each ion in powder sampledetected by the method is in good agreement with the certified value.

Palladium-based Membrane Applications for Hydrogen Purification

It describes the purification of hydrogen isotopes, separation with the preparation of palladium-based membrane's technology, types, application, advantages and disadvantages of palladium in this article. Due to excellent comprehensive properties palladium composite membrane will become the future direction of development. At the same time it will develop preparation methods of the membrane support body with high mechanical strength and heat resistance and low-cost and palladium-based membrane. Also it will explore high service life and high transmittance of novel composite membrane.

Enhanced separation of Pd(Ⅱ)and Pt(Ⅳ)from hydrochloric acid aqueous solution using 2-((2-methoxyethyl)thio)-1H-benzimidazole

Separation of palladium(Pd)and platinum(Pt)by solvent extraction is difficult because of their extremely similar physicochemical properties.Development of new extractants with a high extraction efficiency and excellent separation selectivity is the primary focus for enhancing the separation of Pd and Pt by solvent extraction.In this study,a new extractant,2-((2-methoxyethyl)thio)-1 H-benzimidazole(MOBI),which contains N,S,and O atoms,was synthesized and used to separate Pd(Ⅱ)and Pt(Ⅳ)from a hydrochloric acid aqueous solution.The experimental results revealed that Pd(Ⅱ)and Pt(Ⅳ)were effectively separated under the optimal conditions:MOB I concentration of 0.005 mol·L^(-1),HCl concentration of0.2 mol·L^(-1),organic/aqueous(O/A)phase ratio of 1.0,and contact time of 15 min.The separation coefficient between Pd(Ⅱ)and Pt(Ⅳ)was 1246.40,which indicates that MOBI has a higher selectivity for Pd(Ⅱ)than Pt(Ⅳ).In addition,the mechanism of coordination between Pd(Ⅱ)and MOBI was demonstrated through the slope method,Fourier transform infrared spectroscopy(FTIR),hydrogen-1 nuclear magnetic resonance spectroscopy(^(1)H NMR),and carbon-13 nuclear magnetic resonance spectroscopy(^(13)C NMR).The results revealed that MOBI could coordinate with Pd(Ⅱ)via the N atom in the benzimidazole ring of MOBI molecules to form[Pd(MOBI)_(2)Cl_(2)](O).

Pd-ZSM-5复合膜的制备及其氢气分离性能

为了能够在大孔氧化铝载体表面得到透氢性能良好的钯膜,利用二次生长法在多孔Al_(2)O_(3)载体上生长出一层连续完整的ZSM-5沸石分子筛修饰层,通过化学镀过程在ZSM-5沸石分子筛修饰的载体上沉积一层钯膜,从而得到Pd-ZSM-5复合膜。利用扫描电子显微镜(SEM)对载体、ZSM-5沸石分子筛修饰后的载体和Pd-ZSM-5复合膜的形貌进行详细分析,并通过X线能量色散光谱(EDX)对Pd-ZSM-5复合膜的表面和截面元素分布进行了研究。而且,为了确定该Pd-ZSM-5复合膜的H_(2)渗透性能,在623~773 K范围内,研究了操作温度、操作时间和测试压力对Pd-ZSM-5复合膜透氢性能的影响。研究结果表明,ZSM-5沸石分子筛修饰层能够有效改进载体的表面粗糙度和降低其表面孔径,有助于Pd膜的沉积。所制备的Pd-ZSM-5复合膜表面完整、致密,Pd膜层厚度约为5μm, ZSM-5沸石修饰层厚度约为3μm。当操作温度为773 K、渗透压力为0.1 MPa时,Pd-ZSM-5复合膜的H_(2)渗透通量和H_(2)/N_(2)渗透选择性分别为0.113 mol/(m·s)和468。而且,该Pd复合膜在773 K下,连续操作300 h后,其H_(2)渗透性能保持相对稳定。

铂钯铑分离提纯过程及铑的分布规律

以溶液中铂、钯、铑的短流程与高效分离为目标,系统研究了贵液中铂、钯、铑的分离提纯及铑的分散规律,探索了通过NH4Cl沉铂—氧化沉钯—DETA沉铑流程对贵液中的铂、钯、铑进行分离提纯。分离铂、钯后液中的铑仅占全部铑的20%左右,铑在铂、钯精炼提纯工序分别分散了14.59%、65.33%。对于钯、铑混合物沉淀采用DETA沉淀法优先分离铑的策略,一次沉淀直收率达77.25%,极大简化了铑的分离流程。

预选抛废技术发展现状

随着我国矿产资源的不断开发与利用,天然高品位矿石资源逐步减少,低品位矿石成为目前我国矿产资源的主要来源,因此,预选抛废成为一个必要的选矿环节。重点阐述了人工拣选抛废、光电选抛废、磁选抛废、重选抛废以及浮选抛废五种抛废技术,并介绍了不同技术在预选抛废时使用的设备和工作原理,指出了各种预选抛废技术的优缺点,为预选抛废技术能进一步工业应用提供了一定借鉴意义。

含铟粉尘的处理工艺现状与展望

含铟粉尘是金属冶炼流程产生的固体废弃物之一,包含锌、钾、铝、铁、铟、铅、镉等金属,是回收稀有金属铟的重要原料。针对现阶段含铟粉尘回收铟过程中存在的分散损失严重、回收率低、处理难度大等问题,本文以含铟粉尘回收铟的全流程处理工艺为主线,对含铟粉尘处理过程中火法预处理、湿法浸出、富集分离等环节的常用技术和工艺进行对比分析,探究不同工艺的独特机理和处理流程,同时讨论不同工艺的特点和局限性,指出现阶段各工序工业生产中存在的问题;重点综述铟湿法浸出和富集分离提取两个环节的技术进展,并基于现阶段工业粉尘“无害化、减量化、资源化”的处理目标与发展趋势,提出未来含铟粉尘综合回收处理的新思路,为实现含铟粉尘中铟等高附加值元素回收利用提供参考。

吡啶-氧杂二氮唑在钯离子萃取分离中的应用

高放废液中钯的萃取分离对贵金属钯资源的回收利用和核燃料循环中的玻璃固化过程都有重要意义,其关键在于高效高选择性萃取体系的开发和设计。基于氮杂环配体高效配合钯离子的特性,设计合成了一种具有吡啶-氧杂二氮唑结构的萃取剂6,6′-((4-异丁氧基吡啶-2,6-二基)双(1,2,4-氧杂二氮唑-5,3-二基))双(4-异丁氧基吡啶甲腈)(T2),用于酸性条件下钯离子的选择性萃取。以间硝基三氟甲苯为稀释剂且在1 mol/L 2-溴己酸存在下,配体T2对钯离子体现出较好的萃取能力。萃取动力学表明2 h即可萃取68%的钯进入有机相。该体系适用酸度广泛,在0.2~4 mol/L硝酸条件下均对钯展现出定量萃取,表明其优异的酸稳定性。此外,在多种阳离子共存的条件下,该体系能高选择性地分离萃取出钯离子,表明其良好的实际应用潜力。研究不仅提供了一类高效的钯萃取剂,更为其它新型钯萃取剂和萃取体系的开发提供了重要参考。

火试金-电感耦合等离子体原子发射光谱法测定贵金属催化剂中铂、钯含量

贵金属催化剂是一种能改变化学反应速度而本身又不参与反应的新材料,涉及精细化工、基础化工、环保、新能源等领域,由载体和活性组分构成。贵金属催化剂的催化活性组分以钯(Pd)、铂(Pt)、钌(Ru)、铑(Rh)、铱(Ir)、金(Au)等为主,多以Al2O3、SiO_(2)和活性炭为载体。火试金法是经典的贵金属富集方法。试验将火试金法与电感耦合等离子体原子发射光谱法(ICP-AES)相结合,加入银作为保护剂,富集Pt、Pd形成合粒,王水溶解贵金属合粒后采用ICP-AES测定溶液中Pt、Pd含量。试验结果表明,采用组合方法测定催化剂中Pt、Pd含量,可以消除ICP-AES直接测定催化剂中Pt、Pd时存在的基体干扰,测定结果准确度高,精密度好,加标回收率保持在98.4%~101.2%,方法操作简便快速,可作为催化剂中Pt、Pd测定方法。

DT-1016型阴离子交换树脂分离富集金铂钯

研究了DT - 1 0 1 6型阴离子交换树脂对超痕量Au、Pt、Pd的吸附性能及条件。在0 .0 2 5mol/LHCl介质中 ,流出速度为 0 .5～ 1 .0mL/min时 ,Au、Pt和Pd的富集效果最佳 ,吸附率分别为 99.72 %、99.60 %和 97.95 % ,共存离子无显著性影响。用等离子体质谱测定标准物质中Au、Pt和Pd ,其结果与标准值基本相符。检出限Au为 0 .2 7μg/L ,Pt为 0 .40 μg/L ,Pd为0 .1 9μg/L。对GBW 0 72 94铂族元素国家标准物质进行精密度试验 ,RSD(n =8)Au为 1 9.2 % ,Pt为 2 8.1 % ,Pd为 1 5 .6%。

交联壳聚糖富集分离-石墨炉原子吸收光谱法测定痕量钯的研究

将环氧氯丙烷与壳聚糖进行交联反应制备了不溶于酸、碱的交联壳聚糖（CCTS），研究了不同pH条件下CCTS对于Pd（Ⅱ）的吸附特性，结果表明：在pH1～4时，吸附20min，CCTS对Pd（Ⅱ）的吸附率达98％以上；考察了吸附时间、试样体积、CCTS用量、共存元素等对CCTS吸附Pd（Ⅱ）的影响、吸附容量以及Pd（Ⅱ）的脱附；探讨了吸附机理；建立了CCTS预富集分离，石墨炉原子吸收光谱（GFAAS）测定痕量钯的新方法。该法检出限（3σ，n=8）为0．143μg·L，相对标准偏差（RSD）小于5．47％，用于湖水和海水中痕量钯的检测，回收率在92％～96％之间。该法还可用于钯的回收利用。