N1923从碱性氰化液中萃取金(Ⅰ)的研究

采用放射性同位素１９８Ａｕ示踪法研究了伯胺Ｎ１９２３和ＴＢＰ从碱性氰化液中萃取金（Ⅰ）,考察了酸化率、水相ｐＨ值、萃取剂浓度等对萃取率的影响,以及ＮａＯＨ对载金有机相的反萃作用。结果表明,ＴＢＰ含量大于２０％,酸化的Ｎ１９２３与ＫＡｕ（ＣＮ）２摩尔比值在１：１时,金能够完全被萃取。载金有机相可采用０．ｌｍｏｌ·Ｌ－１的Ｎａ０Ｈ溶液定量反萃。机理研究表明,伯胺和ＴＢＰ萃取Ａｕ（ＣＮ）２－,符合ＢＣ类协同萃取机理。当金浓度大于１０ｇ·Ｌ－１时,在萃取有机相中形成纳米级的聚集体。     

磷酸三丁酯/正辛醇络合萃取对氯苯酚

以对氯苯酚稀溶液为研究对象,以正辛醇为稀释剂,研究了萃取剂种类及其浓度、水相平衡pH、对氯苯酚初始浓度等因素对萃取分配比的影响,并用NaOH对其负载溶质的有机相进行反萃.结果表明,络合萃取对处理高浓度对氯苯酚废水具有优势;磷酸三丁酯(TBP)的浓度和体系的pH是影响络合萃取的关键因素;采用NaOH对有机相进行反萃,当NaOH浓度为0.5mol/L时反萃率达到98.55%.红外光谱分析表明,TBP萃取对氯苯酚基于氢键作用机理.     

湿法电解含金萃取有机相制备金的研究

提出了一种在湿法冶金同时电解载金属有机相制备金属的新方法.并通过电解磷酸三丁酯(TBP)萃取Au(CN)₂^--R₄N⁺的载金有机相制金.考察了电解技术条件、Au浓度、电解质浓度及还原剂等因素对Au回收率的影响.结果表明,此方法不仅可省去冗长的反萃和还原等步骤,而且可以直接以高回收率制备高纯度的金箔;在电解液中加入少量还原剂可明显提高金的回收率.该法也适用于制备银和铜,制备银时所用体系与金相似,但制备铜则在D₂EHPA-正庚烷为载铜有机相及电解质的酸性溶液为水相的体系中进行.     

十四烷基二甲基苄基氯化铵萃取Au(CN)2-的微观机理

通过萃取平衡、傅里叶变换红外光谱及分峰技术研究了季铵盐十四烷基二甲基苄基氯化铵(TDM-BAC)-磷酸三丁酯(TBP)-正庚烷体系萃取Au(CN)₂^-的机理及过程.提出了萃合物的结构模型是基于氢键的超分子体系,组成为[R₄N⁺]·[Au(CN)₂^-]·4H₂O·4TBP.当有机相金浓度大于3g·L^-1时,有机相中存在聚集现象.通过激光光散射技术测定了有机相中反向胶团的大小,表明萃取过程是分散在水相中的胶团在协萃剂(或助表面活性剂)作用下溶入有机相,转型为反向胶团或微乳液(W/O型)聚集状态.     

伯胺N1923萃取铁的囊效应

由研究伯胺N1923萃取铁(Ⅲ)的平衡,提出了萃取体系中“囊效应”的概念,并用红外光谱和电镜等分析方法加以佐证.当萃取剂伯胺N1923的浓度达到一定值后,在有机相中形成了球状的胶囊(或反向胶团).其萃取过程中既有离子缔合萃取,又有胶束增溶作用,大大提高了伯胺N1923萃取铁的分配比,呈现出“囊效应”特征.     

伯胺N1923萃取体系反胶束的形成研究

伯胺 N1 92 3是重要的国产萃取剂 ,其经酸化后生成的铵盐在有机相中可聚集形成反向胶束或微乳液[1] ,但在盐酸和硫氰酸等一元酸介质中萃取金属时 ,萃取剂的聚集现象对萃取机理影响不大 ,可用斜率法分析实验结果 ,确定萃合物组成 [2 ] .而在硫酸介质中却表现出特殊的萃取现象 ,发生胶束萃取[3] .对此 ,本文试图从表面与胶体化学的角度对伯胺萃取体系反胶束的形成作深入研究 ,以期对伯胺萃取体系的萃取机理获得更深入的了解 .1　实验部分1 .1　试剂与仪器　伯胺 N1 92 3( RNH2 ) ,平均分子量 2 91 .8(中国科学院上海有机化学研究所实验厂 ) …     

伯胺N1923和三苯基氧化膦萃取金(Ⅲ)的动力学Ⅱ:二元萃取剂体系萃取AuCl4-

用恒界面池法研究了伯胺N1923和三苯基氧化膦(TPPO)二元萃取剂体系从盐酸介质中萃取AuCl_4~-的动力学,提出了界面化学反应控制机理。认为在界面区域内同时进行着N1923、TPPO以及二者的缔合物萃取AuCl_4~-的三个平行反应,三者的共同作用使Au(Ⅲ)向有机相的传质较N1923或TPPO的一元萃取剂体系明显加速。文中对这种动力学加速现象和动力学协同效应以及它们与热力学协同萃取的关系进行了讨论。     

N_5O_3-TRPO混合萃取剂从碱性氰化液中萃金

研究 N5O3- TRPO混合萃取剂从碱性氰化液中萃取金 ,考察了平衡时间、水相初始 PH值、水相离子强度、金浓度、N5 0 3浓度、磷类添加剂的种类及其浓度、稀释剂、温度、相比等因素对金萃取率的影响 ,绘制了萃取等温线 ,测定了金的饱和容量 ,考察了所选定的萃取体系对银 ( )、铁 ( )、铜 ( )、镍 ( )、锌 ( )的萃取性能 ,计算出了金与这些杂质元素的分离系数。研究了负载有机相中金的反萃。结果表明 N5O3- TRPO ROH正十二烷体系对 Au( CN) 2 具有较高的萃取率和选择性 ,可应用于碱性氰化液中金的萃取分离。     

伯胺N1923和三苯基氧化膦萃取金(Ⅲ)的动力学Ⅱ:二元萃取剂体系萃取AuCl4-

用恒界面池法研究了伯胺N1923和三苯基氧化膦(TPPO)二元萃取剂体系从盐酸介质中萃取AuCl4-的动力学,提出了界面化学反应控制机理.认为在界面区域内同时进行着N1923、TPPO以及二者的缔合物萃取AuCl4-的三个平行反应.三者的共同作用使Au(Ⅲ)向有机相的传质较N1923或TPPO的一元萃取剂体系明显加速.文中对这种动力学加速现象和动力学协同效应以及它们与热力学协同萃取的关系进行了讨论.     

伯胺N1923萃取硫氰酸钴（Ⅱ）的动力学

N1923是国产仲碳伯胺萃取剂,已见其对贵金属的萃取理论研究。我们曾考察过它对硫氰酸钴的萃取平衡及该体系的萃合物组成,本文报道用生长液滴法对N1923萃取硫氰酸钴的动力学研究结果。 1 实验 1.1 主要试剂 萃取剂为伯胺N1923(中科院上海有机所实验厂,6.66×10~2Pa、175～205℃下减压蒸镏提纯),其煤油溶液的浓度用标准酸滴定。萃取实验前用HSCN将     

The extraction of low-concentrations of gold(I) with 198Au as a radiotracer

The solvent extraction of gold from alkaline cyanide solution was studied by using ¹⁹⁸Au as a radiotracer. The influence of several variables on the gold extraction, including the concentration of gold, the molar ratio of extractants to gold(I), the volume percentage of cosolvent and the pH value of the aqueous phase, was investigated. The results indicated that the radioactive tracer technique is a quick, accurate, and convenient tool to investigate the extraction behavior of an element existing in low concentrations. The experimental results indicated that the studied amines, tetradecyldimethylbenzylammonium chloride, N1923 and tri-n-octylamine, could be used as extractants for the recovery of gold from aqueous alkaline cyanide solutions.     

多烷基支链仲胺从碱性氰化液中萃取金

研究了多烷基支链促胺从碱性氰化液中萃取金,考察了平衡时间、水相初始pH值、金浓度、离子强度、温度、萃取剂浓度、稀释剂、相比等因素对金萃取率的影响,绘制了萃取等温线,测定了金的饱和容量,考察了萃取体系对银（Ⅰ）、铁（Ⅱ）、铜（Ⅰ）、镍（Ⅱ）、锌（Ⅱ）的萃取性能,计算出了金与这些杂质元素的分离系数,研究了负载有机相中金的反萃,结果表明,该萃取体系在pH5－11范围内对Au（CN）2^－有较高的萃取率和选择性,pH1／2＝11.7,可用于碱性氰化液中金的萃取分离。     

Mechanism of gold solvent extraction from aurocyanide solution by quaternary amines: models of extracting species based on hydrogen bonding

The mechanism of gold solvent extraction from KAu(CN)2 solution was investigated by means of FTIR, EXAFS, ICP and radioactive tracer methods. Two extraction systems were studied, namely N263-tributyl phosphate(TBP)-n-dodecane and N263-iso-octanol-n-dodecane. High-resolution FT IR spectroscopy indicated that the CN stretching vibrations of the two extraction systems differred greatly. In order to interpret the significant difference in CN stretching vibrations, two extracting species models are proposed——supramolecular structures based on the formation of hydrogen bonds between Au(CN)2- and modifiers such as TBP and iso-octanol.     

Transformations of [Au(CN)2]− at the contact with activated carbon surface

We have studied the processes occurring when alkaline aqueous solution of Na[Au(CN)₂] is brought in contact with activated carbon surface. It has been shown that the adsorption of the gold cyanide complex occurs via several independent routes, one of them being accompanied with the partial breakdown of the inner sphere of the compound and free cyanide ions release into the solution. The latter process decreases the gold recovery by aqueous NaOH during the high-temperature (150°C) desorption. A prolonged storage of the adsorbent saturated with [Au(CN)₂]^? in air produces a similar result. The reasons of the observed phenomena have been discussed.     

TiO_2/Fe-杭锦2~#土催化剂光催化降解废水中乙酸的研究

首先采用离子交换法制得Fe-杭锦2#土,以其为载体使用溶胶-凝胶法制备了TiO_2/Fe-杭锦2#土负载型光催化剂,并通过X射线粉末衍射(XRD)、氮气吸附脱附(N2-BET)、固体紫外可见漫反射(UV-Vis DRS)、X射线光电能谱(XPS)和扫描电子显微镜(SEM)分析等对催化剂进行了表征.以光催化降解乙酸为探针反应,考察了Ti的负载量、光源、光照时间、催化剂用量和反应温度等反应条件对催化剂催化性能的影响.实验结果表明,对于浓度为100 mg·L-1的乙酸溶液,选用氧化钛负载量为20%的光催化剂、300 W汞灯为光源、反应温度为50℃、反应时间为6 h、催化剂用量为50 g·L~(-1)时,对乙酸的光催化降解效果相对最优,降解率达到78.30%.     

Aggregation of [Au(CN)4]- anions: examination by crystallography and 15N CP-MAS NMR and the structural factors influencing intermolecular Au···N interactions

To investigate the factors influencing the formation of intermolecular Au···NC interactions between [Au(CN)(4)](-) units, a series of [cation](n+)[Au(CN)(4)](n) double salts was synthesized, structurally characterized and probed by IR and (15)N{(1)H} CP-MAS NMR spectroscopy. Thus, [(n)Bu(4)N][Au(CN)(4)], [AsPh(4)][Au(CN)(4)], [N(PPh(3))(2)][Au(CN)(4)], [Co(1,10-phenanthroline)(3)][Au(CN)(4)](2), and [Mn(2,2';6',2'-terpyridine)(2)][Au(CN)(4)](2) show [Au(CN)(4)](-) anions that are well-separated from one another; no Au-Au or Au···NC interactions are present. trans-[Co(1,2-diaminoethane)(2)Cl(2)][Au(CN)(4)] forms a supramolecular structure, where trans-[Co(en)(2)Cl(2)](+) and [Au(CN)(4)](-) ions are found in separate layers connected by Au-CN···H-N hydrogen-bonding; weak Au···NC coordinate bonds complete octahedral Au(III) centers, and support a 2-D (4,4) network motif of [Au(CN)(4)](-)-units. A similar structure-type is formed by [Co(NH(3))(6)][Au(CN)(4)](3)·(H(2)O)(4). In [Ni(1,2-diaminoethane)(3)][Au(CN)(4)](2), intermolecular Au···NC interactions facilitate formation of 1-D chains of [Au(CN)(4)](-) anions in the supramolecular structure, which are separated from one another by [Ni(en)(3)](2+) cations. In [1,4-diazabicyclo[2.2.2]octane-H][Au(CN)(4)], the monoprotonated amine cation forms a hydrogen-bond to the [Au(CN)(4)](-) unit on one side, while coordinating to the axial sites of the gold(III) center through the unprotonated amine on the other, thereby generating a 2-D (4,4) net of cations and anions; an additional, uncoordinated [Au(CN)(4)](-)-unit lies in the central space of each grid. This body of structural data indicates that cations with hydrogen-bonding groups can induce intermolecular Au···NC interactions, while the cationic charge, shape, size, and aromaticity have little effect. While the ν(CN) values are poor indicators of the presence or absence of N-cyano bridging between [Au(CN)(4)](-)-units (partly because of the very low intensity of the observed bands), (15)N{(1)H} CP-MAS NMR reveals well-defined, ordered cyanide groups in the six diamagnetic compounds with chemical shifts between 250 and 275 ppm; the resonances between 260 and 275 ppm can be assigned to C-bound terminal ligands, while those subject to CN···H-N bonding resonate lower, around 250-257 ppm. The (15)N chemical shift also correlates with the intermolecular Au···N distances: the shortest Au-N distances also shift the (15)N peak to lower frequency. This provides a real, spectroscopically measurable electronic effect associated with the crystallographic observation of intermolecular Au···NC interactions, thereby lending support for their viability.     

十二烷基二甲基苄基氯化铵从碱性氰化液中固相萃取金的研究

建立了一种用十二烷基二甲基苄基氯化铵(BDMDAC)从碱性氰化液中固相萃取金的新方法：在碱性介质中,十二烷基二甲基苄基氯化铵溶液(BDMDAC)与Au(CN)2-络阴离子生成离子缔合物,该离子缔合物可被反相键合硅胶固相萃取柱萃取、富集,用乙醇洗脱,反相键合硅胶固相萃取柱可重复使用。该方法用于从碱性氰化液中固相萃取痕量金,萃取回收率可超过98%。     

十二烷基二甲基苄基氯化铵从碱性氰化液中固相萃取金的研究

建立了一种用十二烷基二甲基苄基氯化铵(BDMDAC)从碱性氰化液中固相萃取金的新方法:在碱性介质中,十二烷基二甲基苄基氯化铵溶液(BDMDAC)与Au(CN)2-络阴离子生成离子缔合物,该离子缔合物可被反相键合硅胶固相萃取柱萃取、富集,用乙醇洗脱,反相键合硅胶固相萃取柱可重复使用。该方法用于从碱性氰化液中固相萃取痕量金,萃取回收率可超过98%。     

Au(I) extraction by LIX-79/n-heptane using the pseudo-emulsion-based hollow-fiber strip dispersion (PEHFSD) technique

The extraction of Au(I) from alkaline cyanide solutions through PEHFSD was conducted in a microporous hydrophobic polypropylene hollow-fiber membrane contactor. The organic extractant LIX-79 (N,N-bis(2-ethyl hexyl)guanidine) in n-heptane was used. The alkaline cyanide feed solution containing Au(I) was passed through the tube side, and pseudo-emulsions of LIX-79/n-heptane and NaOH were passed through the shell side in counter-current mode, using a single microporous hydrophobic polypropylene hollow-fiber contactor for extraction and stripping. In PEHFSD the aqueous strip (0.2 M NaOH) solution is dispersed in the organic (12% LIX-79/n-heptane) membrane solution in a container with a mixing arrangement (impeller stirrer) designed to form a strip dispersion. The strip dispersion is circulated from the mixer to the membrane module to provide a constant supply of the LIX-79/n-heptane solution to the membrane pores. Various hydrodynamic and chemical parameters, such as variation in feed pH; gold cyanide concentration in feed; variation in concentrations of NaOH, LIX-79/n-heptane and Au(I); variation in feed, strip and LIX-79/n-heptane volume ratios and variation in feed and strippant flow rates, were investigated. Mass transfer modeling was performed and the validity of the model was evaluated with experimental data and found to tie in well with theoretical values. It was possible to concentrate Au(I) in product (NaOH) using the PEHFSD technique.