硝酸铀酰—硝酸—磷酸三丁酯体系的反萃取动力学研究

本文采用恒界面池法和上升单液滴法研究了UO_2(NO_3)_2/HNO_3/TBP-环己烷体系的反萃取动力学。得出扩散控制下的反萃速率方程为R=k_1[U]_(O)[TBP]_(O)~(-1.17)[HNO_3]~(-1.70;在恒定硝酸浓度下化学反应控制的反萃速率方程为R=k_2[U]_(O)[TBP]_(O)~0,并对二种速控类型下的反萃机制进行了讨论。     

萃取Fe3+和氨水-乙醇反萃沉淀法制备α-Fe2O3

以磷酸二异辛基酯(P204)为萃取剂,CCl4为溶剂,从Fe(NO3)2水溶液中萃取铁离子,以氨的乙醇溶液反萃含铁的有机相,通过优化控制相间传质过程,获得了Fe(OH)3前驱体,经煅烧后得α-Fe2O3粉体,采用TEM、FTIR、XRD等测试技术对α-Fe2O3进行表征。 研究表明,在油水相比为1∶1,水相c(Fe3+)=0.10 mol/L(pH=3.0)、油相P204为V(P204)∶V(CCl4)=1∶3、平衡时间为20 min,Fe3+萃取率达98.44%;反萃取溶液V(氨水)∶V(乙醇)=1∶7、陈化温度约10.0 ℃,制备纳米α-Fe2O3的煅烧温度为600 ℃较宜。     

HEH/EHP萃取剂中钍的反萃性能研究

研究了含钍HEH/EHP(2-乙基己基膦酸单-2-乙基己基脂)萃取剂中钍的反萃性能。采用HCl,HNO3和H2SO4三种矿物酸分别对钍进行了反萃试验研究,结果表明,当反萃酸浓度为[H+]=6 mol.L-1时,HCl和HNO3反钍率小于1%,而硫酸的反钍率接近69%,表明H2SO4是钍的有效反萃剂。以H2SO4作为反萃剂,研究了相比、反萃酸浓度、酸用量、萃取剂浓度及钍负载量对钍的反萃性能的影响。在此基础上,对钍的逆流反萃过程进行了研究,当起始酸浓度为7 mol.L-1时,分别采用1∶1和4∶1的相比进行3级逆流反萃,反萃率分别为92.10%和53.29%。     

有机-无机杂化Keggin型硅钨酸盐[Fe~(Ⅱ)(phen)_3]_2[α-SiW_(12)O_(40)]·H_2O的水热合成与晶体结构（英文）

在水热条件下,用Na10[α-SiW9O34]·18H2O,Fe2(SO4)3与phen反应合成了一种有机-无机杂化Keggin型硅钨酸盐[FeII(phen)3]2[α-SiW12O40]·H2O(1),并借助IR光谱、X射线光电子能谱和单晶X射线衍射等对其结构进行了表征.晶体学研究表明化合物1的分子由1个饱和的[α-SiW12O40]4-多阴离子、2个[FeII(phen)3]2+配离子和1个结晶水分子构成,其中3个1,10-菲啰啉分子中的6个氮原子与Fe2+离子配位形成了八面体构型.     

一个基于β-[Mo_8O_(26)]和5-(3-吡啶基)-四唑桥连的二核镍配合物构筑的无机-有机杂化化合物

通过水热合成了一种有机-无机杂化化合物[Ni4(3-Hpt)6(H2O)10Mo8O26]·Mo8O26·10H2O(3-Hpt=5-(3-吡啶基)-四唑),IR和X-射线单晶衍射实验测定和结构解析结果表明,该化合物是由双支撑形结构的[Ni4(3-Hpt)6(H2O)10Mo8O26]阳离子,β构型[Mo8O26]簇阴离子及晶格水组成的。在阳离子中,β构型[Mo8O26]簇通过中心对称的2个端基氧与2个双核配阳离子[Ni2(3-Hpt)3(H2O)5]4+的镍原子配位形成双支撑形结构。将所得化合物制成碳糊电极(1-CPE),该电极在酸性水溶液中对亚硝酸根,溴酸根的还原有较好的催化活性。     

“抑制-萃取”法从含铁酸溶液中选择性提钒

酸法浸出石煤提钒因具有环保、金属收率高的特点而备受关注,但同时进入母液的铁(高含量的Fe³⁺)严重影响了钒的富集和产品生产。 对此,本文提出一种基于“抑制-萃取”效应的钒/铁分离混合萃取体系(P507(2-乙基己基磷酸-单2-乙基己基酯)+ N235(三辛/癸烷基叔胺)+磺化煤油),并详细研究了各因素对钒铁分离和钒富集的影响规律。 结果表明,P507是钒铁萃取的主体,N235不具萃Fe³⁺能力,是产生抑制铁萃取的关键因素,其浓度越高铁萃取率越低;对于酸度较高(pH≤0.4)的原料液钒/铁的分离效果仍较好,这表明了该“抑制-萃取”混合萃取体系对高酸度浸出液钒/铁分离的适用性。 采用氨水从负载有机相中反萃取钒铁,当氨水浓度为6 mol/L时钒的反萃率99%以上,25 ℃,V(有机相)∶V(水相)=2∶1时的反萃液中钒质量浓度14.73 g/L,铁质量浓度小于0.022 g/L,m(V)/m(Fe)=669.5。 该“抑制-萃取”法分离钒/铁操作简单、经济高效,极具工业化前景。     

从太平洋中部深海粘土盐酸浸出液中萃取回收钇的研究

针对太平洋中部深海粘土HCl浸出液酸度高、成分复杂等特点,克服现有萃取剂不足,采用新型萃取剂P535从高浓度HCl浸出液中直接萃取回收Y~(3+),考察料液酸度、萃取剂浓度、萃取时间和相比对萃取的影响以及HCl,H2SO4反萃剂对反萃的影响,分别绘制萃取平衡等温线和反萃平衡等温线,确定反萃方案并完成转型。结果表明:以有机相组成为10%P535(质量分数)+磺化煤油作为萃取剂,料液酸度为1.12 mol·L-1HCl,其最佳萃取条件为:萃取时间5 min,相比O/A=1∶2。经过3级逆流萃取,Y~(3+)萃取率达到98%,Fe~(3+)共萃进入有机相,其他金属基本不萃取。负载有机相用2 mol·L-1的H2SO4溶液可选择性反萃Y~(3+),得到Y_2(SO_4)_3溶液,反萃Y~(3+)的有机相再用8 mol·L-1HCl溶液反萃共萃的Fe~(3+),完成转型。     

2006年全国高中学生化学竞赛理论试题参考答案

第1题1-1.A:Na2WO4;B:H2WO4或WO3·H2O;C:WO3⑴4FeWO4(s)+8NaOH(l)+O2(g)4Na2WO4(l)+2Fe2O3(s)+4H2O(g)2MnWO4(s)+4NaOH(l)+O2(g)2Na2WO4(l)+2MnO2(s)+2H2O(g)(产物写成Mn2O3或Mn3O4也可)⑵Na2WO4(aq)+2HCl(aq)H2WO4(s)+2NaCl(aq)⑶H2WO4(s)WO3(s)+H2O(g)1-2.[1]2WO3(s)+3C(石墨)2W(s)+3CO2(g)[2]反应在298.15K时的标准焓变、标准熵变和标准自由能变化分别为:ΔH=ΣυΔfH m=[2×0+3×(-393.51)-2×(-842.87)-3×0]kJ/mol=505.21 kJ/molΔS=ΣυS=[2×32.64+3×213.64-2×75.90-3×5.74]J·mol-1·K-1=537.…     

Keggin型铁取代杂多阴离子PW_(11)O_(39)Fe(Ⅲ)(H_2O)~(4-)光催化降解硝基苯

以Keggin型铁取代杂多阴离子PW11O39Fe(Ⅲ)(H2O)4-[PW11Fe(Ⅲ)(H2O)]代替传统光芬顿方法中的Fe3+作为光催化剂,构成一个新颖的光催化体系并用于水体生物难降解有机污染物硝基苯(NB)的降解.详细研究了在紫外光照射和H2O2存在下,PW11Fe(Ⅲ)(H2O)对NB降解的均相光催化作用.考察了NB初始浓度、溶液pH、H2O2和PW11Fe(Ⅲ)(H2O)浓度对光催化降解反应速率的影响.实验结果表明,1.0mmol·L-1PW11Fe(Ⅲ)(H2O)+5.0mmol·L-1H2O2+1.0mmol·L-1NB的中性溶液在300W汞灯照射下反应120min,NB的降解率达93%,总有机碳(TOC)去除约31%,显示了该新颖体系对NB光催化降解的高效性和优越性.     

三有机锡(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯的合成、结构和体外抗癌活性

利用三有机锡氢氧化物和手性配体(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸(HL)反应合成了3个三有机锡(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯R3SnL[1,R=c-C6H11(a),C6H5(b),C6H5C(CH3)2CH2(c)],通过元素分析、IR、1H NMR和X-射线单晶衍射表征了其结构。化合物1a属正交晶系,P212121空间群;化合物1b属单斜晶系,P21空间群。二者均为由羧基氧和内酰胺羰基氧桥联配位形成的右螺旋链状有机锡配位聚合物,锡原子具有五配位[SnC3O2]畸变三角双锥构型。化合物1a和1b对体外2种人癌细胞Colo205和Bcap37增殖均有强的抑制作用,其活性为1b1a。     

Studies on Alternating Pulse Current-ChronopotentiometricStripping Analysis

BasedonthefirstideaspresentedbyBeck',anewmethodcalledalternatingpulsecurrent-chronopotentiometricstrippinganalysis(APC-CPSA)hasbeendeveloped.Inthistechnique,duringthestrippingstepthecurrentimposedontheelectrol,ysi$cellcomprisesofanalternatingpulsecurrent(APC)andtheinherentdirectcurrentofCPSA.TheAPCisoperatedwithahighfrequencyinasquarewavemode.isandiRisdefinedastheanodicandcathodicpulsecurrent,respectively,isandtRisthetimeforwhichthesecurrentsflow.So,whenisandiRalternates,partsofthestri…     

超微盘电极上电位溶出分析法理论

本文提出了超微盘电极上电位溶出分析法理论,内容包括:过渡时间(τ)方程式、电位(E)-时间(t)曲线方程式及微分电位溶出分析法dt/dE-E曲线方程式,并对该曲线的性质进行了论述。     

Cathodic and Adsorptive Stripping Votammetry of Naftazone

Abstract

Naftazone (1,2-naphthoquinone-2-semicarbazone) undergoes a reversible two-electron transfer in both acidic and alkaline solutions and also gives rise at pH > 7 to an anodic wave attributed to the formation of a mercury derivative. Cathodic stripping voltammetry is proposed to determine the compound down to 5 × 10^?9 M after accumulation of its mercury salt formed at -0.05V in a 0.05M sodium hydroxide solution. These results have been compared with those obtained by performing an adsorptive collection of the drug in a pH 3 sodium perchlorate solution. Concentrations ranging from 1 × 10^?7 to 2 × 10^?7M can be easily investigated, the detection limit being 7 × 10^?11M. The influence of several operational parameters has also been considered.     

Fast cathodic stripping analysis with ultramicroelectrodes

Hemispherical ultramicroelectrodes (2.5–12.5 μm in radius) fabricated from silver or amalgamated copper, gold or platinum were used in the cathodic stripping of various anions. A comparison is presented between the results obtained using electrodes of a conventional size at slow sweep rates (ca. 100 mV s^?1) and those obtained using ultramicroelectrodes under fast linear-sweep conditions (ca. 700 V s^?1). Problems in maintaining reproducible electrode surfaces under various experimental conditions are discussed. In addition, the benefit of using electrodes of microscopic dimensions is illustrated by their utilization in the analysis of very small volumes of analyte that result from a solvent back-extraction process.     

电化学分析法测定硒的研究进展

本文综述了国内外电化学分析(极谱和溶出伏安法)测定痕量硒的研究进展,主要包括极谱催化波、吸附波以及阴极溶出伏安法,阳极溶出伏安法,并从反应体系、催化波类型、检出限和电极反应机理等方面进行归纳与评述,展望了硒分析方法的研究方向和发展前景,对进一步研究硒的电化学性质和探索测定硒的新体系有重要参考价值。     

硫代硫酸根的溶出伏安吸附性质及应用

在 0 .0 1mol·L-1LiNO3介质中 (pH 2 .70 )S2 O32 -有一灵敏的阴极溶出峰( - 0 .42V) ,其峰电流与S2 O32 -浓度在 1× 1 0 -7mol·L-1～ 4× 1 0 -6mol·L-1范围内有线性关系。当富集 2 0 0s时 ,检测限可达 5× 1 0 -8mol·L-1。溶出峰具有吸附性质 ,在悬汞电极上的吸附符合Frumkin等温式。测得在悬汞电极上的饱和吸附量为 1 .0 3× 1 0 -9mol·cm-2 。该方法用于PbS2 O3溶度积的测定 ,结果与文献值基本一致。     

Application of abrasive stripping voltammetry in corrosion science. I. determination of the corrosion potentials of metals

The application of abrasive stripping voltammetry for the determination of the corrosion potential of metal powders is described. Micro amounts of a metal are fixed on a paraffin-impregnated graphite electrode immersed in suitable electrolyte solutions and polarization curves are recorded. The value of the corrosion potential is determined by Tafel analysis. The precision of the method is ±0.5% (mean rel. dev.) of the final potential value. Received: 24 March 1998 / Accepted: 27 August 1998     

Adsorptive stripping voltammetric determination of dimenhydrinate at a hanging mercury drop electrode

Dimenhydrinate exhibits a single adsorptive stripping peak at a hanging mercury drop electrode after accumulation at 0.0V vs Ag/AgCl electrode at pH 3.8 (acetate buffer). The addition of trace amounts of copper ions enhanced the dimenhydrinate peak and its height depends on the concentration of each dimenhydrinate and Cu²⁺. The adsorptive stripping response was evaluated with respect to accumulation time and potential, concentration dependence, electrolyte, the presence of other purines, surfactants and other metal ions, and some variables. The calibration graph for dimenhydrinate determination is linear over the range 2.0×10^–8–2.0×10^–7 M (pre-concentration for 60s). The correlation factor is found to be 0.985 and RSD is 3.2% at 1.0×10^–7 M. Detection limit is 1.0×10^–8 M after 5 min accumulation. The determination of dimenhydrinate in pharmaceutical formulations by the proposed method is also reported.     

Studies on substituted phenols by differential pulse cathodic stripping voltammetry: 1. Pentachlorophenol

A study of chlorophenols using differential pulse cathodic stripping voltammetry (dpcsv) is reported. Of the wide range of chlorophenols investigated, only pentachlorophenol and 2,3,4,6-tetrachlorophenol yield stripping peaks.For pentachlorophenol in water, two peaks are obtained at stripping potentials of –1.2 V and –1.58 V versus SCE. In methanol, pentachlorophenol shows one peak with a stripping potential at –1.6 V versus SCE.In the case of 2,3,4,6-tetrachlorophenol in water, two peaks are observed at –1.06 V and –1.6 V versus SCE, while in methanol only one peak arises at a stripping potential of –1.6 V. A procedure was developed for the determination of pentachlorophenol in natural waters.     

还原溶出计时电位法测定水中痕量锰

提出了在pH 8.8的H3BO3-Na2B4O7介质中,用还原溶出计时电位法测定水中痕量锰的方法。锰的检出限为0.5ng·ml-1,相对标准偏差为4.5％,线性范围为0.5～25ng·ml-1。采用标准曲线法对五份不同浓度的水样进行了测定,结果与原子吸收法相符。