P507萃淋树脂分离-电感耦合等离子体质谱法快速测定化探样品中的银

应用电感耦合等离子体质谱法(ICP-MS)测定化探样品中低含量的Ag时,常受到Zr、Nb氧化物离子91Zr16O和93Nb16O的严重干扰,使得低含量Ag结果误差较大.本文报道了一个简易的测定化探样品中Ag的新方法,将用于ICP-MS测定常规微量元素的溶液通过P507萃淋树脂交换柱,Zr、Nb等干扰元素被P507树脂强烈吸附,而Ag和内标元素Rh通过交换柱,实现了化探样品中待测元素Ag和内标元素Rh与干扰元素Zr、Nb的有效分离,Ag和Rh的回收率达到95％以上,检出限为0.05 μg/g,标准样品的测定结果准确可靠.该方法在测定常规微量元素的基础上,不需要另外称样及处理样品,相对于其他方法,流程简单、快速,适合化探样品Ag的测定,且树脂经氢氟酸处理后可重复使用,降低了实验成本.     

氨水分离-电感耦合等离子体质谱法测定化探样品中的银

应用电感耦合等离子体质谱法(ICP-MS)测定化探样品中的Ag时,两个同位素107Ag和109Ag分别受90Zr16O1H、91Zr16O和92Zr16O1H、93Nb16O等的干扰,即使采用干扰系数法校正,测定结果误差仍较大。本文采用硝酸-氢氟酸-高氯酸封闭分解样品,氨水沉淀分离干扰元素Zr后以103Rh为内标用ICP-MS测定,溶液中残留Zr对107Ag的测定干扰采用干扰系数法进行校正。方法检出限(3σ)为4.1 ng/g,相对标准偏差(n=12)为2.5%~7.8%。经53个地球化学标准物质验证,溶液中的Ag未见损失。本方法是在氨性介质中Ag与氨形成稳定的络合离子,而Zr则生成氢氧化物沉淀,实现了Ag和Zr的分离,大大减小了Zr对Ag的测定干扰;采用封闭分解样品,减少用酸量,降低了样品空白值,操作方法比高压密闭分解和P507萃淋树脂分离方法更简便快速。     

酸溶分解-电感耦合等离子体质谱内标法测定地质样品中的痕量银

应用电感耦合等离子体质谱法(ICP-MS)测定地质样品中的痕量银时,Zr、Nb、Mo的氧化物以及氢氧化物对银的两个质量数~(107)Ag和~(109)Ag造成严重的质谱重叠干扰,导致结果有明显的偏差。针对此问题,本文基于~(107)Ag的质谱干扰相对单一,只有~(90)Zr~(16)OH~+和~(91)Zr~(16)O~+对~(107)Ag产生干扰,在ICP-MS分析中选用~(107)Ag对银进行测定。样品前处理中采用氢氟酸、高氯酸、硝酸敞开消解,在浸提液中加入过量氨水,将~(107)Ag的主要干扰元素Zr通过生成沉淀实现分离,以Re作内标补偿基体效应和信号漂移,采用ICP-MS测定了水系沉积物、岩石、土壤国家标准物质中痕量银的含量,测试值与认定值一致,方法检出限为0.0031μg/g,相对标准偏差(RSD)为4.38%。该方法简捷,在浸取液中加入氨水之前可以先测定常见金属元素,实现了浸取溶液的循环再利用。     

动能歧视模式ICP-MS测定地球化学样品中14种痕量元素

应用传统ICP-MS法测定勘查地球化学样品中Ag、Cd等痕量元素,基体效应和多原子离子干扰严重,准确测定的难度较大。本文基于当前ICP-MS消除干扰技术,分析了ICP-MS标准模式(STD)及动能歧视模式(KED)测定地球化学样品中Ag、Cd等14种痕量元素的有效性,通过比较这两种模式的测定效果,在此基础上确定了各元素的有效测定模式。结果表明:在KED模式下,基体元素如Zr、Nb氧化物的产率降低,基本上消除了Zr、Nb氧化物对痕量元素Ag、Cd的多原子离子干扰。KED模式提高了信噪比,降低了方法检出限,如Ag、Cd的检出限分别为0. 004mg/kg、0. 005mg/kg,其他12种元素的检出限也低于多目标地球化学调查76种元素分析方案中的检出限。测定痕量元素的准确度显著优于STD模式。实验中采用简单的硝酸-氢氟酸-高氯酸消解样品,残渣用王水复溶,结合KED模式下优选出干扰较小的同位素作为测定同位素,以Rh作为内标校正仪器产生的信号漂移,将样品溶液稀释至1000倍,基体效应降低至最小。本方法经国家一级标准物质的验证,测定结果与认定值相符,可为勘查地球化学提供高质量数据。     

P507负载泡塑反相色层富集岩石中的稀土元素

研究了Ｐ５０７负载泡塑萃取柱色谱分离富集稀土元素的条件，并与Ｐ５０７萃淋树脂柱进行了对比；拟定了Ｐ５０７负载泡塑反相色属富集岩石中稀土元素的方法。在ｐＨ２．５介质中ＲＥＥ上柱率９８％，用５０ｍｌ２．５ｍｏｌ／ＬＨＮＯ３作洗脱液，ＲＥＥ总回收率达９６．１％，干扰测定的Ｔｈ，Ｕ，Ｔｉ，Ｚｒ，Ｈｆ等均被除法。方法用于标样分析验证，结果与推荐值相符。     

载炭泡塑吸附-电感耦合等离子体发射光谱法测定金矿石的金量

载炭泡塑吸附法对金有良好的吸附性能,但只能用于抽滤吸附不能振荡吸附,分析手续繁杂。本文以载炭泡塑振荡吸附-电感耦合等离子体发射光谱法测定金矿石的金量。样品在650℃高温灼烧2 h,用50%王水和10%氯化铁加热溶解,溶液冷却后加入5%高锰酸钾氧化,用中密度规格的载炭泡塑两次振荡吸附溶液中的金,然后于580℃高温灼烧后以50%王水溶解灰分,直接用ICP-OES测定金量。方法检出限(3σ)为0.002μg/g,精密度(RSD,n=11)小于3.7%。本方法对金的吸附率大于99.9%,测定范围为0.01~90μg/g,对不同类型金矿石的适应性强,解决了以往泡塑吸附法吸附率较低、标准系列与样品需同时预处理的问题,对低含量和高含量样品均有较高的准确度。     

辉钼矿单矿物化学全分析

本文拟定了一个简单,快速的分析流程,200—300mg试样可完成辉钼矿单矿物中Mo、S、W、Re,As、Sn、Fe、Al、Ti、Bi、Cu、Pb、Zn、Co、Ni、Ca、MS、Mn等项主、次、痕量元素测定。同时,本文就基体元素Mo对其它元素测定的干扰和采用TBP萃淋树脂富集分离Re和W的条件作了考查,对Mo的硫氰酸盐光度测定法作了改进。所拟定的方法用于辉钼矿单矿物和钼精矿全分析,所得结果满意。     

磷酸沉淀分离-电感耦合等离子体质谱法测定化探样品中的痕量银

应用电感耦合等离子体质谱法(ICP-MS)分析化探样品中的痕量银,通常在标准模式下用干扰校正法或动能歧视模式进行测定。银的两个稳定同位素均受锆和铌的氧化物或氢氧化物的质谱干扰,对于干扰元素锆、铌含量较高而银含量低的样品,测定误差较大,需要将干扰元素与银分离。本方法采用硝酸、氢氟酸、高氯酸消解样品,浓盐酸复溶提取,加入磷酸使大部分溶出的干扰元素锆、铌转化为难溶的磷酸盐化合物,通过沉淀与待测元素银分离。ICP-MS测定时以~(103)Rh为内标,用~(90)Zr~(16)O~+同质量数的同位素~(106)Pd间接校正~(91)Zr~(16)O~+、~(90)Zr~(16)O~1H~+对~(107)Ag的质谱干扰。经国家一级标准物质验证,分析结果在标准值的允许误差范围内,相对标准偏(n=12)为4.3%～12.1%,方法检出限(3SD)为0.0072μg/g。本方法适合土壤、水系沉积物及岩石等化探样品中痕量银的分析。样品处理中引入的磷酸不影响其他常规元素,可用同一份消解液进行测定。     

氯化反应在发射光谱分析上的应用—同时测定化探样品中十个痕量元素

本方法提出化探样品中测定十个痕量元素(W、Bi、Ag、Ga等)。这些在矿物中的痕量元素和化学反应剂,在电极高温电弧中立即转化成易挥发的化合物。然后达到与基体元素有效的分离。十个元素测定下限为(ppm):W1,Tl1,Cdl,Bi0.3,Ga0.3,In 0.3,Ge 0.3,Mo 0.3,Sn0.3,Ag 0.01。     

乙醇介质制备载炭泡塑及其在地质样品金测定中的应用

载炭泡塑相较于无负载泡塑,可有效提高泡塑对金的吸附能力,但现有制备载炭泡塑的方法制备效率不高。为了缩短制备载炭泡塑的时间,提高制备效率,本文采用活性炭-乙醇溶液制备载炭泡塑,通过优化制备条件,包括负载介质的种类、试剂浓度、浸泡时间,使得制备100个载炭泡塑的时间可以控制在30 min之内,并结合ICP-OES建立了测定地质样品中金的方法。实验结果表明:该方法的振荡时间可以缩短至20 min。金的质量浓度在0～100. 00μg/mL范围内与光谱强度呈良好的线性关系,相关系数为0. 9997,方法检出限(3σ)为0. 0066μg/g,测定结果相对标准偏差为0. 81%～2. 11%(n=10)。该方法经4个国家标准物质验证,准确度与精密度良好,能够满足地质样品中金的分析测试要求。     

Elastic and thermoelastic properties of synthetic Ca<Subscript>2</Subscript>MgSi<Subscript>2</Subscript>O<Subscript>7</Subscript> (åkermanite) and Ca<Subscript>2</Subscript>ZnSi<Subscript>2</Subscript>O<Subscript>7</Subscript> (hardystonite)

Elastic and thermoelastic constants of large single crystals of Ca₂MgSi₂O₇ and Ca₂ZnSi₂O₇ have been derived from ultrasonic resonance frequencies of plane-parallel plates and their shift upon variation of temperature, respectively. In addition, coefficients of thermal expansion and dielectric constants were determined. Both species possess quite similar properties. As observed in other isotypic magnesium and zinc compounds, the mean elastic stiffness and the deviation from the Cauchy relations are significantly larger in the zinc compound, due to a covalent contribution of the Zn–O bond. Positive thermoelastic constants T₄₄ and T₆₆ in Ca₂MgSi₂O₇ allow temperature-independent ultrasonic generators and oscillators to be manufactured.     

硅酸盐玻璃中的Na和K含量电子探针分析条件设定探讨

含Ti硅酸盐玻璃在基础科学研究和应用技术开发上均有重要价值,亟需对其进行准确的成分分析,为进一步的科研工作提供重要的数据支撑.对玻璃进行电子探针分析时,由于样品的易损性和其中(Na和K)阳离子在电子束轰击下极易发生迁移和扩散,因此往往需要经过条件实验来确定合适的分析条件,确保样品在该条件下能够保持尽量稳定的状态,才能获...     

Hydrometallurgical processing and recovery of molybdenum trioxide from spent catalyst

Hydrometallurgical processing of spent hydrodesulphurisation (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixtures was investigated. The results indicated that the recovery of molybdenum was largely dependent on the concentrations of Na₂CO₃ and H₂O₂ in the reaction medium, which controls the acidity of the leach liquor and carry over of impurities such as Al, Ni, P, Si and V. Leaching process was exothermic and leaching efficiency of molybdenum decreased with increasing solid to liquid ratio. Large scale leaching of spent catalyst, under optimum conditions: 20% pulp density, 85 g/L Na₂CO₃, 10 vol.% H₂O₂ and 1 h reaction, resulted a leaching efficiency of 84% Mo. The obtained leach liquor contained (g/L): Mo — 22.0, Ni — 0.015 and Al — 0.82, P — 1.1, Si — 0.094 and minor quantities of V — 8 mg/L, As and Co — < 1 mg/L. Recovery of Mo from leach solution as MoO₃ of 97.30% purity was achieved by ammonium molybdate precipitation method.     

A computer simulation study of OH defects in Mg2SiO4 and Mg2GeO4 spinels

Classical atomistic simulation techniques have been used to investigate the energies of hydrogen defects in Mg₂SiO₄ and Mg₂GeO₄ spinels. Ringwoodite (γ-Mg₂SiO₄) is considered to be the most abundant mineral in the lower part of the transition zone and can incorporate large amounts of water in the form of hydroxyls, whereas the germanate spinel (γ-Mg₂GeO₄) corresponds to a low-pressure structural analogue for ringwoodite. The calculated defect energies indicate that the most favourable mechanisms for hydrogen incorporation are coupled either with the reduction of ferric iron or with the creation of tetrahedral vacancies. Hydrogen will go preferentially into tetrahedral vacancies, eventually leading to the formation of the hydrogarnet defect, before associating with other negatively charged point defects. The presence of isolated hydroxyls is not expected. The same trend is observed for germanate, and thus γ-Mg₂GeO₄ could be used as a low-pressure analogue for ringwoodite in studies of water-related defects and their effect on physical properties.     

Low-temperature heat capacities of MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript> and spinels of the MgCr<Subscript>2</Subscript>O<Subscript>4</Subscript>–MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript> solid solution

We present results from low-temperature heat capacity measurements of spinels along the solid solution between MgAl₂O₄ and MgCr₂O₄. The data also include new low-temperature heat capacity measurements for MgAl₂O₄ spinel. Heat capacities were measured between 1.5 and 300 K, and thermochemical functions were derived from the results. No heat capacity anomaly was observed for MgAl₂O₄ spinel; however, we observe a low-temperature heat capacity anomaly for Cr-bearing spinels at temperatures below 15 K. From our data we calculate standard entropies (298.15 K) for Mg(Cr,Al)₂O₄ spinels. We suggest a standard entropy for MgAl₂O₄ of 80.9 ± 0.6 J mol⁻¹ K⁻¹. For the solid solution between MgAl₂O₄ and MgCr₂O₄, we observe a linear increase of the standard entropies from 80.9 J mol⁻¹ K⁻¹ for MgAl₂O₄ to 118.3 J mol⁻¹ K⁻¹ for MgCr₂O₄.     

Elastic behavior of vanadinite,Pb<Subscript>10</Subscript>(VO<Subscript>4</Subscript>)<Subscript>6</Subscript>Cl<Subscript>2</Subscript>, a microporous non-zeolitic mineral

The high-pressure behavior of a vanadinite (Pb₁₀(VO₄)₆Cl₂, a = b = 10.3254(5), c = 7.3450(4) Å, space group P6₃/m), a natural microporous mineral, has been investigated using in-situ HP-synchrotron X-ray powder diffraction up to 7.67 GPa with a diamond anvil cell under hydrostatic conditions. No phase transition has been observed within the pressure range investigated. Axial and volume isothermal Equations of State (EoS) of vanadinite were determined. Fitting the P–V data with a third-order Birch-Murnaghan (BM) EoS, using the data weighted by the uncertainties in P and V, we obtained: V ₀ = 681(1) Å³, K ₀ = 41(5) GPa, and K′ = 12.5(2.5). The evolution of the lattice constants with P shows a strong anisotropic compression pattern. The axial bulk moduli were calculated with a third-order “linearized” BM-EoS. The EoS parameters are: a ₀ = 10.3302(2) Å, K ₀(a) = 35(2) GPa and K′(a) = 10(1) for the a-axis; c ₀ = 7.3520(3) Å, K ₀(c) = 98(4) GPa, and K′(c) = 9(2) for the c-axis (K ₀(a):K ₀(c) = 1:2.80). Axial and volume Eulerian-finite strain (fe) at different normalized stress (Fe) were calculated. The weighted linear regression through the data points yields the following intercept values: Fe _a (0) = 35(2) GPa for the a-axis, Fe _c (0) = 98(4) GPa for the c-axis and Fe _V (0) = 45(2) GPa for the unit-cell volume. The slope of the regression lines gives rise to K′ values of 10(1) for the a-axis, 9(2) for the c-axis and 11(1) for the unit cell-volume. A comparison between the HP-elastic response of vanadinite and the iso-structural apatite is carried out. The possible reasons of the elastic anisotropy are discussed.     

High-T phase transition of synthetic ANaB(LiMg)CMg5Si8O22(OH)2 amphibole: an X-ray synchrotron powder diffraction and FTIR spectroscopic study

The synthetic amphibole Na_0.95(Li_0.95Mg_1.05)Mg₅Si₈O₂₂(OH)₂ was studied in situ at high-T, using IR OH-stretching spectroscopy and synchrotron X-ray powder diffraction. At room-T the sample has P2₁ /m symmetry, as shown by the FTIR spectrum. It shows in the OH region two well-defined and intense absorptions at 3,748 and 3,712 cm⁻¹, respectively, and two minor bands at 3,667 and 3,687 cm⁻¹. The main bands are assigned to the two independent O–H groups in the primitive structure. The two minor bands evidencing the presence of small amount of vacant A-site (^A□_0.05). With increasing T, these bands shift continuously and merge into a unique absorption at high temperature. A change as a function of increasing T is revealed by the evolution of the refined unit-cell parameters, whose trend shows a transition to C2/m at about 320–330°C. The spontaneous scalar strain, fitted with a tricritical 2–6 Landau potential, gives a T _c of 325(10)°C (β parameter = 0.27). Comparison with the second-order P2₁ /m ⇔ C2/m phase transition at 255°C for synthetic amphibole ^ANa_0.8^B(Na_0.8Mg_1.2)^CMg₅Si₈O₂₂(OH)₂ indicates that the substitution of Na with Li at the B-sites strongly affects the thermodynamic character and the T _c of the phase transition. The comparison of LNMSH amphiboles with cummingtonitic ones shows that the high-T thermodynamic behaviour is affected by A-site occupancy.     

Structural changes and valence states in the MgCr<Subscript>2</Subscript>O<Subscript>4</Subscript>–FeCr<Subscript>2</Subscript>O<Subscript>4</Subscript> solid solution series

The influence on the structure of Fe²⁺ Mg substitution was studied in synthetic single crystals belonging to the MgCr₂O₄–FeCr₂O₄ series produced by flux growth at 900–1200 °C in controlled atmosphere. Samples were analyzed by single-crystal X-ray diffraction, electron microprobe analyses, optical absorption-, infrared- and Mössbauer spectroscopy. The Mössbauer data show that iron occurs almost exclusively as ^IVFe²⁺. Only minor Fe³⁺ (<0.005 apfu) was observed in samples with very low total Fe. Optical absorption spectra show that chromium with few exceptions is present as a trivalent cation at the octahedral site. Additional absorption bands attributable to Cr²⁺ and Cr³⁺ at the tetrahedral site are evident in spectra of end-member magnesiochromite and solid-solution crystals with low ferrous contents. Structural parameters a₀, u and T–O increase with chromite content, while the M–O bond distance remains nearly constant, with an average value equal to 1.995(1) Å corresponding to the Cr³⁺ octahedral bond distance. The ideal trend between cell parameter, T–O bond length and Fe²⁺ content (apfu) is described by the following linear relations: a₀=8.3325(5) + 0.0443(8)Fe²⁺ (Å) and T–O=1.9645(6) + 0.033(1)Fe²⁺ (Å) Consequently, Fe²⁺ and Mg tetrahedral bond lengths are equal to 1.998(1) Å and 1.965(1) Å, respectively.     

Yellow fluorescence from baghdadite and synthetic Ca3(Zr,Ti)Si2O9

Baghdadite from Fuka, Okayama Prefecture, Japan shows a bright yellow fluorescence under UV (Hg 253.7 nm) excitation. The photoluminescence (PL) spectrum at 300 K consists of one large band near 580 nm and two small UV bands at 318 and 397 nm. The optical excitation spectrum of the bright yellow fluorescence consists of two bands near 220 and 250 nm. The temperature dependence of the PL intensity exhibits linear thermal quenching. To reveal the origin of the bright yellow fluorescence from baghdadite, powder Ca₃(Zr,Ti)Si₂O₉ crystals are synthesized. Synthetic Ca₃(Zr,Ti)Si₂O₉ shows luminescence spectra similar to those of baghdadite, and the intensity of the yellow fluorescence is markedly increased by titanium addition. The origin of the bright yellow fluorescence from baghdadite is ascribed to the existence of titanium.