酶催化分光光度法测定环境水中痕量钒

钒对牛血红蛋白模拟酶催化过氧化氢氧化罗丹明B体系有强烈的抑制作用, 据此建立了酶催化分光光度法测定痕量钒的新方法。试验从pH值、罗丹明B浓度、过氧化氢浓度、牛血红蛋白浓度和反应时间等方面探讨了体系的实验条件。在pH 9.8的NH₃·H₂O-NH₄Cl缓冲溶液中, 当罗丹明B、H₂O₂和血红蛋白的浓度分别为1.5×10^-5 mol/L、1.5×10^-4 mol/L和 2.0×10^-6 mol/L时, 测定钒的线性范围为3.1×10^-4 ~6.2×10^-3 g/L, 方法的检出限为2.1×10^-6 g/L。1 000倍Na⁺、K⁺、Cl^- 、NO₃^-、NH₄⁺ 、F^-、BrO₃^-, 500倍Ca²⁺、Fe³⁺ 、Al³⁺、 Mn²⁺、Ba²⁺、CO₃^2-, 100倍C₂O₄^2-, 5倍Cu²⁺对钒的测定没有干扰。对环境水样中痕量钒进行测定, 结果的相对标准偏差(n=7)为3.7%, 与萃取分光光度法的结果基本一致, t检验结果表明两种方法没有显著性差异。     

聚L-苏氨酸修饰电极方波溶出伏安法测定铅

在pH 3.5的NaAc-HAc缓冲液中,用循环伏安法制备聚L-苏氨酸修饰玻碳电极,探讨了Pb²⁺在修饰电极上的方波阳极溶出伏安特性,建立了方波阳极溶出伏安法测定Pb²⁺的方法。在最佳实验条件下,铅离子浓度在5.00×10^-8～7.50×10^-6 mol/L范围内与峰电流呈良好的线性关系,检出限为5.0×10^-9 mol/L。测定2.50×10^-6 mol/L Pb²⁺,当相对误差在±5%时,至少1 000倍K⁺、Na⁺、SO₄^2-、PO₄^3-、NO₃^-、Cl^-、Ca²⁺、Ba²⁺、Mn²⁺、Mg²⁺、Al³⁺、Zn²⁺、Fe³⁺、Cr³⁺、Co²⁺、Cd²⁺,200倍Cu²⁺不干扰Pb²⁺的测定。按照实验方法测定2个污水样中痕量铅,结果的相对标准偏差(RSD,n=6)分别为1.4%和2.4%,加标回收率分别为99%和103%。     

锗在十六烷基三甲基溴化铵-KI-水体系中的浮选分离和富集

研究了十六烷基三甲基溴化铵（CTMAB）-KI-水体系浮选分离锗的行为及锗与一些金属离子分离的条件。结果表明: 在水溶液中, Ge(Ⅳ)与CTMAB和KI形成不溶于水的三元缔合物［GeI₆2-］［CTMAB+］₂,此三元缔合物沉淀浮于水相上层形成界面清晰的液-固两相;当溶液中CTMAB和KI的浓度分别为6.0×10^-4mol/L和8.0×10^-3mol/L时, Ge(Ⅳ)可与Co^2＋、Ni^2＋、Mn^2＋、Mg^2＋、Zn^2＋、Al³⁺、Fe^2＋、Cr³⁺、V(Ⅴ)和W(Ⅵ)离子定量分离,Ge(Ⅳ)的浮选率在97.4 %以上。该方法简便、迅速,不污染环境,在微量锗的分离和富集分析中有很好的实用价值。     

十六烷基三甲基溴化铵-硫氰酸钾-水体系浮选分离钛

研究了十六烷基三甲基溴化铵（CTMAB）-硫氰酸钾-水体系浮选分离钛的行为。结果表明, 在水溶液中, Ti与CTMAB和硫氰酸钾形成不溶于水的三元缔合物［Ti(SCN)₆^2- ］［CTMAB⁺］₂,此三元缔合物沉淀浮于水相上层形成界面清晰的液-固两相。当溶液中CTMAB和硫氰酸钾的浓度分别为2.0×10^-3mol/L和7.0×10^-2mol/L时, Ti可与CdⅡ、Cr、MnⅡ、V、Al、NiⅡ、FeⅡ、MgⅡ和Ga离子定量分离。该方法简便迅速,不污染环境,在微量钛的分离和富集分析中有很好的实用价值。     

铬天青S-正丙醇-氯化钠体系萃取分离铝

研究了铬天青S-正丙醇-氯化钠体系析相萃取分离和富集铝的行为及与一些金属离子分离的条件,结果表明,氯化钠能使正丙醇的水溶液分成两相,在分相过程中,Al³⁺和铬天青S(CAS)生成的Al(CAS)₂^-与质子化正丙醇C₃H₇OH₂⁺ 形成的缔合物［Al(CAS)₂^-］［C₃H₇OH₂⁺］能被正丙醇相完全萃取,当溶液pH值为4,正丙醇、铬天青S和氯化钠的浓度分别为30 %（V/V）、5.0×10^-4 mol/L和0.17 g/mL时,Al³⁺的萃取率达到97.8%以上,而Ru³⁺、Ir⁴⁺、Pd²⁺、Fe²⁺、Ni²⁺、Co²⁺、Cr³⁺、Mg²⁺、V⁵⁺ 和 Ag⁺基本不被萃取,实现了Al³⁺与上述金属离子的分离。对合成水样和镍铬铝合金中铝的分离和测定,结果满意。该方法在微量铝的分离和富集分析中有一定的实用价值。     

氰化尾渣浸出液光催化制备草酸亚铁及再生C2O42-的研究

针对草酸浸出氰化尾渣过程产出的大量浸出液资源化利用问题,在分析Fe³⁺-H₂C₂O₄-H₂O体系中Fe³⁺和C₂O₄^2-的形态分布及电位-pH图的基础上,提出采用光催化法处理浸出液制备草酸亚铁和再生C₂O₄^2-。初步研究了静态和磁力搅拌状态下浸出液中C₂O₄^2-氧化率、铁沉淀率及草酸亚铁沉淀形貌与晶型。结果表明：与静态光催化相比,磁力搅拌虽可缩短光催化时间,强化光催化效果,减小β-FeC₂O₄·2H₂O粒度,但破坏其形貌,并使C₂O₄^2-氧化率增加,不利于C₂O₄^2-...     

硝酸钠-硫氰化铵-溴化十六烷基吡啶体系浮选分离和富集铑

研究了硝酸钠-硫氰化铵-溴化十六烷基吡啶(CPB)体系浮选分离富集铑的新方法。探讨了酸度、硝酸钠、硫氰化铵和溴化十六烷基吡啶的浓度等对Rh³⁺浮选率的影响,确定了浮选分离Rh³⁺的最佳条件,并讨论了Rh³⁺的浮选分离机理。结果表明,在最佳条件下,Rh³⁺与硫氰化铵和溴化十六烷基吡啶生成不溶于水的三元缔合物[CPB⁺]₃[(Rh(SCN)₆^3-],此三元缔合物浮于盐水相上层形成界面清晰的液-固两相。控制溶液酸度为pH 2,在0.2 g/mL硝酸钠、8.0×10^-3mol/L硫氰化铵和3.0×10^-3 mol/L溴化十六烷基吡啶(CPB)的条件下,实现了Rh³⁺与Al³⁺、Mn²⁺、Ga³⁺、Fe²⁺、Cd²⁺、Mg²⁺、V、Ni²⁺、和Cr³⁺的定量分离。方法用于合成水样中微量Rh³⁺的浮选分离,回收率为97.6%～99.1%。     

酶催化荧光猝灭法测定土壤中痕量硒

在牛血红蛋白催化作用下,H₂O₂能够氧化L-酪氨酸产生荧光,而硒对该荧光体系具有较强的猝灭作用。据此,建立了一种酶催化荧光猝灭法测定痕量硒的新方法。实验从pH值、L-酪氨酸溶液浓度、H₂O₂浓度,牛血红蛋白溶液浓度和反应时间等方面进行了探讨。在pH 9.8的NH₃·H₂O-NH₄Cl缓冲溶液中,当L-酪氨酸、H₂O₂和血红蛋白的浓度分别为7.5×10^-5 mol/L、1.0×10^-4 mol/L和 2.0×10^-7 mol/L时,测定硒的线性范围为0.3~50 μg/mL,方法的检出限为0.05 μg/mL。方法应用于富硒花生土壤中痕量硒的测定,测定值与原子吸收光谱法的测定值基本一致,相对标准偏差为4.6%～4.9%。     

离子液体-石墨烯-二氧化锰复合材料修饰玻碳电极差分脉冲伏安法测定土壤中铅和镉

采用涂滴法将石墨烯(GR)-二氧化锰(MnO₂)分散液滴在玻碳电极(GCE),然后利用循环伏安法将离子液体(OMIMPF₆)聚合制备得OMIMPF₆/GR/MnO₂/GCE复合材料修饰玻碳电极,建立了差分脉冲伏安法测定土壤中铅和镉的方法。实验表明,以4μL 2mg/mL的石墨烯-二氧化锰混合物分散液涂滴,电聚合离子液体30圈所制备的修饰电极,在0.1mol/L的醋酸-醋酸钠缓冲溶液(pH4.5)的支持电解液中,Pb²⁺和Cd²⁺的氧化峰电流值相对较高。Pb²⁺和Cd²⁺的浓度均在5.0×10^-8~1.4×10^-5mol/L范围内呈良好线性关系,Pb²⁺和Cd²⁺检出限分别达到5.0×10^-10mol/L和4.0×10^-9mol/L。对含10μmol/L Pb²⁺和10μmol/L Cd²⁺的标准混合溶液平行测定9次和连续扫描30次,Pb²⁺和Cd²⁺峰电流值的相对标准偏差均分别小于1.3%和4.3%,说明该修饰电极具有良好的重现性、稳定性。采用建立的方法用于土壤中铅和镉的检测,测得结果与原子吸收光谱法(GB/T 17141—1997)基本一致,相对标准偏差(RSD,n=6)均小于5.3%,回收率在97%~105%之间。     

碳酸根和碳酸氢根野外现场快速检测仪的研发与应用

CO₃^2-和HCO₃^-含量能够反映碳的地球化学行为和碳循环特征，是重要的地球化学指标。本文利用双电极测量技术，研发一套测量CO₃^2-和HCO₃^-含量的小型野外现场快速检测仪，以一键式操作方式自动完成水质样品中CO₃^2-和HCO₃^-含量的快速检测，满足了野外现场调查要求，提高了野外现场测试效率。该仪器具有较低的检出限，CO₃^2-仪器检出限为0.001 mg/L,HCO₃^-仪器检出限为2.5 mg/L;对1×10^-3 mol/L CO₂标准溶液平行测量7次，CO₃^2-、HCO₃^-分析结果的相对标准偏差(RSD,n=...     

Dissolution behaviour of a beryl ore for optimal industrial beryllium compound production

This study involves the leaching of the beryl ore with sulphuric acid (H₂SO₄) solution for predicting optimal beryllium extraction conditions with the aim of assessing the importance of leachant concentration, reaction temperature and particle size on the extent of dissolution. A kinetic model to represent the effects of these variables on the leaching rate was developed. It was observed that the dissolution of beryl ore increases with increasing H₂SO₄ concentration, temperature, decreasing particle size and solid to liquid ratio. At optimal leaching conditions, 89.3% of the ore was reacted by 1.25?mol/L at 75°C temperature and 120 minutes with moderate stirring, where 1612.0?mg/L Be²⁺, 786.7?mg/L Al³⁺, 98.1?mg/L Fe³⁺ and 63.4?mg/L Ag⁺ were found as major species in the leach liquor. The unleached products constituting about 10.7% were examined by X-ray diffraction (XRD) and found to contain primarily, siliceous compounds such as Xonotlite, Antigorite, Chrysolite and Kaolinite.     

过氧化氢-钛-氟化物体系褪色光度法测定熔盐中氟

在pH 3.2～3.5的硫酸介质中,Ti与氟离子络合形成H₂TiF₆,使Ti与H₂O₂生成的黄色络合物(TiO·H₂O₂)SO₄褪色,且褪色的程度与氟离子含量呈线性关系,据此提出了一种褪色光度法测定熔盐中氟含量的方法。试样采用氧化锌、碳酸钠和石英砂的混合熔剂熔融,经水浸取、过滤后,分取适量样品溶液,加入二氧化钛溶液,用硫酸调节pH值,加入双氧水溶液进行反应15 min后在波长410 nm处测定吸光度。氟含量在0.5～6μg/mL时,校准曲线呈线性关系,相关系数r=0.999 6,方法检出限为0.35 μg/mL。测定0.5 μg/mL的氟,5倍的SO₄^2- 、10倍的Na⁺、20倍的K⁺和Cl^-不干扰测定,熔盐样品中的Ca²⁺、Fe³⁺、Mg²⁺因其在试样熔融后已被沉淀分离,也不干扰测定。用本法对海绵钛厂镁电解车间2个熔盐样品中氟进行测定,结果与氟离子选择电极法和极谱法一致,相对标准偏差（n=5）分别为2.2%和4.2%。     

Decomposition of pyrite in acids by pressure leaching and anodization: the case for an electrochemical mechanism

Abstract

The oxygen pressure leaching of pyrite has been studied with regard to reaction mechanism by oxygen-18 tracer tests, electrochemical simulation and actual leaching experiments over a range of variables; temperature, 85 to 130°C; pressure, 0 to 976 psi O₂ (66.4 atm); and acid concentration, 0.01 to 3M H₂SO₄. The dissolution mechanism has been found to be electrochemical and is a potentiostatically controlled steady state between sulphate-forming and elemental sulphur-forming anodic reactions:

1. FeS₂+8H₂O→Fe⁺²+2SO₄⁼+16H⁺+14e^?

2. FeS₂+Fe⁺²+2SO^o+2e^?

Ferric ions are produced primarily by a slow homogeneous reaction:

4Fe⁺²+O₂+4H⁺→4Fe⁺³+2H₂O

The cathodic reaction initially involves the reduction of oxygen:

1/2O₂+2H⁺+2e^?→H₂O

This reaction is supplemented by cathodic reduction of ferric ions after these have built up to a significant concentration

The electrochemical model has been cited to explain the effect of oxygen pressure on the system and acid production or consumption by pyrite during leaching.

Résumé

On a étudié la lixiviation de la pyrite en autoclave par lapos;oxygène, s'arrêtant en particulier sur le mécanisme de réaction, la simulation électrochimique, la pression et les concentrations dans les limites suivantes: °C 85–130, O₂ O – 66.4 atm., concentration d'acide sulfurique 0.01 à3M. Le mécanisme

de la réaction est électrochimique. Elle est contrôlée par deux réactions anodiques en competition, l'une formant l'anion sulfate, l'autre donnant du soufre:

1. FeS₂ + 8H₂O → Fe⁺² + 2SO₄⁼ + 16H⁺ + 14e^?

2. FeS₂ → Fe⁺² + 2S^o + 2e^?

Les ions ferriques sont produits surtout par une lente réaction homogàne:

4Fe⁺² →O₂ + 4H⁺ → 4Fe³⁺ + 2H₂O

La réaction cathodique initiale comprend la réduction de l'oxygène:

1/2O₂ + 2H ⁺ + 2e^?→ H₂O

A cette réaction s'ajoute la réduction cathodique des ions ferriques et celle-ci prend plus au moins d'importance selon la concentration des ions ferriques.

Le modèle électrochimique permet d'expliquer l'effet de la pression d'oxygene sur la reaction globale ainsi que, la production et la consommation de l'acide par la pyrite pendant la lixiviation.     

Reaction mechanism for the acid ferric sulfate leaching of chalcopyrite

The acid ferric sulfate leaching of chalcopyrite, CuFeS₂ + 4Fe⁺³ = Cu⁺² + 5Fe⁺² + 2S⁰ was studied using monosize particles in a well stirred reactor at ambient pressure and dilute solid phase concentration in order to obtain fundamental details of the reaction kinetics. The principal rate limiting step for this electrochemical reaction appears to be a transport process through the elemental sulfur reaction product. This conclusion has been reached in other investigations and is supported by data from this investigation in which the reaction rate was found to have an inverse second order dependence on the initial particle diameter. Furthermore, the reaction kinetics were found to be independent of Fe⁺³, Fe⁺², Cu⁺² and H₂SO₄ in the range of additions studied. The unique aspect of this particular research effort is that data analysis, using the Wagner theory of oxidation, suggests that the rate limiting process may be the transport of electrons through the elemental sulfur layer. Predicted reaction rates calculated from first principles using the physicochemical properties of the system (conductivity of elemental sulfur and the free energy change for the reaction) agree satisfactorily with experimentally determined rates. Further evidence which supports this analysis includes an experimental activation energy of 20 kcal/mol (83.7 kJ/mol) which is approximately the same as the apparent activation energy for the transfer of electrons through elemental sulfur, 23 kcal/ mol (96.3 kJ/mol) calculated from both conductivity and electron mobility measurements reported in the literature. formerly Metallurgy Graduate Student, University of Utah.     

Trace detection of Ce3+ by adsorption strip voltammetry at a carbon paste electrode modified with ion imprinted polymers

To develop a convenient method for sensitive and selective determination of Ce3+ in aqueous phase with complicated matrices, a carbon paste electrode(CPE) modified with ion imprinted polymers(IIPs) were fabricated. The polymers were prepared by precipitation polymerization using Ce3+ as template, allyl phenoxyacetate(APA) as monomer, ethylene glycol dimethacrylate(EGDMA) as crosslinker and azobisisobutyronitrile(AIBN) as initiator under the molar ratio of Ce3+, APA and EGDMA as 1:4:40, respectively. Ce~(3+) was detected directly by differential pulse adsorptive stripping voltammetry(DPASV) and its oxidation peak appears at about 0.93 V. All parameters affecting the sensor's response are optimized and a calibration curve is plotted at a linear range of 1.0 × 10~(-6)-1.0 x 10~(-5) mol/L and 1.0×10~(-5)-2.0 × 10~(-4)mol/L with the detection limit of 1.5 × 10~(-7) mol/L. All other rare earth ions have no interference with the determination of Ce~(3+) even at a concentration 500 times higher than that of Ce~(3+).This sensor was successfully applied to determination of Ce~(3+) in two catalyst sample solutions with RSD≤3.3%(n = 5)and recoveries in the range of 99.2%-106.5% at our optimal conditions.     

Application of three Ln(Ⅲ)-coordination polymers in fields of luminescence,antibacteria and detection of Fe3+ and 4-nitrophenol

Three lanthanide-based coordination polymers(Ln-CPs) with layered structure,{[La₂(L)₃(DMF)(H₂O)₃]·H₂O}_n(1),{[Eu₂(L)₃(DMF)₂(H₂O)]·(H₂O)}_n(2){Tb₂(L)₃(DMF)₂(H₂O)]·H₂O}n(3) were successfully synthesized from H₂L(N,N’-bis(4-carbozylbenzyl)aniline).Remarkably,compound 3 has extremely high sensitivity to 4-n...     

氢化物发生-原子荧光光谱法测定处理废水中砷

研究了氢化物发生-原子荧光光谱法测定砷钙渣固化、高砷烟尘湿法中和、苄基砷酸及仲钨酸铵生产等废水中砷的最佳条件。实验表明,废水样经化学处理,在稀盐酸介质中用硫脲-抗坏血酸将砷预还原为砷,Fe³⁺、Ca²⁺、Na⁺、Cu²⁺、F^-、S^2-、Bi³⁺、Sn⁴⁺、Sb⁵⁺等23 种离子的允许量（mg/50 mL）中高者达250或低至0.5。载液盐酸浓度为5%（V/V）,定量样品与15 g/L硼氢化钾碱性溶液混合生成砷化氢。在选定条件下, 砷量在 2～100 μg/L范围内线性关系良好,检出限（3σ/K）为0.001 4 μg/L。方法用于实际废水样品分析, 相对标准偏差（n=9～11）为1.6%～5.9%,加标回收率在93%～118%之间,固化废水测定值与砷锑钼蓝光度法相符。     

Simulation ofin situ uraninite leaching-part II: The effects of ore grade and deposit porosity

A combined partial equilibrium-mixing cell model has been used to investigate the effects of fluid flow, mineral content, porosity, and lixiviant concentrations onin situ leaching of uraninite. The model couples the rate processes of reactive transport (uraninite and calcite dissolution kinetics and leach solution flow) with solution phase equilibria (acid-base and complexation equilibria). Solution circulation and porosity changes have been explicitly treated in the following way: reacted solution was assumed to be pumped from the system at a constant rate and replaced by fresh lixiviant; the additional void volume resulting from CaCO₃ or UO₂ dissolution was immediately filled with lixiviant. A solution volume of 1 cm³ was taken for the base, and it was assumed that on each 1200-second increment, loaded solution was removed at the rate of 1.67 × 10^-5 cm s^-1, equivalent to removal of 2.0 pct of the base volume. The lixiviant considered was NH₄HCO₃ (NH₄)₂CO₃-H₂O₂ with reference case concentrations of 1.0 × 10^-4, 1.0 × 10^-4, and 2.2 × 10^-5 mol cm^-1. The parameters that were varied in this investigation were the mass fractions of UO₂ (0.000 to 0.015) and CaCO₃ (0.00 to 0.40) and the initial porosity of the deposit (0.20 and 0.30). Major factors found to affect the uranium content of the solution were UO₂ content and initial porosity. Higher UO₂ grades were associated with higher U(VI) concentrations, and these were maintained for much longer periods; the consumption of the peroxide oxidant was under mass transfer control. As the leaching reaction slowed, solution replacement began to control the component concentrations, causing decreasing U(VI) concentrations. Higher porosity caused reduced maximum U concentrations and a faster decline. The calcite content had a slight effect on the rate of U leaching; this occurred because high CaCO₃ mass fractions led to increased HCO₃ ^- concentrations. Early in the leaching process, a lower initial porosity or a higher calcite content led to a higher (less negative) value of the CaCO₃ saturation index; however, for the conditions simulated, the solution did not actually become saturated. Also, decreases in the saturation index occurred sooner for higher initial porosities or lower calcite grades. The final porosity was effectively determined by the initial calcite content; dissolution of calcite continued until it had completely reacted, and the uraninite content was too low for it to contribute significantly. Changes in concentrations of the various solution species occurred more rapidly if the ore was more porous, but there were no other significant differences attributable to initial porosity. The H⁺ concentration was virtually constant throughout leaching if the ore did not contain any calcite; with high calcite contents (40 pct), it remained constant for an extended period following an initial sharp decrease. Changes in the OH^-, NH4/+ and NH₃ concentrations could be readily predicted from those of H⁺, and changes in the Ca species concentrations were closely related to those of the Ca and CO₃ components. Total U and total H₂O₂ concentrations behaved oppositely (as required by the reaction stoichiometry), but changes in the concentrations of the minor U(VI) and peroxo species were more complicated. The concentrations of the CO₃ ^2- and HCO₃ ^- species could not readily be predicted from the reaction kinetics, and variations in their concentrations did not reliably indicate pH.     

分光光度法直接测定矿石中铬

铬在碱性介质中呈黄色,最大吸收波长373 nm处的吸光度与铬的浓度符合比尔定律,据此建立了测定铬的方法。试验了铬的显色条件,确定了显色介质种类、稳定时间。考察了20余种离子的干扰量,表明只有Mn²⁺和Bi³⁺对铬的测定有严重干扰,并提出了有效的消除方法,实现了铬的测定。铬的质量浓度在0.14～14 mg/L范围内符合比尔定律,表观摩尔吸光系数为4.77×10³ L·mol^-1·cm^-1。方法已成功地应用于一般矿石样品中0.5%以上铬的测定。