过硫酸钠修复土壤中多环芳烃的准确测定

多环芳烃(PAHs)是一类具有致癌、致突变、致畸的碳氢化合物,具有较高的辛醇-水分配系数,易被土壤颗粒吸附而影响环境和人体健康。过硫酸钠(Na₂S₂O₈)氧化法是近些年来国内外修复PAHs污染土壤较为常用的方法,但现阶段在测定修复后土壤中PAHs含量、进行土壤修复效果评估时亟待解决的问题是：经该方法修复的土壤,若土壤中残留有过硫酸钠,在样品前处理过程中由于提取温度较高,可能会进一步加速多环芳烃的氧化反应,从而影响土壤中PAHs的准确测定。本文建立了一种在修复后土壤中加入还原剂抗坏血酸,与残留的过硫酸钠反应生成脱氢抗坏血酸,采用索氏提取结合气相色谱-质谱法(GC-MS)同时测定土壤中16种PAHs的方法,PAHs加标回收率为76.2%～110.0%。而修复后土壤若不加还原剂直接进行索氏提取,用GC-MS测定,可能会使部分PAHs及替代物的测定不准确,PAHs加标回收率仅为6.0%～72.4%。通过对比分析表明,在样品提取前加入还原剂,可以有效地消除残留过硫酸钠的影响,提高测定修复后土壤中PAHs含量的准确性。     

地下水中钙和镁的离子色谱法同时测定

改进了离子色谱分析地下水中钙和镁的方法。以IonPac CS12A为分离柱,稀盐酸为淋洗液,电导检测器检测,对地下水中的锂、钾、钠、钙和镁进行同时测定。方法具有较宽的线性范围和较高的灵敏度,钙、镁的浓度分别在0～500mg/L和0～250mg/L内呈良好的线性关系;钙的检出限为1.50μg/L,镁的检出限为0.89μg/L。对不同浓度钙、镁水质标准样品进行分析测定,同时对实际样品进行不同稀释倍数分析验证,方法精密度(RSD,n=8)为0.19%～1.89%,无显著的基体效应影响。方法可满足全国地下水调查评价规范要求,适于地下水样品中锂、钾、钠、钙和镁离子的同时测定。     

多巴胺在聚3，4-吡啶二羧酸修饰电极上的电化学行为及其测定

制备了聚3,4-吡啶二羧酸修饰电极,研究了多巴胺在修饰电极上的电化学行为。结果表明聚3,4-吡啶二羧酸聚合物膜对多巴胺的氧化具有明显的催化作用,并且可以消除抗坏血酸对多巴胺测定中的干扰。多巴胺的浓度在2.0×10-6～4.0×10-5mol/L内与其氧化电流呈线性关系,相对标准偏差为3.2%(n=10),检出限为8.0×10-8mol/L。将该修饰电极用于分析模拟样品和注射液样品中的多巴胺,分析结果表明,该修饰电极有望用于实际样品分析。     

电感耦合等离子体发射光谱法测定油田水中的硼

样品经硝酸酸化、滤膜过滤处理后,用电感耦合等离子体发射光谱法直接测定其中硼的含量。通过正交实验优选仪器参数和分析谱线,在选定的波长208.959 nm下,对样品稀释倍数和介质酸种类进行选择,结果表明,硼含量低于10 mg/L的样品不用稀释,高于10 mg/L的样品一般稀释20倍,介质选用硝酸可使测定结果更加准确。对油田水中共存的7种主要金属元素进行了干扰试验,样品中存在20 mg/L的Sr、Ba、Fe,50mg/L的Mg、Ca,100 mg/L的K,200 mg/L的Na对待测元素的测定没有影响。选取油田水样品进行加标回收试验,方法平均回收率为95.3%～102.0%,精密度(RSD,n=11)为0.43%～0.92%,检出限为0.0020mg/L。方法简便、快速,结果令人满意,与姜黄素分光光度法比较,克服了分析流程长、使用试剂较多且不易操作的不足。     

电感耦合等离子体发射光谱法测定多金属矿石中的钼

样品经盐酸-硝酸-氢氟酸-高氯酸-硫酸(五酸)加热分解完全,利用浓硫酸的氧化性,可将钼转化为钼酸盐进入溶液中,盐酸溶解盐类至溶液清亮,用电感耦合等离子体发射光谱法在波长202.0 nm处测定多金属矿石中的钼,克服了盐酸-硝酸-氢氟酸-高氯酸(四酸)分解样品测定结果偏低的问题,同时解决了国标方法分析流程长、成本高、使用试剂较多且不易操作的难题。方法检出限为2.8μg/g,经国家一级标准物质分析验证,测定值与标准值相符。对自制监控样品测定6次,方法精密度(RSD)为2.16%。通过不同溶矿方法、不同检测方法及不同实验室进行验证,证明该方法线性范围宽(0～50 mg/mL),操作简单,适用于批量多金属矿石样品中0.001%～2.00%钼的测定。     

原子荧光光谱法测定土壤样品中的硒

应用碳酸钠-氧化锌混合熔剂对土壤样品半熔,断续流动氢化物发生原子荧光光谱法对样品中的硒进行测定。测定中研究了溶液酸度、硼氢化钾浓度对测定结果的影响。该方法的最低检出限为0.12ug/L,方法精密度RSD为3.65%,方法的回收率为94%¹11%。     

三乙醇胺增敏火焰原子吸收光谱法测定地质样品中的钼

样品经王水分解,加入适量的三乙醇胺增敏,用空气-乙炔火焰原子吸收光谱法测定地质样品中的钼。选择了三乙醇胺的最佳用量;比较了钼在盐酸-磷酸-铝盐、盐酸-三乙醇胺、盐酸-三乙醇胺-磷酸、盐酸-三乙醇胺-磷酸-铝盐等4种不同介质中的特征浓度。结果表明,在盐酸-三乙醇胺-磷酸-铝盐介质中,钼的质量浓度≤40 mg/L内线性良好,方法检出限为0.2 mg/L,相对标准偏差为5.2%(n=6),加标回收率为96%~102%。对国家一级标准物质进行测定,结果与标准值相符。     

电感耦合等离子体质谱法测定地下水中44个元素

采用电感耦合等离子体质谱法(ICP-MS)同时测定地下水中44个元素。结果表明,ICP-MS可同时测定地下水中44个元素,方法检出限为0.002～0.981μg/L,大多数元素的精密度(RSD,n=10)均小于10%,加标回收率在90.0%～110.0%,符合中国地质调查局地质调查技术标准对无机组分测试质量控制的要求。方法应用于直接测定元素浓度范围在ng/L～mg/L级的实际地下水样品,快速、简便,结果准确。     

原子荧光光谱法测定土壤样品中的硒

应用碳酸钠-氧化锌混合熔剂对土壤样品半熔,断续流动氢化物发生原子荧光光谱法对样品中的硒进行测定。测定中研究了溶液酸度、硼氢化钾浓度对测定结果的影响。该方法的最低检出限为0.12ug/L,方法精密度RSD为3.65%,方法的回收率为94%~111%。     

电感耦合等离子体发射光谱法(ICP-AES)测定冶炼副产品硫酸镍中砷、锌、钴

冶炼副产品硫酸镍组成成分复杂,准确分析杂质元素As、Zn、Co含量对设计硫酸镍提纯工艺有重要意义。采用硝酸-盐酸-氢氟酸-高氯酸体系对样品进行前处理,优化仪器工作条件,建立了电感耦合等离子体发射光谱法(ICP-AES)测定冶炼副产品硫酸镍中As、Zn、Co的方法。本实验分别以As 189.042nm,Zn 206.200nm,Co 228.616nm为分析谱线。实验结果表明:待测溶液中20g/L硫酸镍基体及1g/L Cu、20mg/L Cd、Cr、Fe、Sb、Ca、Mg、Al、Mn、Sn、Bi等共存杂质元素对As、Zn、Co的测定结果基本无影响。As、Zn、Co的标准曲线线性相关系数均在0.9999以上,方法检出限为0.0021～0.026mg/L,方法定量限为0.0063～0.078mg/L。采用实验方法测定冶炼副产品硫酸镍实际样品中As、Zn、Co,所得结果的相对标准偏差(RSD,n=11)介于1.51%～2.77%之间,加标回收率在89.6%～108.4%之间。     

电感耦合等离子体发射光谱法同时测定锡矿石中锡钨钼铜铅锌

锡矿石是难分解的矿物,共生与伴生元素多,其中的锡钨钼在单一盐酸溶液中易沉淀,准确测定锡矿石中的主次量元素一直是分析技术难点。本文以过氧化钠为熔剂,高温熔融样品,在酒石酸-盐酸-双氧水体系中进行酸化,选用该矿种中仅含有少量的钴作为内标,建立了电感耦合等离子体发射光谱同时测定锡矿石中锡钨钼铜铅锌的分析方法。方法线性范围为0.00~40.0 mg/L;方法检出限为锡10 mg/kg,钨30 mg/kg,钼3.3 mg/kg,铜12 mg/kg,铅15 mg/kg,锌40 mg/kg;方法精密度(n = 9)小于5.0%,实际样品的测定值与传统化学方法及国家标准方法的测定值吻合较好。本方法采用过氧化钠碱熔锡矿石,溶样彻底,并省去了氢氟酸挥发硅的蒸酸过程,节约了样品处理时间;采用酒石酸-双氧水-盐酸体系溶解熔融物,有利于溶液中的锡钨钼形成稳定的络合物,避免了单纯盐酸体系下产生钨酸、钼酸和锡酸沉淀导致测定结果偏低的问题。     

Degradation of polyvinyl alcohol in aqueous solutions using UV-365 nm/S2O8 2− process

This investigation evaluates the effectiveness of UV-365 nm/S₂O₈ ^2? process in degrading polyvinyl alcohol in aqueous solutions. The effects of pH, Na₂S₂O₈ dosage, and temperature on the degradation efficiency of polyvinyl alcohol were studied. Under acidic conditions, the degradation efficiency of polyvinyl alcohol exceeded that under alkaline conditions. Additionally, a higher Na₂S₂O₈ dosage and a higher temperature were associated with a higher degradation efficiency of polyvinyl alcohol. The degradation rates of polyvinyl alcohol followed a pseudo-first-order kinetic model. Moreover, the observed degradation rate coefficient increased from 0.0078 to 0.4081 min^?1 when the temperature was increased from 10 to 55 °C. Also, the activation energy estimated using the observed degradation rate coefficients and the Arrhenius equation was 64 kJ/mol. At UV-365 nm, pH 3, an Na₂S₂O₈ dosage of 0.06 g/L, a temperature of 55 °C, and an initial polyvinyl alcohol concentration of 20 mg/L, around 100 % of polyvinyl alcohol was degraded, indicating that UV-365 nm/S₂O₈ ^2? process has great potential in degrading polyvinyl alcohol in aqueous solutions.     

Formation and sorption behavior of the palladium thiosulfate complexes under natural conditions (model experiments)

The formation of significant amounts of thiosulfate ion (up to 42 mg/L) was established in experiments on the interaction of sulfide-bearing rocks with water. The possibility of the formation of palladium compounds with thiosulfate ion [Pd(S₂O₃)₂]^2– was demonstrated. The stability constant of the complex is 3.7 × 10⁹, which may provide intense migration of this palladium species in ecosystem. The study of the behavior of palladium thiosulfates during interaction with inorganic and organic components of geochemical barriers showed that around 50–55% of thiosulfate-bound palladium is extracted by humic acid in the pH range typical of natural waters. Under these conditions, ferrihydrite sorbes palladium quantitatively, and may serve as efficient barrier to the interaction of palladium compounds with particulate matters of waters and bottom sediments.     

Rapid photo-oxidation of Mn(II) mediated by humic substances

The oxidation of Mn(II) by O₂ to Mn(III) or Mn(IV) is thermodynamically favored under the pH and pO₂ conditions present in most near surface waters, but the kinetics of this reaction are extremely slow. This work investigated whether reactive oxygen species, produced through illumination of humic substances, could oxidize Mn at an environmentally relavent rate. The simulated sunlight illumination of a solution containing 200 μM Mn(II) and 5 mg/L Aldrich humic acid buffered at pH 8.1 produced ∼19 μM of oxidized Mn (MnO_x where x is between one and two) after 45 minutes. The major oxidants reponsible for this reaction appear to be photoproduced superoxide radical anion, O₂⁻, and singlet molecular oxygen, ¹O₂. The dependencies of MnO_x formation on Mn(II), humic acid, and H⁺ concentration were characterized. A kinetic model based largely on published rate constants was established and fit to the experimental data. As expected, analysis of the model indicates that the key reaction rate controlling MnO_x production is the rate of decomposition of a MnO₂⁺ complex formed from the reaction of Mn(II) with O₂⁻. This rate is strongly dependent on the Mn(II) complexing ligands in solution. The MnO_x production in the seawater sample taken from Bodega Bay, USA and spiked with 200 μM Mn(II) was well reproduced by the model. Extrapolations from the model imply that Mn photo-oxidation should be a significant reaction in typical surface seawaters. Calculated rates, 5.8 to 55 pM h⁻¹, are comparable to reported rates of biological Mn oxidation, 0.07 to 89 pM h⁻¹. Four fresh water samples that were spiked with 200 μM Mn(II) also showed significant MnO_x production. Based on these results, it appears that Mn photo-oxidation could constitute a significant, and apparently unrecognized geochemical pathway in natural waters.     

电感耦合等离子体发射光谱法测定铬矿石中的二氧化硅

以过氧化钠为熔剂,经高温熔融-热水提取-盐酸酸化前处理样品,选用金为内标元素,电感耦合等离子体发射光谱法测定铬矿石中的二氧化硅。试验了熔融试样时引入的基体元素钠对被测元素的干扰情况,结果表明,钠含量高于300 mg/L时,二氧化硅的回收率均低于92.5%。采用金内标法有效克服了基体效应及仪器波动产生的影响,改善和提高了准确度和精密度。二氧化硅的检出限为0.0075 mg/L,测定范围为0.025%～10.0%。对铬矿石标准物质进行测定,结果与标准值一致,方法精密度(RSD,n=9)小于2%。与常规化学分析法进行比对试验,二氧化硅的测定值吻合较好,但克服了常规化学分析方法步骤繁琐、耗时长、工作量大的不足,提高了工作效率。本方法也可用于同时测定铬矿石中铝、铁、钙、镁、磷等主次量成分。     

Sulfur speciation with high performance liquid chromatography as a tool for El Chichón volcano,crater lake monitoring

The monitoring of sulfur species in crater lakes has proven to be useful for forecasting episodes of volcanic unrest in certain active volcanoes, including Poás, Costa Rica; Kusatsu-Shirane, Japan; and Mt. Ruapehu, New Zealand. In this study, we have improved the current geochemical monitoring of El Chichón volcano through the setting of optimal high-performance liquid chromatography conditions (HPLC) for the analysis of S²⁻, SO₃²⁻, S₂O₃²⁻, S₄O₆²⁻ and SO₄²⁻ using a common chromatographic system. The procedure was applied to the analysis of lake samples taken in March, July and October of 2014 and April of 2015. The results were promising, since nearly all species were detected (with the exception of S₂O₃²⁻) in measurable amounts, including S²⁻ (<0.85–5.05 mg/L), SO₃²⁻ (<2.77–26.1 mg/L), S₄O₆²⁻ (108.27–303.82 mg/L) and SO₄²⁻ (489.58–676.26 mg/L). The spatial distribution of these species along the lakeshore showed zones of increased concentrations to the east and southeast of the lake, which provides information on the distribution of faults or cracks that feed hydrothermal fluids to the lake. This method thus provides additional information linked to the volcanic and hydrothermal activity of the volcano.     

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.     

Direct Current Plasma Emission Spectrometric Determination of Major, Minor and Trace Elements in Microwave Oven Acid Leachates of Powdered Whole Coal Samples

Major concentrations of Al₂O₃, Fe₂O₃, MgO, CaO, Na₂O and K₂O, minor levels of TiO₂, P₂O₅ and thirty petrologically, geochemically and environmentally significant trace elements have been determined in microwave oven acid leachates of whole powdered coal samples by direct current plasma‐atomic emission spectrometry (DCP‐AES). A single sample preparation procedure was suitable for all the determinations with no additional dilution step for major elements solution. Dried samples (0.5 g) were treated in low‐pressure PFA digestion vessels with HF/HCl/HNO₃/HClO₄ acids to quantitatively extract the analytes from the bulk material, while leaving the major part of organic matrix as a residue. The major constituents of geological samples, in particular the easily ionised elements (EIEs) such as alkali and alkaline earths, may complicate the instrumental determinations in DCP‐AES because of differential enhancements of elemental emission intensities and stray light interferences. Taking account of these factors, the coal matrix is considered to have very low major oxide totals as compared to many other common geo‐environmental and related materials (rocks, sediments, soil, ashes etc.). The sample size employed here, while yielding a relatively concentrated solution to cover a wide range of elemental determinations, provided a sample matrix that significantly diminished interferences for DCP measurements. The need for closely matching the unknowns and calibrators was eliminated except for overall acidity and an excess quantity of caesium for EIE buffering. Calibration of the spectrometer was accomplished by simple aqueous single element solutions as high concentration calibrators in addition to a reagent blank as a low concentration calibrator. Two point working curves were established to allow for the maximum concentrations of each element expected in the unknowns. The precision of determinations under routine conditions as well as the reproducibility of the leaching and precision of instrumental measurements have been evaluated. Relative standard deviations (RSD) were of 1–2% for those elements whose concentrations in solid samples were well above the limits of quantification. Method detection limits in the buffered solutions were also evaluated. To evaluate the accuracy of the microwave oven‐DCP method a suite of eight certified coal reference materials of differing rank, were analysed with good agreement with the certified and/or available published data. Results are presented for the uncertified major oxides in the AR series reference materials.     

蒸馏分离-电感耦合等离子体质谱法测定地球化学样品中痕量钌和锇

建立了蒸馏分离-电感耦合等离子体质谱法测定地球化学样品中痕量钌和锇的分析方法。进行了蒸馏温度和时间、氧化剂、吸收液等条件的选择,消除了等离子体质谱法测定钌和锇的干扰。样品用过氧化钠熔融,酸化后以高锰酸钾-过硫酸钾-氯化钠作为同时蒸馏钌和锇的氧化剂,采用20 mL 50 g/L水合肼溶液同时吸收从混合物中分离出来的痕量钌和锇,用电感耦合等离子体质谱法测定。方法的检出限Ru为0.020 ng/g,Os为0.015 ng/g;方法加标回收率Ru为94.0%~102.7%,Os为96.0%~102.4%;精密度为4.72%~9.58%(n=12)。方法经国家一级标准物质验证,钌和锇的测定结果与标准值相符。     

Fe~(2+)活化过硫酸盐在石油污染土壤中修复实验研究

硫酸根自由基的高级氧化技术以高效率、污染少等优点被广泛用于环境污染治理。本文以实际石油污染土壤为对象,运用该体系对土壤进行修复研究,分别从Na_2S_2O_8/Fe~(2+)摩尔比、体系pH值、Na_2S_2O_8/Fe~(2+)投加量等方面开展了实验研究。实验表明:当Na_2S_2O_8/Fe2+摩尔比为2∶3时,石油污染物的降解效果最好,体系的pH值对降解效果影响不大,1 g土壤中浓度为0.1 mol/L的过硫酸钠和硫酸亚铁溶液的最佳加入量为2 m L、3 m L时,对土壤的降解效果最为明显,故每吨污染土壤的添加量大约为2×10~6m L、3×10~6m L。