煤基甲醇溶液中微量铬的测定

以糠醛和1,3-二胺基硫脲合成的糠醛缩-1,3-二氨基硫脲为中性载体,将其与碳粉混合,以液体石蜡为黏合剂,制备了新型的铬(Ⅲ)离子选择性电极.室温下,电极对Cr3+的能斯特响应范围为4.00×10-7～1.00×10-2 mol/L,斜率为-20.33 mV/dec,检出限为1.55×10-7 mol/L.电极响应时间...     

新型离子电极用于煤基甲醇溶液中微量铬测定

煤基甲醇制烯烃是以煤为原料合成甲醇,然后通过甲醇制取低碳烯烃。以煤代油生产低碳烯烃是实现中国能源战略,保证国家能源安全的重要途径之一。近年来,煤基甲醇制烯烃技术在我国得到了快速发展和应用,煤基甲醇根据其不同的工艺特点,产品甲醇溶液中存在的微量铬等重金属离子严重影响煤基甲醇制烯烃催化剂的使用性能。以乙基香兰素和1,3-二氨基硫脲合成的席夫碱乙基香兰素缩-1,3-二氨基硫脲为中性载体,将其与碳粉混合,以液体石蜡为粘合剂,制备了新型的铬(Ⅲ)离子电极。室温下,以饱和甘汞电极作参比电极,离子电极作指示电极,对煤基甲醇中的Cr~(3+)进行测定,取得了较好的效果。     

糠醛缩-邻苯二胺敏感膜铜(Ⅱ)离子选择性电极

以糠醛和邻苯二胺合成的双席夫碱糠醛缩-邻苯二胺(以下简称FFDB)为中性载体,将其与碳粉混合,以液体石蜡为粘合剂,制备了一种新型的铜离子选择性电极。电极对Cu2+的能斯特响应浓度范围为5.00×10-6～1.00×10-2mol/L,检测下限为1.65×10-6mol/L,电极的响应时间小于30 s,稳定性好,使用寿命长。可成功的用于工业废水中的Cu2+进行测定。     

一种新型PVC膜铜(Ⅱ)离子选择性电极的研制

以邻香草醛和2-氨基酚合成的席夫碱邻香草醛缩-2-氨基酚(以下简称VAP)为活性物质,制备了一种高灵敏的PVC膜铜离子选择性电极。电极的能斯特响应浓度范围为1.00×10-5～1.00×10-2 mol/L,检测下限为6.38×10-6 mol/L。电极的响应时间小于30 s,稳定性好、选择性高、使用寿命长,可成功的用于工业废水中Cu2+的测定。     

工业废水中微量碘离子的分析方法研究

对碘离子的分析方法进行总结,同时采用碘离子选择性电极测定工业废水中碘离子含量,且对氯化钾、硫酸钾的存在对碘离子测定的影响进行了探讨。     

离子选择电极测定工业用水中的氯离子

建立了氯离子选择性电极对工业用水中氯离子含量的测定方法,建立工作曲线进行定量,通过精密度实验测定及实际样品检测验证方法简单、快速、准确,为检测工业用水建立提供了理论依据。     

离子选择性电极测定蔬菜中的碘含量

采用碘离子选择性电极法,测定紫菜、菠菜、白菜、芹菜四种蔬菜中碘含量的方法.并研究了温度、酸度、搅拌速度、响应时间、还原保护剂的用量等条件对测定结果的影响.实验结果表明:温度、酸度、搅拌速度、响应时间、还原保护剂的用量等条件对测定结果都有影响,在所选择的最佳测定条件下,线性范围为1×10-2～5×10-6mol/L,相关系数为0.9995,回收率为94.5％101％.     

离子选择性电极测定混合电解质溶液中离子活度系数

应用离子选择性电极法测定混合电解质溶液中离子活度系数,由实验结果对该方法的可行性和混合电解质水溶液活度系数随温度和浓度的变化关系进行了讨论,并对单一电解质溶液和混合电解质溶液中离子的活度系数进行了对比分析。结果表明,该方法快速、简便、灵活、成本低,是测定混合电解质溶液离子活度系数的有效方法。     

氟离子选择性电极测定牙膏中氟的含量

本实验通过氟离子选择电极直接电位法测定牙膏样品中氟的含量,实验利用标准曲线法和连续标准加入法测牙膏中氟的含量。标准加入法测得样品纳爱斯营养维c牙膏中氟的含量为0.06805%,样品佳洁士牙膏中氟含量为0.05769%(质量分数)。讨论了选择性电极空白值,搅拌及响应时间,TISAB用量对测定结果的影响以。求出了纳爱斯牙膏平均回收率在105%～107%之间,佳洁士牙膏的回收率在103%～109%之间,方法简便,准确。     

离子选择性电极—流动技术测定锅炉软水中硬度

用离子选择性电极－流动技术对锅炉软化水中硬度的测定进行了在线分析研究。选择管长１００－１５０ｃｍ,内径３ｍｍ,流速１ｍＬ／ｓ,该法简单,快速,变异系数０．３％,与传统的络合滴定法比较,结果令人满意。     

光度法测定痕量铬(Ⅲ)新方法

基于铬(Ⅲ)对过氧化氢氧化R(二甲基黄)褪色有显著的催化作用及聚丙烯酸钠对催化的增敏效应,提出聚丙烯酸钠增敏催化过氧化氢氧化R(二甲基黄)褪色光度法测定痕量铬(Ⅲ)的新方法。在所选条件下,Cr(Ⅲ)含量在0.40~2.80μg/L范围内符合比尔定律,线性回归方程为:ΔA=0.0857+0.2205CC r(Ⅲ),γ=0.9973,检出限为9.6×10-11g/mL。可用于测定水样中Cr(Ⅲ)的含量,结果令人满意。     

Determination of Cr ions in biological and environmental samples by a chromium(III) membrane sensor based on 5-amino-1-phenyl-1H-pyrazole-4-carboxamide

A highly Cr³⁺-selective ionophore, based on 5-amino-1-phenyl-1H-pyrazole-4-carboxamide (APC) as a carrier, was synthesized in order to obtain a Cr³⁺ ion-selective electrode. The demonstrated characteristics of the sensor included a linear dynamic range between 1.0 × 10^− 6 and 1.0 × 10^− 1 M with a near Nernstian slope of 19.6 ± 0.4 mV per decade, a detection limit of 5.3 × 10^− 7 M, a very good selectivity for Cr³⁺ over other cations in a wide pH range (3.2-6.3). Furthermore, the newly-designed electrode presented a fast response time of 10 s with a lifetime of at least 2 months indicating no considerable potential divergence. The sensor accuracy was investigated by the potentiometric titration of a Cr(III) solution with EDTA as well as the monitoring of Cr(III) in mixtures of three and five different ions. As a result, the developed sensor provided satisfactory results after its application in the Cr³⁺ determination in biological samples (urine and synthetic plasma) and also in wastewater of chromium electroplating industries.     

Effects of dissolved iron and chromium on the performance of direct methanol fuel cell

Effects of Fe³⁺ and Cr³⁺ ions on the performance of direct methanol fuel cell were investigated. The results show that the cell performance decreased remarkably when the concentration of Fe³⁺ or Cr³⁺ exceeded 1 × 10⁻⁴ mol L⁻¹. Fe³⁺ displayed a strong negative effect on the catalytic oxidation of methanol, while Cr³⁺ affected the cell performance primarily by exchanging with protons of the membrane/ionomer and resulted in ionic conductivity losses. Complete recovery of the cell performance was not obtained after flushing the cell with deionized water.     

A glue method for fabricating membrane electrode assemblies for direct methanol fuel cells

We present a simple glue method for fabricating membrane electrode assemblies (MEA) for direct methanol fuel cells (DMFC). Rather than the conventional “dry” hot-pressing method that relies solely on hot-pressing at a high pressure and temperature to form a MEA, the “wet” method developed in this work introduces a binding agent, consisting of Nafion^® solution, between a polymer electrolyte membrane (PEM) and an anode/cathode. The introduced binding agent can provide a better adhesion and stronger binding force between a membrane and an electrode, thereby facilitating a better interfacial contact between the electrode and the Nafion^® membrane, which has been proved by scanning electron microscopy (SEM) analyses to the cross-sectional morphology of the MEA after long-term operation. The cell performance characterization showed the MEA fabricated by the glue method was more stable in cell performance than that fabricated by the conventional hot-pressing method. Cyclic voltammetry (CV) results also demonstrated the MEA fabricated by the glue method exhibited a higher electrochemical surface area (ESA) as a result of the improved interfacial contact between the Nafion^® membrane and the electrodes. Finally, the DMFC with the MEA fabricated by the glue method was characterized by the electrochemical impedance spectroscopy (EIS).     

直接甲醇燃料电池参比电极的设计与稳定性

提出了用于原位测量直接甲醇燃料电池(DMFC)极化的参比电极的结构设计,并考察了电解质的润湿程度对参比电极的电位及其电位稳定性的影响.结果表明：在可逆氢电极(RHE)作为参比电极的DMFC中,RHE的电位随电解质润湿程度的增加而降低,其电位的稳定性主要取决于其表面状态的稳定性.提出要获得电位稳定及测量准确的极化曲线,RHE处的电解质应处于对侧液态水润湿的状态,且电极表面要有适量、稳定流速的氢气.     

苹果中微量铅的荧光光度法测定

建立了利用荧光法测定苹果中微量铅的新方法。该方法的线性范围0.03～2.00mg/mL,检出限为9.1×10-3mg/mL,用于鲜苹果样品中微量铅的测定,加标回收率96.22%～100.04%。     

Biocomposite based electrode for effective removal of Cr (VI) heavy metal via capacitive deionization

Abstract

This study focuses on the fabrication of biocomposite electrode and removal of Cr (VI) ions from wastewater using a capacitive deionization (CDI) method. The activated carbon (AC) was synthesized from Bael fruit shell (BS). The synthesized AC surface has a macroporous and mesoporous structure with the large specific surface area (617.72?m² g^?1) and high adsorption capacity. The cyclic voltammetry and CDI were performed for the detection and for the removal of chromium (VI) ions, respectively. The lower level of detection of Cr (VI) by a modified electrode was found to be 10 ppt. SEM, BET, and FTIR analyses were performed to explore the surface properties of electrode materials. The removal efficiency was achieved 100% by using biocomposite electrode with an applied potential of 15?V. The highest percent removal mechanism consists of electrosorption and electroreduction due to the affinity between polyvinyl alcohol modified electrode and Cr (VI) ions, under electrochemically faradic process.     

Development of a novel electrochemical immuno-assay using a screen printed electrode for the determination of secretory immunoglobulin A in human sweat

This paper reports on the steps involved in the development of a novel electrochemical immunoassay for secretory immunoglobulin A (sIgA) determinations in human sweat. This novel immunoassay involves an initial step whereby sweat sIgA is adsorbed onto a polyvinylidene fluoride (PVDF) membrane (sweat patch). Following a wash step, a solution containing bovine serum albumin (BSA) is used to block any sites at which non-specific binding might occur. After a second wash step, the PVDF sweat patch is transferred to a second tube to which is added diluent and anti-sIgA antibody conjugated to horseradish peroxidase (HRP). Following an incubation step, an aliquot of supernatant containing unbound antibody is transferred to a well in a 96 well plate format which had been previously coated with sIgA. After a second incubation step and wash step, 3,3′,5,5′-tetramethylbenzidine (TMB) is added to the same well and left to undergo enzymatic oxidation. Finally a screen-printed carbon electrode (SPCE) is inserted into the well and any oxidised TMB is detected by chronoamperometry using an applied potential of +50 mV. The resulting reduction current is then referred to a calibration plot to deduce the unknown sIgA concentration. The optimisation of the steps involved in this assay is described in detail. Some preliminary data is presented on sweat sIgA levels collected from human volunteers who had undergone a controlled exercise regime on a bicycle (Ergociser). To our knowledge this is the first report where a sweat patch and a SPCE have been successfully incorporated into an immunoassay for sIgA.     

多壁碳纳米管修饰电极测定水样中痕量镉

通过多壁碳纳米管修饰玻碳电极,建立了水样中痕量镉的线性扫描阳极溶出伏安分析法。优化了支持电解质及pH、修饰剂用量、富集电位及时间等测定条件,在pH 4.0的NaAc-HAc缓冲液中,-1.10 V富集5 min后,溶出峰电流与Cd2 浓度在2.0×10-8~5.0×10-5mol/L的范围内呈良好的线性关系,检测限为8.0×10-9mol/L。该法用于实际水样中痕量镉的测定,平均回收率在98.7%~105.0%之间,结果满意。     

An electrochemical methanol sensor based on a Pd-Ni/SiNWs catalytic electrode

A novel electrochemical methanol sensor based on a catalytic electrode of palladium-nickel/silicon nanowires (Pd-Ni/SiNWs) is presented in this paper. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods are employed to investigate the Pd-Ni/SiNWs electrode materials. These nanocomposite materials exhibit a highly ordered, wire-like structure with a wire length of ∼50 μm and a wire diameter ranging from 100 to 300 nm. The substrate has good electrocatalytic activity towards the oxidation of methanol in alkaline solutions. The performances of the prototype sensor are characterized by cyclic voltammetry and fixed potential amperometry techniques. In a 1 mol L⁻¹ KOH solution containing different methanol concentrations, the sensor exhibits a good sensitivity of 1.96 mA mmol⁻¹ L cm⁻² with R² = 0.99 and the corresponding detection limit of 18 μmol L⁻¹ (signal-to-noise ratio = 3, S/N = 3) for cyclic voltammetry. Meanwhile, the electrode also displays a sensitivity of 0.48 mA mmol⁻¹ L cm⁻² with R² = 0.98 and the corresponding detection limit of 25 μmol L⁻¹ (S/N = 3) for a fixed potential amperometry at −0.3 V versus an Ag/AgCl reference electrode. The results demonstrate that the Pd-Ni/SiNWs catalytic electrode has potential as an efficient and integrated sensor for methanol detection.