电极/溶液界面pH值的现场测量

一般认为阴极表面功能陶瓷电沉积层的形成是由于基底 /溶液界面化学环境变化造成的 [1,2 ] ,但目前还没有直接的实验数据加以证明 .原位测量电极 /溶液界面 p H的变化存在两方面的困难 :(1 )传统方法是采用玻璃 p H计 ,由于其体积较大、强度脆弱等原因 ,使其在测量固 /液界面化学环境变化的应用方面受到一定限制 [3 ] ;(2 )将 p H微探针置于电极表面 ,将会影响功能陶瓷在电极表面的沉积 ,从而使测定的界面 p H值不能真实反映电沉积过程中固 /液界面化学环境的变化 .本文基于功能陶瓷电沉积过程不受影响的情况下现场直接测量电极 /溶液界面…     

纳米Co3O4型固体pH电极的响应及应用

测定酸度目前广泛采用玻璃电极 .然而 ,由于玻璃电极是采用极薄的玻璃膜作为 H+的敏感膜 ,致使电极极易破碎 ,亦难以用于对玻璃有腐蚀作用的体系 ,如含氟体系 .此外它还具有体积大、成本较高、膜阻抗高而难以实现微型化、以及使用前需活化处理等缺点 .多年来对非玻璃型 p H电极的研究一直是个热门的研究课题 .其中以金属 /金属氧化物型固体 p H电极倍受关注 [1～ 6 ] .本文对氧化钴 (Co3 O4 )型固体 p H印刷电极的响应性能、选择性、重现性以及在含氟腐蚀体系 p H测定中的应用进行了研究 .Ф1 2型 p H计 (BECKMAN公司 ) ,2 3 2型饱和…     

丝网印刷纳米金属氧化物型固态pH电极的研制

近年来对非玻璃型 p H电极的开发一直是化学传感器研究领域中的活跃课题之一 ,其中又以氧化物型的 p H电极倍受关注 [1～ 5 ] .与玻璃电极相比 ,氧化物型的固体 p H电极可呈现出如下的优势 :成本低、响应快、机械强度高 ,且可应用于多种玻璃电极不能适宜的测试环境如高温、强腐蚀或有强制对流等体系 .然而迄今为止 ,已研究过的氧化物种类 (包括 Ir O2 ,Ru O2 ,Pt O2 等 )极为有限 ,且价格较昂贵 .本工作以纳米级的几种过渡金属氧化物 (氧化锰、氧化钴、氧化铅、氧化钛 )为敏感材料 ,利用丝网印刷技术制备了各种氧化物电极 ,对电极的 p H…     

纳米二氧化锰型固体pH电极的研制及其在含氟腐蚀体系中的应用

1引言酸度的测定在工业、农业、生物、医学、环保等领域有着十分重要的意义,目前广泛采用玻璃电极测量。然而,玻璃电极存在一定的不足,由于它是采用极薄的玻璃膜作为H+的敏感膜,致使玻璃电极极易破碎,难以适宜于强搅拌体系和对玻璃有腐蚀作用的体系,如含氟体系。故多年来对非玻璃型pH传感器的研究一直是个热门的研究课题。其中又以金属/金属氧化物型固体pH电极倍受关注。由于纳米MnO2电极具有较好的pH响应性能,本文利用丝网印刷技术制备了MnO2印刷电极,并研究了此印刷电极在含氟体系pH测定中的应用。2实验方法2．1仪器与试剂φ1…     

非玻璃型pH敏感电极的研制——(一)固体离子交换树脂膜电极

在实验室研究或工业流程监控中,一般均采用玻璃PH电极来测量pH。但玻璃电极不能用于含氟化物的酸性溶液,在强碱性溶液,它也有不同程度的钠干扰,因此,研究其他类型的pH膜电极正逐渐受到人们的重视。为了解决国内生产实际中的有关分析问题,我们系统研究了不同类型的pH电极。本文重点介绍离子交换树脂膜电极的研究结果。仪器和试剂仪器:Accumet 750选择性离子自动分析仪(Fisher Co.美国),709 YP-24型粉末     

工业pH测量中电极失效原因

在工业中,特别是化学、电力、造纸、制糖等工业中往往需要测量工艺流程的pH。目前工业上多采用玻璃电极和饱和甘汞电极测量其pH。电极法能否成功地应用于工业pH测量,除了与被测介质的性质有关外,很大程度上还取决于对仪器和电极的使用技术。为此,本文将以表格的形式分析工业pH测量中电极失效原因,并给出检查和解决的方法。     

英国研制出无需校验的pH传感器

英国牛津大学的研究员们正致力于改进最常见的科学测量参数pH值的测量方式，取消其对校验的需要。研究员们已经开发出完整的新pH传感器，既廉价义耐用，能广泛应用于pH值测量领域，对pH值的微小变化很敏感，同时耐高压和高温，最重要的是不需要校验。目前用于测量pH值的技术已经有70多年的历史，传统的玻璃电极需要经过培训的人员用昂贵的缓冲液连续地反复校准，还需要仔细地适度储存，     

纳米SiO2/HPAM/SDS分散体系稳定性的改进及其对驱油性能的影响

分析了60℃、1. 0×104mg/L氯化钠盐水和模拟地层水中纳米SiO2/HPAM/SDS分散体系的浊度实验及Zeta电位,发现Ca2+、Mg2+离子是体系失去稳定性的主要原因。根据沉降实验及Zeta电位分析仪探讨了降低p H值和添加络合剂对模拟地层水中纳米SiO2/HPAM/SDS体系稳定性的改善效果及机理,同时利用流变仪及界面张力仪分析了两种方法对体系驱油性能的影响。结果表明,p H值降低,体系的Zeta电位绝对值降低,但SiO2周围H+保护层的形成及水化作用力的增强改善了体系的稳定性;络合剂Na2EDTA、ATM P和Na4EDTA均能增强体系的稳定性,Na2EDTA和ATM P络合Ca2+、Mg2+的同时降低了体系的p H值,而体系的黏度随p H值的降低急剧下降; Na4EDTA加入后,体系的p H值增大,稳定配位化合物的形成使体系的Zeta电位绝对值、黏度、储能模量和损耗模量增加,降低界面张力的能力增强。因此,在SiO2质量分数为0. 5%的体系中加入质量分数为0. 4%的Na4EDTA(最佳质量分数),采收率提高了3. 1%。     

用玻璃电极测定直到15m的浓盐酸体系的活度系数

本文在25℃下,对0.01844—15.02mol kg~(-1)浓度范围内的盐酸体系,用自制Agl AgGl电极和氢电极,测定了Harned电池的电动势。在此基础上,以玻璃电极代替氢电极,测量上述盐酸体系的电动势,计算了HCl的平均活度系数和H_2O的活度。实验结果表明,玻璃电极在浓盐酸体系的“标准电势”是稳定的,且遵从Nernst响应,重现性良好,响应速度快;在高浓度和稀溶液中交替测量时,电势无明显偏差。这说明电极有较好的可复性。求得的HCl的活度系数与文献值偏差小于1.2％。玻璃电极的“标准电势”的标准偏差为0.016％。     

用玻璃电极测定直到15 m的浓盐酸体系的活度系数

本文在25 ℃下, 对0.01844—15.02 mol kg~(-1)浓度范围内的盐酸体系, 用自制Ag|AgGl电极和氢电极, 测定了Harned电池的电动势。在此基础上, 以玻璃电极代替氢电极, 测量上述盐酸体系的电动势, 计算了HCl的平均活度系数和H_2O的活度。实验结果表明, 玻璃电极在浓盐酸体系的“标准电势”是稳定的, 且遵从Nernst响应, 重现性良好, 响应速度快; 在高浓度和稀溶液中交替测量时, 电势无明显偏差。这说明电极有较好的可复性。求得的HCl的活度系数与文献值偏差小于1.2％。玻璃电极的“标准电势”的标准偏差为0.016％。     

A New pH Sensor Based on a Glassy Carbon Electrode Coated with a Co/Al Layered Double Hydroxide

A glassy carbon electrode has been coated by electrodeposition with a thin film of cobalt based layered double hydroxide (LDH) and used as a pH sensor. The developed electrode displays a linear super‐Nernstian response (?76.2±0.6 mV/pH) in the pH range between 2 and 14 and it is particularly suitable to operate in strongly alkaline solution. The reproducibility of the sensor construction is good with a relative standard deviation of the calibration curve slopes of±2.5 % (n=4). The electrode has a response time comparable to that exhibited by commercial glass electrodes in the pH range examined and is not affected by interference from the most common anions and cations.     

A surface renewable iridium oxide-glass composite hydrogen ion electrode

A robust and surface renewable iridium oxide-based pH glass composite electrode was prepared by modifying glass matrix with iridium oxide particles. Fine glass powder coated with iridium oxide was prepared by pyrolyzing ammonium hexachloroiridate-coated glass powder under oxygen atmosphere. First the glass powder was molded into a disk, by using a press, then was sintered in high temperature, and was finally fabricated. The electrode showed linear response between pH 1 and 13 with close slopes to the theoretical value, − 59.2 mV/pH. The electrode showed low hysteresis upon sudden changes of pH from 2 to 6, but in extreme conditions, from pH 13 to 1, it showed values near 16 mV. The electrode maintained the pH response for 36 days, without a significant slope drift, in various storage conditions — deionized water, a pH 7 buffer solution, 4 M KCl, and even in the air. Most of the cations and anions, except electrochemically active compounds or ions, did not interfere with the electrodes seriously. The electrode surface can be renewed reproducibly, by a simple grinding process whenever it becomes fouled or deactivated. The electrode matrix was durable and showed extended lifetime although it was ground repeatedly with 2000 grit SiC emery paper for surface renewal.     

纳米氧化铅型固体pH电极的研制及其应用

纳米;PbO电极;氢氟酸体系;纳米氧化铅型固体pH电极的研制及其应用     

Intra- and Inter-molecular Sulf- hydryl Hydrogen Bonding: Facilitating Proton Transfer Events for Determination of pH in Sea Water

This work presents the electrochemical response of a 2-(methylthio)phenol glassy carbon based electrode for a promising voltammetric pH sensor in both buffered and low-buffered solutions. Electropolymerization of the redox species was performed with the resulting polymer presenting a Nernstian response in buffered media, with a sensitivity of 51 mV/pH unit. The effectiveness of the sulfhydryl bond to facilitate proton transfer from the bulk solution to the phenol molecules has been confirmed, providing an accurate pH measurement of 8.28 in sea water media, compared to that measured with a calibrated glass pH probe of 8.30.     

A mercury(II) ion-selective electrode based on N,N-dimethylformamide-salicylacylhydrazone as a neutral carrier.

A new PVC membrane mercury(II) ion electrode based on N,N-dimethylformamide-salicylacylhydrazone (DMFAS) as an ionophore is described, which shows excellent potentiometric response characteristics and displays a linear log[Hg(2+)] versus EMF response over a wide concentration range between 6.2 x 10(-7) and 8.0 x 10(-2) M with a Nerstian slope of 29.6 mV per decade and a detection limit of 5.0 x 10(-7) M. The response time for the electrode is less than 30 s and the electrode can be used for more than 2 months with less than a 2 mV observed divergence in a potentials. The proposed electrode exhibits very good selectivity for mercury(II) ions over many cations in a wide pH range (pH 1 - 4). The electrode was also applied to the determination of a mercury(II) ion in vegetables and in Azolla filiculoides.     

Capillary Melt Method for Micro Antimony Oxide pH Electrode

In this work, a new approach named “capillary melt method” was developed to fabricate micro antimony wires, and the wire surface was then oxidized in a nitrate melt at high temperature to obtain an antimony/antimony oxide pH electrode. Characterization results show that the oxide layer on the wire surface is porous, and consists of Sb₂O₃ crystal phase. The pH electrode, made using this method, showed good sensing performance in buffer solutions in the tested pH range of 2–12. Its EMF signal was found to have a linear relationship with pH value of the solution, with a sensitivity of 54.1 mV/pH and a fitting correlation coefficient of R²=1.00. The advantages of the electrode are long‐term stability, fast response, reproducibility and low cost.     

复合型扫描微pH电极及其在局部腐蚀中的应用

研制了一种新型的微米级复合型扫描pH探针.该探针具有体积小、响应速度快、稳定性好和制作方便等优点，能很好地满足微区pH快速测定的要求.应用复合型扫描微pH电极技术研究了Al/Cu合金在0.01 mol•L－1 NaCl溶液中开路状态下局部腐蚀发生的早期过程.     

All Solid‐State pH Electrode Based on Titanium Nitride Sensitive Film

Titanium nitride was used as pH‐sensitive material to fabricate all solid‐state pH electrode. The fabrication and the response performance of the pH electrode were described in the paper. The TiN film electrode showed a linear response in the pH range of 2–12 with a near‐Nenstian response (?55 mV/pH). The response time was within 1 min, and the electrode had good reproducibility, stability and low sensitivities for different species. Compared with the glass pH electrode, the electrode exhibited some advantages, for example, without activation, rapid response and high mechanical strength. In addition, the electrode performed excellently in a corrosion medium containing F^?(1 M). Electrochemical behaviors of TiN electrode in Britton‐Robinson buffers were studied with Electrochemical Impedance Spectroscopy (EIS).     

Potentiometric behavior of N,N,N',N'-tetrabenzylmethylenediamine-based hydrogen ion-selective electrodes

H(+)-ion selective electrodes (H(+)-ISE) based on N,N,N',N'-tetrabenzylalkylenediamine (alkylene: methylene, ethylene, propylene, hexylene) are prepared. We are compared with their response potentials to carbon numbers between diamino groups. They were showed linear selective to hydrogen ion in the range of pH 1.5-9.0, 2.5-9.0, 3.5-9.0 and 4.0-9.0, and their Nernstian slopes were 57.3, 53.5, 57.4 and 56.1 mV pH(-1) at 20+/-0.2 degrees C (theoretical value: 58.2 mV pH(-1)), respectively. The interference effect on the cations were measured to alkali metal ions, alkaline earth metals ions. Selectivity coefficients were measured by the mixed-solution method. Among all electrodes the N,N,N',N'-tetrabenzylmethylenediamine (TBMDA)-based electrode has shown the best selectivity in acidic solution.