氟硅酸溶液中氟硅酸及氢氟酸含量的测定

基于生成氟硅酸钾沉淀和该沉淀水解均析出不同量酸，用碱滴定完成氟硅酸及氢氟酸的连续测定。该方法用于生产实践，结果令人满意。     

Effect of La2CuO4 electrode area on potentiometric NOx sensor response and its implications on sensing mechanism

The intent of this work is to look at the effects of varying the La₂CuO₄ electrode area and the asymmetry between the sensing and counter electrode in a solid state potentiometric sensor with respect to NO_x sensitivity. NO₂ sensitivity was observed at 500-600 °C with a maximum sensitivity of ∼22 mV/decade [NO₂] observed at 500 °C for the sensor with a La₂CuO₄ electrode area of ∼30 mm². The relationship between NO₂ sensitivity and area is nearly parabolic at 500 °C, decreases linearly with increasing electrode area at 600 °C, and was a mixture of parabolic and linear behavior 550 °C. NO sensitivity varied non-linearly with electrode area with a minima (maximum sensitivity) of ∼−22 mV/decade [NO] at 450 °C for the sensor with a La₂CuO₄ electrode area of 16 mm². The behavior at 400 °C was similar to that of 450 °C, but with smaller sensitivities due to a saturation effect. At 500 °C, NO sensitivity decreases linearly with area.We also used electrochemical impedance spectroscopy (EIS) to investigate the electrochemical processes that are affected when the sensing electrode area is changed. Changes in impedance with exposure to NO_x were attributed to either changes in La₂CuO₄ conductivity due to gas adsorption (high frequency impedance) or electrocatalysis occurring at the electrode/electrolyte interface (total electrode impedance). NO₂ caused a decrease in high frequency impedance while NO caused an increase. In contrast, NO₂ and NO both caused a decrease in the total electrode impedance. The effect of area on both the potentiometric and impedance responses show relationships that can be explained through the mechanistic contributions included in differential electrode equilibria.     

NOx adsorption behavior of LaFeO3 and LaMnO3+δ and its influence on potentiometric sensor response

NO_x adsorption behavior on LaFeO₃ (LFO) and LaMnO_3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO₂ was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NO_x species than LMO and was shown to be more active for NO_x surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO₂ decomposition mechanism to NO and O₂ for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NO_x sensing mechanisms were considered and predicted based on the types and quantities of surface species formed.     

A technique for monitoring SO2 in combustion exhausts: Use of a non-Nernstian sensing element in combination with an upstream catalytic filter

Detection of sulfur dioxide (SO₂) at high temperature (600–750 °C) in the presence of some interferents found in combustion exhausts (NO₂, NO, CO₂, CO, and hydrocarbon (C₃H₆)) is described. The detection scheme involves use of a catalytic filter in front of a non-Nernstian (mixed-potential) sensing element. The catalytic filter was a Ni:Cr powder bed operating at 850 °C, and the sensing elements were pairs of platinum (Pt) and oxide (Ba-promoted copper chromite ((Ba,Cu)_xCr_yO_z) or Sr-modified lanthanum ferrite (LSF)) electrodes on yttria-stabilized zirconia. The Ni:Cr powder bed was capable of reducing the sensing element response to NO₂, NO, CO, and C₃H₆, but the presence of NO₂ or NO (“NO_x”, at 100 ppm by volume) still interfered with the SO₂ response of the Pt–(Ba,Cu)_xCr_yO_z sensing element at 600 °C, causing approximately a 7 mV (20%) reduction in the response to 120 ppm SO₂ and a response equivalent to about 20 ppm SO₂ in the absence of SO₂. The Pt–LSF sensing element, operated at 750 °C, did not suffer from this NO_x interference but at the cost of a reduced SO₂ response magnitude (120 ppm SO₂ yielded 10 mV, in contrast to 30 mV for the Pt-(Ba,Cu)_xCr_yO_z sensing element). The powder bed and Pt–LSF sensing element were operated continuously over approximately 350 h, and the response to SO₂ drifted downward by about 7%, with most of this change occurring during the initial 100 h of operation.     

化学因子分析法测定液体推进剂A

基于测定推进剂Ａ现有分析方法准确度低,神经网络法对仪器要求高等不足,提出了的一种新的分析方法。该方法利用已知酸的电位滴定数据建立多元线性回归数学模型,利用化学因子分解该模型,对未知样进行浓度测定。实际测定结果表明本方法的最大分析误差不超过０．１７％,标准偏差不超过１．９％,满足样品分析要求。     

多元分析法在沉淀滴定中的应用

将多元分析法应用于沉淀滴定之中 ,提出固定电位的方法 ,建立了沉淀滴定中各组分浓度与体积之间关系的数学模型 ,对卤素和硫氰酸盐混合体系进行了测定。     

库仑滴定法测定工业废水中微量砷

以库仑滴定法测定工业废水中微量砷，以死停终点法确定滴定终点，最后以EXCEL处理实验数据，本方法具有灵敏度高，准确，简便快速，仪器便宜，易于推广的特点，特别适用于工厂及县级以下环境监测站进行水中微量砷的检测，方法的回收率为99．3％。     

锂离子电池负极材料 Na2Li2Ti6O14的嵌脱锂过程动力学研究

为了研究钛酸钠锂(Na2Li2Ti6O14)负极材料嵌脱锂的动力学行为,用溶胶-凝胶法合成 Na2Li2Ti6O14负极材料,采用 X 射线衍射法(XRD)和电子显微镜(SEM)分别对材料进行物相分析和微观形貌的观察.采用恒流充放电测试、循环伏安法(CV)和恒电流间歇滴定法(GITT)研究了 Na2Li2Ti6O14的电化学性能和嵌脱锂过程动力学.研究结果表明,制备的 Na2Li2Ti6O14材料纯度高,结晶度良好,循环稳定性好;由不同扫描速率的循环伏安法测出的 Na2Li2Ti6O14中锂离子在氧化、还原峰对应的化学扩散系数 Da和 Dc分别为7.3×10-11和7.8×10-11cm2/s;由恒电流间歇滴定技术测得的锂离子在 Na2Li2Ti6O14电极中的扩散系数为10-11~10-8cm2/s.     

卡尔曼滤波同时pH滴定法研究

将卡尔曼滤波(KF)递推算法，用于多组分同时pH滴定中，讨论了方法原理，pH通道的选挥，同时对二、三、四元系统混合酸(碱)试祥，进行了多次测定，获得满意结果。     

电位滴定法在环境监测中的应用

本文简要介绍了运用电位滴定法对水中Ca2 ，Mg2 ，Cl-及F-离子进行测定，利用化学计量点时电位的突跃来确定终点．方法简便、快速、灵敏、准确，符合定量分析要求，可用于环境监测之中．