Electrode , oxide antimony

Antimony electrode (or antimony-antimony oxide electrode) -> pH-sensitive electrodes... 

BRI/ROB] Britton, H. T. S., Robinson, R. A., The use of the antimony-antimonious oxide electrode in the determination of the concentration of hydrogen ions and in potentiometric titrations. The Prideaux-Ward universal buffer mixture, J. Chem. Soc., (1931), 458-473, Contains report of measurements by W. L. German. Cited on page 141. 

Other pH-sensing transducers used in biosensors are metal oxide electrodes. Beside the common antimony oxide electrode, palladium oxide and iridium oxide probes have been coupled with immobilized enzymes. These sensors may be miniaturized by using chemical vapor deposition technology. Moreover, they are mechanically more stable than glass electrodes. Unfortunately the measuring signal of metal oxide electrodes is affected by redox active substances. 

Antimony or antimony oxide electrodes with continuous cleaning by corundum blades may be used for slightly oily water (outlet of API oil separator or DAF). However, they are sensitive to overly wide variations in redox potential. In this case, a probe with a glass electrode and ultrasound cleaning may be preferred but it is more sensitive to greases. 

The antimony-antimony oxide electrode consists of pure antimony metal dipping in a solution of an electrolyte. A skin of antimony oxide forms on the surface of the metal and this is in equilibrium with the antimony ions in solution ... 

Stock JT, Purdy WC, Garcia LM (1958) The antimony-antimony oxide electrode. Chem Rev 58(4) 611-626. doi 10.1021/cr50022a001... 

Two methods are used to measure pH electrometric and chemical indicator (1 7). The most common is electrometric and uses the commercial pH meter with a glass electrode. This procedure is based on the measurement of the difference between the pH of an unknown or test solution and that of a standard solution. The instmment measures the emf developed between the glass electrode and a reference electrode of constant potential. The difference in emf when the electrodes are removed from the standard solution and placed in the test solution is converted to a difference in pH. Electrodes based on metal—metal oxides, eg, antimony—antimony oxide (see Antimony AND ANTIMONY ALLOYS Antimony COMPOUNDS), have also found use as pH sensors (8), especially for industrial appHcations where superior mechanical stabiUty is needed (see Sensors). However, because of the presence of the metallic element, these electrodes suffer from interferences by oxidation—reduction systems in the test solution. 

Metal insoluble- oxide These are similar to the previous electrodes. An example is the antimony, antimony trioxide electrode, Sb Sb2031 OH-. An antimony rod is covered with a thin layer of oxide and dips into a solution containing OH ions. The electrode reaction is Sb (s) + 3 OH- 0.5 Sb203 + 1.5 H20 (1) + 3 e-. 

Metal oxide electrodes are also of the second type. A well known example is a rod of antimony coated with Sb203 (or bismuth with Bi203), which can function as a pH electrode33 ... 

Wrighton MS, Morse DL, Ellis AB, Ginley DS, Abrabamson HB (1976) Photoassisted electrolysis of water by ultraviolet irradiation of an antimony doped stannic oxide electrode. J Am Chem Soc 98 44-48... 

For those redox couples that involve a metal ion plus the metal, the logical electrode system is the metal itself. In other words, if the measured quantity is to be cupric ion [copper(II)], a practical indicator electrode is a piece of copper metal. All second-class electrodes involve an active metal in combination with an insoluble compound or salt. Thus, the silver/silver chloride electrode actually is a silver/silver ion electrode system that incorporates the means to control the silver ion concentration through the chloride ion concentration [Eq. (2.14)]. A related form of this is the antimony electrode, which involves antimony and its oxide (an adherent film on the surface of the antimony-metal electrode) such that the activity of antimony ion is controlled by... 

Figure 40. (A)TEM (left) and SEM (right) images of AOB nanorods. (B)Cyclic voltammograms of HRP (equal amount HRP) at different modified electrodes in pH 7.0 PBS with scan rate 0.02VS"1 (a) HRP-Chi-AOB/GC and (b) HRP-Chi/GC.( Reprinted from Biomaterials 27, X. Lu, Z. Wen,Hydroxyl-containing antimony oxide bromide nanorods combined with chitosan for biosensors, 5742, 5744, Copyright(2006) with permission from Elsevier.

Standard commercial electrodes are manufactured by Corhart Refractories (Saint-Gobain SEPR) under the name T-1186. These electrodes are doped with copper oxide and antimony oxide to allow sintering up to about 93% of theoretical density and to have good electrical conduction from room temperature up to operating temperature. Typical properties for T-1186 electrodes are reported in Table 1 and a view of the microstructure is presented in Figure 3. 

For pH measurements, different metal-metal oxide electrodes such as oxide film cowered antimony, stainless steel, iridium [11] have also been used. 

III, Does the Antimony Electrode Behave Simply as a Metal-Metal Oxide Electrode in Air J. Chem, Soc. London. 752-755 (1948). 

The use of antimony microelectrodes which are metal/metal oxide electrodes, is shown in Fig. la. They consist of antimony-filled glass capillaries, which are drawn out in order to obtain a fine bevelled tip, which is pH-sensitive and can be introduced into the tubular lumen. These electrodes have also been used to measure titratable acidity and ammonia in an in vitro" system, according to Solomon et al (16) and Karlmark (6). In this paper we will restrict ourselves to the discussion of some aspects of tubular acidification which can be studied due to the rapid response of the antimony electrode system to pH changes, permitting the kinetic study of the tubular acidification mechanisms. 

Longhi et al. [176] proposed to use the mercuiy(II) oxide electrode for estimation of OH concentration at high temperatures in strrMigly alkaline solutions (e.g., 1-10 mol dm NaOH), where typical electrodes such as glass or antimony cannot be rather applied. The dependence of the potential of such electrode on NaOH molality, m, was expressed as follows ... 

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