DE2134101B2 - Electronically conductive glass and its use in a glass electrode for measuring the oxidation potential of liquid media - Google Patents

Description

+ 1200 mV in a measuring range from pH 3 to 9. SiO ₈ 45 to 65;

Fe ₂ O ₈ 25 to 50;

Na ₂ O 4 to 15;

Li ₂ O 2 to 10.

The invention relates to an electron-conducting glass 30

From SIO ₂ , Fe ₂ O ₃ , Li ₂ O and Na ₄ O, which is used to produce such large amounts of iron, a high exchange of a sensing element for glass electrodes flows at the glass-solution boundary. At the same time, a potentiometer measurement of the suppressed the presence of two alkaline oxidation potentials of liquid media can be provided for the oxides, the ionic conduction and ensures good loading. 35 operating properties and a high chemical

The electrodes are widely used with permanence Givers of continuously acting monitoring and The most favorable properties have a glass with Control systems for technological processes in marriage (in percent by weight)

mix, pulp, paper, textile and pharmaceuticals sjq 55;

Industry and hydrometallurgy. 4 »Fe.0 37 * The electrodes contain a hollow glass tube of Na ₂ O ⁸ 4;

with a current lead, at one end of which a L O '

Sensing element is soldered. _{0 (} y _er ^a * An embodiment of the sensing element from §jq 5g is known. Glass on lithium silicate and sodium aluminosilicate 45 p _e q 39.

base, which has an ionic conduction. Such elec- Na * O * 7- '

but do not allow the oxidation potential of Li b 4 '

lial (eH) of control media. ^a

Usually the sensing element is used for measuring. B. 5 »play as well as a drawing to be explained in more detail, ftus gold, platinum. showing a glass electrode.

In addition to considerable costs, the electrodes have The proposed glass is made from chemically pure

with such sensing elements additionally the following powdery ones, previously up to constant weight

Disadvantages: made of dried oxides.

They are caused by catalyst poisons (for example 55 suitable glasses are indicated in the table: by H ₂ S and other sulfur compounds, arsenic

compounds, cyanide ions, etc.) poisoned, d. H. the oxides

catalytic activity of the electrode surface is

and the reversibility of the electrode process is disturbed. Gaseous acid or water 60

substance in the control medium acts on the electrode Li ₈ O

potential on, whereby the measuring accuracy is reduced. Na ₂ O

is set. In addition, the noble metals Fe ₂ O

the decomposition of some redox systems (e.g. SiO.

s

(Weight percent) 4422 10 326 74 15 44484 39 37 38 33 40 50 42 25 50 55 45 61 46 43 48 65 of hydrogen peroxide). 65

Electrodes with a feeler are significantly cheaper. The glasses are made as follows:

element made of carbonaceous materials. However, a crucible with a carefully mixed one does not guarantee a high accuracy of the measurement of the quantity set in a previously heated to 1100 ° C

Example no. 456

<f

Furnace inserted. In 4 hours the temperature in the furnace to 1350 ° C is brought, and at this temperature the glass mass is kept l ¹ / »hours. During this time, the melt is periodically mixed and then poured into a mold.

In the following, this glass becomes the sensing element of an electrode shown in the drawing manufactured

The glass obtained in the manner described is melted in the flame of a burner on which Transfer the end of a glass tube 1, carefully warm it through and until a ball has formed blown.

Before the cavity of the tube 1 is filled, the outer and inner surface of the is used as a sensing element 2 serving ball a thin layer of glass removed, the composition and structure of which changes when the sensing element 2 is soldered to the tube 1 could have changed.

The electrode for measuring the oxidation potential contains a tube 1, at one end of which is a Sensing element 2 made of glass of the composition mentioned is soldered on. The cavity of the tube 1 is filled with an electrically conductive material 3 in which a conductor 4 is housed. Of the The upper part of the tube 1 is covered with a cap 5.

An electrode with the sensing element made of the glasses described allows an oxidation potential within the limits of -200 to + 120OmV (0 mV = potential of a normal hydrogen electrode) to measure in a measuring range from pH 3 to 9.

The working range of the electrode is 0 to 90 ⁰ C, the electrical resistance <1 μΏ.

The glass according to the invention has the advantage that the catalyst poisons present in the solution Speed of electron exchange between the glass and the solution is not affected

1 sheet of drawings

Claims (4)

-..-, oxidation potential in relation to the oxidation claims: Reduction of a small buffering capacity having redox systems. 1. Electron-conducting glass made of SiO ₈ , Fe ₂ O ₃ , the well-known alkali silicate material> only has LiA Na ₈ O, characterized by a 5 hectare conductivity, when iron oxide is very large 45 to 65 percent by weight SiO ₈ ; Concentration prevails what the genetic 25 to 50 weight percent Fe ₂ O ₃ ; and chemical resistance impaired. There- 4 to 15 percent by weight NaJ) and beyond that, such a sensing element can only be used in 2 to 10 weight percent Li ₂ O. ^{dnem äußefSt} ^ nzten concentration range of 2. Glass according to claim 1, characterized marked io redox systems for measuring the oxidation potential net that it can be used from. 55 percent by weight SiO, the purpose of the invention is to conduct electrons 37 percent by weight Fe ₂ O ₃ glass that is chemically resistant and a 4 percent by weight Na ₂ O has good production-related behavior and 4 percent by weight Li ₂ O is made, which allows the measurement range for the concentration 3. Glass according to claim i, characterized by expanding the redox systems. net that it is made to achieve the stated and other goals 50 percent by weight SiO ₂ - the task is set, a Züiaimnenseizung of 39 weight percent Fe ₂ O ₃ ; To choose iron silicate glass, the significant currents than 7 percent by weight Na ₂ O- ao result of an electron exchange at the limit 4 weight percent Li ₂ O consists. Glass control solution secures and is indifferent to the 4. Use the glass after one of the pre-control solutions is available. previous claims as a sensing element in a glass The task is solved in that the elec- Electrode for measuring an oxidation potential of electron-conducting glass in percent by weight as follows of liquid media has within the limits -200 to »5 components: