Electrochemical apparatus.

Abstract

Abstract 1,177,406. Electro-chemical measuring electrodes. CORNING GLASS WORKS. April 24, 1967 [May 3, 1966], No.18736/67. Heading G1N. An electrode for measuring an ionic concentration in an aqueous phase comprises an organophilichydrophobic porous membrane 14 through which a liquid organic phase 18 containing an organic ion exchange material capable of exchanging ions with the aqueous phase and immiscible with the aqueous phase, can flow in minute quantities and form an interface with the aqueous phase at the outer surface of the membrane. As shown in Fig.1, the electrode includes an internal reference electrode comprising a platinum wire 28 with a silver-silver chloride coating 30 and a salt bridge 34 of saturated potassium chloride solution gelled with gelatinous silica or agar. A glass wool plug 32 soaked in the salt bridge solution enhances mechanical stability. Alternatively, Fig.2 (not shown), glass tube 24 may continue downwards and be attached to the membrane 14, e.g. by solder glass. Porous membrane. The membrane 14 may comprise a microporous glass disc about 0À5mm. thick having a nominal maximum pore size of 0À9 to 1À4 microns or silver having a porosity of 0À2 microns maximum pore size and a thickness between 1 and 2 mils and is treated with an agent to import the organophilic-hydrophobic property. Suitable agents are: silicone liquids; silane coupling agents, e.g. methacrylate propyl trimethoxysilane; fluorinated hydrocarbons or polymers; and beeswax. Processes for applying and curing the agents are described. Ion exchange materials. Cationic and anionic types can be used for measuring alkaline earth metal ions, e.g. Ca<SP>++</SP> and halogen ions, e.g. Cl<SP>-</SP> respectively. The ion exchange material may be a liquid or a solid dissolved in a liquid. Suitable liquid cation exchangers are: bis-(2-ethylhexyl) phosphoric-acid; either or both of the mono- and diforms of n-butyl phosphoric-acid and amyl phosphoric acid; certain carboxylic acids, e.g. caproic-acid and caprylic acid; and perfluorobutyric acid. Suitable liquid anion exchangers are: primary, secondary and tertiary amines, e.g. N-trialkyl methylamine, N-lauryl-N-trialkyl methylamine, and N, N, N-triiso-octylamine. Suitable solid ion exchangers include: dioctadecyl amine, tetraheptyl ammonium iodide, cetyl pyridinium chloride, nonadecyl phosphoric acid and dinonyl naphthalene sulphoric acid. Appropriate liquids for dissolving solid ion exchangers or for diluting liquid ion . exchangers preferably have high dielectric constants, e.g. octyl and dodecyl alcohols, 2-pentanoes, nitrobenzene, orthodichlorobenzene, trialkylphosphates and mixtures of mineral oils in phosphonates. Specific examples of complete electrodes are given. The electrodes of the invention may be used in conjunction with a calomel or silversilver chloride reference electrode.

Inventors

No inventors recorded.

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