Patent GB-1012163-A (GB)
Title: Methods and apparatus for estimating the concentrations of ions in dilute aqueous solutions
IPC: G01N27/02
Filed: 1961-08-18
Abstract: 1,012,163. Determining relative quantities of fluid mixture constituents. CENTRAL ELECTRICITY GENERATING BOARD, G. W. BOWN and F. B. E. SCARLON. Nov. 16, 1962 [Aug. 18, 1961], No. 29947/61. Heading G1N. A method of estimating the concentration of ions in dilute aqueous solutions comprises measuring the conductivity of the solution, treating the solution to remove ions and an equivalent amount of oppositely charged ions, and measuring the conductivity of the resulting solution as an indication of the concentration in the original solution, of ions removed from the solution. The invention uses an ion-exchange resin in a form such that the counter ion for example Ag<SP>+</SP> is one which forms an insoluble compound with one or more of the ions to be removed and may be used to estimate the total concentration of chloride, bromide, iodide, cyanide, ferrocyanide, ferricyanide, oxalate and thiocyanate in aqueous solutions containing one or more of these ions, the concentration of sulphate phosphate carbonate fluoride or nitrate ions in a solution containing one or more of them and one or more of them and one or more of the above halides, or the concentration of fluoride ions in a solution containing it, and any other halide. The chloride concentration in boiler feed water may be determined by passing it through a resin such as carbonaceous zeolite in its H<SP>+</SP> form and measuring the conductivity T of the effluent and then passing the effluent through a resin in Ag<SP>+</SP> form and again measuring its conductivity C R , the conductivity C C2  representing the chloride concentration being equal to C T -C R  which may be directly indicated. Phosphate concentration in a solution as above may be similarly determined, the solution being divided into two portions from one of which such chloride, bromide, iodide, cyanide, ferrocyanide, ferricyanide oxalate, thyocyanate, phosphate, and carbonate ions as are present are removed together with an equivalent amount of oppositely charged ions, and the remaining +VE charged ions are exchanged for hydrogen ions. The other portion has its +VE charged ions exchanged for hydrogen ions; chloride, bromide, iodide, cyanide, ferrocyanide, ferricyanide, oxalate, and thiocyanate and an equivalent amount of hydrogen ions removed and is further passed through a cation resin in H<SP>+</SP> form. The two final conductivities are measured and their difference used as a measure of the original concentration of phosphate ions. An apparatus for carrying out the test comprises a column 1 packed with carbonaceous zeolite in H<SP>+</SP> form, and a column 2 comprising two half columns 31 in Ag<SP>+</SP> form and 32 in H<SP>+</SP> form, each having a conductivity cell 4. 6 at its outlet end, and a column 3 comprising two half columns as in column 2 and having a conductivity cell 8. The cell electrodes are of graphite, and the inlets to the columns include flowmeters 17,18, the valves 15,16, being set to give approximately equal flows of 4. 5 ml. per minute or less. Manners of preparation of the columns are described and some test results are given.