BIPOLAR HYPOCHLORITE CELL

1419366 Bi-polar electrolytic cells DIAMOND SHAMROCK CORP 22 July 1974 [23 July 1973] 32359/74 Heading C7B An electrolytic cell, for producing alkali metal (Na or K) O Cl solution e.g. of 1 to 20 g/l concentration by direct electrolysis of alkali metal chloride solution e.g. of 5 to 100 g/l concentration at pH 7 to 10, comprises: a vertical container 1 having an electrolyte inlet 3 at the bottom and an electrolysis product outlet 5 at the top; a plurality of horizontal non-conducting partitions 9 dividing the container into a plurality of cell units 7 through which electrolyte and electrolysis products pass from bottom to top e.g. via holes 11 in diagonally opposite corners of the partitions to provide a tortuous flow-path; terminal foraminous monopolar sheet anode 13 and U-shaped cathode 17 in the respective first and last cell units 71 711 e.g. each connected to respective current supply and withdrawal means 15, 19 via connecting portions 33, 35; at least one foraminous bi-polar electrode comprising a sheet anode portion 21 and a U-shaped cathode portion 23 joined by a conductive connecting portion 25 held between an edge of the partition and a container sidewall 29, the bipolar electrode being horizontally disposed in adjacent cell units on opposite sides of a partition so that the anode portion is encompassed by an adjacent cathode and the cathode portion encompasses an adjacent anode, parallel to and spaced from e.g. by spacers 27 the partition. Preferably the bi-polar electrode comprises a continuous S sheet of expanded Ti, the anode portion bearing an electrocatalytic coating e.g. of Pt group metal (oxide). Alternatively the anode portion may be butt welded to connecting and cathode portions of perforated stainless steel, Ni or Pd- Ti alloy. The container and partitions may be of (chlorinated) PVC, "Lucite" or "Perspex" (Registered Trade Mark) a gasket 31 being provided between the sidewall 29 and a partition edge to hold the connecting portion 25 of the bi-polar electrode.