detailed description of this type of membrane modification can be found in u s application ser no 277 918 filed oct 22 1982 issuing as u s pat no 4 421 579 in the name of covitch et al and incorporated herein by reference suitable anodes which may be used or bonded to the membrane include anodes of graphite alone or with a foraminous valve metal such as titanium or tantalum having an electrochemically active coating over at least a portion of the anode surface suitable coatings include those of a platinum group metal platinum group metal oxide an alloy of a platinum group metal or mixtures thereof the term 34 platinum group metal 34 means an element of the group consisting of ruthenium rhodium platinum palladium osmium and iridium coatings containing mixtures of valve metal oxides such as ruthenium oxide are described in u s pat no 3 632 498 issued to h b beer on jan 4 1972 other anodes which may be employed include those described in u s pat no 4 333 805 issued jun 8 1982 to c r davidson et al u s pat no 4 240 887 issued dec 23 1980 to d e hall u s pat no 4 200 515 issued apr 29 1980 to e e hall et al u s pat no 4 042 484 issued aug 16 1977 to g thiele et al u s pat no 3 962 068 issued jun 8 1976 to zoellner et al.