Pure arsenic triselenide recovery by distn. of waste - for direct re-use as a photoconductor

The waste is distilled in a current of inert gas and the vapour condensed in liq. As2Se3; the liq. As2Se3 then flows dropwise from nozzles into cold water, where it solidifies to form a granulate. The waste As2Se3 is pref. distilled at or above atmos. pressure, esp. at 0.01 atu; alternatively, distn. may be at reduced pressure, esp. at 10-2 to 10-4 atmospheres. The inert gas is pref. N2 and/or Ar, flowing at 15-20 l/h with an equal vol. of As2Se3. The quartz glass pref. uses a distn. flask at 800-900 degrees C.; a rectifier column at 650-700 degrees C; and condensn. device at 550-600 degrees C. As2Se3 is employed as a photoconductor, e.g. in electrophotography, where a layer of As2Se3 is obtd. by vapour deposition. Pure As2Se3 with stoichio metric compsn. is recovered from the waste and is directly re-usable.