| abstract |
A method which comprises exposing an oxidised white liquor, produced by oxidising a white liquor with an oxygen containing gas in the presence of lime mud, manganese dioxide or both, to a controlled temperature effective to increase the concentration of PSUV measured at 285 or 286 nm or PSVIS measured at 416 nm and the PSUV/PSGR or PSVIS/PSGR ratio of polysulfiphide in the oxidised white liquor, for a time of from 1 to 72 hours. |