CHEMICAL-STABILITY OF CHLORINATED COMPONENTS IN PULP BLEACHING LIQUORS

Raising the pH and temperature of spent chlorination (C) stage liquor caused a substantial removal of organically bound halogen. Chloropheno ls, chloroguaiacols, chlorovanillins, and chloroacetic acids were rath er stable in both alkali extraction (E) and C-stage liquor in the pH r ange 2-12, even at higher temperatures (100-degrees-C). The concentrat ion of chlorocatechols decreased at pH > 8, whereas the concentration of chloroguaiacols increased. In C-stage liquor the concentration of c hlorovanillins increased at pH > 4. Treatment with UV light in combina tion with hydrogen peroxide caused a rapid removal of AOX (adsorbable organic halogen) and of chlorophenolic compounds in both C- and E-stag e liquor, but it had no effect on chloroacetic acids or chloroacetones .