the non oxidized sample compared to the oxidized samples in example 1 however the 45 sulfur loss is considerably larger than in example 1 further treatment of the non oxidized sample at 750 u00b0 c increases the total sulfur loss to 56 while the reduction efficiency is unchanged at 58 thus from comparison of examples 1 and 2 it is clear that a strongly oxidized black liquor is preferred in order to minimize the sulfur loss and maximize the reduction efficiency about 10 mg of oxidized black liquor solids were pyrolyzed in a thermobalance by linearly increasing the temperature from 20 u00b0 to 750 u00b0 c at a rate of 20 u00b0 c minute the gas atmosphere was pure nitrogen up to 550 u00b0 c and 88 n 2 plus 12 co above 550 u00b0 c after stabilization of the temperature at 750 u00b0 c co 2 is added to a concentration of 20 with the remaining gas being 10 co and 70 n 2 the addition of co 2 leads to gasification of the carbon in black liquor char as indicated by the recorded weight loss and co production the composition of black liquor char during gasification is shown in table 4 the results in table 4 show a continuous decrease in inorganic sulfur content while the reduction efficiency is maintained at 80 90 cos was measured gas chromatographically as the only sulfur gas produced during gasification the reaction responsible for the sulfur loss is the high s 2 o 2 3 content is due to rapid oxidation of s 2 in aqueous solution before analysis of the water leachate of black liquor char by ion chromatography the small sample size and the presence of carbon makes it extremely difficult to prevent the oxidation it should also be.