FLOCULATION EFFECT OF BaCl2 TO BLACK LIQUOR COOKED WITH DIFFERENT Na2SO3 DOSAGE

摘要

In the process of alkaline cooking, the addition of the Na2SO3 can make the alkali lignin in black liquor sulfonated, becoming lignin sulfonate which is more widespread use than alkali lignin. But lignin obtained from this method is difficult to separate and extract. The wastewater treatment gets more difficult too. BaCl2 has the effect of flocculent on the black liquor. It is found that the more BaCl2 dosage added into the black liquor, the more sediment can be obtained, and amount of 10% of the sediment tend to be the maximum. At different pH value, the organic matter content in BaCl2 sediment is basically the same. When adding BaCl2 into the black liquor with different dosage of Na2SO3, it is found that with the increasing of Na2SO3 dosage, the proportion of organic flocculants gradually decreases, and at the amount of 10% Na2SO3, the proportion tends to reach equilibrium, compared with the similar tendency of the hydrochloric acid sediment. Infrared spectroscopy of the sediment of the BaCl2 shows that in about 947 cm-1 there is a new absorption peaks, and the absorption peak intensity increase gradually with the increase of the amount of Na2SO3. Preliminary judgment of the absorption peaks is considered to be surface vibration absorption peaks CH2 of CH2 = CH - M (M for the metal).