Ultrafiltration Treatment and Physical Properties of Ammonia Sulfite Pulping Liquor of Wheat Straw

Ammonia sulfite pulping liquor of wheat straw was treated by ultrafiltration. Experimental results indicated that the membrane with a cut-off of 10kDa was suitable for concentrating wheat straw liquor and had good anti-fouling property against pulping liquor. Permeability of ash turn higher with the increasing of volume reduction at the operating condition of 200 kPa and 25°C, and retentate was concentrated when volume reduced. Influences of ultrafiltration on physical properties of ammonia sulfite pulping liquor and its retentate after ultrafiltration were studied. Results showed that retentate had better performances as surfactant, concrete additive and dispersant. Surface tension of 1% lignin solution of retentate was 54.7 mN/m, which was lower than that of the untreated original lignosulfonate by 2.2 mN/m. Dispersing effect of retentate on cement was also investigated, it was found that flowability of neat cement paste improved from 70mm to 102mm.