Upgrading spent liquors from NSSC process: IV. Utilization of spent liquors as papermaking additives

AREA, M.C., BENGOECHEA, D., FELISSIA, F.E., VENICA, A.D., VALADE, J.L.

Orlando, USA

Congreso; Tappi Pulping Conference; 1999

TAPPI

Hemicelluloses and NSSC spent liquors were studied as papermaking additives. Isolated NSSC hemicelluloses, and spent liquors from a previous work were used as raw materials. The preliminary trials consisted in different hemicelluloses and spent liquors dosages combined with cationic starch at pH = 7.5. Dynamic jar tests were performed and turbidity, cationic demand and conductivity were determined. The results were statistically analyzed using multifactor ANOVA tests and indicate that the pulps did almost not retain the hemicelluloses and spent liquors incorporated, and they remained as anionic trash. The influence of pH (4.5 and 7.5) was determined by a factorial design, with and without starch, at a hemicellulose concentration of 1.5%. A 2 3 factorial design was performed to see the influence of aluminum sulfate on retention. Variables studied in this case were aluminum sulfate, hemicelluloses or spent liquors and cationic starch. Alum sulfate does not have any significant influence on soluble substance retention. A strong interaction between starch and alum is evidenced; being starch more attached to fines. The best points were selected and additions of 1% of starch, and 1.5% of hemicelluloses, spent liquors and an ultrafiltration retentate of spent liquors were applied to pulp furnish. Britt jar tests for fines retention measurements, turbidity, and drainage of the filtrate were also executed. Physical tests on handsheets were made at standard conditions and at high humidity conditions.