Evaluation of pulp making properties and kraft lignin precipitation from Ficus exasperate (Vahl.)

Abstract

This research aimed to evaluate pulp making properties and kraft lignin precipitation from F. exasperata. Fibre morphology, Kraft pulp yield, kappa number, isolation and precipitation of Kraft lignin were carried out to check the suitability of the raw material. The chips were obtained from the base, mid-stem and stem-top of the tree while cooking liquor was prepared by dissolving 40g NaOH: 13g NaS₂ in 1000mL of distilled water to obtain 17 and 20% effective alkaline. The ratio of NaOH to NaS₂ was 3:1, Liquor to chip ratio was 5:1 and at a varied temperature of 140, 160 and 180^°C. The highest pulp yield and kappa number were obtained at 140^°C and the lowest was recorded at 180^°C. Pulp yield decreases from base to the stem-top along the sampling height from 53.38 – 47.87% at the base, 51.31 – 47.64% at the mid-stem and 50.31 – 45.67% at the stem-top. While the pulp at the base (34.67 -24.00) gave the highest kappa number, followed by (32.44 -30.67) at the mid-stem while the lowest kappa number of 31.89 -29.22 was recorded at the stem-top. Isolated and precipitated Kraft lignin recorded highest yield of 21.3% at 160^°C cooking liquor. This study concluded that F. exasperata could be easily pulped using Kraft pulping to acceptable yield with moderate Kappa number. Also, kraft lignin was successfully recovered from spent liquor of F. exasperate.