Cellulosic pulp from Leucaena diversifolia by soda–ethanol pulping process

Abstract

A selection of the best wood raw materials for cellulose pulp and papermaking from five varieties of the Leucaena has been made ( Leucaena diversifolia, Leucaena collinsii and three varieties of Leucaena leucocephala) with growth periods of one, two and three years. In accordance with biomass production and the features of the raw materials and cellulose pulp obtained, L. diversifolia in its second year of growth was selected as the most suitable material for pulp and papermaking. Pulping of L. diversifolia by soda–ethanol was studied using an experimental design in order to investigate the effects of cooking variables: temperature, time, soda concentration, ethanol concentration and wash-disintegrate temperature on the chemical composition of the obtained pulps (yield, kappa number, viscosity, solubles substances, lignin, holocellulose and α-cellulose contents) and the physico-chemical characteristics of paper sheets (tensile index). The results were evaluated using the response surface methodology. The optimum pulping conditions were established for this lignocellulosic material, using the model predictions. The pulp obtained at these conditions has suitable chemical (pulp) and physical (paper sheets) characteristics: yield (46.5%), 1%NaOH solubles (3.04%), hot water solubles (0.63%), ethanol–benzene extractives (0.44%), holocellulose contents (96.7%), α-cellulose contents (75.8%), lignin contents (0.85%), viscosity (1367) kappa number (15.2) and tensile index (19.2 kN m/kg).