Pulping and bleaching of pulp from olive tree residues

The influence of operating conditions (active alkali concentration, tempera ture and time) used in the kraft pulping of wood from olive trimming residu es on the yield and kappa index of the pulp and the stretch index, burst in dex and tear index of paper sheets obtained from it, as well as that of the chlorine dioxide concentration used to bleach the pulp according to the D1 ED2 sequence (chlorine dioxide-alkaline extraction-chlorine dioxide) on the yield, kappa index, brightness and viscosity of the bleached pulp, were st udied. A 2 " central composite factor design was used to derive equations t hat relate the dependent variables to the operating variables considered in the pulping and bleaching processes. The equations reproduce the experimen tal results with errors less than 10%. Based on the pulping results, obtain ing readily bleached pulp of acceptable strength-related properties entails using an active alkali concentration of 25%, a temperature of 175 degreesC and a time of 93 min. Based on the bleaching results, using chlorine dioxi de concentrations of 7.5 and 1% in steps D-1 and D-2, respectively, ensures the obtainment of acceptably bright (> 88%) pulp with little loss of yield (< 2%) and viscosity (< 3%). (C) 2001 Elsevier Science Ltd. All rights res erved.