Use of Ethanolamine–Soda–Water Mixtures for Pulping Olive Wood Trimmings

Abstract

This paper reports on the influence of independent variables in the pulping of olive wood trimmings [viz. cooking temperature (165–195°C) and time (30–90 min), ethanolamine concentration (5–15%), soda concentration (2.5–7.5%) and liquid–solid ratio (4–6)], on the yield, viscosity and holocellulose, α -cellulose and lignin contents of the pulps. By using a central composite factorial design, equations that relate each dependent variable to the different independent variables were obtained that reproduced the experimental results for the dependent variables with errors less than 15%. Obtaining pulp with the maximum possible holocellulose content, α -cellulose content and viscosity (viz. 84.0%, 68.2% and 697.5 ml g –1 , respectively) and the lowest possible lignin content (11.4%) entails using high ethanolamine and soda concentrations, and also high temperature (except if the holocellulose content is to be maximized, in which case it should be 187°C); a long cooking time (to maximize viscosity and minimize the lignin content) and medium, high and low liquid–solid ratio for optimal α -cellulose content, viscosity and lignin content, respectively. Pulp obtained using high ethanolamine and soda concentrations, and high temperature, short cooking time and low liquid–solid ratio, exhibits values of the holocellulose, α -cellulose and lignin contents and viscosity which differ by less than 0.8, 3.2, 8.8 and 14.7%, respectively, from the optimum values, and a pulp yield that is only 22.6% lower than the maximum value (52.2%). These operating conditions result in capital savings from the use of smaller facilities, shorter cooking times and reduced amounts of liquid.