Title
Effect of alkaline pre-hydrolysis on soda pulping of wheat straw
Authors
A. JAHAN LATIBARI and K. POURALI

Received January 22, 2018
Published Volume 53 Issue 1-2 January-February
Keywords hemicelluloses, pre-hydrolysis, cellulose, lignin, yield, strength

Abstract
The influence of alkaline pre-hydrolysis on hemicelluloses removal and the impact of the treatment on soda pulp quality were investigated. The pre-hydrolysis conditions were selected as NaOH – 5 and 7.5% based on the oven dry weight of the sample, time – 30, 60 and 90 minutes, and temperature – 60 and 90 °C. Each treated sample was divided into two portions: one-third was used for chemical analysis and the other two-thirds for soda pulping. The influence of the pre-hydrolysis conditions was determined by measuring the cellulose and lignin content and the removal of hemicelluloses. The lignin and cellulose content increased under the intense treatment conditions and the hemicellulose removal was higher at higher dosages of NaOH, temperatures and times, varying between 4.55% and 8.31%. The treated sample was subjected to soda pulping during 20 minutes pulping time, at 175 °C temperature and 16% sodium hydroxide (based on dry weight). Then, the pulping yield, kappa number and strength properties of the unbleached pulp were determined by corresponding Tappi standard test methods. The pulping yield and kappa number ranged from 41 to 46.6% and from 41.6 to 61.85, respectively. The highest values of tensile strength, tear strength and burst strength indices were determined as 75.35 Nm/g, 17.9 mN.m2/g and 3.31 kPa.m2/g, respectively.