Dergiler / Turkish Journal of Agriculture and Forestry / 2002 / Cilt: 26 - Sayı: 5
Production of Dissolving Grade Pulp from Poplar Wood by Ethanol-Water Process
- Sayfa
- 239–245
- DOI
- —
Özet
The possibilities of dissolving grade pulp production from poplar by an ethanol-water process were investigated. The effects of ethanol ratio, cooking temperature and acid catalyst ratio on unbleached, bleached and alkali-purified pulps were studied. It was seen that catalyst ratios exceeding 0.01% caused serious yield and viscosity losses. The results showed that with the catalyst ratio to pulping liquor exceeding 0.01%, pulp yield and viscosity were reduced to an unacceptable level. The best pulping result was obtained at 40% ethanol consistency, 180 ºC pulping temperature and 150 min reaction time without the addition of acid catalyst to the pulping liquor. After bleaching and alkali purification, the pulp obtained had a 30.7% yield, 95.8% a-cellulose content, 677 cm3/g viscosity, 83% ISO brightness, 1.80% residual pentosans, 0.33% copper number and 0.14% ash content. However, brightness was increased to 88.5% ISO level with the application of a multistage bleaching (CEHDED) sequence instead of chlorite bleaching without serious losses in yield or a-cellulose content at normal viscosity levels. It is concluded that these pulps meet dissolving grade pulp quality requirements.
Abstract
The possibilities of dissolving grade pulp production from poplar by an ethanol-water process were investigated. The effects of ethanol ratio, cooking temperature and acid catalyst ratio on unbleached, bleached and alkali-purified pulps were studied. It was seen that catalyst ratios exceeding 0.01% caused serious yield and viscosity losses. The results showed that with the catalyst ratio to pulping liquor exceeding 0.01%, pulp yield and viscosity were reduced to an unacceptable level. The best pulping result was obtained at 40% ethanol consistency, 180 ºC pulping temperature and 150 min reaction time without the addition of acid catalyst to the pulping liquor. After bleaching and alkali purification, the pulp obtained had a 30.7% yield, 95.8% a-cellulose content, 677 cm3/g viscosity, 83% ISO brightness, 1.80% residual pentosans, 0.33% copper number and 0.14% ash content. However, brightness was increased to 88.5% ISO level with the application of a multistage bleaching (CEHDED) sequence instead of chlorite bleaching without serious losses in yield or a-cellulose content at normal viscosity levels. It is concluded that these pulps meet dissolving grade pulp quality requirements.