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Pulp washing: Influence of temperature on lignin leaching from kraft pulps

Gunnar Eriksson (Institutionen för kemisk apparat- och anläggningsteknik) ; Urban Grén (Institutionen för kemisk apparat- och anläggningsteknik)
Nordic Pulp & Paper Research Journal Vol. 12 (1997), 4, p. 244-251.
[Artikel, refereegranskad vetenskaplig]

The leaching of lignin from the fibre wall was studied in order to investigate the effects in the clean end of the fibre line. The focus was set on the short time intervals representative for the washing operation in industrial applications. The influence of temperature, pulp type and kappa number was investigated.

It could be seen that there are different diffusivities for the soluble lignin in the wall at short and long time of leaching, probably due to the existence of a more open structure in an outer layer of the fibre wall, in which the lignin diffuses more easily and which is also emptied relatively fast, while diffusion of the lignin from the inner layers is significantly slower. There is also a relation between the leaching of sodium out of the wall and the short term diffusion time of lignin, indicating a possible ion-ion interaction with the lignin in the outer layer of the fibre wall. The diffusivity of lignin increases more rapidly at temperatures above 80-90°C. This temperature effect was confirmed in the results of wash test equipment experiments, giving noticeable differences above 100°C. It was found that the experimentally determined lignin diffusivity differs for different kappa number and for type of pulp. The general behaviour of the phenomena, however, is the same.

Nyckelord: Pulp washing, Diffusion, Lignin, Temperature, Kraft pulp, Fibres



Denna post skapades 2006-08-28.
CPL Pubid: 20889

 

Institutioner (Chalmers)

Institutionen för kemisk apparat- och anläggningsteknik (1983-2001)

Ämnesområden

Pappers-, massa- och fiberteknik
Kemisk apparatteknik

Chalmers infrastruktur