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- Ek, Monica, et al.
(författare)
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Study on the Selectivity of Bleaching with Oxygen-Containing Species
- 1989
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Ingår i: Holzforschung. - 0018-3830 .- 1437-434X. ; 43:6, s. 391-396
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Tidskriftsartikel (refereegranskat)abstract
- In the bleaching of pulp, the term Selectivity is widely used but poorly defined.This work is an attempt to quantify the selectivity of bleaching with Oxygen-containing species by generating hydroxil radicals and measuring their reaction rates with some lignin and carbohydrate models. Results of this investigation show that the selectivity factor defined as the ratio of the rate constants for a given pair of lignin and carbohydrate models, lies between 5 and 6.
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- Zhang, W, et al.
(författare)
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Membrane characterization by the contact angle technique: II. Characterization of UF-membranes and comparison between the captive bubble and sessile drop as methods to obtain water contact angles
- 1989
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164. ; 72:3, s. 263-273
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Tidskriftsartikel (refereegranskat)abstract
- Several commercial UF-membranes are characterized by water contact angles. Two different methods of contact angle measurements, the sessile drop and the captive bubble methods, are compared. Differences in results between the two methods occur for the DDS GR 61 membrane; otherwise the methods give rather consistent results. The advancing and the receding contact angles are measured for the UF-membranes. All membranes show considerable contact angle hysteresis. The cellulose acetate and the polyacrylonitrile membranes show less hysteresis than the polysulfone and the polyolefine membranes. The order of hydrophobicity according to advancing contact angle is polyolefine > polysulfone > cellulose acetate > polyacrylonitrile. The contact angle data are compared with Hansen's solubility data. Some correlation between θr and δtotal can be seen. θa correlates to the hydrogen and the polar part of the solubility parameter.
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