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RISS 인기검색어
- 검색키워드
- 저자 : B.Holmbom (검색결과 2 건)
- 무료
- 기관 내 무료
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[Oral Session 3] DISSOLVED AND COLLOIDAL SUBSTANCES RELEASED INTO WATER FROM BLEACHED CHEMICAL PULPS
B.Holmbom,T.Soderlund,W.Berger 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-
Dissolved and colloidal substances released from pulps into process waters can accumulate and give detrimental effects on papermaking, especially in paper machine systems with a high degree or water system closure. It has been reported in the literature that beating of chemical pulps in the stock preparation can result in considerable dissolution and dispersion of fibre substances.<br/> Three ECF- and four TCF-bleached pulps delivered in dry form to the Sappi Austria AG fine paper mill in Gratkorn, including both softwood and hardwood pulps, were beaten in a Valley laboratory beater. Refiner beating in the mill was investigated by analysis of samples taken before and after the refiners. The dissolved and colloidal substances in the waters were separated from the fibres by centrifugation and were ana lysed by standard determinations and by GC analysis of carbohydrates and lipophilic extractives (resin).<br/> Considerable amounts of organic material was dissolved and dispersed already during slushing of the pulps. During beating in the Valley beater the concentrations increased further by 6-32%. Beating in the paper mill released little organic material from the pulps. The released dissolved and colloidal substances were mainly composed of hemicelluloses. with xylans as the dominant group. both for hardwood and softwood pulps. More lipophilic extractives were released from birch pulps than from eucalypt and softwood pulps. In mill samples. starch was the dominating dissolved material. Starch is used in the mill both in the wet end and as a coating color component.<br/> It was concluded that the amounts of dissolved and colloidal substances coming in with chemical pulps to the wet end of papermaking are dependent mainly on the cfficiency of pulp washing in the pulp mill. Only some additional fibre material is dissolved or dispersed during beating.
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[Poster Presentation] DETERMINATION OF ALKENYL SUCCINIC ANHYDRIDE(ASA)IN PULP AND PAPER SAMPLES
K.Sundberg,B.Holmbom,R.Ekman,J.Axberg,J.Nyman 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-
A method for the determination of alkenyl succinic anhydride (ASA) in pulp, paper and water samples is presented. The method, based on gas chromatography (GC), enables the determination of ASA in its different forms, that is fiber-bound ASA and unbound ASA. The latter normally comprises metal soaps of alkenyl succinic acid.<br/> In order to distinguish between bound and unbound ASA, the unbound ASA must first be extracted from the sample. In this study, we have shown that unbound ASA can be efficiently extracted from paper either with acidic acetone or acetone in the presence of KH₂PO₄. Acetone alone is not the proper solvent, since unbound ASA in paper often occurs as Ca-soaps which are not very soluble in acetone. For GC analysis, derivatization of the extracted components is necessary.<br/> Regarding determination of bound ASA, acid methanolysis on one hand, and alkaline hydrolysis followed by methylation<br/> with diazomethane on the other, gave similar recoveries of bound ASA. The different derivatization methods evaluated here, namely silylation, methylation with diazomethane, and methylation during acid methanolysis, all resulted in similar amounts of detected ASA.<br/> Resin acids may severely interfere with the quantification of ASA due to overlapping in GC analysis. This is especially true for wood-containing or rosin-sized paper grades, where resin acids are abundant. For reliable quantification, GC-MS used in selected-ion-monitoring (SIM) mode is recommended.
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