Pretreatment kraft pulping

Fig. 17. Pretreatment of organic wastewater on trickling filters. Industry types for which coordinates have been plotted are 1, kraft pulp and paper 2, mixed iadustry 3, wet com milling 4, dairy 5, tannery 6, meat packiag 7, food 8, pharmaceutical 9, refinery and 10, textile.

Table II. Reductions of kappa numbers after peroxide delignification of en matically pretreated pine kraft pulps using of different en me preparations...

Occurrence, formation, structure and reactions. Wiley-Interscience, New York, 511-573 Andersson S-I, Samuelson O (1985) Formation of soluble compounds during pretreatment of kraft pulp with nitrogen dioxide. Sven Papperstidn 88 R102-R104 Bagby MO, Nelson GH, Helman EG, Clark EF (1971) Determination of lignin in non-wood plant fiber sources. Tappi 54 1876-1878... 

Taircell impregnated with 3.5% acid and without pretreatment gave levoglucosenone yields of up to 17 %. The amount of levoglucosan is the same as for initial cellulose, namely 19 %, which is a proof for a catalytic effect of phosphoric acid on cellulose depolymerisation. Thermocell and Kraft pulp showed an increase in the summary yield of 1,6-anhydrosaccharides after impregnation with of 3.5 % acid... 

A peroxide stage, P stage, is occasionally used as a polishing bleach for chemical pulps, using the conditions discussed. Peroxide has also been tested for initial bleaching of softwood kraft pulps after an acid pretreatment. A significant reduction in waste loads is obtained but at high cost [28]. 

J Gierer, I Noren. Oxidative Pretreatment of Pine Wood to Facilitate Delignification during Kraft Pulping. Holzforschung 36 123, 1982. 

C Jacobs-Yonng, JA Heitmann, RA Venditti. Conventional kraft pulping using enzyme pretreatment technology Role of chip thickness, specie and enzyme combinations. In BN Brogdon, PW Hart, JC Ransdell, BL Scheller, eds. Innovative Advances in the Forest Products Industries. New York Amer Inst Chemical Engineers, 1998, pp. 1-15. 

CJ Jacobs-Young, RR Gustafson, JA Heitmaim. Conventional kraft pulping using enzyme pretreatment technology Role of diffusivity in enhancing pulp uniformity. Paperi Ja Puu-Paper and Timber 82(2) 114—119, 2000. 

Xylanases are enzymes of great potential for industrial applications. They are mainly used in the pretreatment of Kraft pulp, improving bleachability of pulp while decreasing consumption of chlorine chemicals [5, 6]. These enz3mies are also used as additives to pig and poultry cereal-based diets, to improve nutrient utilization [7], in flour improvement for bakery products [8], in saccharification of agricultural, industrial and municipal wastes [9], and in juice and wine clarification [1]. 

Southern pine wood chips were subjected to a series of laccase-mediator (LMS) bio-pretreatments for kraft pulping employing 2,2 -azino-bis(3-ethylbenzthiazoline-6-sulfonate)... 

NMR analysis of black liquor lignins indicated increases in the ratio of substituted to unsubstituted aromatic carbons, suggesting that lignin from these bio-pretreatments may be more condensed than that obtained from a normal kraft pulp. 

These yield results, together with kappa number results, reinforce that employing LMS bio-pretreatments are feasible for kraft pulping. Further experimentation may be required to find the most suitable mediator, mediator dosage, etc., to further enhance the delignification and yield properties of these pulps. 

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