Polysulfide pulping

The additional sulfur for polysulfide pulping can upset the sodium—sulfur balance in the kraft recovery cycle and increase sulfur emission problems. In the MOXY (Mead Corp.) process, polysulfide is formed from kraft white Hquor by catalytic oxidation of sodium sulfide in the white Hquor using air. 

Of the stabilization methods, the polysulfide pulping process is of practical importance. The influence of polysulfides is based on a specific oxidation of the end groups to carboxyl groups via glucosone intermediates (cf. Section 8.1.3). Polysulfides can be prepared by catalytic oxidation of sulfide in the white liquor or by adding elemental sulfur into the kraft cooking liquor ... 

Teder, A. (1969). Some aspects of the chemistry of polysulfide pulping. Sven. Papperstidn. 72, 294-303. 

Kappa number = chlorine number x 4 82 Kraft and polysulfide pulps... 

FIGURE 10.19 Aryl-glyoxylic acids observed in polysulfide pulping. (Berthold, R, Lindgren, C.T., and Lindstrom, M.E., Holzforschung, 52, 197-199, 1998.)... 

G Brunow, GE Miksche. Some Reactions of Lignin in Kraft and Polysulfide Pulping. ApplPolym Symp 28 1155-1168, 1976. 

Aqueous polysulfide electrolytes are regularly the matter of fundamental photo-electrochemical studies (see Sect. 5.2 in Volume 6) and of the development of high-energy efficiency and highly stable photoelectrochemical solar cells [100,101]. Aqueous polysulfide solution chemistry is also of importance to the pulp and paper industry [102], and provides an opportunity for a battery cathode based on the... 

Waste-to-energy boilers Coal-fired Boilers Pulp and paper digesters Kraft recovery boilers Municipal waste containing chloride, sulfur, alkali metals, zinc and lead Sulfidation attack boiler tube wastage (50-60 mpy) Thiosulfate and polysulfides Sulfate, thiosulfate Chloride 59 (alloy 625 overlay weld metal used) 8 (alloy 625 and 309 SS) 21 (overlaid with 309 SS) 11 (309 L on lower furnace sidewalls 625 on floor tubes and smelt opening)... 

FIGURE 10.9 Products obtained on oxidation of coniferyl alcohol with polysulfide solution at pulping temperature. (Brunow, G. and Miksche, G.E., Acta Chem Scand, B29, 349-352, 1975 Berthold, E. and Gellerstedt, G., Holzforschung, 52, 490-498, 1998.)... 

Another pulping reagent that could oxidize lignin is polysulfide. The formation of aryl-glyoxylic acids (4), e.g., oxidation prodncts, has been observed in the pnlping liquors obtained from polysulfide treatment of softwoods and hardwoods (Figure 10.19) [120]. Both polysulfide and AQ are mild oxidants and, thus, carbohydrate damage is not very extensive [2,121]. 

DR Dimmel, S Anderson, P Izsak. A Study Aimed at Understanding the AQ/Polysulfide Synergistic Effect in Alkaline Pulping. J Wood Chem Technol 23 141-159, 2003. 

Chemical pulping Kraft, polysulfide kraft, prehydrolysis kraft Soda-anthraquinone (AQ) Acid sulfite, bisulfite, alkali sulfite-AQ Multistage sulfite 35-60... 

Chiyoda Corporation and Mitsubishi Paper Mills [32-34] developed a system for in situ oxidation of sodium sulfide in white liquor to polysulfide increasing the pulp yield in the pulping process. 

An electrochemical reactor with anolyte and catholyte divided by a cation-permeable membrane or semipermeable separator is required to preclude the diffusion of sulfide/polysulfide anions from anolyte to catholyte and to avoid reduction of polysulfide formed at the anode by reaction (9), being reduced at the cathode by the reverse reaction. Similar processes have been reported [18] for producing polysulfide (and hydroxide) solutions at current densities of 5 kA m for Kraft paper pulping processes. 

Dorris, G. M., and V. C. Uloth (1994). Analysis of oxidized white liquors n. Potentio-metric titrations for the determination of polysulfides and sulphoxy anions, J. Pulp Paper ScL, 20(9), J242-J248. 

Uloth, V., G. Dorris, R. Thring, R. Hogikyan, J. Wearing, L. Tench and J. Ayton (1996). In situ production of polysulfide liquor in a kraft mill s causticizers, Proc. Tappi Pulping Conference, Tappi Press, Atlanta, GA, pp. 813-836. 

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