3. Pulping of bamboo (G. scortechinii)

Traditionally, kraft pulping has been the most commonly reported pulping milieu for bamboo species [33]. This is due to its strong bundle sheathes, impenetrable epidermis, a complete absence of ray cells and limited area of conducting tissues. As good as this pulping technique is, it is saddled with a lot of environmental legislative issues. The present paradigm shift in the pulp and paper making toward environmental benign pulping has informed the search for better pulping method for bamboo species.

and kraft pulping processes. According to the authors, the chemical materials that make up the ASAM process are sodium sulfite (Na2SO3), sodium hydroxide (NaOH), anthraquinone (AQ) and methanol (CH3OH). These materials play a unique role in the pulping milieu because, sodium sulfite and sodium hydroxide are the major ingredients of the alkaline sulfite process while the anthraquinone and methanol act as catalysts to enhance the chemical penetration delignification of the lignocellulose biomass. Table 3 shows the characteristics of cooking parameters in the ASAM pulping process, while Table 4 gives a summary of the key role of

Alkaline Sulfite Anthraquinone and Methanol (ASAM) Pulping Process of Tropical Bamboo…

http://dx.doi.org/10.5772/intechopen.76806

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The mechanism of ASAM pulping process can be viewed with respect to the cooking param-

Sodium sulfite and sodium hydroxide are two major active constituents in ASAM pulping process playing the dual role of delignification and increasing pulp brightness. Several research trials toward the effect of replacement of sodium hydroxide with sodium carbonate

Cooking parameters Value Total alkali (NaOH) 20–25 o.d Alkali ratio (Na2SO3/NaOH) or (Na2CO3/NaOH) 80/20–70/30 Anthraquinone (AQ) 0.075–0.1% Methanol 10–15 by vol Temperature 175–180C Cooking time at maximum temperature 120–180 min

Table 3. Characteristic cooking parameters of ASAM pulping process. Source [38].

Increases the cooking PH

Methanol Enhances chemical penetration into the woody chips

Sodium sulfite changed lignin to solvable material

and highest brightness than sodium hydroxide

Methanol improves the solubility of the AQ

Sodium hydroxide accelerant delignification in comparison with sodium carbonate

Sodium carbonate generates pulp with the strongest tensile index, highest pulp yield,

Act as effective stabilizer in both wood and non-wood polysaccharides

Cooking parameters Significance

Table 4. ASAM cooking parameters and their role.

Alkali ratio (Na2SO3/NaOH) or

(Na2CO3/NaOH)

Total alkali (NaOH) Accelerant delignification

Anthraquinone (AQ) Enhances the delignification rate

each chemical constituent in ASAM blend.

3.2.1. Effect of sodium hydroxide addition in ASAM pulping

eters.

o.d = oven dry.
