Question

The residual lignin content in chemical pulp accounts for_______ of the mass.

(a) 8%–9%

(b) 5%–8%

(c) 2%–5%

(d) 1%–2%

I got this question in quiz.

My question is based upon Pulping, Digestion and Bleaching in section Paper and Paper Based Packaging Materials of Food Packaging Technology

Answer 1

The correct option is (c) 2%–5%

To explain: The residual lignin content in chemical pulp accounts for 2%–5% of the mass. It is responsible for the dark color of the unbleached pulp. The reagents for full bleaching of chemical pulp are mostly oxidative and since the carbohydrates are also susceptible to oxidation, bleaching must be accomplished under the mildest conditions.