Question

An important step in the manufacture of pulp for paper industry from the woody tissues of plants is the

• A. Removal of water from the wood by prolonged heating at approximately 50${}^o$C.
• B. Treatment of wood with chemicals that break down cellulose.
• C. Removal of oils present in the wood by treatment with suitable chemicals.
• D. Preparation of pure cellulose by removing lignin.

Answer 1

The correct option is D Preparation of pure cellulose by removing lignin.

Cellulosic materials are comprised of lignin, hemicellulose and cellulose and are thus, sometimes called as lignocellulosic materials. One of the primary functions of lignin is to provide structural support for the plant. Thus, in general, trees have higher lignin contents then grasses. Unfortunately, lignin which contains no sugars, encloses the cellulose and hemicellulose molecules, making them difficult to reach.

Cellulose molecules consist of long chains of glucose molecules, as do starch molecules, but have a different structural configuration. These structural characteristics plus the encapsulation by lignin makes cellulosic materials more difficult to hydrolyze than starchy materials. So, preparation of pure cellulose by removing lignin is an important step in the manufacture of pulp for paper industry from the woody tissues of plants to make a better quality papers. Removal of water from the wood by prolonged heating at approximately 50${}^o$C, treatment of wood with chemicals that break down cellulose and removal of oils present in the wood by treatment with suitable chemicals are not the important step in the manufacture of pulp for paper industry. Thus, the correct answer is option D.