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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 $50^\circ C$
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
Detailed Solution
Paper is made from cellulose fibres.
In wood, the cellulose fibres are bound together by lignin, a complex polymer that makes the cell walls hard and gives a brown colour.
In pulp manufacture, the wood chips are treated with chemicals (for example in the sulphate or sulphite process) that dissolve the lignin.
This frees the cellulose fibres and gives a relatively pure cellulose pulp, which is then bleached and made into paper.
Breaking down the cellulose itself would destroy the fibres needed for paper, and removing water or oils is not the key step.
So the important step is the preparation of pure cellulose by removing lignin.
In wood, the cellulose fibres are bound together by lignin, a complex polymer that makes the cell walls hard and gives a brown colour.
In pulp manufacture, the wood chips are treated with chemicals (for example in the sulphate or sulphite process) that dissolve the lignin.
This frees the cellulose fibres and gives a relatively pure cellulose pulp, which is then bleached and made into paper.
Breaking down the cellulose itself would destroy the fibres needed for paper, and removing water or oils is not the key step.
So the important step is the preparation of pure cellulose by removing lignin.