Intermediate Topic 1077 of 1102 Biochemistry, Environment & Industry

Paper Industry

Wood pulp is chemically treated to separate cellulose.

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In-depth explanation of Paper Industry

Paper is made from plant fibres, mostly cellulose, which must be separated from the lignin and other components of wood. In the kraft process, wood chips are cooked with sodium hydroxide and sodium sulfide, which dissolve lignin and free the cellulose fibres. The pulp is washed, bleached with chlorine dioxide or hydrogen peroxide to whiten it, then refined and pressed into sheets. The spent cooking liquor is recovered and burned in a recovery boiler, which regenerates the chemicals and produces energy. Recycled paper uses less energy and fewer chemicals than virgin pulp.

Going deeper: Paper Industry

Key ideas: Wood is about 50 percent cellulose, 25 percent hemicellulose, 25 percent lignin. Kraft process cooks chips in NaOH and Na2S (white liquor) to dissolve lignin, leaving cellulose fibers; bleaching with ClO2 or H2O2 whitens. Recycling uses deinking. Acidic paper made with alum rosin sizing yellows and decays, so archival paper is alkaline (CaCO3 filler).

Common mistakes and connections: Mistake: assuming the pulp is made by simply grinding; mechanical pulp keeps lignin and yellows. Chlorine bleaching made dioxins, so ECF and TCF are used. The spent black liquor is burned for energy and chemical recovery. Links to cellulose and hydrogen bonding between fibers.

Visualization of Paper Industry

Approximate softwood composition. Kraft pulping dissolves the lignin so the cellulose fibres can be bleached and made into paper. The interactive lesson shows this as a live animation or chart.

Worked example and use case

Kraft pulping removes most of the lignin, so the cellulose fibres can be bleached to white paper.

Frequently asked questions about Paper Industry

What is Paper Industry?

Wood pulp is chemically treated to separate cellulose.

Is Paper Industry a beginner, intermediate or advanced topic?

Paper Industry is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.

What should I learn before Paper Industry?

Study these earlier topics in Biochemistry, Environment & Industry first: Sulfuric Acid Industry, Ammonia Industry, Chlorine Industry.

What comes after Paper Industry?

The next topics in Biochemistry, Environment & Industry are Soap Making and Glass Manufacture.

Can I practise Paper Industry with quizzes?

Yes. The interactive lesson includes a self-check question on Paper Industry, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.

Where Paper Industry fits in Biochemistry, Environment & Industry

Paper Industry is topic 102 of 127 in Biochemistry, Environment & Industry.