Question

The common bleaching agent of recycled paper is
A)Hydrogen peroxide
B)Sodium hydrosulfite
C)Chlorine
D)Both A and B

Answer 1

Paper recycling is a process wherein, the paper that is used, discarded by the consumer, is collected and transported to paper mills.

Complete answer:
Paper recycling is one of the most well known services in the midst of different businesses .Generally paper is the most recycled product in the world. Such scrap can also be used in the preparation of new paper products and profit the economy significantly. Furthermore, almost all kinds of papers are recyclable. Paper items which are not characteristically acceptable in collection bins include brown and craft envelopes, carbon paper, paper towels, tissues, candy wrappers, coffee cups, and pizza boxes. Some of the most usually recycled paper items include cardboard, newsprint and magazines, manuals and booklets, and assorted office papers.

Most important part of recycled paper comes from industrial and commercial sources, in view of the fact that it is the easiest, cleanest and most economical to collect.
The papers are mixed with water and chemicals, broken down, converted into paper pulp and transformed into reusable form. The pulp which is obtained is colored and bleaching is performed to remove the color. The chemicals which are used for bleaching are hydrogen peroxide, sodium hydrosulfite or sodium dithionite. These chemicals help in deinking the pulp and increasing brightness. The most common bleaching agents for recycled pulp are peroxides and dithionite. The advantages of hydrogen peroxide are excellent environment compatibility, effectiveness under alkaline conditions, and non prohibitive cost, but heavy metals and enzymes catalyze its decomposition.

Hence, the correct answer is option (D)

Note: Using hydrogen peroxide to delignify chemical pulp requires more vigorous conditions than for brightening mechanical pulp. Both pH and temperature are higher when treating chemical pulp. The chemistry is very similar to that involved in oxygen delignification, in terms of the radical species involved and the products produced.