Sodium Hydroxide in Paper Production and Recycling

caustic soda in paper production

Sodium Hydroxide in Paper Production
There are three significant steps in paper manufacturing:
The raw material is pulped to obtain fibers that can be used to produce paper. The pulp is brightened or bleached.
This bleacher or brightened pulp is then developed into the paper.

Cellulose has always been used to make paper. According to conventional methods, the plant containing this natural fiber is cut into tiny pieces and then mashed in water so that the fibers get isolated. This mixture is then poured into a wire mesh mold followed by pressing out the excess water and drying the paper sheet.

To obtain a smooth printing surface and meet other specific requirements some paper products use fillers, coating, and other additives. An increasing number of paper manufacturers currently use wood as a source of cellulose.

materials used in Papermaking Process

Four essential materials are used in the manufacturing process of paper. These materials include water, energy, chemicals, and fibers.

Water: Water is used to carry the fibers through all the manufacturing steps and chemical reactions. It also separates organic residues from the pulp.
Energy: The papermaking process involves the usage of both electricity and steam. Energy for this process is obtained from oil, coal, natural gas, or hydroelectric power.
Chemicals: Chemicals are used in additives like fillers and coatings to meet the specific requirements of all kinds of papers. Caustic soda is used to clean the recovered fibers. Wood chips are cooked in a chemical solution during the kraft and sulfite pulping process to dissolve the lignin that compresses fibers. Caustic soda is added to increase the pH in the pulping process of fibers. The higher pH of the paper fiber solution causes the fibers to smoothen and swell. it is important for the grinding process of the fibers.

In many papermaking processes, wood is treated with a solution containing sodium sulfide and sodium hydroxide. This helps dissolve most of the unwanted material in the wood. leaving relatively pure cellulose, which forms the basis of the paper. In the paper recycling process, sodium hydroxide is used to separate the ink from the paper fibers allowing the paper fibers to be reused again.
Sodium hydroxide is also used to refine raw materials for wood products such as cabinets and furniture and in wood bleaching and cleaning.

Fibers: Cellulose fibers are the main components in making paper. Lignin, organic glue, is made from flexible cellulose fibers obtained from wood. This glue is found in plenty in softwood trees than in hardwood trees. Several non-wood plants are used as raw materials for paper and some of the fibers obtained from these plants can be grouped into agricultural residues.

How Paper Gets Recycled Wood is the best source of pulp for making paper, but the used paper is also a rich source of pulp. Writing and printing on paper does not remove the fiber content, and fiber eventually becomes paper.

Recycling Paper Process

Sodium Hydroxide in Paper Production and Recycling
Here’s How the Process of Recycling Paper Works:
Recycling start by collecting paper from multiple sources such as offices, homes, and universities. After the paper is collected, it is then graded to sort a similarly graded paper together. Grading is essential because it determines the amount of fiber that can be extracted from the pulp. The sorted paper is then turned into pulp using water, hydrogen peroxide, and caustic soda with soap. The pulp thus formed is screened for non-paper debris such as staples and plastic. The pulp is now all fiber and will be repeatedly de-inked until it becomes white. The whitened pulp is fed into rollers, which removes most of the water after which it is moved onto a dryer.

Lastly, the almost dry pulp is pushed through an ironing-board-type machine that rolls it into the desired paper grade.
It is essential to note here that paper recycling is not comparable to other types of recycling, like aluminum recycling. With metals, the metallic properties are retained after repeated recycling, but recycling paper leads to a reduction in the length of fibers. Eventually, recycled paper will
reach a point where it can no longer be recycled.
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