System and method for repulping of paper products and improvement of water quality with dipolar solvents and recovery

Abstract

An enhanced method of repulping paper and improving water quality by placing used paper product material in an aqueous solution of dipolar aprotic protophylic solvent, processing it, and recovering recycled pulp based on two physical reactions of the dipolar solvent: first with water from one part of the solvent, and second with cellulosic material from the other part of the solvent. The water reaction involves a rearrangement of hydrogen bonds within the water, improving its reactivity and solvent capacity, and the cellulosic reaction involves dissolution of hemicellulose in a manner which results in reduced fibre loss and improved pulp quality. The net result is more efficient pulping and reduced environmental impact.

Description

FIELD OF THE INVENTION[0001]This invention relates to the treatment of water and the repulping of paper products.BACKGROUND OF THE INVENTION[0002]In the pulp manufacturing industry water is used extensively and is a vital element of the process of repulping paper. It is used for dissolving pulp, and as a component in loading, sizing, and coloring ingredients as well as in the transportation of pulp fibres through the manufacturing process as it moves through storage tanks, screens, refiners and paper-making machines.[0003]The current process of repulping paper involves pulping, screening, cleaning, and de-inking by processes like bleaching and the application of alkaline chemicals which contaminate the water. Waste paper treatment methods are variable depending on the type of paper and may involve de-inking of toner from laser printers or photocopiers, or the removal of other contaminants from the paper.[0004]Pollution sometimes causes water molecules to form large clusters which su...

AI Technical Summary

Benefits of technology

[0029]The invention is designed to provide an enhanced method of repulping paper and improving water quality with dipolar solvents and recovery. These objects are discussed in two parts, first with respect to the repulping objects, and second with respect to the water quality improvement objects. Essentially the repulping objects are to reduce fibre losses and improve pulp quality. There are a number of aspects to this as discussed below under part 1. The primary water quality improvement objects are to increase its reactivity and solvent capacity. This has numerous advantages as discussed below under part 2.

Problems solved by technology

However, if the water molecule was instead near the methyl groups of aprotic solvent no such alternative bonding would be possible.

HEMPT however has the disadvantage that it is considered to be carcinogenic, mutogenic and toxic to reproduction in animals.

Acetone as a repulping solvent has the disadvantage that it brings about considerable disproportionality on the cellulose chain, by forming isopropylidene derivatives on the sugar rings of the residual cellulose.

This would provide a low degree of polymerization of the cellulose and would have a negative impact on the strength of a paper sheet formed from the re-pulpled material.

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