Enzymatic Deinking of Recycled Paper Pulp

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional deinking processes for recycled paper pulp, which rely on alkaline chemicals, cause irreversible changes to pulp fibers, lead to yellowing, and result in additional costs and runnability issues due to solubilization of papermaking additives and coatings.

Innovation Solution

A neutral deinking method using a combination of lipase and at least one second enzyme, such as xylanase or cellulase, along with a non-ionic surfactant, to effectively remove ink from printed paper pulp, maintaining or increasing brightness without the use of harsh alkaline chemicals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If alkaline chemicals are used for deinking, then ink removal efficiency is improved, but fiber damage and yellowing occur

Engineering Contradiction:

Improveink removal efficiencyVSAvoidfiber damage and yellowing

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the pH parameter from alkaline (conventional) to neutral (pH 6-8), eliminating fiber damage and yellowing while maintaining effective ink removal through enzymatic action. The neutral pH regime preserves fiber integrity throughout the deinking process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces chemical deinking mechanisms (alkaline hydrolysis and saponification) with enzymatic deinking mechanisms. Enzymes such as lipases, proteases, and amylases specifically target and break down ink components without damaging cellulose fibers, substituting harsh chemistry with selective biocatalysis.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If alkaline deinking chemicals are used, then ink removal is achieved, but additional costs and runnability issues occur

Engineering Contradiction:

Improveink removalVSAvoidprocess cost and runnability

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent employs enzymes as biodegradable, specific reagents that can be added in controlled amounts and decompose after use, replacing expensive and problematic alkaline chemicals. The enzymatic system provides cost-effective deinking without the runnability issues associated with alkaline chemistry.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces enzymes as intermediary substances that mediate between the pulp and ink, providing selective binding and removal of ink components. This intermediary approach enables ink removal without the need for harsh alkaline chemicals that cause runnability problems.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If conventional alkaline deinking is used, then ink particles are removed, but irreversible fiber changes occur

Engineering Contradiction:

Improveink particle removalVSAvoidfiber composition stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the fundamental chemical environment from alkaline to neutral pH, preventing irreversible fiber changes. The neutral pH regime maintains fiber composition stability while still enabling effective ink removal through enzymatic specificity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes alkaline chemical action with enzymatic action, where enzymes specifically target ink molecules through biochemical recognition and catalysis. This selective mechanism removes ink particles without causing the non-specific chemical changes that occur with alkaline treatment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves efficient ink removal with reduced fiber damage, maintaining pulp brightness and minimizing the use of costly and environmentally harmful chemicals, thereby improving the economic and environmental sustainability of the deinking process.

Implementation Method 1

treating the pulp slurry with an ink removing system, which system comprises: (i) a combination of lipase and at least one second enzyme chosen from amylase, xylanase or cellulase

Methodology Applied

Scientific EffectEnzyme: Enzyme

Implementation Method 2

a non-ionic surfactant, in amounts effective to release ink from said pulp slurry

Methodology Applied

Scientific EffectSurfactant: Surfactant

Implementation Method 3

separating the released ink from the pulp slurry in a deinking step (e.g., a deinking flotation stage)

Methodology Applied

Scientific EffectFlotation: Froth Floatation

Data Source

PatentUS9587350B2Method for removing ink from paper

Publication Date: 2017.03.07 KEMIRA OY

AI summary

A method for removing ink from printed paper comprising: (a) pulping printed paper at least 25 wt % of which is old newsprint at a consistency of at least about 3% to obtain a pulp slurry; (b) treating the pulp slurry with an ink removing system, which system comprises: (i) a combination of lipase and at least one second enzyme chosen from amylase, xylanase or cellulase, and (ii) a non-ionic surfactant, in amounts effective to release ink from said pulp slurry, wherein the lipase is present in an amount of at least about 0.001 wt % based on the dry content of the pulp slurry and the ratio of the at least one second enzyme:lipase is at least about 1.2:1; and (c) separating the released ink from the pulp slurry, wherein the treating step is carried out prior to a deinking flotation stage.