Haloperoxidase Treatment for Hexenuronic Acid Reduction in Cellulosic Pulp
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for chemical pulping, such as hot acid and hot chlorine dioxide bleaching, fail to effectively reduce hexenuronic acids (HexA) in cellulosic pulps, leading to increased chemical consumption, brightness reversion, and fibre strength reduction, while also increasing costs and retention time in bleaching lines.
Innovation Solution
A method involving the use of haloperoxidase, hydrogen peroxide, and halide ions (chloride, bromide, iodide, or thiocyanate) to reduce HexA content in cellulosic pulps, optionally with tertiary amines, which improves pulp brightness without significantly decreasing HexA levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If hot acid or hot chlorine dioxide bleaching is used to reduce hexenuronic acids, then brightness improvement is achieved, but fibre strength is reduced and chemical consumption increases
Solution Approach 1:
The patent introduces an intermediary substance (metal complex or organic compound) that mediates the reaction between chlorine dioxide and hexenuronic acids. This intermediary forms a catalytic system that selectively removes HexAs through formation of a chloramine intermediate, thereby achieving brightness improvement without the harsh effects of direct hot acid or hot chlorine dioxide treatment on fibre strength
Solution Approach 2:
The patent changes the chemical parameters of the bleaching process by introducing metal complexes (Fe, Cu, Mn) or organic compounds that modify the reactivity of chlorine dioxide. This creates a controlled chemical environment where HexAs are removed under milder conditions, preserving fibre strength while achieving the desired brightness improvement
2Illumination intensity
If hot acid or hot chlorine dioxide bleaching is used to reduce hexenuronic acids, then brightness improvement is achieved, but chemical consumption increases and retention time increases
Solution Approach 1:
The patent employs a catalytic system where the metal complex or organic compound facilitates the decomposition of chlorine dioxide and its reaction with hexenuronic acids. The catalyst is regenerated in the process, enabling it to continue facilitating the reaction without being consumed, thereby reducing overall chemical consumption and process retention time while maintaining brightness improvement
Solution Approach 2:
The patent modifies the chemical kinetics parameters by introducing catalytic agents that lower the activation energy for the reaction between chlorine dioxide and hexenuronic acids. This accelerates the removal process, reducing the time required and the amount of chemicals needed compared to conventional hot acid or hot chlorine dioxide treatment
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
This approach effectively reduces HexA content, enhances pulp brightness, and maintains fibre strength, thereby reducing chemical usage and bleaching line retention times, leading to more stable and efficient pulp processing.
Implementation Method 1
contacting the cellulosic pulp with an aqueous composition comprising 1) haloperoxidase, 2) hydrogen peroxide, and 3) halide ions/ions selected from the group consisting of chloride, bromide, iodide, and thiocyanate ions
Implementation Method 2
haloperoxidase, hydrogen peroxide, and halide ions to reduce HexA content in cellulosic pulps
Data Source
AI summary
The present invention provides an enzymatic method for reducing the content of hexenuronic acids in a chemical cellulosic pulp and/or improvement of the brightness of cellulosic pulp using haloperoxidase.