Magnesium Ion Stabilization of Cellulose During Ozone Pulp Bleaching
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Solution Overview
Problem
The bleaching of chemical paper pulps using ozone leads to significant depolymerization of cellulose during the ozone processing and subsequent alkaline extraction, which is not effectively addressed by existing methods, resulting in pulp quality issues.
Innovation Solution
Incorporating magnesium ions (Mg2+) during the alkaline extraction phase following ozone processing, either before, during, or after the alkaline extraction, to minimize cellulose depolymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ozone processing followed by alkaline extraction is used for bleaching chemical paper pulps, then delignification efficiency and brightness are improved, but cellulose depolymerization increases significantly
Solution Approach 1:
Magnesium ions are introduced as an intermediary substance during the alkaline extraction phase. These ions mediate between the alkaline environment and cellulose molecules, preventing direct harmful interactions that cause depolymerization while allowing the extraction of oxidized lignin products to proceed effectively.
Solution Approach 2:
The chemical environment parameters during alkaline extraction are modified by adding magnesium ions. This changes the ionic composition and pH buffering characteristics of the extraction medium, creating conditions that are less detrimental to cellulose stability while maintaining effective delignification capability.
2Reliability
If conventional bleaching sequences with chlorinated oxidants are used, then delignification is achieved, but organochlorine compounds are formed contaminating the pulp
Solution Approach 1:
The bleaching approach is shifted from chlorinated oxidants to ozone, representing a fundamental change in the chemical parameters of the oxidation process. Ozone provides effective delignification through different reaction mechanisms that do not produce organochlorine contamination.
Solution Approach 2:
The patent addresses the harmful byproducts of conventional bleaching by replacing the oxidant system entirely. Ozone decomposition produces only oxygen as a byproduct, converting a potentially harmful chemical process into an environmentally benign one while maintaining delignification effectiveness.
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 presence of magnesium ions during alkaline extraction significantly reduces cellulose depolymerization, maintaining pulp quality and enhancing the polymerization degree of cellulose, while maintaining delignification and brightness performance.
Implementation Method 1
This treatment is based on the oxidization of the phenolic cycles in the lignin which, after being converted into —COOH hydrophilic groups, can be eliminated by washing in a solution
Implementation Method 2
it has been shown that during a chemical paper pulp process including ozone processing followed by alkaline extraction, it was possible to reduce the depolymerization of the cellulose substantially if the alkaline extraction takes place in the presence of magnesium (Mg2+) cations
Data Source
AI summary
This invention relates to a method for treating chemical paper pulp comprising a step of treating the pulp with ozone followed by a step of alkaline extraction, in which alkaline extraction takes place in the presence of magnesium ions (Mg2+).