Enzymatic Straw Delignification for High-Strength Cellulose Fibres
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Solution Overview
Problem
Current pulping processes, such as mechanical and chemical pulping, generate significant waste and fail to effectively utilize by-products like lignin and hemicellulose, resulting in lower quality products and environmental concerns.
Innovation Solution
A method involving dry mechanical treatment, sieving, and mild enzymatic delignification of straw to produce a cellulose-rich fibre fraction while separating and preserving lignin, hemicellulose, and oligosaccharide-rich by-products, which can be further processed for commercial use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical pulping is used, then pulp yield and cost are improved, but fibre strength and product quality deteriorate due to high lignin content
Solution Approach 1:
The invention extracts and removes lignin from the straw material through enzymatic delignification, separating it from the cellulose fibers. This allows the cellulose-rich fiber fraction to be obtained with improved strength properties while the lignin is recovered as a valuable by-product, resolving the contradiction between maintaining high pulp yield and improving fiber strength.
2Strength
If chemical pulping (Kraft process) is used, then fibre strength is improved through lignin removal, but waste generation and environmental harm increase
Solution Approach 1:
The invention changes the parameters of the delignification process by using mild enzymatic treatment instead of harsh chemical conditions. The process operates at lower temperatures (50-70°C), neutral to slightly alkaline pH (7-9), and uses enzymes rather than strong chemicals, thereby achieving effective lignin removal for improved fiber strength while minimizing waste generation and environmental harm.
Solution Approach 2:
Instead of discarding lignin as waste in conventional chemical pulping, the invention recovers it as a valuable by-product. The delignified liquid fraction containing lignin, hemicellulose, and oligosaccharides is separated and can be utilized for energy production, chemical synthesis, or other industrial applications, thus reducing waste generation while maintaining fiber strength improvement.
3Strength
If chemical pulping (sulfite process) is used, then delignification is achieved, but pollution and chemical recovery limitations occur
Solution Approach 1:
The invention replaces the mechanical/chemical pulping system with a biological system using enzymes. Instead of using sulfurous acid and sulfite/bisulfite salts that cause pollution and chemical recovery issues, the process employs cellulases, hemicellulases, and lignin peroxidases to achieve delignification under mild conditions, eliminating pollution problems while maintaining effective lignin removal.
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 reduces waste generation, retains fibre strength, and allows for the isolation of valuable by-products, enhancing the pulping process's environmental and commercial viability.
Implementation Method 1
a mild enzymatic delignification to obtain a cellulose rich fibre fraction
Implementation Method 2
The combination of sulfurous acid and sulfite/bisulfite salts degrade and dissolves the lignin in the wood known as delignification
Implementation Method 3
Mechanical pulping results in little removal of the lignin content in the organic material
Implementation Method 4
The process ultilize strong alkaline conditions with pH in the range 12-14, high cooking temperatures around 170°C, long reaction times and pressurized vessels in the delignification of the wood
Implementation Method 5
The combination of sulfurous acid and sulfite/bisulfite salts degrade and dissolves the lignin in the wood known as delignification. This process rely mainly on acidic cleavage of ether bonds present in lignin
Implementation Method 6
The process ultilize strong alkaline conditions with pH in the range 12-14, high cooking temperatures around 170°C, long reaction times and pressurized vessels in the delignification of the wood. These harsh reaction conditions results in cleavage of the ether bonds by nucleophilic sulfide and bisulfides present in the mixture
Data Source
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AI summary
The present invention relates to a method for preparing a cellulose rich fibre fraction, said method comprising the steps of: (i) providing straw, (ii) subjecting the straw to a dry mechanical treatment, (iii) subjecting the material obtained in (ii) to a sieving treatment and obtaining at least two fractions, the first fraction passing through the sieve mesh and the second fraction being retained by the sieve mesh, (iv) suspending the second fraction in an aqueous solution comprising one or more enzymes, adjusting pH of the mixture in the range of 4-6.5 and adjusting temperature of the mixture in the range of 30-70°C, (v) subjecting the mixture obtained in step (iv) to a continuous or intermittent mechanical defibration under agitation, (vi) separating the material obtained in step (v) into a cellulose rich fibre fraction and a liquid fraction comprising suspended and/or dissolved lignin, hemicellulose and oligosaccharides, (vii) subjecting the liquid fraction obtained in (vi) to lignin precipitation and obtaining a precipitated lignin rich fraction and a hemicellulose and oligosaccharide rich fraction, and (viii) separating the precipitated lignin rich fraction obtained in step (vii) from the hemicellulose and oligosaccharide rich fraction.