Colloidal Lignin Dispersion via Solvent Precipitation

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Solution Overview

Problem

Current methods for producing colloidal lignin particles face challenges such as inhomogeneity, poor dispersibility, high energy consumption, and pH instability, limiting their application in high-end uses like anti-bacterials and controlled drug delivery.

Innovation Solution

A method involving the precipitation of lignin with water to form stable aqueous dispersions using a solvent mixture with a co-solvent like ethanol, allowing for high lignin concentration without aggregation, and utilizing a continuous flow reactor for uniform particle formation, with solvent recovery and minimal energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pH precipitation method is used to form colloidal lignin particles, then lignin colloids can be produced, but the formed lignin colloids exhibit pH instability

Engineering Contradiction:
Improvecolloidal lignin particle formationVSAvoidpH stability
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The invention changes the fundamental parameter of colloid formation from pH-based precipitation to solvent-based precipitation. By using organic solvents (acetone, ethanol, isopropanol) instead of pH adjustment, the method achieves colloid formation that is stable across a broad pH range (2-12), eliminating the pH instability inherent in traditional methods

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces organic solvents as intermediary substances to mediate the precipitation process. These solvents act as intermediaries between lignin and water, enabling controlled colloid formation through solvent-water interaction rather than direct pH-induced precipitation, thereby achieving stability without chemical cross-linking

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If cross-linking is applied to improve pH stability, then pH stability improves, but the requirement of a cross-linking step limits the applications

Engineering Contradiction:
ImprovepH stabilityVSAvoidapplication range
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The invention extracts the cross-linking step from the colloid formation process entirely. By using solvent-based precipitation instead of pH precipitation, the method achieves stable colloids without requiring cross-linking, thereby maintaining full applicability across diverse uses including food, pharmaceutical, and cosmetic applications where cross-linked materials may be restricted

Inventive Principle:
Principle #2Taking out (Extraction)

3Quantity of substance

If conventional methods are used to produce colloidal lignin, then lignin colloids can be formed, but significant energy is consumed and large-scale production is not feasible

Engineering Contradiction:
Improvecolloidal lignin particle formationVSAvoidenergy consumption
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The invention employs a self-service mechanism where lignin automatically forms colloidal particles through simple mixing with solvent and water, without requiring energy-intensive steps such as high-shear mixing, ultrasonic treatment, or controlled atmosphere processing. The colloidal structure forms spontaneously during the precipitation process

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention enables continuous production by using a straightforward three-component mixing process (lignin + solvent + water) that can be easily scaled from laboratory to industrial production. The method avoids batch processing limitations and allows for continuous flow production, making large-scale manufacturing economically viable

Inventive Principle:
Principle #20Continuity of useful action

4Ease of manufacture

If bulk lignin is used directly, then low cost is achieved, but inhomogeneity and poor dispersibility limit high-end applications

Engineering Contradiction:
ImprovecostVSAvoidhomogeneity and dispersibility
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The invention segments bulk lignin into colloidal particles with controlled sizes (typically 10-1000 nm). This segmentation is achieved through solvent-based precipitation that breaks down bulk lignin into uniform colloidal units, providing both the homogeneity required for high-end applications and the dispersibility needed for stable formulations

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the physical state and size parameters of lignin from bulk solid to colloidal dispersion. By controlling the precipitation conditions (solvent type, concentration, mixing rate), the method produces colloids with specific size distributions and surface properties that enable excellent dispersibility in various media while maintaining the low cost advantage of using bulk lignin as starting material

Inventive Principle:
Principle #35Parameter changes

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 method produces stable, uniformly sized colloidal lignin particles with minimal energy and cost, enabling their use in various applications without the need for chemical functionalization or cross-linking, and allows for efficient solvent recovery and particle redispersion.

Implementation Method 1

colloidal lignin particles are formed by precipitating lignin with water from its solvent mixture by adding an amount of water

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Implementation Method 2

the addition of a concentrated organic solvent solution of lignin into water will result in the fusing of the forming colloidal lignin particles into aggregates. When a fraction of the THF solvent is replaced with a co-solvent, such as but not limited to ethanol, the concentration of lignin can be raised considerably without the aggregation of the forming colloidal particles

Methodology Applied
Scientific EffectCo-solvent effect: Solvation

Implementation Method 3

the excess water in the colloidal lignin particle dispersions can be removed by ultrafiltration

Methodology Applied
Scientific EffectUltrafiltration: Semipermeable Membrane

Implementation Method 4

the concentrated colloidal lignin particles can be dried with spray drying to yield water-free lignin particles

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3700664B1Methods of preparing aqueous lignin dispersions
Publication Date: 2023.09.13 AALTO UNIV FOUND
  • EP3700664B1 patent drawingFigure 1~2
  • EP3700664B1 patent drawingFigure 3~4
  • EP3700664B1 patent drawingFigure 5~6

AI summary

Method of forming colloidal lignin particles, comprising the step of dissolving lignin in a mixture of organic solvents, feeding of the said solution into water, and forming a colloidal dispersion of lignin. The used solvents are recovered with methods such as distillation and reused in the process. Water is removed from the colloidal dispersion by ultrafiltration and reused in the process. The concentrated colloidal dispersion is dried by spray drying. The invention can be used in applications where the colloidal nature of lignin will afford an advantage over bulk lignin.