Cationic Lignin Copolymer Flocculant for Wastewater
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Solution Overview
Problem
Technical lignins lack the high molecular weight and high cationic charge density required for effective wastewater treatment, and existing modification techniques using organic solvents are impractical due to toxicity and cost.
Innovation Solution
A method for preparing a cationic lignin copolymer by copolymerizing kraft lignin with a cationic amine compound, such as [2-(Methacryloyloxy)ethyl]trimethylammonium chloride, under acidic free radical generating conditions in an aqueous suspension, resulting in a water-soluble polymer with enhanced molecular weight and charge density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If technical lignin is used directly for wastewater treatment, then it is available as a natural polymer, but it lacks the high molecular weight and high cationic charge density required for effective treatment
Solution Approach 1:
The patent changes the molecular weight and charge density parameters of lignin through copolymerization with cationic monomers, transforming it from a natural polymer with insufficient properties to a modified polymer with high molecular weight and high cationic charge density suitable for wastewater treatment
Solution Approach 2:
The patent creates a composite material by copolymerizing lignin with cationic amine compounds, combining the natural polymer structure of lignin with the cationic functional groups of synthetic monomers to achieve both high molecular weight and high charge density
2Reliability
If existing modification techniques using organic solvents are employed, then cationic charge density can be increased, but toxicity and production cost increase
Solution Approach 1:
The patent changes the reaction medium parameter from organic solvents to aqueous suspension, eliminating toxicity while maintaining the ability to achieve high cationic charge density through copolymerization with cationic monomers
Solution Approach 2:
The patent replaces expensive and toxic organic solvents with water, a cheap and non-toxic alternative, as the reaction medium for copolymerization, significantly reducing production costs and environmental harm
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 resulting cationic lignin copolymer demonstrates high solubility, thermal stability, and efficiency as a flocculant in various wastewater applications, including municipal and industrial systems, with improved dewatering capabilities and reduced production costs.
Implementation Method 1
under acidic free radical generating conditions to polymerize the lignin and at least one monomer compound
Implementation Method 2
to polymerize the lignin and at least one monomer compound in aqueous suspension and to produce the cationic lignin copolymer
Implementation Method 3
The resulting cationic lignin copolymer demonstrates high solubility, thermal stability, and efficiency as a flocculant in various wastewater applications
Data Source
AI summary
A water-based process was developed for the synthesis of aminated lignin copolymers with high MW, thermal stability and solubility in water over a wide range of p H values. The cationic lignin copolymer described herein comprises: a grafting ratio of (weight of cationic amine compound)/(weight of lignin) of 70 to 200% and a charge density of +1.4-3.0 meq/g. This cationic lignin copolymer can be used as a flocculant in numerous wastewater streams including municipal and industrial systems and sludge dewatering in the pulp & paper, mining and oil industries.