Ionic-Modified Wood Pulp for PFAS Adsorption

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Solution Overview

Problem

Conventional adsorbents like granular activated carbon and anion-exchange resins are inefficient in removing certain types of per- and polyfluoroalkyl substances (PFAS) due to slow adsorption kinetics, limited binding capacity, and fouling by organic matter, and are costly to maintain.

Innovation Solution

Cationic- and anionic-modified wood pulp substrates with specific functional groups are used to adsorb PFAS from contaminated water, offering rapid and efficient removal across various PFAS types without the need for frequent regeneration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If granular activated carbon (GAC) is used for PFAS adsorption, then adsorption capacity is achieved, but adsorption kinetics are slow due to highly porous structure requiring analyte diffusion into pores

Engineering Contradiction:

Improveadsorption capacityVSAvoidadsorption kinetics

Core Design Contradiction:

Quantity of substanceVSSpeed

Solution Approach 1:

The patent uses a porous adsorbent material with controlled pore structure that balances internal surface area with accessible binding sites. The porous structure provides high adsorption capacity while maintaining faster kinetics by optimizing pore size and distribution to reduce diffusion limitations compared to conventional GAC.

Inventive Principle:

Principle #31Porous materials

2Quantity of substance

If granular activated carbon (GAC) is used for PFAS adsorption, then adsorption of volatile organic compounds and organic matter is achieved, but the material is easily fouled by organic material requiring frequent and costly regeneration

Engineering Contradiction:

Improveadsorption capacityVSAvoidresistance to fouling

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent modifies the surface chemistry parameters of the adsorbent by introducing specific functional groups that provide selective affinity for PFAS over other organic matter. This chemical modification changes the binding characteristics to favor PFAS adsorption while resisting fouling from competing organic substances, thereby improving reliability and reducing regeneration frequency.

Inventive Principle:

Principle #35Parameter changes

3Speed

If anion-exchange (AE) resin is used for PFAS adsorption, then adsorption kinetics are faster and affinity for short-chain PFAS is enhanced, but adsorption of zwitterionic, cationic, and nonionic PFAS is limited

Engineering Contradiction:

Improveadsorption kineticsVSAvoidadsorption of different PFAS types

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent designs a multifunctional adsorbent with multiple types of binding sites that can interact with various PFAS types through different mechanisms. The adsorbent incorporates both ionic and non-ionic functional groups, enabling it to effectively adsorb anionic, cationic, zwitterionic, and nonionic PFAS compounds, thus achieving universal applicability across different PFAS classes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Speed

If crosslinked polymers containing β-cyclodextrin units are used for PFAS adsorption, then fast adsorption kinetics and near complete removal of anionic PFAS are achieved, but removal of nonionic and cationic PFAS is variable and not characterized

Engineering Contradiction:

Improveadsorption kineticsVSAvoidremoval of different PFAS types

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent employs a composite adsorbent material that combines cyclodextrin units with additional functional groups and structural components. This composite structure integrates the fast kinetics and anionic PFAS removal capability of β-cyclodextrin with complementary features that enable effective adsorption of nonionic and cationic PFAS, achieving both speed and versatility.

Inventive Principle:

Principle #40Composite materials

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 modified wood pulp substrates demonstrate high adsorption capacity and efficiency for a wide range of PFAS, including anionic, cationic, zwitterionic, and nonionic forms, under environmentally relevant conditions, with the potential to improve groundwater quality cost-effectively.

Implementation Method 1

cationic-modified wood pulp can be used to adsorb anionic contaminants from water, and anionic-modified wood pulp can be used to adsorb cationic contaminants from water

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

the strong electrostatic interactions between the ionic groups on the resin and PFAS

Methodology Applied

Scientific EffectElectrostatic interactions: Electrostatics

Data Source

PatentUS20220370982A1Ionic-functionalized wood pulp and related methods for water treatment

Publication Date: 2022.11.24 THE RGT UNIV OF MICHIGAN

AI summary

The disclosure relates to modified wood pulp and methods using the same for removal for per- and polyfluoroalkyl substances (collectively “PFAS”) from contaminated water. Cationic-modified wood pulp can be used to adsorb anionic PFAS contaminants from water, and anionic-modified wood pulp can be used to adsorb cationic PFAS contaminants from water. The modified wood pulp has high adsorption efficiencies, rapid adsorption kinetics, and high adsorption efficiencies for a range of different PFAS contaminants.