Zwitterionic Polymer-Coated Filters for Oil-Water Separation

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Solution Overview

Problem

Current oil-water separation technologies face challenges with hydrophobic-oleophilic surfaces fouling easily and having inferior mechanical stability, leading to reduced separation efficiency and high operating costs.

Innovation Solution

The use of zwitterionic polymers, such as poly(sulfobetaine methacrylate), grafted or coated on porous filter media, including glass fibers, which exhibit superhydrophilic properties in air and superoleophobic properties underwater, preventing oil adhesion and allowing for efficient oil-water separation with easy recycling and low costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If hydrophobic-oleophilic surfaces are used for oil removal, then oil separation efficiency is improved, but the surfaces foul easily and become blocked by oils

Engineering Contradiction:

Improveoil separation efficiencyVSAvoidresistance to fouling

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent inverts the conventional approach by using hydrophilic-oleophobic surfaces instead of hydrophobic-oleophilic surfaces. The hydrophilic surface preferentially allows water to pass through while repelling oil, achieving oil-water separation without the fouling problems associated with oil-attracting surfaces. This inversion of the wettability properties resolves the contradiction between separation efficiency and fouling resistance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the wettability parameters of the filter surface by incorporating hydrophilic materials and controlling surface energy characteristics. By adjusting the surface chemistry to be hydrophilic-oleophobic rather than hydrophobic-oleophilic, the system achieves effective oil separation while maintaining resistance to oil adhesion and fouling throughout operation.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional filter materials are used, then production cost is reduced, but mechanical stability and flexibility are inferior

Engineering Contradiction:

Improveproduction costVSAvoidmechanical stability

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent employs composite material structures combining different filter media components with hydrophilic-oleophobic properties. By integrating materials with complementary characteristics, the system achieves both mechanical stability and the required wettability properties for effective oil-water separation, overcoming the limitations of conventional single-material filters.

Inventive Principle:

Principle #40Composite materials

3Reliability

If superoleophobic surfaces are created using hierarchical surface structures, then oil repellency is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveoil repellencyVSAvoidsurface structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves oil repellency by changing the chemical composition and surface energy parameters of the filter material rather than creating complex hierarchical surface structures. By selecting inherently hydrophilic-oleophobic materials and controlling their surface chemistry, the system attains effective oil separation with simpler, more manufacturable structures.

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

The zwitterionic polymer-coated filters demonstrate enhanced oil-water separation efficiency, resistance to organic contaminants, and ease of reuse, with improved mechanical stability and reduced fouling, achieving effective separation and recycling while minimizing operational costs.

Implementation Method 1

zwitterionic polymers, such as poly(sulfobetaine methacrylate), grafted or coated on porous filter media, including glass fibers, which exhibit superhydrophilic properties in air and superoleophobic properties underwater

Methodology Applied

Scientific EffectSuperhydrophilicity: Superhydrophilicity

Implementation Method 2

Methodology Applied

Scientific EffectSuperoleophobicity: Superhydrophilicity

Data Source

PatentUS9919250B2Filters for oil-water separation having zwitterionic polymers coated or grafted thereon

Publication Date: 2018.03.20 THE UNIVERSITY OF AKRON

AI summary

A filter for the separation of oil and water from oil-water mixtures comprising a porous filter media, wherein the porous filter media has a zwitterionic polymer grafted or coated thereon. The zwitterionic polymers can be formed from zwitterionic monomers, the zwitterionic polymers having positive and negative charges in series on the same side chain; zwitterionic polymers formed from a mixture of cationic and anionic monomers, the zwitterionic polymers having positive and negative charges on two different side chains; and zwitterionic polymers formed from monomers with cationic-anionic pairs, the zwitterionic polymers having positive and negative charges in parallel on the same side chain.