Visible-Light Self-Cleaning Nanofiltration Membrane for Water Decontamination

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Solution Overview

Problem

Existing nanofiltration membranes suffer from fouling by organic pollutants, which is challenging to remove and requires high energy and solvent treatments, and photocatalytic nanomaterials like TiO2 need UV irradiation, limiting their real-life application.

Innovation Solution

A nanofiltration membrane with a polysulfone/polyethylene terephthalate support and an active layer containing a diacyl chloride compound, tetra-amine compound, and a nanocomposite of graphitic carbon nitride and polypyrrole, which is activated by visible light for self-cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If photocatalytic nanomaterials like TiO2 are used in the membrane, then self-cleaning capability is improved, but UV irradiation is required which limits real-life application

Engineering Contradiction:

Improveself-cleaning capabilityVSAvoidlight source compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the optical activation parameter from UV to visible light by replacing TiO2 with graphitic carbon nitride (g-C3N4) photocatalyst. This parameter change enables the membrane to be activated by visible light (400-700 nm) which is abundant in sunlight and everyday lighting, thus improving adaptability while maintaining self-cleaning capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite photocatalyst system comprising graphitic carbon nitride (g-C3N4) combined with polypyrrole (PPy). This composite material synergistically enhances both the self-cleaning capability and visible light absorption efficiency, resolving the contradiction between maintaining high photocatalytic activity and enabling visible light activation

Inventive Principle:

Principle #40Composite materials

2Reliability

If nanofiltration membranes are used to remove organic pollutants, then decontamination performance is improved, but fouling by organic pollutants occurs which is challenging to remove

Engineering Contradiction:

Improvedecontamination performanceVSAvoidorganic fouling

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements self-service by incorporating photocatalytic self-cleaning functionality directly into the membrane structure. The g-C3N4/PPy composite photocatalyst embedded in the active layer automatically degrades organic foulants on the membrane surface when exposed to visible light, enabling the membrane to clean itself without external intervention

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent converts the harmful effect of organic pollutant adsorption (fouling) into a beneficial self-cleaning process. By incorporating photocatalytic materials, the accumulated organic foulants on the membrane surface become the substrate for photocatalytic degradation, transforming the fouling problem into an automated cleaning mechanism that restores membrane performance

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 membrane achieves self-cleaning under visible light, effectively removing organic fouling and maintaining high permeate flux and salt rejection, without the need for UV activation.

Implementation Method 1

Incorporating various inorganic photocatalytic nanomaterials, such as TiO2, ZnO, and ZnS, in the membrane is an option for mitigating the fouling of the membrane through photocatalytic self-cleaning under light irradiation

Methodology Applied

Scientific EffectPhotocatalysis: Catalysis

Implementation Method 2

the nanocomposite including graphitic carbon nitride and polypyrrole, which is activated by visible light for self-cleaning

Methodology Applied

Scientific EffectVisible light absorption: Absorption (EM radiation)

Implementation Method 3

nanofiltration membranes (NFMs) have potential for advanced industrial saline wastewater treatment

Methodology Applied

Scientific EffectNanofiltration: Semipermeable Membrane

Implementation Method 4

The foulants adsorb on the membrane surface through various interactions such as electrostatic interactions, hydrophobic interaction and hydrogen bonding

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS12465895B2Porous water decontamination membrane

Publication Date: 2025.11.11 KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS

AI summary

A membrane including a polysulfone/polyethylene terephthalate (PSf/PET) support and an active layer on an outer surface of the PSf/PET support. The active layer comprises reacted units of a diacyl chloride compound, a tetra-amine compound, and a nanocomposite including graphitic carbon nitride and polypyrrole. The membrane of the present disclosure is self-cleaning following exposure to radiation and finds application in water decontamination and de-salination.