Copper Nanoparticle Paper for Water Purification

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Solution Overview

Problem

There is a need for affordable and effective point-of-use water purification systems that can eliminate disease-causing organisms, such as bacteria, viruses, and protozoan parasites, from inadequately treated water, particularly in rural communities where access to clean water is limited.

Innovation Solution

A method of embedding copper nanoparticles in cellulosic papers, prepared by contacting absorbent cellulose papers with an alkaline copper hydroxide solution and reducing the copper ions with ascorbic acid, creating a paper-based water purification system that releases antimicrobial copper ions when water passes through it.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper nanoparticles are embedded in cellulosic paper for water purification, then antimicrobial activity is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveantimicrobial activityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The copper ions embedded in the paper perform self-service by automatically releasing antimicrobial copper ions when water passes through the filter, eliminating the need for external power sources, control systems, or complex operational mechanisms. The paper itself serves as both the filter medium and the antimicrobial delivery system.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the physical-chemical parameters of the paper by embedding copper ions and reducing them to copper nanoparticles, which fundamentally alters the paper's properties from a simple filter to an active antimicrobial purification system. This parameter change enables long-lasting antimicrobial activity without complex manufacturing.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If copper ions are released for antimicrobial activity, then pathogen elimination is improved, but copper concentration in effluent may exceed safety limits

Engineering Contradiction:

Improvepathogen eliminationVSAvoidcopper concentration in effluent

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the release parameters of copper ions by controlling the reduction of copper ions to copper nanoparticles and embedding them in the paper matrix. This controlled release mechanism ensures that sufficient copper ions are released to kill pathogens while maintaining effluent copper concentrations below safety limits (1.3 ppm), thus resolving the contradiction between pathogen elimination and safety.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional filtration is used, then water flow is maintained, but pathogen removal is insufficient

Engineering Contradiction:

Improvewater flowVSAvoidpathogen removal

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention merges two functions into a single paper filter: physical filtration (maintaining water flow) and chemical antimicrobial action (pathogen removal). The copper-containing paper simultaneously acts as the filter medium and the antimicrobial agent, allowing water to flow through while copper ions are released to eliminate pathogens, thus resolving the contradiction between flow and pathogen removal.

Inventive Principle:

Principle #5Merging (Combining)

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 copper nanoparticle paper effectively reduces bacterial counts by 8.8 log for E. coli, maintaining safe copper concentrations in the effluent water, making it a cost-effective and long-lasting solution for water purification, suitable for use in resource-limited settings.

Implementation Method 1

copper ions embedded in the paper are reduced by contacting the paper with an ascorbic acid solution

Methodology Applied

Scientific EffectChemical reduction: Reduction

Implementation Method 2

These papers are useful as antimicrobials based, in one aspect, on their ability to release copper, which has antimicrobial activity

Methodology Applied

Scientific EffectIon release: Solvation

Data Source

PatentUS9611153B2Compositions and methods for preparing copper-containing paper and uses thereof

Publication Date: 2017.04.04 UNIV OF VIRGINIA PATENT FOUND

AI summary

The invention comprises an environmentally benign method for the direct in situ preparation of copper nanoparticles (CuNPs) in paper by reducing sorbed copper ions with ascorbic acid. Copper nanoparticles were quickly formed in less than 10 minutes and were well distributed on the paper fiber surfaces. Paper sheets were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic absorption spectroscopy. Antibacterial activity of the CuNP sheets was assessed for by passing Escherichia coli bacteria suspensions through the papers. The effluent was analyzed for viable bacteria and copper release. The CuNP papers with higher copper content showed a high bacteria reduction of log 8.8 for E. coli. The paper sheets containing copper nanoparticles were effective in inactivating the test bacteria as they passed through the paper. The copper levels released in the effluent water were below the recommended limit for copper in drinking water (1 ppm).