Substrates with metal nanoparticles, related articles, and a continuous process for making same
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Solution Overview
Problem
Existing methods for incorporating metal nanoparticles into cellulosic substrates, such as paper, are primarily batch processes that are complex, time-consuming, and not scalable for industrial production, leading to uneven nanoparticle distribution and adherence issues, which are costly and inefficient for large-scale applications like water filtration.
Innovation Solution
A continuous process where an aqueous solution of metal nanoparticle precursors, including a metal salt and a reducing agent, is applied to cellulosic fibers during manufacturing, allowing in situ synthesis of metal nanoparticles within the substrate, enabling uniform distribution and strong adhesion without altering the paper's surface chemistry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batch methods are used to treat paper with metal nanoparticles, then nanoparticle adhesion to cellulosic fibers is improved, but production time and complexity increase significantly
Solution Approach 1:
The patent implements a continuous paper machine process where metal nanoparticle precursors are applied to the paper web in aqueous solution and continuously dried to form nanoparticles during the manufacturing process, eliminating the need for separate batch treatment steps, oven heating, washing, and drying cycles that characterize traditional methods
Solution Approach 2:
The patent applies metal salt and reducing agent solutions to the paper web before the drying step, allowing nanoparticle synthesis to occur during the drying phase itself rather than requiring subsequent separate treatment steps
2Reliability
If surface oxidation is used to increase metal uptake, then nanoparticle adhesion is improved, but paper properties deteriorate due to altered pore structure and hydrogen bonding
Solution Approach 1:
The patent utilizes the paper drying step itself to provide the thermal energy needed for nanoparticle synthesis, eliminating the need for separate surface oxidation or chemical treatment steps that would alter paper properties
Solution Approach 2:
The patent changes the physical state of the metal precursor from solid to aqueous solution form, allowing uniform distribution throughout the paper matrix during the drying process without requiring surface modification
3Productivity
If pre-formed nanoparticles are applied to paper, then production speed is improved, but nanoparticle distribution uniformity deteriorates due to aggregation
Solution Approach 1:
The patent applies metal salt and reducing agent solutions to the paper web before the drying step, allowing nanoparticle synthesis to occur during the drying phase itself rather than requiring subsequent separate treatment steps
Solution Approach 2:
The patent changes the physical state of the metal precursor from solid to aqueous solution form, allowing uniform distribution throughout the paper matrix during the drying process without requiring surface modification
4Manufacturing precision
If batch treatment methods are used, then thorough coating of thick paper is improved, but production cost and complexity increase
Solution Approach 1:
The patent implements a continuous paper machine process where metal nanoparticle precursors are applied to the paper web in aqueous solution and continuously dried to form nanoparticles during the manufacturing process, eliminating the need for separate batch treatment steps, oven heating, washing, and drying cycles that characterize traditional methods
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
This method enables the rapid and efficient production of large quantities of nanoparticle-embedded cellulosic substrates with consistent nanoparticle distribution and strong adhesion, enhancing their antibacterial properties and reducing production costs, suitable for industrial-scale water filtration and other applications.
Implementation Method 1
an aqueous solution of nanoparticle precursors is applied to an assembly of cellulosic fibers. The nanoparticle precursors include a metal salt and a reducing agent... drying gives rise to metal nanoparticles in the substrate
Implementation Method 2
drying the assembly of cellulosic fibers with thermal energy in a continuous operation to form the substrate, thereby drying gives rise to metal nanoparticles in the substrate
Data Source
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AI summary
An embodiment of the present disclosure is a method for forming a substrate. The method includes applying an aqueous solution of nanoparticle precursors to an assembly of fibers, wherein the nanoparticle precursors include a metal salt and a reducing agent. The method also includes drying the assembly of fibers with thermal energy in a continuous operation to form the substrate, thereby drying gives rise to metal nanoparticles in the substrate. The metal nanoparticles have a size that ranges from 1 to about 200 nanometers in at least one dimension.