Nano Silver Particle Size Control via Periodic Heating
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Solution Overview
Problem
Conventional methods for producing nano silver particles with controlled sizes larger than 30 nm are inadequate, as they either fail to achieve the desired size range or result in bio-toxic effects due to particle size limitations, particularly with mechanical grinding and chemical reduction methods producing particles smaller than 30 nm.
Innovation Solution
A method involving the mixing of polyvinyl pyrrolidone (PVP) and silver nitrate in a solvent, with heating and the addition of an accelerating agent, such as glucose or hydrogen, to control the formation reaction temperature and time, resulting in nano silver particles with sizes between 50 nm to 120 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical reduction method is used to prepare nano silver particles, then particle size control is improved, but particle size becomes too small (less than 30 nm) causing bio-toxic effects
Solution Approach 1:
The patent changes the reaction parameters by using a two-stage heating process (first heating to 60-80°C, then cooling and reheating to 90-110°C) and controlling reaction time (5-50 hours) to produce nano silver particles with controlled particle size of 50-120 nm, avoiding the bio-toxic effects of particles smaller than 30 nm while maintaining manufacturing precision
Solution Approach 2:
The patent employs periodic heating and cooling cycles during the reaction process - heating to initiate particle formation, cooling to control growth, and reheating to achieve desired particle size. This periodic action allows precise control over particle size to avoid bio-toxicity while maintaining manufacturing precision
2Ease of manufacture
If mechanical grinding method is used to prepare nano silver particles, then production simplicity is improved, but particle size control becomes poor and particle size is too large (about 500 nm)
Solution Approach 1:
The patent replaces the mechanical grinding method with a chemical reduction method using silver nitrate, polyvinyl pyrrolidone, and reducing agents (glucose, hydrogen, or amine). This chemical approach provides precise particle size control (50-120 nm) while maintaining ease of manufacture through simple mixing and heating procedures, eliminating the need for complex mechanical grinding equipment
3Reliability
If particle size is reduced to enhance anti-bacterial and anti-viral properties, then biological activity is improved, but bio-toxic effects increase
Solution Approach 1:
The patent optimizes the particle size parameter to fall within the specific range of 50-120 nm, which is large enough to avoid bio-toxic effects but small enough to maintain strong anti-bacterial and anti-viral properties. The controlled reaction conditions (temperature, time, reducing agent type) ensure consistent particle size within this optimal range
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 effectively produces nano silver particles within the desired size range of 50 nm to 120 nm, reducing bio-toxic risks while maintaining anti-bacterial and anti-viral properties, suitable for mass production.
Implementation Method 1
mixing polyvinyl pyrrolidone (PVP) and silver nitrate (AgNO3) in a solvent to form a reactive solution
Implementation Method 2
heating the reactive solution to a temperature less than the boiling point of the solvent for the formation reaction of nano silver particles
Implementation Method 3
adding an accelerating agent into the reactive solution during the formation reaction of the nano silver particles
Implementation Method 4
The chemical reduction method involves adding a reduction to agent into silver nitrate solutions to make silver ion in the solutions gain an electron to be reduced to silver
Data Source
AI summary
The invention provides a method for preparing nano silver particles comprising mixing polyvinyl pyrrolidone (PVP) and silver nitrate (AgNO3) in a solvent to form a reactive solution, heating the reactive solution to a temperature less than the boiling point of the solvent for the formation reaction of nano silver particles, adding an accelerating agent into the reactive solution during the formation reaction of the nano silver particles, and terminating the formation reaction when the size of the nano silver particles formed in the reaction solution reaches about 50 nm to 120 nm in diameter.