Cobalt Oxide Nanoparticle Dispersion Stability
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Solution Overview
Problem
There is a need for simple methods to prepare cobalt oxide nanoparticles with a narrow size distribution and precise control over average particle size, using low-cost and environmentally friendly materials, that can be dispersed in water at high suspension densities and remain stable for use in chemical catalysis and electronic materials applications.
Innovation Solution
A method involving the formation of a reaction mixture with cobalt(II) ions, carboxylic acids, bases, and oxidants, with optional heating or cooling, and pH adjustments, to produce cobalt oxide nanoparticles that can be isolated and dispersed in water to form stable aqueous dispersions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to prepare cobalt oxide nanoparticles, then the preparation process is simple, but the particle size distribution is broad and control over average particle size is poor
Solution Approach 1:
The patent applies parameter changes by systematically varying reaction conditions including pH (adjusted to alkaline conditions), temperature (heating or cooling options), oxidant concentration (single or multiple portions), and reaction time to precisely control nanoparticle size and distribution. This resolves the contradiction by achieving narrow size distribution through controlled parameter variations rather than complex equipment
Solution Approach 2:
The patent employs periodic action through controlled addition of oxidants in single or multiple portions during the reaction process. This staged addition allows progressive oxidation and size control, achieving precise particle size distribution without requiring complex continuous processing equipment
2Productivity
If high suspension densities are used in aqueous dispersions, then the catalytic activity is enhanced, but the stability of the dispersion decreases
Solution Approach 1:
The patent uses carboxylic acids as intermediary agents that adsorb onto the cobalt oxide nanoparticle surfaces, providing steric and electrostatic stabilization. This mediator layer allows high nanoparticle concentrations to be maintained in aqueous dispersions without aggregation, simultaneously achieving high catalytic activity and long-term dispersion stability
3Object-affected harmful factors
If environmentally friendly and low cost materials are used, then the process is sustainable, but the manufacturing precision and control over particle size may be compromised
Solution Approach 1:
The patent employs self-service principles where simple, environmentally friendly reagents (carboxylic acids, peroxide, ammonia water) automatically provide the necessary size control and stabilization functions through their inherent chemical properties. The carboxylic acids self-adsorb onto particle surfaces providing steric stabilization, and peroxide provides controlled oxidation, achieving precise particle size control without requiring expensive specialized reagents or complex processing
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 method effectively produces stable cobalt oxide nanoparticle dispersions with controlled sizes, enhancing catalytic activity and extending catalyst life, while being environmentally friendly and cost-effective.
Implementation Method 1
forming a reaction mixture comprising cobalt(II) ion, a carboxylic acid, a base, an oxidant and water; forming cobalt oxide nanoparticles in the reaction mixture
Implementation Method 2
adjusting the pH of the reaction mixture to alkaline conditions by addition of a base
Data Source
AI summary
A method of making stable aqueous dispersions and concentrates of cobalt oxide nanoparticles is described, wherein a reaction mixture comprising cobalt(II) ion, a carboxylic acid, a base, an oxidant and water is formed, and in which cobalt oxide nanoparticles are formed. Cobalt oxide nanoparticles ranging in average crystallite size from about 4 nm to 15 nm are described. The cobalt oxide nanoparticles may be isolated and redispersed to form stable, homogeneous, aqueous dispersions of cobalt oxide nanoparticles containing from about 1 to about 20 weight percent cobalt oxide.