Concentrated Neutral Titanium Dioxide Sol Preparation
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Solution Overview
Problem
Current photoactive, neutral titanium dioxide sols are limited by low titanium dioxide concentration, leading to high solvent content, which complicates their use and transportation due to excessive volume and cost, and restricts their applications.
Innovation Solution
Methods involving washing and dewatering of hydrous titanium dioxide gel with low cation concentration aqueous solvents, followed by peptization with alkaline agents and neutralization with concentrated acids to achieve titanium dioxide sols with concentrations of 30% or greater, maintaining pH neutrality and photocatalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photoactive, neutral titanium dioxide sols are prepared with conventional methods, then the sols are stable and neutral in pH, but the titanium dioxide concentration is limited to about 10-15% by weight
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters during preparation - specifically using alkaline peptizing agents (like ammonium hydroxide or sodium hydroxide) followed by controlled acid neutralization. This parameter transformation enables the formation of concentrated sols with TiO2 concentrations of 30% or greater while maintaining pH stability in the neutral range of 7-9, resolving the contradiction between concentration and pH stability.
2Ease of manufacture
If titanium dioxide sol is prepared with low concentration (10-15%), then the sol is easy to prepare and stable, but it requires substantially large volume of solvent leading to excessive transportation and storage space
Solution Approach 1:
The patent applies the extraction principle by removing excess solvent from the system through the peptization and concentration process. By using alkaline peptizing agents to disperse TiO2 particles and then concentrating the sol to 30% or greater TiO2 content, the method extracts unnecessary solvent volume while maintaining sol stability and neutrality, thereby reducing transportation and storage requirements.
3Object-affected harmful factors
If conventional neutral titanium dioxide sol is used, then the sol is odorless and non-flammable, but the high solvent content (approximately 90% by weight) adds excessive volume and cost
Solution Approach 1:
The patent applies parameter changes by transforming the solvent content parameter from approximately 90% by weight in conventional sols to 70% or less by weight in the concentrated sols. This is achieved through controlled peptization with alkaline agents and subsequent concentration, while maintaining the beneficial properties of being odorless and non-flammable through proper pH control in the neutral range.
Data Source
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AI summary
The present disclosure relates to methods of preparing sols of titanium dioxide nanoparticles that are photoactive, neutral, and in a substantially concentrated form. The methods particularly provide for concentrated sols in light of washing and dewatering under low cation concentrations and utilizing rapid peptizing through addition of the filter case to the peptizing agent. Concentrated acid may be utilized to maintain high TiO2 concentration while still avoiding precipitation of the colloidal TiO2. Concentrated photoactive, neutral titanium dioxide sols are also provided as well as compositions thereof and photoactive coatings formed therewith.