Nanoparticulate Titanium Dioxide Production via Ammonium Carboxylate Neutralization
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Solution Overview
Problem
Current methods for producing nanoparticulate titanium dioxide using neutralization with calcium hydroxide result in cracking of the filter cake, making washing impossible, while neutralization with sodium hydroxide produces a finely divided product difficult to handle, and both methods leave residual soluble compounds in aqueous systems.
Innovation Solution
A method involving the hydrolysis of an acidic titanyl compound, followed by filtration, washing, neutralization with an aqueous solution of alkali silicate and/or alkali aluminate, and thermal treatment to produce a nanoparticulate titanium dioxide product with insoluble compounds and a readily washable filter cake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calcium hydroxide is used for neutralization, then insoluble calcium sulfate is formed, but the filter cake cracks during washing making intensive washing impossible
Solution Approach 1:
The patent changes the chemical composition parameters of the neutralizing agent from conventional calcium hydroxide or sodium hydroxide to an ammonium salt of a carboxylic acid with 1-18 carbon atoms. This parameter change transforms the neutralization reaction products into ammonium sulfate (soluble) and the corresponding carboxylic acid (insoluble), which forms a stable, non-cracking filter cake structure that can be intensively washed.
Solution Approach 2:
The ammonium salt acts as an intermediary neutralizing agent that provides dual functionality: it neutralizes the sulfuric acid to form soluble ammonium sulfate that washes away easily, and simultaneously forms insoluble carboxylic acid that creates a stable filter cake structure without cracking, thus mediating between the conflicting requirements of washability and structural integrity.
2Ease of operation
If sodium hydroxide is used for neutralization, then readily soluble sodium sulfate is formed that can be washed out completely, but a very finely divided titanium dioxide product is formed which is difficult to handle
Solution Approach 1:
The patent changes the cation parameter from sodium ion to ammonium ion in the neutralizing agent. This parameter change results in the formation of insoluble carboxylic acid instead of soluble sodium sulfate, which precipitates and forms a stable filter cake structure. This resolves the handleability issue while the soluble ammonium sulfate byproduct maintains easy washability.
Solution Approach 2:
The neutralization process creates a composite system where soluble ammonium sulfate and insoluble carboxylic acid coexist in the filter cake. The insoluble carboxylic acid forms a matrix structure that provides mechanical stability and handleability to the fine titanium dioxide particles, while the soluble ammonium sulfate can be washed away, combining the benefits of both previous methods.
3Reliability
If conventional neutralization methods are used, then neutralization is achieved, but residual soluble compounds remain in aqueous systems
Solution Approach 1:
The patent changes the anion parameter from chloride or sulfate to carboxylate (from carboxylic acids with 1-18 carbon atoms) in the neutralizing agent. This parameter change ensures that the neutralization product (ammonium sulfate) is highly soluble and washable, while the corresponding carboxylic acid is insoluble and forms a stable precipitate. This eliminates residual soluble harmful compounds from the final product while maintaining effective neutralization.
Solution Approach 2:
The patent converts the potentially harmful residual soluble compounds into beneficial insoluble carboxylic acid precipitates. The carboxylic acid with 1-18 carbon atoms, formed during neutralization, has low solubility in water and forms a stable filter cake, thereby transforming what would be a contamination issue into a benefit for product purity and ease of separation.
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 results in a nanoparticulate titanium dioxide product with improved washability and purity, suitable for use as an adsorbent, photocatalyst, or process catalyst, offering enhanced handling and performance in aqueous systems.
Implementation Method 1
hydrolyzing the titanyl compound to produce a titanium oxide-hydrate suspension
Implementation Method 2
thermally treating the filter cake
Data Source
AI summary
The invention relates to a method for obtaining nanoparticulate titanium dioxide in agglomerate form from a hydrolyzed acidic titanyl compound, the thus obtained titanium dioxide as well as the use thereof as a photocatalyst, process catalyst or adsorbent, especially in aqueous systems.