Silica Particle Manufacturing Process pH Conductivity Control

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Solution Overview

Problem

Current methods for producing silica-based products are limited in terms of pH control and conductivity adjustment, which affects the quality and versatility of silica sols and doped silica materials used in various industrial applications.

Innovation Solution

A method involving a silica-containing precursor with pH adjustment from 7 or less to greater than 7, accompanied by the addition of salt to achieve conductivity of 4 mS/cm or higher, followed by optional filtering, drying, and functionalization with organosilanes or metal species, to produce functionalized metal oxide or sulfide-doped silica products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If pH adjustment and conductivity adjustment are performed in conventional sequences, then process control is simplified, but product quality and versatility are limited

Engineering Contradiction:
Improveproduct versatilityVSAvoidprocess complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by adjusting the pH to greater than 7 and adding salt to achieve conductivity of 4 mS/cm or higher BEFORE adding the silica-containing precursor. This preliminary preparation of the aqueous medium ensures optimal conditions for particle formation, leading to improved particle size distribution and product versatility while maintaining a clear, sequential process structure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by specifically controlling pH (greater than 7) and conductivity (≥4 mS/cm) as critical process parameters. These parameter specifications enable precise control over silica particle formation, resulting in improved particle size distribution and enhanced product versatility across different applications.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If conventional silica production methods are used, then manufacturing simplicity is maintained, but particle size distribution and surface area are insufficient

Engineering Contradiction:
Improveparticle size distributionVSAvoidmanufacturing simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent achieves improved particle size distribution and surface area by implementing specific parameter changes: adjusting pH to greater than 7, controlling conductivity at 4 mS/cm or higher, and maintaining these conditions during silica precursor addition. These controlled parameter changes enable precise particle formation while keeping the overall process straightforward and industrially viable.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If doping is performed at high pH, then metal incorporation is improved, but particle morphology control deteriorates

Engineering Contradiction:
Improvemetal doping efficiencyVSAvoidparticle morphology
Core Design Contradiction:
Quantity of substanceVSShape

Solution Approach 1:

The patent applies preliminary action by preparing the aqueous medium with appropriate pH (>7) and conductivity (≥4 mS/cm) conditions BEFORE adding the silica-containing precursor and metal species. This preliminary preparation ensures that metal doping occurs under optimized conditions that simultaneously achieve high metal incorporation efficiency and maintain good particle morphology control.

Inventive Principle:
Principle #10Preliminary action

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 enhances the quality and versatility of silica-based products by improving particle size distribution, surface area, and functionalization, making them suitable for a wide range of applications including coatings, filtration, and mercury removal.

Implementation Method 1

adding salt to achieve a conductivity of at least 4 mS/cm

Methodology Applied
Scientific EffectConductivity adjustment through salt addition: Electrolyte

Implementation Method 2

adjusting the pH of the solution to greater than 7

Methodology Applied
Scientific EffectpH-induced polymerization: Hydrolysis

Data Source

PatentEP2556021B1Silica particle manufacturing process
Publication Date: 2019.07.24 NALCO CO

AI summary

Methods of forming a silica-based products are disclosed. One method comprises: (a) providing a silica containing precursor (SCP) contained in solution that has a pH less than or equal to a pH of 7; (b) optionally doping the SCP with one or more metal species, wherein said doping occurs when the solution has a pH less than or equal to a pH of 7; (c) adjusting the pH of the solution to greater than 7; (d) adding an effective amount of salt to the solution so that the conductivity of the solution is greater than or equal to 4 mS, wherein said addition occurs prior to, simultaneous with, or after the pH adjustment in step 1c; (e) optionally filtering and drying the SCP; and (f) optionally reacting the dried product from step e with a functional group and optionally wherein the resultant functionalized dried product is at least one of the following: a functionalized metal oxide-doped or metal sulfide-doped silica product. Another method comprises: (a) providing a silica containing precursor (SCP) contained in solution that has a pH greater than 7; (b) adjusting the pH of the solution to less than or equal to 7; (c) optionally doping the SCP with one or more metal species, wherein said doping occurs when the solution has a pH less than or equal to a pH of 7; (d) adjusting the pH of the solution to greater than 7; (e) adding an effective amount of salt to the solution so that the conductivity of the solution is greater than or equal to 4 mS, wherein said addition occurs prior to, simultaneous with, or after the pH adjustment in step 2d; (f) optionally filtering and drying the SCP; and (g) optionally reacting the dried product from step f with a functional group and optionally wherein the resultant functionalized dried product is at least one of the following: a functionalized metal oxide-doped or metal sulfide-doped silica product.