Silicate Ion Removal Electrodes That Maintain pH During Adsorption
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Solution Overview
Problem
Conventional methods such as CDI and MCDI struggle to effectively remove silicate ions from aqueous solutions due to the pH decrease during the ion adsorption process, causing silicate ions to change into solid-phase silicate, which are not adsorbed by electrodes, leading to low removal rates.
Innovation Solution
A silicate ion removal device and system that maintains or increases the pH of the aqueous solution using a porous carbon electrode and graphite electrode configuration, generating hydroxide ions to keep silicate ions in anionic form, combined with a cation exchange membrane to enhance adsorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CDI method is used to remove silicate ions, then ion adsorption occurs, but pH decreases causing silicate ions to change into solid-phase silicate which cannot be removed
Solution Approach 1:
The patent changes the pH parameter from decreasing (conventional CDI) to increasing or maintaining high pH through hydroxide ion generation at the negative electrode. This parameter change keeps silicate ions in soluble anionic form rather than converting them to solid-phase silicate, enabling continuous ion adsorption and removal.
Solution Approach 2:
The patent uses a composite electrode system combining porous carbon material at the positive electrode with graphite at the negative electrode. This composite configuration enables simultaneous ion adsorption at the positive electrode and hydroxide ion generation at the negative electrode, resolving the pH stability issue while maintaining high removal efficiency.
2Manufacturing precision
If pore size of 1 to 2 nm filters are used, then filtration is achieved, but extremely fine silicate ionic particles cannot be removed
Solution Approach 1:
The patent replaces the mechanical filtration system (pore-based physical filtering) with an electrochemical system using electrode adsorption. This substitution enables removal of extremely fine silicate ionic particles through electrostatic attraction and surface adsorption mechanisms rather than physical sieving, overcoming the size limitation of conventional filters.
3Productivity
If silicate ions are removed through ion adsorption, then removal efficiency should increase, but pH decrease converts silicate ions to solid-phase making them non-adsorbable
Solution Approach 1:
The patent creates a feedback mechanism where hydroxide ion generation at the negative electrode continuously supplies OH- ions to maintain high pH levels. This feedback loop ensures that silicate ions remain in the anionic form suitable for adsorption, preventing the conversion to solid-phase silicate and maintaining reliable adsorption effectiveness throughout the process.
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 system significantly increases the removal rate of silicate ions by maintaining them in anionic form, achieving removal rates up to three times higher than conventional methods, effectively reducing product defects in semiconductor manufacturing.
Implementation Method 1
a positive electrode configured to adsorb the silicate ions
Implementation Method 2
generating hydroxide ions from the fluid with the negative electrode
Implementation Method 3
a cation exchange membrane between the positive electrode and the flow path
Data Source
AI summary
A silicate ion removal device according to an embodiment is a device for removing silicate ions from fluid containing silicates. The silicate ion removal device comprises a positive electrode comprising a porous carbon electrode, a negative electrode spaced apart from the positive electrode and comprising graphite, a current collector on one side of each of the positive electrode and the negative electrode and configured to supply power to the positive electrode and the negative electrode, a flow path configured such that the fluid is configured to flow between the positive electrode and the negative electrode, and a cation exchange membrane between the positive electrode and the flow path, wherein the positive electrode is configured to adsorb the silicate ions.