Ligand-Modified Filter Media for Metal Removal in Acidic and Basic Fluids
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Solution Overview
Problem
Conventional filters are ineffective in removing metal contaminants from acidic or basic solutions, especially in microelectronic manufacturing processes, as these solutions can strip metal ions from conventional filters and pose aggressive chemical conditions, limiting their effectiveness.
Innovation Solution
Ligand-modified filter materials, specifically those with polyol ligands comprising three or more hydroxyl groups and polyphosphonic acid ligands, are used to effectively remove metal ions from both basic and acidic solutions by contacting the filter materials with the liquid compositions, thereby reducing metal contamination levels suitable for microelectronic manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filters are used to remove metal ions from acidic or basic solutions, then the filter structure provides physical support and particle filtration, but the filter cannot effectively remove metal ions due to stripping by aggressive chemical conditions
Solution Approach 1:
A ligand-modified layer is introduced as an intermediary between the filter support structure and the liquid composition. This ligand layer (containing chelating agents like iminodiacetic acid, ethylenediamine tetraacetic acid, or hydroxymethyl ethylenediamine triacetic acid) selectively binds metal ions through coordination chemistry, preventing direct contact between aggressive basic/acidic solutions and the conventional filter structure, thereby enabling effective metal ion removal while maintaining filter integrity
Solution Approach 2:
The filter comprises a composite structure combining a conventional filter support material (providing mechanical strength and porosity) with a ligand-modified layer (providing selective metal ion binding). This composite architecture allows the filter to simultaneously withstand aggressive chemical conditions while effectively removing metal ions through the ligand's chelating properties
2Reliability
If separate filtration members are used for basic and acidic solutions, then each filter can be optimized for specific conditions, but the system complexity and number of components increases
Solution Approach 1:
The ligand-modified filter is designed with universal applicability to handle both basic and acidic solutions. The ligand layer (with chelating groups such as -NHCH2COO-, -N(CH2COO-)2, or -N(CH2COO-)3) provides pH-resilient metal ion binding capability, allowing a single filter design to perform effectively across varying pH conditions without requiring separate specialized filters for acidic and basic streams
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 ligand-modified filters demonstrate excellent reduction in metal and metal ion contamination in fluid processing streams, outperforming conventional ion-exchange ligands, and can be used in systems requiring metal removal from both basic and acidic solutions without the need for separate filtration members.
Implementation Method 1
the filter material comprising (a) an polyol ligand comprising three or more hydroxyl groups, (b) a polyphosphonic acid ligand, or both (a) and (b). In contacting, the filter reduces an amount of the one or more metal or metal ions in the liquid composition
Data Source
AI summary
Described are filter materials including a polyol ligand, such as n-methylglucamine, and/or a polyphosphonic acid ligand, which are highly effective for filtering metals or metal ions from fluids. The filter materials can be particularly useful to filter basic and acidic fluid compositions, such as those used for wet etching, removing photoresist, and cleaning steps in microelectronic device manufacturing.