Calcium Silicate Hydrate Adsorbent for Phosphate Removal
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Solution Overview
Problem
Current methods for removing phosphates, nitrates, and heavy metals from aqueous solutions are inefficient, often require additional pH adjustments, and are not suitable for use in potable water or food processing applications, with limitations in adsorption capacity and contaminant profiles.
Innovation Solution
Compositions comprising multiple calcium silicate crystalline structures and amorphous structures, produced through a hydrothermal process with specific molar ratios and heating, which provide alkalinity for effective phosphate removal without pH adjustment and can adsorb various cations and anions, including heavy metals, in a form that can be reused as a fertilizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flocculation/precipitation methods using metal salts are used to remove phosphates, then phosphate removal is achieved, but additional pH adjustment and polymer additives are required
Solution Approach 1:
The invention changes the chemical composition parameters by using calcium silicate hydrate (C-S-H) with specific Ca/Si ratios (1.5-3.0) and controlled pH (8.0-10.0) to achieve phosphate removal without requiring additional pH adjustment or polymer additives. The C-S-H structure provides inherent alkalinity and adsorption capacity that eliminates the need for conventional metal salts and polymers.
Solution Approach 2:
The invention employs composite calcium silicate hydrate materials with specific crystalline and amorphous phase compositions. The composite structure includes C-S-H gel,tobermorite, and xonotlite phases that work synergistically to provide both alkalinity for pH maintenance and high phosphate adsorption capacity, replacing multiple conventional chemicals with a single composite material.
2Productivity
If xonotlite and tobermorite are used for phosphorus removal, then phosphorus removal is achieved, but efficiency is reduced at high pH due to bicarbonate conversion
Solution Approach 1:
The invention optimizes the Ca/Si ratio parameter to 1.5-3.0 and controls pH to 8.0-10.0, which maintains the effectiveness of calcium silicate hydrate across a broader pH range. This parameter optimization prevents the bicarbonate conversion issue that plagues conventional tobermorite and xonotlite applications at high pH.
Solution Approach 2:
The invention creates localized optimal conditions around the C-S-H particles by controlling the surrounding pH environment. The material's inherent alkalinity creates a local pH buffer zone that maintains optimal adsorption conditions even when bulk solution pH varies, thereby reducing pH sensitivity.
3Productivity
If struvite formation is used for phosphorus removal, then phosphorus removal is achieved, but high ammonia levels and magnesium sources are required
Solution Approach 1:
The invention extracts the phosphate removal function from the struvite formation pathway, which requires magnesium and high ammonia levels. Instead, it uses calcium silicate hydrate's inherent adsorption capability that does not depend on these additional chemical inputs, thereby eliminating the requirement for magnesium sources and high ammonia concentrations.
Solution Approach 2:
The invention uses a simpler, more readily available material (calcium silicate hydrate) that does not require the complex chemical conditions needed for struvite formation. This disposable-like approach uses a single additive that works effectively without needing to maintain specific chemical environments or add multiple substances.
4Productivity
If conventional phosphate removal methods are used, then phosphates are removed, but the compositions are not suitable for potable water and food processing applications
Solution Approach 1:
The invention changes the chemical parameters by using food-grade calcium silicate hydrate with controlled composition and pH (8.0-10.0). This parameter optimization ensures the material is safe for potable water and food processing applications while maintaining high phosphate removal efficiency, unlike conventional metal salts that may leave harmful residues.
5Adaptability or versatility
If multiple treatment methods are used for different contaminants, then various contaminants are removed, but the process becomes complex and application-specific
Solution Approach 1:
The invention creates a universal phosphate removal solution using calcium silicate hydrate that works across different water matrices (potable water, wastewater, industrial effluents) without requiring method changes. The material's broad pH tolerance and high adsorption capacity provide multi-functional performance that replaces multiple application-specific treatment protocols.
Solution Approach 2:
The composite C-S-H material with specific crystalline and amorphous phases provides multiple functions simultaneously: pH buffering, phosphate adsorption, and turbidity reduction. This single composite material replaces multiple specialized chemicals and processes, simplifying the overall treatment system while maintaining versatility across different contaminant profiles.
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 compositions achieve high efficiency in phosphate, nitrate, and heavy metal removal, with fast adsorption kinetics and pH stability, suitable for use in various water sources and food processing, and can recover phosphates for fertilizer use, maintaining water quality and reducing eutrophication.
Implementation Method 1
compositions comprised of multiple calcium silicate crystalline structures and amorphous structures
Implementation Method 2
provide alkalinity for effective phosphate removal without pH adjustment
Implementation Method 3
manipulated in ways to adsorb various cations and anions given that the aqueous solutions contemplated in connection with the present invention have differing contaminant profiles
Data Source
Figure 1~2
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Figure 5~6
AI summary
Compositions and methods for removing phosphates, nitrates and heavy metals from aqueous solutions.