Amorphous Calcium Carbonate Stabilization via Ammonium Mediation
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Solution Overview
Problem
Current methods for producing amorphous calcium carbonate (ACC) are impractical due to its instability in aqueous solutions, making large-scale commercial production challenging, as it rapidly crystallizes into more stable polymorphs, and existing stabilization methods often require toxic substances or result in low calcium carbonate concentrations.
Innovation Solution
A method involving the stepwise addition of hydrogen bonding molecules as stabilizers and a water miscible organic solvent to a suspension of calcium and carbonate solutions, maintaining the ACC in a stable form for extended periods by controlling the addition of stabilizers and solvents within a specific time frame and concentration range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ACC is produced using conventional methods with soluble calcium salts and carbonate sources, then ACC can be synthesized, but it rapidly crystallizes within seconds and cannot be stabilized for commercial production
Solution Approach 1:
The patent introduces an intermediary substance (ammonium ion) that mediates between the calcium salt and carbonate source. The ammonium ion forms a transient complex with carbonate, preventing direct precipitation and allowing ACC to form and remain stable in solution for extended periods, resolving the contradiction between synthesis and stabilization.
Solution Approach 2:
The patent changes the chemical parameters of the reaction system by using ammonium carbonate instead of conventional carbonate sources. This parameter change (using ammonium as the cation) fundamentally alters the reaction kinetics and thermodynamics, enabling ACC to remain stable in solution for hours rather than seconds, thus resolving the stability contradiction.
2Productivity
If large scale production is attempted with hundreds or thousands of liters, then commercial production volume increases, but standard liquid-solid phase separation techniques cannot separate ACC within the available time frame
Solution Approach 1:
The patent applies preliminary action by stabilizing ACC in solution for extended periods (hours) before phase separation is needed. This preliminary stabilization allows large volumes to be processed at standard production rates without rushing the separation process, enabling commercial-scale productivity with adequate time for separation.
3Stability of the object's composition
If existing stabilization methods are used to extend ACC stability, then ACC can be stabilized longer, but toxic substances like ammonia are required which are impractical for commercial use
Solution Approach 1:
The patent uses ammonium ion as a temporary, consumable stabilizing agent that performs its function and then decomposes into harmless substances (ammonia and carbon dioxide). This disposable approach provides extended stability during the critical production window without requiring persistent toxic stabilizers, making the process commercially viable.
4Quantity of substance
If calcium carbonate concentration is increased for practical industrial use, then production efficiency improves, but ACC becomes even more unstable and crystallizes faster
Solution Approach 1:
The ammonium ion acts as a mediator that allows high concentrations of calcium carbonate to coexist in solution without immediate crystallization. By controlling the interaction between ammonium, calcium, and carbonate, the patent enables high concentrations to be maintained stably, resolving the contradiction between quantity and stability.
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 produces ACC with increased stability, allowing for practical commercial production by maintaining the amorphous form for several hours to days, enabling standard liquid-solid phase separation techniques and reducing the need for toxic substances.
Implementation Method 1
A method involving the stepwise addition of hydrogen bonding molecules as stabilizers and a water miscible organic solvent to a suspension of calcium and carbonate solutions
Implementation Method 2
adding a water miscible organic solvent and a solution comprising a second stabilizer, simultaneously or sequentially in any order so long as the second stabilizer and organic solvent contact the ACC suspension within about 2 minutes of its formation
Implementation Method 3
combining a solution comprising a soluble calcium salt and a first stabilizer with a solution comprising a soluble carbonate so as to form an ACC suspension
Data Source
AI summary
Provided is a method for preparing a stable amorphous calcium carbonate (ACC), which can be obtained either in suspension or as a powder. The method comprises stepwise combination of a soluble calcium salt, a soluble carbonate, a first and second stabilizer, and a water miscible organic solvent as described herein. The present invention further relates to stable ACC suspensions and dry powders produced by the method of the present invention.