Squaramide Crown Ether Receptor for Oxanion Extraction
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Solution Overview
Problem
Current methods for removing oxoanions, particularly sulfate(VI) anions, from aqueous solutions are inefficient and costly due to their high water solubility and similar chemical properties, posing challenges in industrial-scale purification and radioactive waste treatment, where their presence can lead to borosilicate glass corrosion and hazardous leaks.
Innovation Solution
A receptor with amide groups and crown ether moieties that simultaneously binds oxoanions and their counterions, forming soluble complexes that can be extracted from the aqueous phase to an organic phase, allowing for efficient removal and regeneration, and is designed to work across a wide pH range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to remove oxoanions from aqueous solutions, then removal efficiency is limited, but the process becomes burdensome, long-lasting and expensive due to preliminary purification requirements
Solution Approach 1:
The receptor molecule is segmented into distinct functional domains: amide groups for oxoanion binding and crown ether moieties for counterion binding. This segmentation allows simultaneous interaction with both ions in the ion pair, enabling direct removal without preliminary purification steps and dramatically reducing process time while maintaining high removal efficiency
Solution Approach 2:
The receptor is designed with pre-positioned binding domains that are spatially arranged to simultaneously capture both oxoanions and counterions upon contact with the aqueous solution. This preliminary structural arrangement eliminates the need for sequential purification steps, reducing both time and operational complexity
2Reliability
If sulfate(VI) anions are removed using conventional methods, then removal can be achieved, but the process requires preliminary purification from other anions making it burdensome and expensive
Solution Approach 1:
The receptor exhibits local quality through its specialized binding domains: amide groups with specific hydrogen bonding capability for oxoanions and crown ethers with specific cavity sizes for different counterions. This localized functionality provides high selectivity for sulfate(VI) and its counterions, enabling reliable removal without complex preliminary purification steps
Solution Approach 2:
The receptor combines different functional groups (amide and crown ether) into a single composite molecular structure. This composite design enables simultaneous recognition and binding of both oxoanions and counterions, simplifying the removal process while maintaining high effectiveness and selectivity
3Productivity
If liquid-liquid extraction is used to transfer oxoanions to organic phase, then transfer can be achieved, but the method requires both receptor and bulky counterion making it burdensome and expensive
Solution Approach 1:
The invention merges the oxoanion binding function (amide groups) and counterion binding function (crown ether moieties) into a single receptor molecule. This unified structure eliminates the need for separate receptor and counterion components, simplifying the extraction method while maintaining high efficiency for transferring ion pairs from aqueous to organic phase
Solution Approach 2:
The receptor performs multiple functions simultaneously: it binds oxoanions through amide groups, binds counterions through crown ether moieties, and facilitates phase transfer to organic solvent. This multi-functionality reduces the number of components needed and simplifies the overall extraction 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 receptor effectively removes oxoanions and their counterions from aqueous solutions, preventing glass corrosion and enabling safe vitrification of radioactive waste, while being regenerable and suitable for industrial use.
Implementation Method 1
The receptor binds oxoanions with amide groups
Implementation Method 2
containing amide groups specifically coordinating the oxoanions, as well as moieties specifically coordinating cations
Implementation Method 3
forming soluble complexes that can be extracted from the aqueous phase to an organic phase
Data Source
AI summary
A receptor for the simultaneous removal of oxoanions and their counterions from aqueous phase, particularly containing radioactive wastes, containing amide groups specifically coordinating the oxoanions, as well as moieties specifically coordinating cations, according to the present invention is characterised in that it contains within one molecule domains binding oxoanions and domains binding cations, preferably adapting a molecular structure of a general formula: (I) wherein Z this is a group containing crown ether, preferably a benzocrown group, X is any substituent, including the Y—Z grouping, and Y is any substituent or 0 (i.e. a direct bond between N and Z), where the oxoanion binding domain is a squaramide unit coordinating the oxoanions through amide groups, and squaramide contains additional substituents that increase or decrease the acidity of its amide protons, compared to unsubstituted squaramide, whereas the counter ion binding domain is a crown ether of a size adjusted to the type of binding cation, which forms part of at least one of the aforementioned substituents of squaramide, where the receptor has the ability to remove oxoanions and their counterions from aqueous phase to another water-immiscible phase, preferably to organic phase, and has the ability to form soluble complexes in at least one of the aforementioned phases. The invention considers also a method of removing oxoanions in the form of inorganic salts from aqueous phase, using receptors of the invention in the form of organic molecules containing amide groups, according to the invention is characterised in that it uses the aforementioned receptors for simultaneous binding of oxoanions and their counterions in aqueous phase, preferably acidic when using the receptor with substituents increasing acidity of squaramide protons, or alkaline when using the receptor with substituents decreasing acidity of squaramide protons. A sensor for detecting oxoanions according to the invention is characterised in that it uses the aforementioned receptors, dissolved or suspended in an organic solvent or in a mixture of organic solvents, forming coloured complexes in contact with the phase containing given oxoanions. The preparation for removing oxoanions from aqueous solutions, particularly containing radioactive waste at the stage preceding their disposal by vitrification, is characterised in that it contains the receptor according to the invention, dissolved or suspended in the water-immiscible phase, and the appropriate amount of counterion facilitating extraction. A process of utilisation of aqueous solutions by vitrification, particularly solutions containing radioactive waste, is characterised in that vitrification step is preceded by the step of oxoanions removal, preferably sulfate(VI) anions, by the method according to the invention, using the receptors according to the invention, preferably using the preparation according to the invention.