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Solvent Extraction in the Nuclear Fuel Cycle
Published in Reid A. Peterson, Engineering Separations Unit Operations for Nuclear Processing, 2019
Gabriel B. Hall, Susan E. Asmussen, Amanda J. Casella
Molecular recognition allows for high selectivity in the separation of fission products from aqueous streams using macrocyclic compounds and is an important development for separations that has emerged in recent decades (Collins, Del Cul, and Moyer 2011). Crown ethers initially showed the greatest promise for Cs extraction (CSEX) using molecular recognition. However, more recently, calixarenes have replaced crown ethers as the extractant of choice, as Cs extraction by crown ethers is difficult due to weak extraction strength and only moderate selectivity (Collins, Del Cul, and Moyer 2011). Calixarenes have a dramatically increased binding strength and selectivity for Cs in comparison to crown ether compounds (Collins, Del Cul, and Moyer 2011). Structurally, these compounds resemble crown ethers with the addition of aromatic rings that protrude above and below the crown cavity in a vase-like structure.
Quantum Dots for Bioimaging
Published in Li Jun, Wu Nianqiang, Biosensors Based on Nanomaterials and Nanodevices, 2017
A coating method for the biosensor application of QDs involves the use of different cyclodextrins.79,80 The hydrophobic pockets of the polysaccharide interact with the aliphatic chains of the TOPO present on the QD surface, wherein the immobilized cyclodextrins retain their capability of engaging molecular recognition. This phenomenon and the observed fluorescence changes during analyte–binding make this method very promising for possible sensor applications.80 Similar to this approach is the use of calixarenes, which are similar organic cyclic systems81,82 that preserve the emission intensity of the QDs and their small diameter. Calixarenes are cyclic oligomers formed from the hydroxyalkylation of phenol and an aldehyde. These could be functionalized with sugars or peptides to allow biological applications of the resulting coated QDs.81
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Published in Luis Liz-Marzán, Colloidal Synthesis of Plasmonic Nanometals, 2020
Verónica Montes-García, Jorge Pérez-Juste, Isabel Pastoriza-Santos, Luis M. Liz-Marzán
Calixarenes are another type of macrocyclic compounds that can be synthesized via base catalyzed condensation of para-alkyl phenol and formaldehyde (Fig. 17.1B). The number of aromatic rings present in the oligomer is determined by the type of base used. Generally this type of supramolecular macrocycle resembles a calix and consists of several arene rings, this being the reason why they are called calix[n]arenes, with n the number of the arene moieties present in the structure. The fact that they can adopt alternate conformations provides them with a larger conformational variability as compared to cyclodextrins.
Adsorption behaviors and emission properties of p-sulfonatocalixarene/ammonium-based surfactant systems: A comparison between the effects of gemini surfactant and its corresponding monomeric surfactant
Published in Journal of Dispersion Science and Technology, 2022
Chunyang Liu, Jiaxin Zhu, Meiling Lei, Xia Guo
Calixarenes are cyclic oligomers containing repeating units of phenol and methylene.[1,2] They are an important family of molecular receptors because of their ease of preparation and post-modification.[1–7] The modification of ionized groups brings calixarenes good water solubility; p-sulfonatocalix[n]arenes (SC[n]) were the first described and probably have been the most studied water-soluble calixarenes to date.[1–6]
Surface coating of silica with amine functionalized calix[4]arene and its application in metal ion extraction
Published in Journal of Dispersion Science and Technology, 2023
Nida Shams Jalbani, Amber R. Solangi, Shahabuddin Memon, Ranjhan Junejo, Asif Ali Bhatti
Keeping in view the toxicity of these metal ions, different methodologies were applied for the separation and removal of metal ions from water such as coagulation, on-line dialysis ion exchange chromatography, adsorption, chemical precipitation, electrolytic process, solvent extraction and reverse osmosis. Among all these techniques, adsorption is an efficient, low cost and simple technique, which uses selective as well as re-generable materials.[10] Calixarenes are considered as cheaper, reusable and selective materials for the removal and separation of ionic as well as neutral species.[11] Basically, calixarenes are cyclic oligomers that can be prepared by condensation reaction of phenol and formaldehyde and they can be functionalized to synthesize well-known attractive and excellent ionophores.[12] Calixarenes have upper and lower rims, which can be derivatized with selective moieties such as amines, amides, carbonyls, nitriles that have ability to bind with neutral molecules, anions and cations.[13,14] Previously, different studies have been carried out on calixarenes, such as diethylamine-calix[4] arene coated silica resin has been prepared and applied for the removal of Cd2+, Pb2+, and Hg2+ metal ions from water.[15] In another study, the piperdinomethylcalix[4] arene attached silica resin has been synthesized and applied for the adsorption of Cu2+ and Pb2+ metal ions from water.[16] Moreover, these calix[4] arene coated silica resin have been used for treatment of dyes contaminated wastewater such as diethanolamine-calix[4] arene coated silica resin was applied for the removal of DB-38 dye,[17] while the amine-functionalized calix[4] arene resin used for the removal reactive dyes.[18] In our previous work, the diphenylaminomethylcalix[4] arene silica resin has been synthesized and applied for the selective removal of Hg2+ ions from water under the optimized parameters.[19] Present study deals with the synthesis of low cost and easy adsorbent material i.e., calixarene coated silica resin for the application in solid phase extraction of metal ions from aqueous media.