Calix[4]arene-Decorated Covalent Organic Framework Conjugates for Lithium Isotope Separation

Abstract

Lithium isotope separation has attracted extensive interest due to its important role in fusion and fission reactions. Up to now, it is still a great challenge to separate lithium isotopes (6Li and 7Li) in an efficient manner due to the low capture ability for lithium ions of related materials and highly similar physicochemical properties between lithium isotopes. In this work, three calix[4]arene-decorated crystalline covalent organic frameworks (COFs) with wave-like extension and AA-stacking configuration were designed and utilized for lithium adsorption and its isotope separation. Experimental studies show that these COFs exhibit an outstanding lithium adsorption capacity up to 94.66 mg·g–1, which is about 2 times beyond that of adsorbents reported in the literature. The high adsorption capacity of COFs could be attributed to the abundant adsorption sites from calix[4]arene unit. More importantly, this study demonstrates for the first time that calixarene groups can separate lithium isotopes with an excellent separation factor up to 1.053 ± 0.002, comparable to the most successful solid-phase lithium separation adsorbent. The calculation based on density functional theory showed that calixarene played an important role in the lithium adsorption. Interestingly, the lithium isotope separation performance is mainly affected by the amine bridging units. This work demonstrated that calixarene COFs are promising adsorbents for lithium isotope separation.

Progress of Triboelectric Nanogenerators with Environmental Adaptivity

“…Waterproofness of materials can be realized by microstructure design, [193] coating with hydrophobic micro-nano materials [194,195] and chemical modification to change the active groups. [196] Wang et al developed a wet-resistant, stretchable single-electrode TENG based on a porous flexible layer (PDMS) and a waterproof flexible conductive fabric (Ag nanoparticles modified spandex fabric/ polydopamine/ reduced graphene oxide). [197] In addition, the functional coating can also give the textile additional waterproofness, realizing textile TENG with water energy collection and fluid sensing functions.…”

“…By simulating the biological fluid environment in vitro, a certain foundation can be established for the biodegradability research of implantable TENG. Also, 45% [196] 60% [195] 92% [192] Mechanical durability 100 cycles [196] 5000 cycles [217] 500 cycles [48] 7 days [218] 1000 cycles [219] 7200 cycles [220] 10000 cycles [68] 4000 cycles [221] Waterproofness (water contact angle)…”

Selective Recovery of Lithium from Salt Lake Brine by Using Ion-Imprinted Polymers

“…Calixarene, composed of methylene bridge-linked phenolic units, is a kind of macrocyclic compounds with a cavity-like structure, which has been widely used to capture metal ions due to its variable hole sizes and excellent trapping ability for metal ions. 36,37 While conventional IIPs usually use crown ethers as ligands, in this paper we synthesized calix [4] aromatic hydrocarbons with size-adjustable "cavities" as ligands and prepared lithium-ion imprinted polymers [Li(I)-IIPs] with high-capacity, fast equilibrium adsorption, and recycling of Li + by using the bulk polymerization method. The Li(I)-IIPs were analyzed by Fourier transform infrared (FT-IR), 13 C NMR, scanning electron microscopy (SEM), Brunauer−Emmett− Teller (BET) and X-ray photoelectron spectroscopy (XPS) to analyze the characteristic groups, morphology, specific surface area, and elemental compositions.…”

Water-Mediated Hydrogen Bond Network Drives Highly Crystalline Structure Formation of Crown Ether-Based Covalent Organic Framework for Sr Adsorption

“…Over the past decade, versatile macrocycles, such as phthalocyanine, , γ-cyclodextrin, calixarenes, , and crown-ether, , have been integrated into COFs. Among them, crown ether COFs (CE-COFs) exhibited good performance in phase-transfer catalysis, carbon dioxide reduction, and fluorescent sensing .…”

“…In particular, a highly ordered porous structure, low density, high surface area, and ease of functionalization endow COFs with great potential in separation, 3−5 sensing, 6−8 sorption, 9−11 and catalysis. 12,13 Over the past decade, versatile macrocycles, such as phthalocyanine, 14,15 γ-cyclodextrin, 16 calixarenes, 17,18 and crown-ether, 19,20 have been integrated into COFs. Among them, crown ether COFs (CE-COFs) exhibited good performance in phase-transfer catalysis, 21 carbon dioxide reduction, 22 and fluorescent sensing.…”