Highly selective CO2 uptake in Calix[4]arene compounds immobilized on silica gel

Carbonate-based hyper-cross-linked polymers with pendant versatile electron-withdrawing functional groups for CO2adsorption and separation

“…performance of porous organic polymers in practical gas adsorptive separation applications. Single-component physisorption isotherms for CO 2 , N 2 and CH 4 were systematically analyzed via volumetric methods at 273.15 K and 298.15 K, and the CO 2 /N 2 and CO 2 /CH 4 gas pairs were comprehensively calculated by employing the initial slope ratios from Henry's law constants of the pure gas adsorption isotherms at the same temperature and low-pressure coverage of less than 0.3 bar, as PVAm/PZEA-Pro/PZEA-Sar (210), 68 MPC-500 (140), 69 PIP-CMC/ TMC (119), 70 and PIM-PI-1 (57.2), 71 the CO 2 /N 2 value of polymer 1 is comparable or exceeds those of CTFs (14.2-20.3), 72 PPFs (14.5-15.4), 73 MF-168-600 ( 16), 74 and PIM-1 S A /S B (12.7) 75 at 273.15 K and HC PPO-Br (20), 76 CCP-6 ( 17), 77 UiO-66 (16.7), 78 Sg (9.9), 79 and SBL-MIP-C-800 (9.5) 29), 87 PIM-Cardo-TOT (25.5), 88 Cu-1 (9), 89 and Ni-MOF (2.9) 90 at 298.15 K. In addition, it should be particularly pointed out that the selective uptake of CO 2 over N 2 and CH 4 is mainly induced by the strong dipole-quadrupole interaction between the structurally accessible polar functional groups, heteroatoms and CO 2 molecules as well as the quadrupole-quadrupole interactions among the CO 2 molecules. On account of the systematic studies above, it has been demonstrated that the utilized carbonates are a family of lowcost and accessible candidates for preparing novel and highly porous hyper-cross-linked polymers possessing hierarchical architectures, versatile functionalities, enhanced gas uptake capacities and adsorption selectivities.…”

“…The data summarized in Table 3 show that the CO 2 /N 2 sorption selectivities are about 20.16, 19.84, and 19.02 at 273.15 K, which theoretically drop to 15.71, 18.12, and 18.00 at 298.15 K from polymer 1 to polymer 3 , respectively. Notably, among the polymers, polymer 1 shows the best sorption selectivity of CO 2 over N 2 at 273.15 K. Although this value is much lower than those of PVA/PAA-C 3 H 7 (341), 67 PVAm/PZEA-Pro/PZEA-Sar (210), 68 MPC-500 (140), 69 PIP-CMC/TMC (119), 70 and PIM-PI-1 (57.2), 71 the CO 2 /N 2 value of polymer 1 is comparable or exceeds those of CTFs (14.2–20.3), 72 PPFs (14.5–15.4), 73 MF-168-600 (16), 74 and PIM-1 S A / S B (12.7) 75 at 273.15 K and HC PPO-Br (20), 76 CCP-6 (17), 77 UiO-66 (16.7), 78 Sg (9.9), 79 and SBL-MIP-C-800 (9.5) 80 at 298.15 K. Likewise, the data collected in Table 3 show that the CO 2 /CH 4 sorption selectivities are theoretically predicted to be about 41.84, 40.22, and 35.08 at 273.15 K and 35.98, 36.14, and 33.64 at 298.15 K for polymer 1 to polymer 3 , respectively. Notably, polymer 1 among these polymers exhibits the highest gas adsorption selectivity of CO 2 over CH 4 at 273.15 K, which is superior to those of Tg-AzoCOF (37), 81 NGA (21.4), 82 MOPI-6-0.5 (18), 83 BOP-1 (5.48), 84 and NPC-1 (3.8) 85 at 273.15 K, and S-D-1.6 (34), 86 CuDTTA (29), 87 PIM-Cardo-TOT (25.5), 88 Cu-1 (9), 89 and Ni-MOF (2.9) 90 at 298.15 K. In addition, it should be particularly pointed out that the selective uptake of CO 2 over N 2 and CH 4 is mainly induced by the strong dipole–quadrupole interaction between the structurally accessible polar functional groups, heteroatoms and CO 2 molecules as well as the quadrupole–quadrupole interactions among the CO 2 molecules.…”

Highly Selective Physical/Chemical CO2 Separation by Functionalized Fe3O4 Nanoparticles in Hollow Fiber Membrane Contactors: Experimental and Modeling Approaches

“…In this regard, the peaks at around 1615 and 1425 cm –1 were attributed to the stretching vibration of COO – and the carbonyl group of NHCOO – , respectively, in the structure of Fe 3 O 4 @SiO 2 -L NPs after CO 2 absorption. Further, a peak at around 2318 cm –1 shows the chemical reaction of amino acid salt and CO 2 and formation of carbamate on the structure of functionalized NPs. − …”

Optimization of toxic metal adsorption on DEA-calix[4]arene appended silica resin using a central composite design

“…Immobilization of a calix[n]arene framework onto the silica surface can enhance its reusability and the quantity of functionalized derivative at the same time. 31 Hence, present study deals with the synthesis of a diethanolamine calix [4]arene (DEA-C4) based silica resin, its characterization and its application for the removal of toxic metal ions (Pb 2+ , Cd 2+ and Hg 2+ ). In order to achieve favourable results, the three most effective parameters, i.e., pH, concentration of the metal ion and adsorbent dosage, were optimized by assessment of central composite design.…”