The use of fossil fuels for energy production is accompanied by carbon dioxide release into the environment causing catastrophic climate changes. Meanwhile, replacing fossil fuels with carbon-free nuclear energy has the potential to release radioactive iodine during nuclear waste processing and in case of a nuclear accident. Therefore, developing efficient adsorbents for carbon dioxide and iodine capture is of great importance. Two nitrogen-rich porous polymers (NRPPs) derived from 4-bis-(2,4-diamino-1,3,5-triazine)-benzene building block were prepared and tested for use in CO and I capture. Copolymerization of 1,4-bis-(2,4-diamino-1,3,5-triazine)-benzene with terephthalaldehyde and 1,3,5-tris(4-formylphenyl)benzene in dimethyl sulfoxide at 180 °C afforded highly porous NRPP-1 (SA = 1579 m g) and NRPP-2 (SA = 1028 m g), respectively. The combination of high nitrogen content, π-electron conjugated structure, and microporosity makes NRPPs very effective in CO uptake and I capture. NRPPs exhibit high CO uptakes (NRPP-1, 6.1 mmol g and NRPP-2, 7.06 mmol g) at 273 K and 1.0 bar. The 7.06 mmol g CO uptake by NRPP-2 is the second highest value reported to date for porous organic polymers. According to vapor iodine uptake studies, the polymers display high capacity and rapid reversible uptake release for I (NRPP-1, 192 wt % and NRPP-2, 222 wt %). Our studies show that the green nature (metal-free) of NRPPs and their effective capture of CO and I make this class of porous materials promising for environmental remediation.

Tuning the binding affinity of small gases and their selective uptake by porous adsorbents are vital for effective CO2 removal from gas mixtures for environmental protection and fuel upgrading. In this study, an amine-functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized by a combination of pre- and postsynthetic modification techniques in two steps. Presynthetic incorporation of nitro groups resulted in stoichiometric functionalization (1 nitro/phenyl) in addition to noninvasive functionalization, where more than 80% of the surface area maintained compared to BILP-6. Experimental studies presented enhanced CO2 uptake and CO2/CH4 selectivity in BILP-6-NH2 compared to BILP-6, which are governed by the synergetic effect of benzimidazole and amine moieties. DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2 and confirmed the efficacy of amine groups. Encouraged by the enhanced uptake and selectivity in BILP-6-NH2, we have evaluated its performance in landfill gas separation under vacuum swing adsorption (VSA) settings, which resulted in very promising working capacity and sorbent selection parameters outperforming most of the best solid adsorbent in the literature.

Summary The present study reports the economic and sustainable syntheses of functional porous carbons for supercapacitor and CO2 capture applications. Lignin, a byproduct of pulp and paper industry, was successfully converted into a series of heteroatom‐doped porous carbons (LHPCs) through a hydrothermal carbonization followed by a chemical activating treatment. The prepared carbons include in the range of 2.5 to 5.6 wt% nitrogen and 54 wt% oxygen in its structure. All the prepared carbons exhibit micro‐ and mesoporous structures with a high surface area in the range of 1788 to 2957 m2 g−1. As‐prepared LHPCs as an active electrode material and CO2 adsorbents were investigated for supercapacitor and CO2 capture applications. Lignin‐derived heteroatom‐doped porous carbon 850 shows an outstanding gravimetric specific capacitance of 372 F g−1 and excellent cyclic stability over 30,000 cycles in 1 M KOH. Lignin‐derived heteroatom‐doped porous carbon 700 displays a remarkable CO2 capture capacity of up to 4.8 mmol g−1 (1 bar and 298 K). This study illustrates the effective transformation of a sustainable waste product into a highly functional carbon material for energy storage and CO2 separation applications.

Development of efficient sorbents for carbon dioxide (CO) capture from flue gas or its removal from natural gas and landfill gas is very important for environmental protection. A new series of heteroatom-doped porous carbon was synthesized directly from pyrazole/KOH by thermolysis. The resulting pyrazole-derived carbons (PYDCs) are highly doped with nitrogen (14.9-15.5 wt %) as a result of the high nitrogen-to-carbon ratio in pyrazole (43 wt %) and also have a high oxygen content (16.4-18.4 wt %). PYDCs have a high surface area (SA = 1266-2013 m g), high CO Q (33.2-37.1 kJ mol), and a combination of mesoporous and microporous pores. PYDCs exhibit significantly high CO uptakes that reach 2.15 and 6.06 mmol g at 0.15 and 1 bar, respectively, at 298 K. At 273 K, the CO uptake improves to 3.7 and 8.59 mmol g at 0.15 and 1 bar, respectively. The reported porous carbons also show significantly high adsorption selectivity for CO/N (128) and CO/CH (13.4) according to ideal adsorbed solution theory calculations at 298 K. Gas breakthrough studies of CO/N (10:90) at 298 K showed that PYDCs display excellent separation properties. The ability to tailor the physical properties of PYDCs as well as their chemical composition provides an effective strategy for designing efficient CO sorbents.

A novel luminescent azo-linked polymer (ALP) has been constructed from 1,3,6,8-tetra(4-aminophenyl)pyrene using a copper(I)-catalyzed oxidative homocoupling reaction. The polymer displays high porosity with a Brunauer–Emmett–Teller surface area of 1259 m 2 g –1 and narrow pore size distribution (1.06 nm) and is able to take up a significant amount of CO 2 (2.89 mmol g –1 ) at 298 K and 1.00 bar with a high isosteric heat of adsorption of 27.5 kJ mol –1 . Selectivity studies applying the ideal adsorbed solution theory revealed that the novel polymer has moderately good selectivities for CO 2 /N 2 (55.1) and CO 2 /CH 4 (10.9). Furthermore, the ALP shows fluorescence quenching in the presence of Hg 2+ , Pb 2+ , Tl + , and Al 3+ ions. Compared with these ions, the ALP showed no sensitivity to light metal ions such as Na + , K + , and Ca 2+ in ethanol–water solution, clearly indicating the high selectivity of the ALP toward heavy metal ions. The exceptional physiochemical stability, high porosity, and strong luminescence make this polymer an excellent candidate as a fluorescent chemical sensor for the detection of heavy metal ions.