Development and CO2 capture of nitrogen-enriched microporous carbon by coupling waste polyamides with lignocellulosic biomass.

Due to the substantial emissions of global CO2, there has been growing interest in nitrogen-enriched porous carbonaceous materials that possess exceptional CO2 capture capabilities. In this study, a novel N-enriched microporous carbon was synthesized by integrating waste polyamides with lignocellulosic biomass, involving carbonization and physicochemical activation. As-synthesized adsorbents demonstrated significant characteristics including a high specific surface area (1710 m2/g) and a large micropore volume (0.497 cm3/g), as well as abundant N- and O-containing functional groups, achieved through activation at 700 °C. They displayed remarkable CO2 capture capability, achieving uptake levels of up to 6.71 mmol/g at 1 bar and 0 °C, primarily due to the filling effect of narrow micropore along with electrostatic interaction. Furthermore, the adsorbent exhibited a rapid capacity for CO2 capture, achieving 94.9% of its saturation capacity within a mere 5 min at 30 °C. This impressive performance was accurately described by the pseudo second-order dynamic model. Additionally, as-synthesized adsorbents displayed a moderate isosteric heat of CO2 adsorption, as well as superior selectivity over N2. Even after undergoing five consecutive cycles, it maintained ∼100% of its initial capacity. Undoubtedly, such findings hold immense significance in the mitigation of global plastic pollution and greenhouse effect.

Facile and efficient chitosan-based hygroscopic aerogel for air dehumidification.

Sorption dehumidification, as an energy-saving and eco-friendly approach, has been emerging in application for air dehumidification. Here, a prospective method is proposed to prepare biomass-based hygroscopic aerogels that are easily applicable, sustainable, high-efficient, and recyclable. The chitosan-based aerogel with a porous and hydrophilic network acts as the carrier and water reservoir for the uniformly distributed lithium chloride hygroscopic salt, and provides the hygroscopic salt with more liberal water channels to facilitate moisture capture and transfer. As a consequence, the prepared chitosan/polyvinyl alcohol@lithium chloride (chitosan/PVA@LiCl) hygroscopic aerogel exhibits an excellent moisture absorption capacity of up to 2.77 g g-1 at a relative humidity of 90 %. Meanwhile, as the chitosan/PVA@LiCl aerogel is set in a closed space about 2200 times larger than its own volume, the relative humidity can be reduced from 90 % to 32 % within 2 h, and further lower to 25 % after 4 h. Furthermore, combined with multi-walled carbon nanotubes, the photothermal hygroscopic aerogel is obtained that can rapidly desorb water under sunlight, thus to realize energy-free cycle. Overall, the renewable biomass-based aerogel materials with the advantages of simple preparation and excellent hygroscopic performance provides a new path for the development of sorption dehumidification technology.

Cleanup of oils and organic solvents from contaminated water by biomass-based aerogel with adjustable compression elasticity.

Leakage of oils and organic solvents poses a significant threat to aquatic environments. Here, low-temperature carbonized aerogels with highly porous and anisotropic structures obtained only from biomass-derived materials were proposed to absorb polymorphic oils from contaminated water. Specifically, carbonized aerogels prepared at temperatures of 300 °C and 350 °C exhibited ultra-high absorption capacities (40‒125 g g-1) and oil-water separation efficiencies (> 99%) even in harsh environments, which were attributed to their exceptional properties, including high porosity, abundant macropores, excellent thermal stability, and hydrophobicity. Through citric acid crosslinking and low-temperature carbonization, the aerogels exhibited superior compression elasticity and could be cyclically utilized through simple extrusion while realizing the recovery of oils. Moreover, the outstanding photothermal conversion properties obtained through carbonization contributed to the high temperature and fluidity of the oils surrounding the aerogels, which is crucial for improving the absorption performance of high-viscosity oils. Such absorbent materials are used to separate crude oil from oil-water mixtures, which can achieve maximum absorption of 56 g g-1 and increase the absorption rate (from several days to 10 min) in a low-temperature (4 °C) seawater environment.