Amination on Porous Cellulose Aerogel for Direct CO2 Capture from Atmosphere Air

Given the substantial emissions of carbon dioxide (CO2) into the atmosphere, currently at a level of over thirty billion metric tons annually, there is a critical need of effective CO2 adsorbents at scale, ideally derived from abundant natural resources as sustainable materials. In this work, microcrystalline cellulose (MCC) derived from cotton was used to fabricate cellulose aerogel as porous support via a NaOH/urea-based dissolution and regeneration process, followed by surface modification with a series of amino silane coupling agents to produce aminated cellulose aerogel as CO2 adsorbent. The as-synthesized optimal adsorbent exhibited a high CO2 sorption capacity of up to 1.5 mmol/g and 1.3 mmol/g at 0 °C and 25 °C at 1 bar, respectively. Notably, in-depth analysis showed that the adsorbent achieved an impressive capacity of CO2 uptake of 0.65 mmol/g at 25 °C at an exceptionally low CO2 pressure of 0.4 mbar, i.e., under ambient CO2 pressure. It implies its potential use as adsorbent both for the traditional point-source capture and the direct air capture as an emerging negative emission technology. This study underscores the environmentally friendly, cost-effective, and biosourced attributes of aminated cellulose aerogel as a compelling alternative for carbon capture, contributing to global initiatives combating CO2 emissions and stressing the key role of sustainable materials in tackling this global environmental challenge.