Lignin derived absorbent for efficient and sustainable CO2 capture

The novel and efficient lignin-based CO 2 bio-adsorbent was fabricated by Mannich reaction, which verified the synergistic absorption mechanism of CO 2 based on multiple active sites. High and cost-efficient capture of CO 2 is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges ( e.g . high cost, low efficiency, less sustainability, etc .) of existing petroleum-based CO 2 absorbents, herein, a class of efficient and sustainable lignin-based absorbents were resoundingly prepared by grafting the active amine group on a lignin derived compound vanillin and alkali lignin. The results demonstrated that vanillin modified by acrylamide achieved the excellent absorption capacity among the three adsorbents, whose ability was 0.114 g CO 2 per gram of absorbent under 25 °C and 100 kPa. In addition, the absorbent retained stable absorbability of CO 2 after 6 cycles. The absorbing capacity of the absorbent formed by the coupling of vanillin and acrylamide to CO 2 was much greater than their own ( i.e. 0 g CO 2 ∙g –1 vanillin, 0.01 g CO 2 ∙g –1 acrylamide, respectively). Detailed information revealed the multi-site synergistic absorption mechanism, in which CO 2 has C and O double interactions with the amide group of the absorbent, and single interaction with the hydroxyl oxygen on the benzene ring of the absorbent. The absorption capacity of modified lignin for CO 2 is as high as 0.12 g CO 2 per gram of absorbent, which is comparable with that of model compound vanillin. This work not only provides a new idea for the design of bio-absorbents for CO 2 capture, but explores the application potential of lignin-based materials.