Gaseous formaldehyde adsorption by eco-friendly, porous bamboo carbon microfibers obtained by steam explosion, carbonization, and plasma activation

To develop an eco-friendly biomass adsorbent for indoor formaldehyde, porous bamboo carbon microfibers (BCMFs) with different types and contents of oxygen (O)-containing and nitrogen (N)-containing functional groups were firstly prepared by combining high-pressure steam explosion, carbonization, and plasma activation. The BCMF adsorbents were characterized, and their adsorption performance and mechanism were evaluated and theoretically calculated. BCMF carbonized at 800 degrees C (BCMF-800) showed the highest specific surface area of 526.862 m2 g- 1. The surfaces of the BCMFs were etched, with many additional micro/nanoscale pores and cavities. Functional groups, including O-C--O, C-O, C--O, quaternary N, oxidized N, pyridinic N, amine N, and pyrrolic N were successfully introduced by plasma activation at various powers and atmospheres. BCMF-800 samples activated by O2 plasma at 240 W (BCMF-800-O-240) and by N2 at 120 W (BCMF-800-N-120) exhibi-ted the highest formaldehyde adsorption capacities (179.53 mg g- 1 and 205.28 mg g-1), which were 85.90 % and 112.50 % higher than that of BCMF-800, respectively. The samples introduced by carboxyl and pyrrolic N showed the highest adsorption energies (-14.54 kcal mol-1 and-11.58 kcal mol-1) with an increase of 83.82 % and 46.40 %, respectively, compared with the control, which were proved to be the optimal O-containing and N-containing functional groups for enhancing formaldehyde adsorption. This work provides a new insight into the natural biomass-based adsorbents for gaseous formaldehyde with a clean and eco-friendly preparation and modification process.