Activated carbons from the Amazonian biomass andiroba shells applied as a CO2 adsorbent and a cheap semiconductor material

Amazonian andiroba shell was used as a non-expensive, renewable biomass resource to produce a porous activated carbon as a CO2 adsorbent and a cheap supercapacitor material. Activated carbons were prepared by CO2 physical activation of hydrochars obtained from hydrothermal carbon of biomass. The effect of activation times (1 h, 5 h, and 10 h) at 880 ºC on the physical characteristics of the activated carbons was investigated. A significant increase of surface area (from 616 to 1937 m2/g) with respect to the activation time was observed. AC-AND-5 h showed good microporosity, with the highest adsorption capacity of CO2 was obtained as 3.2 mmol/g and 6.1 mmol/g at 25 ºC and 0 ºC up to 1 bar, respectively. The sample AND-AC-5 h shows a good CO2/N2 selectivity and fast adsorption kinetics that be easily regenerated with superior cyclic stability after multiple cycles. Moreover, it proved that the photogenerated electrons and holes in wide band gap carbon can be easily transferred into carbon, resulting in a suppressed charge recombination. The best charge transfer processes was received for AC-AND-1 h sample.