Preparation and characterization of activated carbons from biomass material - giant knotweed (Reynoutria sachalinensis)

Activated carbons from biomass material of giant knotweed Reynoutria sachalinensis (F. Schmidt ex Maxim.) Nakai were obtained. Use of this plant for manufacturing activated carbon has not been studied yet. Therefore, the first activated carbons of giant knotweed origin are described. Both physicochemical (by steam and CO2) and chemical (by KOH) activation methods were applied. Influences of temperature (500, 600, 700 and 800 degrees C), burn-off [10, 25 and 50 wt. % (daf)] and KOH concentration on pores surface area and volume distribution of the obtained activated carbons were explored. Porosity of the elaborated sorbents was determined by benzene and carbon dioxide sorption measurements. Sorbents obtained by steam activation were micro-and mesoporous with surface area and volume of pores increasing with temperature and burn-off to V = 0.351 cm(3) g(-1) and S = 768 m(2) g(-1) at 800 degrees C at 50% burn-off. Carbon dioxide activation resulted with notably microporous activated carbons with porous texture parameters also increasing with burn-off to V = 0.286 cm(3) g(-1) and S = 724 m(2) g(-1) at 50% burn-off. The highest BET surface area of 2541 m(2) g(-1) was achieved when chemical (KOH) activation was performed using KOH to char ratio 4:1.