Physicochemical and microtextural characterization of activated carbons produced from water steam activation of three bamboo species

The bamboo species Guadua angustifolia, Bambusa vulgaris striata and Bambusa oldhamii, were used as raw materials to obtain sixteen activated carbons. The physicochemical characterization showed wide adsorption capacity values (measured as iodine number) ranging from 280 to 1500 mg/g, activation yields from 80 to 85%, average point of zero charge ≈9.9 and high content of quinonic surface groups. The influence of the bamboo species, particle size, time and temperature on the final surface properties was analysed using factorial experimental design methodology. Results indicated that the maximum adsorption capacity was achieved with B. vulgaris striata and 4 h of activation time. The content of superficial oxygenated acidic groups on the samples were identified as the result of the third order interaction (raw material, time and temperature) allowing the control of the surface polarity on the final activated carbons. The scanning electron microscopy micrographs showed the shape conservation of the raw material after carbonization and activation stages. Transmission electron microscopy examinations suggest that structure of the prepared material is formed by highly disordered graphene-like layers as it was confirmed with the diffuse diffraction rings observed by selected area diffraction pattern and the shape of the carbon-K energy-loss near edge structure.

► Activated carbons from G. angustifolia, B. vulgaris striata and B. oldhamii were obtained.
► The two stage process: carbonization-activation increased the adsorption capacity up to 1500 mg/g.
► The use experimental design allowed to analyze their final characteristics.
► These materials showed a high content of quinonic groups.
► The produce ACs consist of highly disordered graphene-like layers, almost 100% sp2.