Activated carbon microspheres derived from hydrothermally treated mango seed shells for acetone vapor removal

Abstract

Mango fruit seed shells were used as starting materials to produce activated carbons for the capture of acetone, a typical volatile organic compound (VOC), from gaseous streams. This fruit waste presents high volatiles and low ashes contents, as expected for the lignocelulosic materials commonly used for the preparation of activated carbons. The starting material was hydrothermally treated at 180 or 250 °C for 5 h and the obtained hydrochars were activated with KOH solutions. The carbon samples were characterized by SEM, EDX, TG/DTA, Raman spectroscopy and textural analysis by physisorption. The adsorption capacity and adsorption cycles were investigated by TG. The hydrochars presented spherical morphology and the activated carbons derived from them presented heterogeneous micropore structures allowing to high capacity of acetone vapor removal, namely 472 mg/g, at 30 °C and 363 mg/g, at 50 °C. The results indicate that the adsorption capacity of the activated carbons is directly related to their Dubinin-Astakhov micropore surface areas and microporous volumes determined by NLDFT. The adsorption of acetone vapor showed a pseudo-first order kinetics and both external and intra-particle transport contributed for the overall process. Highly efficient and stable acetone vapor removal was observed over the activated carbons after five cycles.