Properties of Sunflower Straw Biochar Activated Using Potassium Hydroxide

Biochar is a kind of carbon material with a wide range of sources; it has attracted considerable attention because of its abundant resources and low cost. Potassium hydroxide (KOH) is a strong alkali activator that can effectively change the surface chemical properties and microstructure of biochar. Biochar activated by KOH has a large specific surface area (SSA) and a rich pore structure. Herein, sunflower straw was used as a raw material and KOH as an activator to investigate the preparation of sunflower straw biochar activated by KOH. The effects of synthetic conditions on the performance and structure of the resulting biochar materials were comprehensively analyzed. The final activation conditions were as follows: the impregnation ratio, activation time, and activation temperature were 2:1, 2 h, and 900 °C, respectively. The composition and structure of the prepared biochar were characterized. It was observed by SEM that the surface of the activated biochar became rougher. FTIR, XRD, XPS, and Raman characterization showed that the aromaticity and graphitization degree of the activated biochar increased. The activation process of biochar was analyzed via multiple techniques, aiming to lay the foundation for the wide application of biochar materials.