Characterization and Sodium Sorption Capacity of Biochar and Activated Carbon Prepared from Rice Hus

Abstract

Biochar and activated carbon, as carbon-rich porous materials, have wide environmental applications. In the present research , rice husk (RH) was used for preparation of biochar at 400, 600, and 800 °C unde r simple pyrolysis, physically- activated carbon with water steam, chemically-activ ated carbon with potassium hydroxide (KOH), and physiochemically-activated car bon with KOH and steam. Physical and chemical properties of biochar and activated ca rbons were characterized using nitrogen adsorption–desorption isotherm, Fourier tr ansform, infra-red analysis, and Boehm method. The results showed that carbonization temperature and activation agents had significant effects on the characteristics of t he samples. Activated carbon produced by KOH activation had the highest surface area (2201 m 2 g -1 ) and total pore volume (0.96 cm 3 g -1 ). High concentration of sodium (Na) is an importan t limiting factor to reuse poor quality water resources in arid and semiarid region s. The sorption capacity of biochars and activated carbons was investigated by performin g batch sorption experiments using Na as adsorbate. Na sorption was increased with inc reasing surface area and pore volume. The highest Na sorption capacity of 134.2 m g g -1 was achieved by the KOH activated carbon, which has the highest surface are a and pore volume. The kinetic data were well-fitted to pseudo-first order and intra-pa rticle diffusion models . Keywords: Adsorbent, Diffusion models, Nitrogen isotherm, Ph ysiochemical characteristics, Sorption isotherm.