Influence of Pyrolysis Temperature on Characteristics and Nitrobenzene Adsorption Capability of Biochar Derived from Reed and Giant Reed

摘要

A series of biochar was prepared by pyrolyzing giant reed (Arundo donax) and reed (Phragmites communis), the emergent plants growing in wetland, at temperatures ranging from 300 degrees C to 700 degrees C under nitrogen condition. The structures of biochar was characterized by thermogravimetric analysis (TG-DTG), elemental composition (C, H, N, O), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and BET-N-2 surface area analysis. The nitrobenzene was taken as adsorbed substance to investigate the adsorption properties of giant reed, reed derived biochar for organic pollutant in aqueous solution, and model the adsorption kinetic. The results showed that when the pyrolysis temperature increased from 300 degrees C to 700 degrees C, the surface areas of giant reed and reed biochar increased from 1.53 m(2)/g (GR300) and 2.52 m(2)/g (R300) to 7.62 m(2)/g (GR700) and 8.91 m(2)/g (R700), respectively. The oxygen-containing functional groups and aliphatic components reduced continuously, and the polarity decreased whereas the aromaticity increased, moreover, the pore structure became more abundant. The adsorption experiment showed that the adsorption amount of biochar increased with the increase of carbonization temperature, the final equilibrium adsorption ratios of giant reed and reed biochar were 99.9% (GR700) and 99.5% (R700), respectively. The excess adsorption amount of the adsorbents GR700 and R700 to nitrobenzene were 13.59 mg/g and 13.52 mg/g at 25 degrees C. Furthermore, the adsorption process of giant reed derived biochar can be well described by pseudo-second-order kinetic model, while adsorption dynamic of reed derived biochar fit well with pseudo-first-order kinetic model.