Sorption of polycyclic aromatic hydrocarbons by biochars of wheat straw with different pyrolysis temperatures

Abstract

This study investigated the sorption kinetics of a model solute (phenanthrene and pyrene) with a series of biochars prepared from wheat straw at 100-700 °C (referred as BC100-BC700) to probe the effects of biochars produced at different pyrolysis temperatures on sorption of phenanthrene and pyrene. The samples were characterized by the elemental compositions, Fourier transform IR spectroscopy, and Brunauer-Emmett-Teller-N2 surface areas. The results showed that the sorption parameters (N and lgKf) are linearly related to sorbent aromaticity and the total surface areas, which increase with the pyrolysis temperature. Sorption mechanisms of biochars are evolved from partitioning-dominant at low pyrolysis temperatures to adsorption-dominant at higher pyrolysis temperatures.