ORIGINAL PAPER Impact of biochar produced from post-harvest residue on the adsorption behavior of diesel oil on loess soil Yu Feng Jiang . Hang Sun . Uwamungu J. Yves . Hong Li . Xue Fei Hu Received: 28 December 2014 / Accepted: 7 May 2015 / Published online: 17 May 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract The primary objective of this study was to investigate the effect of biochar, produced from wheat residue at different temperatures, on the adsorption of diesel oil by loess soil. Kinetic and equilibrium data were processed to understand the adsorption mechan- ism of diesel by biochar-affected loess soil; dynamic and thermodynamic adsorption experiments were conducted to characterize this adsorption. The surface features and chemical structure of biochar, modified at varying pyrolytic temperatures, were investigated using surface scanning electron microscopy and Fourier transform infrared analysis. The kinetic data showed that the adsorption of diesel oil onto loess soil could be described by a pseudo-second-order kinetic model, with the rate-controlling step being intraparti- cle diffusion. However, in the presence of biochar, boundary layer control and intraparticle diffusion were both involved in the adsorption. Besides, the adsorption equilibrium data were well described by the Freundlich isothermal model. The saturated adsorption capacity weakened as temperature in- creased, suggesting a spontaneous exothermic pro- cess. Thermodynamic parameter analysis showed that adsorption was mainly a physical process and was enhanced by chemical adsorption. The adsorption capacity of loess soil for diesel oil was weakened with increasing pH. The biochar produced by pyrolytic wheat residue increased the adsorption behavior of petroleum pollutants in loess soil. Keywords Biochar Á Diesel oil Á Loess soil Á Adsorption kinetics Á Adsorption thermodynamics Introduction Petroleum substances have seriously polluted the environment, especially soil ecosystems, during their mining, refining, storage, transport, and use. Petro- leum pollutants percolating through the soil damage the soil structure and reduce soil permeability to nutrients and water, and pollutants residing in the soil will be adsorbed by minerals and organic matter. The behaviors and fate of petroleum pollutants can be greatly affected by soil adsorption and the natural organic matter in soil (Delle Site 2001). The most widely used petroleum products are gasoline and diesel oil (Khalladi et al. 2009). Biochar is a ubiquitous form of black carbon comprising polyaromatic and elemental or graphitic carbon, as compared with organic carbon, which forms covalent bonds with other elements (Chun et al. 2004; Mohan et al. 2014). Biochar can effectively improve soil nutrient availability, crop production, and soil Y. F. Jiang (&) Á H. Sun Á U. J. Yves Á X. F. Hu School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China e-mail: Jiangyf7712@126.com H. Li Lancaster Environment Centre, University of Lancaster, Lancaster LA1 4YQ, UK 123 Environ Geochem Health (2016) 38:243–253 DOI 10.1007/s10653-015-9712-1