Influence of biomass components, temperature and pressure on the pyrolysis behavior and biochar properties of pine nut shells

The aim of this work was to compare the yields, proximate composition, structure and surface morphology of biochar derived from lignin, cellulose, hemicellulose and pine nut shell (PNS) at 400-700 degrees C. PNS biochars obtained at different pyrolysis pressures in the range of 0.1-2.0 MPa were also studied. The results indicate that the interactions of lignin, cellulose and hemicellulose have smaller effects on the ash content, yield and higher heating value (HHV) of the biochar than they do on the fixed carbon and volatile matter contents. Increasing the pyrolysis temperature improves the HHV of the biochar, and increasing the pyrolysis pressure enhances the biochar yield, surface functional groups and combustion characteristics. The kinetic data for Pb2+ adsorption are best fitted by a pseudo-second-order model, indicating a chemisorption-controlled process. The PNSB550 and PNSB1.0 data are optimally fit by the Freundlich and Langmuir models, respectively. The maximum Pb2+ adsorption capacity is 237.3 mg/g.