Co-pyrolysis of pine sawdust with aluminum dross for immobilization of heavy metal and enhancing hydrogen generation

Abstract

Co-pyrolysis of pine sawdust with aluminum dross (AD) for harvesting energy product and safely treated AD-biochar composite was investigated in this work. The catalytic pyrolysis experiment was carried out in a fixed bed reactor. The pyrolysis products were analyzed by gas chromatography (GC), gas chromatography coupled with a mass spectrometer (GC–MS), and solid C-13 Nuclear Magnetic Resonance (13C NMR). The results show that the heavy metals, such as Cu, were immobilized by organic metal-chelating structures as carbon–oxygen-metal (C–O–M) bonds in the AD-biochar composite. In addition, the hydrogen yield from catalytic pyrolysis of pine on AD reaches 131.86 ml/g, significantly higher than the 98.97 ml/g from pure pine pyrolysis. The enhanced hydrogen production is elaborated by the intermediate hybrid mechanism with formation of C–O–M intermediates between the metallic oxides in AD and the oxygen containing functional groups in biomass. Meanwhile, the CO2 yield decreases from 23.68 ml/g to 16.41 ml/g while the CO yield reduces from 49.72 ml/g to 46.85 ml/g. These results may guide to a new exploration on simultaneous treatment of hazardous industrial wastes and utilization of biomass.