CO2 capture and microwave absorption by pine sawdust biochars obtained via molten salt pyrolysis

CO 2 emission and electromagnetic pollution have attracted increasing concern worldwide due to their threats to the environment and human health. Due to the low cost and abundant source, pine sawdust (PS) biochar, prepared via salt-assisted pyrolysis , is employed for CO 2 capture and microwave absorption. Effect of LiCl melt on adjusting the surface functionality, porosity, and carbon structure of the PS biochar is addressed. Impact of pyrolysis temperature on the performances of PS biochars toward CO 2 capture and microwave absorption are investigated. CO 2 adsorption capacity increases at first and decreases subsequently as the temperature rises. MPS700 displays the biggest CO 2 uptake of 2.79 mmol/g, optimal minimum microwave reflection loss ( RL min ) of −50.2 dB, and maximum effective absorption bandwidth (EAB) of 6.05 GHz at thickness of 2.6 mm, which are likely attributed to its biggest specific surface area and highest contents of active oxygen and defective carbon. • Molten salt pyrolysis enriches the pores, active O and carbon defects for biochars. • Temperature visibly affects the structure and performance of pine sawdust biochars. • MPS700 outperforms PS700 toward CO 2 capture and microwave absorption.