Influence of pyrolysis temperature on the characteristics and lead(II) adsorption capacity of phosphorus-engineered poplar sawdust biochar

•KH2PO4-modified biochar (BCP) from poplar sawdust was prepared at different temperature.•KH2PO4 modification increased C retention but decreased surface area of biochar.•Formation of Pb(PO3)2)n, Pb5(PO4)3OH and PbHPO4 contributed to enhance Pb(II) removal by BCP.•Enhanced Pb(II) adsorption by BCP occurred at high Pb(II) concentration.•BCP produced at 300 °C exhibited the maximum Pb(II) adsorption capacity (154.7 mg g−1).