Carbon materials such as nanoparticles have provided new solutions for the removal of various environmental contaminants. In this work, two carbon nanomaterial-biochar nanocomposites (SG-PySA-CNT and SG-PySA-GO) were derived from sweetgum biomass pretreated with carbon nanotubes (CNTs) and graphene oxide (GO) through slow pyrolysis at 600 degrees C. Both SG-PySA-CNT and SG-PySA-GO had higher surface area but much lower pore volume than the pristine biochar (SG). Batch sorption experimental results showed that SG-PySA-CNT and SG-PySA-GO had greater sorption ability to Pb(II) and Cd(II) from aqueous solution than SG. SG-PySA-GO was the best sorbent with maximum sorption capacities higher than 40 and 10 mg g(-1) for Pb(II) and Cd(II), respectively. The enhanced metal sorption by the biochar nanocomposites could be mainly attributed to the excellent sorptive properties of the carbon nanoparticles (CNT/GO) distributed and stabilized on the biochar surfaces within the matrix. Because of its facile synthesis and good sorptive properties, biochar-supported CNT and GO nanocomposites have great potential to be used in various environmental applications for the removal of metal and metalloid contaminants.