Immobilization of Cu(II), Pb(II) and Cd(II) by the addition of rice straw derived biochar to a simulated polluted Ultisol

► The incorporation of biochar made the Ultisol surface charge more negative. ► The Ultisol pH increased markedly after addition of biochar. ► The acid soluble Cu(II) and Pb(II) decreased significantly after biochar amended. ► High adsorption affinity of functional groups on biochar to Cu(II) was found.