A functionalized carbonaceous material was prepared via hydrothermal carbonization (HTC) of biogas residues and denoted as hydrochar (HC). The obtained HC was used to synthesize a hybrid (Ni/Fe-HC) to conduct Pb(II) removal from aqueous solution. SEM images show that Ni-0/Fe-0 was anchored tightly to HC particles due to a cellular structure of HC formed during HTC. Complete Pb(II) removal (>99.5%) was achieved within 1.5 h using Ni/Fe-HC whereas more than 85% of Pb(II) remained in bulk solution after 10 h with bare HC. SEP results indicate that Pb(II) was mainly associated with the fraction bound to carbonates and Fe-Mn oxides in the spent Ni/Fe-HC particles. Consequently, the adsorptive precipitation and specific adsorption dominated Pb(II) removal by Ni/Fe-HC despite minor reduction of Pb(II) to Pb. However, the reduction of Pb(II) to Pb-0 was conducted by the catalytically generated atomic hydrogen rather than Ni/Fe nanoparticles as electron donor. Ni/Fe-HC not only acted as an effective adsorbent for Pb(II) but also played a role of catalyst to generate atomic hydrogen. HC prepared with biogas residues can be used as an excellent supporting material to prepare a hybrid of Ni/Fe-HC for Pb(II) removal. (C) 2016 Elsevier B.V. All rights reserved.