Novel　biosorbents,　graft　copolymers,　were　prepared　via　Mannich　reaction　from　enzymatic　hydrolysis　lignin　with　glycine　and　cystine,　respectively.　The　element　content,　FT-IR　and　fluorescence　spectra,　relative　viscosity,　and　particle　size　of　the　copolymers　were　systematically　investigated.　Furthermore,　effects　of　initial　pH,　ionic　strength,　temperature,　contact　time　and　initial　metal　ion　concentration　on　the　biosorption　capacities　of　Cu(II)　and　Co(II)　ions　onto　the　copolymers　were　studied　using　batch　sorption　technique.　It　was　found　that　the　copolymers　exhibited　excellent　biosorption　characteristics　for　Cu(II)　and　Co(II)　ions.　The　sorption　kinetic　data　can　be　described　well　with　a　pseudo-second-order　model,　and　the　equilibrium　data　can　be　fitted　well　to　the　Langmuir　and　Freundlich　isotherm　for　Cu(II)　and　Co(II)　biosorption　process,　respectively.　Surface　complexation　and　ion-exchange　modeling　were　performed　to　elucidate　the　biosorption　mechanism　involved　because　surfaces　of　the　copolymers　contained　three　main　types　of　acid/base　sites　from　the　amino　acid　grafted　copolymer　units.　©　2011　Elsevier　Ltd.