Tetraethylenepentamine-modified sugarcane bagasse (SCB) was prepared to improve its adsorption capacity and selectivity toward Cu2+. Adsorption performances of the modified sorbent for Cu2+ were studied in batch system. Separation of Cu2+ from Pb2+ by the modified sorbent fixed-bed column were studied under dynamic system with initial molar concentration ratio $$\left( {C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} } \right)$$ C 0 Cu / C 0 Pb ranging from 1:1 to 1:100. The amount of Cu2+ and Pb2+ adsorbed on the saturated column was calculated by the elution curve. Batch experimental results showed that the adsorption capacity of the sorbent for Cu2+ increased from 0.12 to 0.21 mmol g−1 after modification. Dynamic adsorption results showed that the modified SCB had higher adsorption affinity toward Cu2+ than Pb2+. 0.07 mmol g−1 of adsorbed Pb2+ was pushed off by Cu2+ during the competitive adsorption process at $$C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} = {\text{1:1}}.$$ C 0 Cu / C 0 Pb = 1:1 . The breakthrough curves and adsorption kinetics of Cu2+ in the column could be fitted well by the Yoon–Nelson and modified Yoon–Nelson model, respectively. According to the elution curve, the amount of Cu2+ adsorbed on the fixed-bed column were 0.16, 0.16 and 0.15 mmol g−1, while that of Pb2+ were 0.0016, 0.0051 and 0.0094 mmol g−1 when $$C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}}$$ C 0 Cu / C 0 Pb increased from 1:1 to 1:10 and 1:100. Cu2+ could be selectively adsorbed and separated from Pb2+ by using the modified sorbent fixed-bed column.