In this investigation, MCM-41/N-(3-trimethoxysilyl)-propyl)diethylenetriamine (MCM-41/TMSPDETA) adsorbent was prepared via co-condensation method and characterized by FTIR, BET, XRD, TEM, SEM and DLS analytical techniques. Experiments were carried out to investigate the influence of different sorption parameters, such as pH, adsorbent dosage, contact time, initial concentration of heavy metal ions and solution temperature in a batch system. Optimum conditions of sorption experiments were obtained at 20°C with the pH of 6.0 and contact time of 60 min for Pb(II) and 120 min for Ni(II). The pseudo-first-order, the pseudo-second-order and intraparticle diffusion models have been used to analyze the sorption kinetic results. The sorption process was found to be well described by the pseudo-second-order rate model. The Langmuir and Freundlich isotherms have been used to describe the equilibrium sorption; the adsorption data obeyed the Langmuir isotherm. The maximum capacity of the nanosorbent was 77.52 and 58.47 mg g−1 for Pb (II) and Ni (II) ions, respectively. In order to verify the nature of sorption processes as physical or chemical, the equilibrium data were also fitted to the Dubinin-Radushkevitch (D–R) model. Based on D–R isotherm results, the values of mean free energy were 13.36 and 9.13 kJ mol−1 for Pb(II) and Ni(II) sorption, respectively. These values of E (kJ mol−1) indicating chemical sorption for both metal ions. The selectivity order of lead and nickel sorption onto the adsorbent was Pb(II) > Ni(II).

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