In this work, carboxyl functionalized magnetite nanopartides (CMNPs) are developed for the adsorption of Pb(II), Cd(II), and Cu(II). The characterization of CMNPs was performed by Fourier transform infrared spectroscopy, powder X-ray diffraction, and transmission electron microscopy. Studies show that the adsorption kinetics are found to follow the pseudo-second-order kinetic model. The experimental equilibrium adsorption data are fitted well to the Freundlich model. The maximum adsorption capacity at 25 degrees C could reach up to (74.63, 45.66, and 44.84) mg g(-1) for Pb(II), Cd(II), and Cu(II), respectively. Thermodynamic analyses show that the adsorption is exothermic and spontaneous, and thermodynamic parameters, Delta G, Delta H, and Delta S, are calculated. In addition, CMNPs can be used as the recyclable adsorbent for the adsorption of Pb(II), Cd(II), and Cu(II) from aqueous solutions.