Kinetics and equilibrium isotherms of adsorption of Pb(II) and Cu(II) onto raw and arginine-modified montmorillonite

Arg-Mt, was fabricated by modifying sodium montmorillonite (Na-Mt) with Arginine monohydrochloride (Arg salt), to adsorb Pb(II) and Cu(II) in aqueous solution. The X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectrum, thermal analysis (TG/DTG), Brunauer-Emmett-Teller (BET) and Scanning electron microscope (SEM) were employed to investigate the properties of Na-Mt and ArgMt. The effects of the amount of modifier, pH value, the initial concentration of M(II), temperature and contact time were tested in a single adsorption system. The isotherm model was well matched with the Langmuir curve and the kinetic adsorption fitted well with the pseudo-second-order rate equation. The saturated adsorption of Pb(II) and Cu(II) by Arg-Mt were 124.69 and 29.15 mg/g, respectively, which were higher than that of Na-Mt (89.08 and 23.93 mg/g). The thermodynamic equation indicated that the adsorption process was spontaneous, endothermic, and the randomness of the samples changed a little after adsorption. The adsorption capacity of heavy metal ions in the binary co-adsorption system was poor than single adsorption system. Furthermore, the adsorbed M(II) onto Arg-Mt can hardly be dissolved under weak acidic condition (pH > 4) according to the desorption experiments. High-efficiency and low-cost make Arg-Mt to be used in the removal of heavy ions in aqueous solution. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.