Kinetics, isotherms, and thermodynamic studies of Cu (II) adsorption on titanium oxide nanotubes

International audience ; In the present work, titanium oxide nanotubes (TON) were synthesized at the nano-size using the alkaline hydrothermal method and then used to remove Cu(II) ions, by adsorption, from water. The kinetic study of the adsorption of Cu (II) cations on titanium oxide nanotubes was carried out to estimate the amount adsorbed as a function of time and determine the time for maximum adsorption. The results showed that the kinetic equilibrium is reached after a time that increases with the initial concentration of Cu(II). The kinetics and isotherm are studied, considering the effects of different parameters (initial concentration, contact time, pH, and temperature). The pseudo-second-order model perfectly described the adsorption kinetics over the whole concentration range studied. The equilibrium data revealed that the Langmuir isotherm is the best-fitted isotherm. Cu(II) adsorption on TON was pH-dependent. The optimal pH value for Cu (II) adsorption onto TON was 4.5 (for an initial concentration of Cu(II) of 0,283 mmol L-1). The study of the effect of temperature on the adsorption kinetics allowed deducing that it was an endothermic process.