Adsorption characteristics and mechanism for K2Ti4O9 whiskers removal of Pb(II), Cd(II), and Cu(II) cations in wastewater

Adsorption is an effective method to remove heavy metal from water. Here, this paper reported that potassium titanate whiskers exhibit excellent performance for adsorbing heavy metals in wastewater. Potassium tetratitanate whiskers were successfully prepared by the improved solid phase method. The adsorption kinetics, adsorption isotherm, competitive adsorption and regeneration performance for Pb(II), Cd(II), and Cu(II) cations were studied. During the static adsorption process, the maximum saturated adsorbed amount of Pb(II), Cd(II), and Cu(II) cations were up to 319 mg/g, 247 mg/g, 185 mg/g, respectively. The kinetic characteristics were suitable for pseudo-second-order model description, and the isothermal characteristics could be explained by Freundlich model. The adsorption mechanism showed that surfaces and pores of 4-PTW are important adsorption areas, and the results of XRD and XPS proved the unique layered structure of K 2 Ti 4 O 9 enabled the exchange of K(I) cations with heavy metal cations. The competitive adsorption results that the heavy metal cations with a small radius and strong electronegativity were easier to be captured by 4-PTW. The adsorption capacity retained more than 70% after five cycles, shows a good recycling performance. In summary, the adsorption performance of potassium titanate whiskers was evaluated and the adsorption mechanism was explained. • The adsorption capacity reached 319 mg/g, 247 mg/g, and 185 mg/g for Pb(II), Cd(II), and Cu(II) cations, respectively. • The adsorption mechanism includes cation exchange, pores accumulation, and surface adsorption. • Easy desorption and good cyclicity. • 4-PTW tends to trap cation with smaller radii and high electronegativity.