Adsorption of thorium(IV) on magnetic multi-walled carbon nanotubes

The influences of pH, contact time, solid-liquid ratio, temperature and C-60(C(COOH)(2)) (n) on Th(IV) adsorption onto the magnetic multi-walled carbon nanotubes (MMWCNTs) were studied by batch technique. The dynamic process showed that the adsorption of Th(IV) onto MMWCNTs could reach equilibrium in 40 h and matched the pseudo-second-order kinetics model. The adsorption of Th(IV) onto MMWCNTs was significantly dependent on pH values, the adsorption ratio increased markedly at pH 3.0-5.0, and then maintained a steady state as pH values increased. At low pH, different C-60(C(COOH)(2)) (n) content could enhance the adsorption content of Th(IV) onto MMWCNTs, but restrained it at higher pH. Through simulating the adsorption isotherms by Langmuir, Freundlich and Dubini-Radushkevich models, it could be seen respectively that the adsorption pattern of Th(IV) onto MMWCNTs was mainly surface complexation, and that the adsorption process was endothermic and irreversible.