Effect of cerium valence on As(V) adsorption by cerium-doped titanium dioxide adsorbents

In this study, three titanium dioxide (TiO2) adsorbents doped with Ce(III) (Ce3), Ce(IV) (Ce4) and H2O2 oxidized Ce(III) (Ce3O), respectively, were prepared and the effect of cerium valence on arsenate (As(V)) adsorption was investigated. The Ce3, Ce4 and Ce3O adsorbents all existed in amorphous form and Ce3 exhibited a higher micropore surface area and micropore volume than both Ce4 and Ce3O. The adsorption capacity of As(V) on Ce4 and Ce3O decreased significantly when the solution pH was increased, while the adsorption capacity of As(V) by Ce3 was higher and more stable at pH values ranging between 3.7 and 7.0. The adsorption kinetics of As(V) on Ce3 was better fit to pseudo-second order model while both the pseudo-second order and the pseudo-first order model described the adsorption of As(V) on Ce4 and Ce3O well. The equilibrium adsorption data for As(V) on Ce3 was well fit by the Langmuir model, and the adsorption of As(V) on Ce4 and Ce3O was described well by both the Langmuir and Freundlich models. FTIR analysis indicated that the hydroxyl groups on the three adsorbents’ surfaces were involved in As(V) adsorption. The results suggested that the dominant chemical state of cerium valence plays an important role in affecting the adsorption behavior of As(V) by cerium-doped TiO2 adsorbents.

► Titanium dioxide adsorbents doped with different valence of cerium were prepared.
► Sorption behavior of As(V) on the modified adsorbents was investigated and compared.
► Chemical state of cerium plays an important role in As(V) adsorption.