As(V) and As(III) removal from water by a Ce–Ti oxide adsorbent: Behavior and mechanism

Since As(V) and As(III) usually occur in groundwater simultaneously, the synthesis of novel adsorbents for both As(V) and As(III) removal is attractive. In this paper, a Ce–Ti hybrid oxide adsorbent with high sorption capacities for As(V) and As(III) was successfully prepared using a two-step reaction. Environmental scanning electron microscopy (ESEM) revealed that the Ce–Ti oxide adsorbent was composed of nanoparticles in the size range of 100–200 nm. Sorption isotherms show that the powdered adsorbent had high sorption capacity up to 7.5 mg/g for As(V) and 6.8 mg/g for As(III) at the equilibrium arsenic concentration of 10 μg/L, higher than most reported adsorbents. The optimum adsorption capacity on the adsorbent was achieved at pH below 7 for As(V) and at neutral pH for As(III). Fourier transform infrared (FTIR) analysis indicated that the hydroxyl groups on the adsorbent surface were involved in arsenic adsorption, while X-ray photoelectron spectroscopy (XPS) provided further evidence for the involvement of hydroxyl groups in the sorption and the formation of monodentate and bidentate complexes on the adsorbent surface.