Effective adsorption of antimony from aqueous solution by cerium hydroxide loaded on Y-tape molecular sieve adsorbent: Performance and mechanism

Abstract

As a toxic element, antimony (Sb) often exists in contaminated water in the form of Sb(III) and Sb(V), and poses a threat to the environment and human health. To remove Sb from water efficiently, the novel cerium hydroxide loaded Y-tape molecular sieve adsorbent (NaY@Ce) was successfully prepared by co-precipitation method. Adsorption capacity of the adsorbent showed up the increasing trend with the increase of cerium species. With 0.4 % loading of cerium trichloride, the maximum adsorption capacity of Sb(III) and Sb(V) on NaY@Ce was 24.65 mg/g and 7.28 mg/g at pH = 7.0, respectively. The results of batch experiments showed that the Langmuir isotherm well described the Sb(III) adsorption experiments, while Sb(V) better fitted the Freundlich model. Both adsorption behaviors fitted the pseudo-second-order kinetic model. The adsorbent exhibited excellent Sb removal performance in the wide range of pH = 2–10 and co-existing anions such as Cl−, NO3−, HCO3−and SO42- almost have no effect on the adsorption process. And there was almost no release of Ce at pH＞2. The SEM, EDS, XRD, FTIR and XPS analysis confirmed the successful loading of Ce, and explained the possible mechanism of Sb on the adsorbent. Abundant hydroxyl groups and the presence of Ce(Ⅳ) were the basis of adsorption. The adsorption mechanisms for antimony included partial Sb(III) oxidized to Sb(V) and simultaneously adsorbed on NaY@Ce, formed Ce–O–Sb inner-sphere surface complexes between metal hydroxyl groups and antimony and electrostatic attraction. The above results confirmed that NaY@Ce can be used as a promising adsorbent to efficiently remove Sb from aqueous solution.