Modification of Diatomite with Iron Oxide as an Effective Adsorbent of Selenite Ions from Water: Synthesis, Kinetic, and Thermodynamic Studies

In this work, iron oxide–modified diatomite is in the use for the elimination of selenite (Se(IV)) ions from water, and the operation of key factors, including initial anion concentration, contact time, adsorbent dosage, and pH of the solution, is under investigation. Scanning electron microscopy and X-ray diffraction prove the formation of iron oxide within diatomite. It turns out that the proportion of Se(IV) ion removal goes down when there has been a rise in the value of pH to the alkali condition. The high amount of Fe-diatomite adsorption volume is calculated to be 109.5 mg.g −1 based on the Langmuir adsorption isotherm, and the combination of physical and chemical adsorption is considered as the mechanism of the adsorption. Finally, it is determined that both film and intra-particle diffusion are the steps to limit the speed of the Se(IV) ion adsorption onto Fe-diatomite.