Modification of synthetic zeolite X by thiourea and its adsorption for Cd (II)

Zeolite X (ZX) was synthesized by diatomite in a water system, and then the synthetic zeolite was modified by thiourea (TU). The synthetic and modified ZX were characterized by XRD, FT-IR, TG/DTA, elemental analysis (CHNS), FE-SEM, EDX, elemental mapping and N2 adsorption/desorption isotherms, respectively. All the results confirmed that the TU molecules were loaded onto both the exterior and interior surfaces of ZX during the modification process. Compared to the raw ZX, the modified ZX has a higher removal capacity in the Cd(II) removal experiments. In ZX-TU sample, removal of Cd(II) takes place via ion exchange and complexation processes. The maximum adsorption capacity is 92.47 mg/g at 25 °C. This cost-effective zeolite can be a functional material for heavy metal removal.