High Removal Efficiency of Diatomite-Based X Zeolite for Cu(2+) and Zn(2+)

Diatomite-based X zeolite was obtained and its crystallinity, morphology, and interface properties were investigated by XRD, BET, SEM, EDS, and XRF. The obtained X zeolite possessed a unique meso-microporous structure and showed good ion exchange properties for Cu(2+) and Zn(2+). The pseudo-second-order model and Langmuir isotherm model can best describe the adsorption kinetics and isotherms of Cu(2+) and Zn(2+), respectively. The maximal adsorption capacities of X zeolite for Cu(2+) and Zn(2+) were 146 and 195 mg/g at 323 K, respectively. Meanwhile, the adsorption process for Cu(2+) and Zn(2+) were chemical adsorption and ion exchange, respectively. Furthermore, the adsorption data turned out to be an endothermic and spontaneous process. Compared with other reported materials, the adsorption capacity of X zeolite synthesized from diatomite was among the highest. Therefore, it could be a promising adsorbent for the disposal of wastewater that contains metal ions.