The selective heavy metal ions adsorption of zinc oxide nanoparticles from dental wastewater

Zinc oxide nanoparticles (ZnO-NPs) was synthesized using the traditional hydrothermal method and its characterization as well as adsorption performance of heavy metal ions were studied. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) confirmed hexagonal structures and functional groups. N-2 adsorption-desorption techniques suggested the Brunauer-Emmett-Teller (BET) specific surface area was 26.777 m(2)/g, indicating the potential in removal process. Scanning electron microscopy-energy dispersive X-ray (SEM-EDX) further ensured the possible interactions of ZnO-NPs and heavy metal ions. Batch adsorption experiments showed higher affinity towards Cr3+, and the maximal adsorption capacity was 88.547 mg/g at the optimum conditions (pH 3-7, 1 g/L adsorbent, 20 min contacting time, and 20 mg/L initial Cr3+ ions). The adsorption process showed best fit with the pseudo-second-order and Langmuir isotherm model, suggesting a chemisorption procedure and monolayer type removal. The ZnO-NPs could remove Cr3+ ions selectively, and hold the potential application for dental wastewater purification treatment.