Removal of Nitrate Using Synthetic Nano Composite ZnO/Organoclay: Kinetic and Isotherm Studies

This study was conducted to investigate organoclay prepared using montmorillonite clay with zinc oxide (ZnO) nanoparticles and a long-chain organic surfactant hexadecyltrimethylammonium bromide for the removal of nitrate ion from aqueous solutions. Adsorbents were evaluated by X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FT-IR), Transmission Electron Microscopy, Brunauer-Emmett-Teller, Emission Scanning Electron Microscopy, Energy Dispersive X-ray (EDX) spectroscopy devices and adsorption isotherms of nitrate ion on the best adsorbent were measured at the aqueous concentrations of 40 to 150 mg/25 mL. Activated montmorillonite-ZnO showed a much higher adsorption capacity than other materials. The laminated ZnO and modified surfactant enhanced nitrate ion, thus retaining silicates capacity, montmorillonite (17.24 mg/g) < montmorillonite by laminated ZnO (54.05 mg/g) ˂ montmorillonite modified by a surfactant (86.95 mg/g) < montmorillonite loaded by ZnO and surfactant (119.92 mg/g). The adsorbents for the removal of nitrate ion were studied and then regenerated with HCl solution (0.1 M) to be reused in adsorption. Adsorption data of nitrate ion could be interpreted using Langmuir isotherm and pseudo-second-order kinetic model. Therefore, activation of Montmorillonite/ZnO could be used as a suitable adsorbent to separate nitrate ion from wastewater and groundwater.