Hydrothermal synthesis of eco-friendly ZnO/CNT nanocomposite and efficient removal of Brilliant Green cationic dye

In this study, seeking to get a more efficient adsorbent, comparable to the commercially available adsorbent, is attracting significant interest as a good adsorbent for wastewater treatment. An approach according to the use of ZnO NPs loaded on the surface of carbon nanotube (ZnO/CNT) nanocomposite to adsorb Brilliant green (BG) dye. ZnO/CNT nanocomposite was chemically synthesized by hydrothermal method and the physicochemical properties were analyzed extensively by using several techniques such as as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy, (EDX), Transmission electron microscopy (TEM), and Thermogravimetric analysis TGA. The effect of different parameters on adsorption processes such as equilibrium time, pH of solution, adsorbent dosage as well as initial concentration of dye has been examined. Results show contact time was (2.00 h), based on the outputs, high capacity of adsorption even at higher initial concentration of dye. With regard to the kinetic analysis, a pseudo second order kinetic model could successfully describe the process of adsorption (R2 0.9910). Then, we used Langmuir, Freundlich isotherm models to obtain the best fit, indicating the role of a multilayer formation for adsorption of BG on the ZnO/CNT nanocomposite from an aqueous solution. Also, the best multilayer adsorption capacity of BG reached to 94.29 mg g-1. The change in free energy of Gibbs (Delta G), entropy (Delta S), and enthalpy (Delta H) were calculated from experimental adsorption results. The obtained negative value of (Delta G) and positive value of (Delta H) show spontaneous nature and endothermic nature of the adsorption process. The regenerated adsorbents in the acidic media (pH 4.0) and basic media (pH10.0) for their performance to removal of BG. The best regenerating has been distilled water. Therefore, it suggests that (ZnO/ CNT nanocomposite) is an effective adsorbent and friendly environmentally and inexpensive substance for effective elimination of the dye from wastewater effluent.