The efficient removal of bisphenol A from aqueous solution using an assembled nanocomposite of zero-valent iron nanoparticles/graphene oxide/copper: Adsorption isotherms, kinetic, and thermodynamic studies

Abstract

In this study, nanoparticles of zero-valent iron (nZVI) along with graphene oxide (GO) and copper (Cu) was synthesized to apply as a promising adsorbent for the rapid removal of bisphenol A (BPA) from aqueous solution. The characteristics of nZVI-GO-Cu were analyzed by field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), and vibrating sample magnetometer (VSM). The average particle size of nZVI-GO-Cu was found to be 20.89 nm. The effective experimental variables such as pH, adsorbent dosage, contact time, initial BPA concentration, and temperature were surveyed to assess optimum conditions. Results revealed that the maximum removal percentage was obtained at pH of 7, adsorbent dosage of 0.2 g, contact time of 10 min, the BPA concentration of 10 mg/L, and a temperature of 35 °C as optimum conditions. Experimental data were fitted to the Langmuir and pseudo second-order models with a coefficient of determination (R2) equal to 1 and 0.995, respectively. The obtained maximum adsorption capacity (qmax) of the Langmuir isotherm was 21.59 mg g−1. Thermodynamic parameters under the various temperatures confirmed that the adsorption process was endothermic (ΔH = 17,459.4 J/mol and ΔS = 61.23 J/mol/K) and spontaneous (ΔG < 0). As a conclusion, nZVI-GO-Cu can be selected as an efficient adsorbent for the treatment of aqueous media from BPA and the other pollutants, due to its low-cost, high removal efficiency (97%), and rapid adsorption with the minimum time of 10 min compared with the other adsorbents.