Green Synthesis of Nanoscale Zero-Valent Iron/Activated Carbon Composites and their Application for Copper and Chromium Removal from Aqueous Solutions

In this study, nanoscale zero-valent iron (nZVI) particles and their composites with powdered activated carbon (nZVI-PAC) and granular activated carbon (nZVI-GAC) were successfully synthesized via a low-cost green approach with the use of green tea extract. The adsorbents were then used to remove Cr and Cu from aqueous solutions, and their adsorption results were fitted with the Freundlich and Langmuir models. The synthesized adsorbents were characterized using XRD, FTIR, and FESEM techniques. The typical peak of Fe 0 was detected in the XRD patterns of prepared samples, but the presence of organic compounds in green tea extract weakened related peak. The FESEM characterization demonstrated that the nZVI spherical particles had a chain-like structure and ranging in size from 10 to 50nm. The presence of polyphenols peak in the FTIR spectra revealed that the green tea extract was responsible for the reduction of the Fe 2+ to Fe 0 . The maximum adsorbed amount of Cr and Cu was found to be 5.68 and 6.48 mg/g, which was achieved by nZVI-PAC and nZVI, respectively. The nZVI-PAC and nZVI also showed a higher removal efficiency for Cu and Cr by 62% and 94% for an initial concentration of 100 mg/L, respectively. The results showed that nZVI, nZVI-PAC, and nZVI-GAC could be promising and eco-friendly adsorbents for Cr and Cu removal from aqueous solutions.