Green synthesized nanoclusters of ultra-small zero valent iron nanoparticles as a novel dye removing material

Highlights: • Mediterranean cypress (Cupressus sempervirens) was used for the green synthesis of iron based nanostructures. • Diameters of the clusters were measured to be from 9 to 31 nm with 19 nm mean diameter. • The nanoclusters have shown great potential for dye removal from aqueous solution. • Constructed nanoclusters from ultra-small particles provide high efficiency for adsorption or catalytic purposes. Iron based nanoparticles have gained much attention in recent years due to their unique physicochemical properties especially in the environmental remediation practices. There has been an increasing demand for new sustainable techniques for production of these nanoparticles. In the present work, a novel iron nanostructure was successfully fabricated by a facile and green approach using the aqueous extract of Mediterranean cypress (Cupressus sempervirens). In fact, nanoclusters of highly reactive ultra-small (~ 1.5 nm in diameter) iron nanoparticles were constructed. Diameters of iron nanoclusters were measured to be from 9 to 31 nm with mean diameter of 19 nm. Appearance of the characteristic X-ray diffraction peak of zero valent iron at 2θ = 43.5° indicates the great potential of Mediterranean cypress leaf extract for complete reduction of ferric ions. The presence of phytochemicals as organic capping agent was confirmed by IR radiation absorption at 1020 cm^{− 1} and 1623 cm^{− 1} corresponding to the presence of CO and carbonyl groups, respectively. The fabricated nanoclusters also showed a great potential for dye removal from aqueous solution in a time dependent manner. Decolourization efficiency was calculated to be 95% in a 6 h process for methyl orange removal. The results of this study suggest the possibility of using iron nanoclusters for future pollutants removal applications from aqueous environments.