Green Synthesis of Iron Nanoparticle/Clay Composites and Their Effectiveness in Orange II Dye Removal Efficiency

This paper presents a study on orange II sodium salt (OII) degradation based on iron nanoparticles supported by kaolinite clays. The effects of nanoscale iron and initial dye concentration, as well as hydrogen peroxide dosage in a Fenton process, on the degradation of OII were studied. These nanoparticles were synthesized by green methods using coffee bean extract as a natural antioxidant for this process. Aqueous iron chloride was mixed with coffee extract, which is rich in antioxidants, and these antioxidants are responsible for the reduction of metal compounds into nanoparticles. The composite iron nanoparticle-kaolinite composite was synthesized from an aqueous FeCl3 and kaolinite solution with the added coffee bean extract. The results showed that OII removal efficiency increased with the amount of iron nanoparticles (n-Fe) alone and with the amount iron-supported-kaolinite composite. By increasing the amount of composite, the adsorptive surface area increases as well as the number of active sites, which determine the higher removal efficiency. Regarding H2O2 dosage, dye removal was more efficient at lower quantities: 62% removal efficiency with addition of 10 mL H2O2, while for the test conducted with 20 mL H2O2, removal efficiency was 47%. A possible reason for this behavior can be the n-Fe/ H2O2 ratio, which influences the production of degradation products and hinders the degradation.