Green synthesis of Fe₂O₃ from seedless lemon peel extract for anionic dye adsorption

It was shown that the material has a heterogeneous cubic shape with iron and oxygen elements at the ratio of 43% and 12%. The crystal faces (120), (220), (400), (018), the material was identified as γ- Fe2O3 with a characteristic spinel structure with tetrahedral and octahedral shapes. The free functional groups on the surface are OH, Fe-O, with 635.58 cm-1 was attributed to the octahedral and tetrahedral sites of the Fe-O band. Temperature is the least influential factor and value was 30 °C. It can be seen that γ-Fe2O3 is the good adsorbent in the pH4-pH6 range, for 60 to 90 min, at dosage of 0.5 to 2 g/L and a dyes' concentration of 200-300 mg/L. The maximum adsorption capacities of MO, CR, and MR were recorded 31.349 mg/g, 49.071 mg/g, and 119.705 mg/g, respectively. The adsorption mechanism has also been predicted and shown to depend on the type of dye with different interaction and adsorption capabilities. This helps the adsorption capacity of Fe2O3 material from lemon peel extract to be more diverse and applied more widely.