Analysis of Fe Concentration in Iron Sand and the Effect of Stirring Speed on Band Gap Energy in Magnetite Synthesis

The iron sand found on the coast of Aceh has the potential to be developed as a magnetite material. This study aims to analyze the Fe concentration in iron sand and investigate the effect of varying stirring speeds during magnetite synthesis via coprecipitation on the resulting band gap energy. Iron sand was randomly collected from Anoi Itam Beach, Sabang, then separated from non-magnetic material using a bar magnet, washed with distilled water, and ground into a fine powder. The synthesis was carried out using the co-precipitation method with stirring speeds of 800, 900, and 1000 rpm. The Fe content was analyzed using Atomic Absorption Spectroscopy (AAS) in three stages: natural iron sand, prepared iron sand, and dissolved iron sand. After magnetite formation, the energy gap was determined through optical absorption analysis using a UV-Vis spectrophotometer with the Tauc plot approach. AAS results showed an increase in Fe concentration after synthesis after the dissolution of iron sand, while the increase in stirring speed affected changes in the energy gap. This change in the energy gap has implications for the electronic and optical properties of magnetite. It can be concluded that higher stirring speeds result in an increased energy gap, indicating the presence of other iron oxide phases or size quantization effects occurring in the magnetite.