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This study was conducted to investigate the synthesis of magnetite nanoparticles from iron sand collected from the Bah Bolon River in Indonesia, using the coprecipitation method with NaOH and NH4OH as precipitants. The results showed that based on SEM-EDX (scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy) analysis, the Fe content of the raw iron sand, initially at 34.76%, increased to 45.50% following synthesis with NH4OH, indicating enhanced purity in the final product. SEM observations found average particle sizes of approximately 53 nm for nanoparticles synthesized with NaOH and 20 nm for those synthesized with NH4OH. X-ray diffraction (XRD) analysis confirmed that the synthesized nanoparticles retain the magnetite (Fe3O4) phase with a face-centered cubic (FCC) spinel structure. Crystallite size calculations using the Scherrer equation yielded average crystallite sizes of 80.194 nm for NaOH-synthesized samples and 15.124 nm for NH4OH-synthesized samples, demonstrating that NH4OH favors the formation of smaller crystallites. Lattice strain analysis through the Williamson-Hall method showed positive tensile strain values for all samples, indicating structural tension within the crystal lattice. The NH4OH-synthesized nanoparticles had slightly higher lattice strain, suggesting that synthesis conditions impact both crystallite size and lattice tension. In conclusion, this study demonstrated that NH4OH was more effective than NaOH in producing high-purity, small-crystallite magnetite nanoparticles from natural iron sand, with potential implications for enhanced material properties.

One of the components that play an important role in maintaining battery security is the separator. The separator plays a role in preventing short circuits due to direct exchange between the anode and cathode in the battery cell. To avoid leakage or short circuit during the process, the separator must have good mechanical properties. For this reason, modifications are needed to improve the characteristics of the separator. The modification process was carried out by mixing Poyvinylidene Fluoride (PVDF) and cellulose acetate (CA) polymers. The CA used in this study was obtained by utilizing natural waste extracts in the form of empty oil palm fruit bunches (EFB). This study aims to see the effect of variations in the addition of CA EFB and PVDF on the characteristics of the resulting separator. Synthesized CA EFB was characterized using Fourier Transfor Infrared (FTIR) spectroscopy which showed that cellulose had been successfully synthesized into cellulose acetate.. The separator produced in this study showed good electrolyte absorption, indicated by the occurrence of an oxidation-reduction reaction process on the hysteresis curve with a wider and reversible loop upon the addition of 0.2 g CA. The mechanical characteristics of the separator also increased with the addition of CA concentration, the separator with the addition of 0.3 g CA showed the highest tensile strength value of 62.335 MPa and the highest porosity value of 89.35%. The separator with the addition of 0.3 g of cellulose acetate also decomposes more quickly, indicated by a weight loss percentage of 60%. The results of this test indicate that the addition of CA EFB and PVDF can affect the physical and mechanical characteristics of the separator which has the potential to become a battery separator.