Table 3: Physical and chemical properties of α-Fe2O3 nanoparticles prepared using microemulsion method.

Physical and chemical properties Fe2O3 pigment prepared using 0.2 M Fe2(SO4)3 0.4 M Fe2(SO4)3 0.6 M Fe2(SO4)3 Average particles size 9 14 19 Sp. Gr. 5.16 5.1 4.99 Solubility Insoluble Insoluble Insoluble Oil abs. 27 26 24 Hiding power 4.5 4.3 4.1 Resistance against heating at (700°C) Excellent Excellent Excellent Fastness properties against       Sulfuric acid 5% Excellent Excellent Excellent Hydrochloric acid 5% V. Good V. Good V. Good Sod. Hyroxide, 2% Excellent Excellent Excellent Sod, Carbonate, 5% Excellent Excellent Excellent Cal. Hydroxide (Saturated Solution) V. Good V. Good V. Good Organic Solvents* Insoluble Insoluble Insoluble Linseed Oil Insoluble Insoluble Insoluble Oleic Acid Insoluble Insoluble Insoluble

*Water, ethanol, acetone, chloroform, carbon tetrachloride, toluene, xylene, and tetrahydrofuran.