Method of preparing iron oxide nanoparticles

1. A method of preparing oval shaped iron (III) oxide nanoparticles, the method comprising:

preparing a ferric chloride (FeCl 3 ) aqueous solution;

preparing a sodium hydroxide (NaOH) aqueous solution;

obtaining a mixed aqueous solution consisting of the ferric chloride (FeCl 3 ) aqueous solution, the sodium hydroxide (NaOH) aqueous solution, and a sodium sulfate (Na 2 SO 4 ) aqueous solution;

reacting the mixed aqueous solution in an electric convection oven in a temperature range of 100° C. to 105° C. for 90 hours to 100 hours at atmospheric pressure to get a solid product; and

cooling, washing, and drying the solid product to get a dried product,

wherein a concentration of the FeCl 3 aqueous solution is in a range of 2 M to 3 M,

a concentration of the NaOH aqueous solution is in a range of 5 M to 6 M,

a concentration of the Na 2 SO 4 aqueous solution is in a range of 0.5 M to 1 M, and

the dried product consists of iron (III) oxide.

2. The method of claim 1 , wherein a volume ratio of the ferric chloride aqueous solution:the sodium hydroxide aqueous solution:the sodium sulfate aqueous solution is 10:9:x,

where x satisfies 0<x<1.