Influence of anions on the formation of artificial steel rust particles prepared from acidic aqueous Fe(III) solution

► Artificial steel rust particles were prepared in the presence of FeCl3, Fe(NO3)3 and Fe2(SO4)3. ► In FeCl3-Fe(NO3)3 system, added Cl− turned the products from α-FeOOH to β-FeOOH. ► Existence of SO42− formed Schwertmannite and increasing the added SO42− suppressed the formation of steel rust particles. ► Influence of anions on the formation of steel rust particles is suggested to be in order of SO42− ≫ Cl− > NO3−.