Effect of Microwave Irradiation on Physicochemical Properties of Ilmenite Surface

In this research, the microwave energy was used to modify the physicochemical properties of ilmenite surface for improvement of ilmenite floatability. The XPS analysis showed that microwave irradiation oxidizes the Fe2+ ions to Fe3+ ones; and the relative content of Fe3+ on the surface of ilmenite increases from 48.5% to 66%. This oxidation process decreases the ilmenite zeta potential; as its PZC (Point of Zero Charge) was changed from pH=5.4 to pH=3.0. The increase of Fe3+ ions increases the chemisorption of oleate ions on the surface of ilmenite; and results in the formation of more insoluble ferric iron oleate. The maximum adsorption of oleate ions occurs at a pH range of 6-7. After microwave irradiation the measured contact angle of ilmenite increases from 91 to 96 degrees. After oleate adsorption, the surface zeta potential of non-irradiated and irradiated ilmenite is obtained -66.3 mV and -78.1 mV, respectively. Thus, the changes in the physicochemical properties of ilmenite occurred by microwave irradiation improves the hydrophobicity and floatability of ilmenite in a wide pH range.