Synthesis of aluminum tri-polyphosphate anticorrosion pigment from bauxite tailings

Aluminum tri-polyphosphate was synthesized from bauxite tailings and phosphoric acid with a P/Al molar ratio of 3. This is highly advantageous from a waste recycling perspective as bauxite tailings are generally regarded as unusable waste. The acidity, whiteness and mean particle size of prepared aluminum tri-polyphosphate are all improved after modification. The possibility of using modified aluminum tri-polyphosphate as an anticorrosive pigment was also investigated by electrochemical impedance spectroscopy. The resistance of the coatings with modified aluminum tri-polyphosphate is 7×107 Ω for 40 d of immersion, which is superior or at least comparable to that of coatings containing APW-2, which exhibits a resistance of 5.7×107 Ω.