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Optimization of ferrous iron removal conditions by freezing from industrial titanyl sulfate solution for high purity TiO2 preparation

Congxue Tian

School of Vanadium and Titanium, Panzhihua University, Panzhihua, People’s Republic of China



Received: 5 October 2022  Accepted: 3 March 2023


Removing ferrous iron from the industrial titanyl sulfate (TiOSO4) solution by freezing was an effective sustainable and green method to prepare high purity TiO2. Using response surface methodology based on the Box–Behnken design approach, the freezing conditions were conducted to determine the effects of three independent freezing factors (freezing temperature, freezing time and concentration of TiO2) on the Fe content. The freezing conditions had great effects on the Fe content of TiOSO4 solution, affected the solubility of ferrous ion, the balance of ferrous ion precipitation and viscosity of the TiOSO4 solution, and they also had synergistic effects, ultimately affected the purity of TiO2. The response surface methodology had a good fitting result in the prediction model with correlation coefficient of 0.9999. The effects of the freezing conditions could be calculated from a second-order polynomial equation. The verification experiments confirmed that the Fe content could be achieved at the value of 9.56 g/L under the optimal conditions of freezing temperature 4.1 °C, freezing time 9.7 h, concentration of TiO2 172 g/L and the regression model was reliable. The purity of the prepared TiO2 after iron removal and purification was higher than 99.9%.

Keywords: Ferrous ion removal; Titanyl sulfate; Freezing; High purity TiO2

Full paper is available at

DOI: 10.1007/s11696-023-02773-9


Chemical Papers 77 (8) 4235–4244 (2023)

Tuesday, June 25, 2024

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