Green Separation of Scandium and Titanium Using Citric Acid via Organic Complexation Scrubbing

Aiming at the bottleneck of the difficult scrubbing and separation of scandium and titanium in the solvent extraction process for scandium recovery, a novel strategy for scandium–titanium separation via citrate complex scrubbing is proposed based on the difference in complexation properties between scandium/titanium and hydroxycarboxylic acids. The mixed Na₃Cit + H₂O₂ system was screened as the optimal scrubbing agent. The effects of key parameters including dosages of Na₃Cit and H₂O₂ and phase ratio (O/A) on scrubbing performance were systematically investigated. The optimal process conditions were determined as follows: temperature of 25 °C, molar ratio n(Na₃Cit)/n(Ti) = 30:1, molar ratio n(H₂O₂)/n(Ti) = 3:1, phase ratio (O/A) of 1:1, shaking speed of 200 r/min, and scrubbing time of 30 min. Under the optimal conditions, the titanium scrubbing efficiency reaches 97.37% with zero co-scrubbing efficiency of scandium. The separation efficiency is 14.47 times higher than that of the conventional H₂SO₄ + H₂O₂ scrubbing system, which significantly enhances the scandium–titanium separation performance. This work provides a feasible technical route for the deep separation and purification of scandium and titanium from titanium white waste acid.