Method for purification of spent sulfuric acid from titanium dioxide rutile industry

A method of purifying waste sulfuric acid from a titanium dioxide production process, the method comprising:

• contacting a waste sulfuric acid solution having an initial titanium ion concentration of up to about 20,000 ppm Ti4+ ions with an acidic precipitant to form a first reactant mixture;
• adding a first volume of water to the first reactant mixture to form a second reactant mixture;
• heating the second reactant mixture at a temperature of from about 75° C. to about 150° C. to form a first digest mixture;
• adding a second volume of water to the first digest mixture to form a third reactant mixture;
• heating the third reactant mixture at a temperature of from about 75° C. to about 150° C. to form a second digest mixture comprising a supernatant and a precipitate;
• separating the supernatant from the precipitate;
• and
• collecting the supernatant, wherein the supernatant comprises a purified sulfuric acid solution having a Ti4+ ion concentration that is less than the initial titanium ion concentration.