Spectrophotometric determination of titanium in high-Ti-bearing blast-furnace slag with diantipyrylmethane

Due to low reactivity and difficult dissolution of blast-furnace slag, the furnace slag was ball-milled below 100-mesh. The sample was fused at 900 ℃ for 30 min with boric acid and sodium carbonate (2+1) as flux. The platinum crucible was replaced by porcelain crucible with laid graphite for the fusion of sample. Then, the melt was leached with sulfuric acid (φ=10%) under the condition of heating. The interference of Fe³⁺ was masked by ascorbic acid. Finally, the content of titanium in high-Ti-bearing blast-furnace slag was determined by diantipyrylmethane spectrophotometry. The yellow complex formed by diantipyrylmethane and titanium had maximum absorption wavelength at 390 nm. The apparent molar absorptivity was 1.06×10⁴ L·mol^-1·cm^-1. Beer’s law was obeyed for titanium in the range of 0.5-20 μg/mL with the correlation coefficient of0.999 8. The proposed method was applied to the determination of titanium in CRM and actual sample of blast-furnace slag . The results were consistent with the certified values and those obtained by high ferric ammonium sulfate titration. The relative standard deviation (RSD, n=5) was 0.24%-0.57%,and the recoveries were between 99 % and 101 %.