Spectroscopic Investigations of the Oxidative Polymerization of Hydroquinone in the Presence of Hexavalent Chromium

Figure 3

The changes in the solution colors of 105 mg L⁻¹ Cr(VI) reacting with 200 mg L⁻¹ and 400 mg L⁻¹ H₂Q at pH 3.0 and 25°C, denoted as Cr(VI) + 10x H₂Q and Cr(VI) + 20x H₂Q, respectively, for 1 and 75 min and 24 h. 1 d (pH 1) indicated that the sample was obtained by mixing 200/400 mg L⁻¹ H₂Q and 105 mg L⁻¹ Cr(VI) at pH 3.0 for 24 h, followed by the acidification treatment at pH 1.0 for 1 d.