Semi-permanent hair dyes degradation at W/WO₃ photoanode under controlled current density assisted by visible light

The indiscriminate use of hair dyes has attracted great deal of attention due to its toxicological and mutagenic aspects demonstrated by some of these substances. Thus, the effluent from beauty salons and domestic sewages if not properly treated can reach water treatment plants and water sources, enhancing human health and environmental protection concern. This work explores the application of photoelectrocatalytic process on Basic Brown 16 and Basic Blue 99 degradation as model of basic hair dyes pollutants. W/WO₃ electrode was used as photoanode under optimized conditions of 0.10 mol L^-1 Na₂SO₄ as electrolytic solution, pH 2.0, under 1.25 mA cm^-2 of controlled current density application and visible light irradiation. The process leads to complete color removal, and up to 59% and 44% mineralization of Basic Brown 16 and Basic Blue 99, respectively. The use of W/WO₃ photoanodes under visible irradiation could assist on development of wastewater treatment technology.