Decolorisation and mineralisation of homo‐ and hetero‐bireactive dyes under Fenton and photo‐Fenton conditions

The degradation of two commercial reactive dyes, CI Reactive Red 141 (homo‐bireactive) and CI Reactive Red 238 (hetero‐bireactive), using Fenton's reagent in the dark and under either artificial or solar irradiation, has been investigated. The main parameters that govern the complex reactive system, i.e. type of irradiation, temperature and initial concentrations of iron(II) and hydrogen peroxide, have been studied at pH 3. Temperature and the use of light have beneficial effects on the removal of colour, aromatic compounds, total organic carbon, acute toxicity, given as changes in EC₅₀ values (against the marine photobacteria Vibrio fischeri) and changes in the biodegradability. The advanced oxidation processes used in this study have proven to be highly effective for the treatment of such types of reactive dyes and several advantages concerning the technique application arise from the study. The possibility of a combined advanced oxidation process‐biological treatment is proposed.