Application of solar photo-Fenton process to treat Eriochrome Black-T in water and wastewater from water hardness determination

The determination of water hardness is performed by EDTA complexometric titration, in the presence of Eriochrome Black T (EBT) as a visual end point indicator. EBT is an azo dye that can be an environmental problem. Therefore, the present work investigated the possibility of using the solar photo-Fenton system as a treatment to remove EBT from the wastewater of hardness determination process. The solar photo-Fenton reagents were potassium ferrioxalate, at 1 mmol L−1, as the catalyst and the source of iron, and hydrogen peroxide, at 10 mmol L−1. The efficiency of the treatment was monitored by COD, BOD, TOC, HPLC, and ecotoxicological analyses. Organic matter removal values higher than 60