Fenton process by volcanic ash to eliminate aniline of aqueous solution from the dyeing of toquilla straw crafts

The toquilla straw hat is a cultural tourist attraction in the province of Azuay-Ecuador. Its production is carried out artisanally, with the dyeing process being one of the major problems due to the production of difficult-to-treat water that has an ecotoxicological impact on water-receiving bodies. A highly effective alternative for decoloring dyes is Advanced Oxidation Processes (AOP), the Fenton-like process that uses waste as catalysts as a source of iron that can be removed by filtration. In this work, the removal of dyes (red and black) in an aqueous solution used in the dyeing of handicrafts was carried out using ashes from the Cotopaxi volcano as a catalyst. The variable evaluated was the dye concentration reached when different amounts of ash and H²O² were tested. Also, acute ecotoxicity tests were carried out with Daphnia Magna (D.M.) to determine its immobilization after 48 hours of exposure. For the black dye, a discoloration of 98.2 % was achieved after 48 hours of treatment using a Fe³⁺: H2O2 ratio of 2:2 (gml^-1), while for the red dye in the same timeframe, a discoloration of 75.62 % was achieved with a ³⁺: H2O2 ratio of 2:4 (gml^-1). Regarding the tests with D.M., they showed complete immobilization before the treatment and 0 % immobilization after the treatment, demonstrating water quality recovery. Keywords: Fenton-like; volcanic ash, dyes.