Modified Sepiolite for Wastewater Treatment: Integrating Pollutant Removal with Waste Valorisation

Abstract Heavy metals and phenolic compounds are frequently present in industrial effluents. These accumulate in environmental matrices such as soil, air, and water due to their resistance to degradation, posing significant risks to ecosystems and human health. Here, sepiolite was grafted with (3-mercaptopropyl)trimethoxysilane, and MPTMS-Sep was used in the adsorption of Cu 2+ . Subsequently, Cu-MPTMS-Sep was evaluated in the photocatalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), a less toxic compound with industrial added value. Furthermore, MPTMS-Sep showed a high Cu 2+ removal efficiency of up to 99.91%. Evenmore, Cu-MPTMS-Sep showed potential application in the photocatalytic reduction of 4-NP to 4-AP. In this way, the efficiency of Cu 2+ adsorption in modified clay and the possibility of the reusing spent adsorbents for the photoreduction of the pollutant 4-NP have been demonstrated. Graphical Abstract