Photocatalytic MXenes-magnetite capsules for industrial dye wastewater treatment

Despite their remarkable optical, adsorption, and photocatalytic properties, MXenes face handling challenges that hinder their application in photocatalysis. In this study, we encapsulated Ti₃C₂T_x and Nb₂CT_x MXenes with magnetite in macro-scale sodium alginate capsules. Capsules containing 1 % magnetite and 0.1 % Ti₃C₂T_x MXene demonstrated a 60 % removal rate of 25 mg L⁻¹ methylene blue solution under UV and white light exposure. Additionally, magnetite incorporation facilitated easier handling and collection of the capsules. Tests on factory-delivered industrial dye (E133) showed an almost 80 % degradation rate. Furthermore, high dye degradation rates were maintained even after 4 cycles of regeneration, and in various pH conditions, ranging from 4 to 12. The exceptional performance was attributed to dye absorption and degradation within capsules, where ROS are generated under UV light. Our capsules offer an optimal, reusable solution for fully degrading industrial dyes in wastewater while protecting the active material and allowing its reusability.