Urea-based immobilisation of activated carbon onto alumina spheres for adsorption of organic micropollutants and regeneration by catalytic wet peroxide oxidation

Activated carbon (AC) was mixed with different doses of urea (U) and subjected to a single-step thermal treatment process. The AC-based materials were synthesised in powder form (AC/U x , x representing the U:AC weight ratio) and also immobilised onto alumina spheres (S-AC/U x ). The materials were characterised by different techniques, including diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis), photoluminescence (PL) spectroscopy, N 2 adsorption-desorption isotherms, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was demonstrated, for the first time, that U allows for the proper one-pot solvent-free immobilisation of AC onto alumina supports. In batch adsorption experiments, the best-performing material in powder form (AC/U 50 ) showed a venlafaxine (VFX) removal of 67.1 ± 7.6 % in 60 min. In continuous flow mode adsorption experiments performed with VFX spiked in tap water (packed-bed configuration), the respective supported material (S-AC/U 50 ) reached a VFX removal of 70 %. Adding hydrogen peroxide (H 2 O 2 ) improved the removal of VFX up to 99 %, demonstrating the ability of the material to activate H 2 O 2 at room temperature. This catalytic wet peroxide oxidation (CWPO) process not only enhances the degradation of VFX but also reveals the potential for regenerating S-AC/U 50 , offering a promising route for sustainable and efficient drinking water treatment. • Best adsorbent (AC/U 50 ) prepared with 50 g of urea (U) / g of activated carbon (AC). • AC successfully immobilised onto alumina spheres (S) by urea-rich thermal method. • S-AC/U 50 removed up to 70 % of VFX from tap water, reaching saturation in 5 days. • S-AC/U 50 with H 2 O 2 improves VFX removal up to 99 % at room temperature. • CWPO allows for 5 days of continuous operation with no loss of catalytic activity.