Magnetic TiO2/Carbon dots composites for solar-based photocatalytic removal of antibiotics from water: Assessment of synthesis routes and efficiency

Solar-based photocatalysis offers a sustainable strategy to remove antibiotics, such as Amoxicillin (AMX), Sulfamethoxazole (SMX) and Trimethoprim (TMP), from water. TiO 2 /Carbon dots (CD) composites possess promising photocatalytic efficiency; however, their recovery and reuse remain challenging. To surpass this problem, different production methods were explored to create a novel magnetic (MP) TiO 2 /CD composite. Five methodological approaches were investigated, namely (i) oxidative hydrolysis, (ii) hydrothermal treatment, (iii) co-precipitation, (iv) sonication and calcination, and (v) functionalization and coupling via carbodiimide chemistry. Considering the synthesis simplicity, rapidity and cost-effectiveness, together with its solar-driven photocatalytic efficiency, TiO 2 @CD@MP obtained by co-precipitation was found as the most favourable option among the synthesised composites. This photocatalyst enabled 95.6 ± 0.9%, 48 ± 2% and 43 ± 1% AMX, SMX and TMP removal, respectively, under simulated solar irradiation. Furthermore, TiO 2 @CD@MP showed high consistency and repeatability in terms of synthesis yield, magnetic properties and photocatalytic performance across three production batches. This magnetic composite demonstrated strong potential for sustainable solar-based water treatment for antibiotic removal. • Synthesis of magnetic TiO 2 /CD was investigated via 5 different methodologies • Stable magnetic TiO 2 /CD achieved by co-precipitation and carbodiimide chemistry coupling • The composite obtained by the co-precipitation (TiO 2 @CD@MP) showed superior results • TiO 2 @CD@MP offered repeatable results of yield, M S and photocatalytic efficiency • TiO 2 @CD@MP showed higher efficiency in antibiotics removal compared to literature