Modelling and optimisation of MXene-derived TiO2/Ti3C2 synthesis parameters using Response Surface Methodology based on the Box–Behnken factorial design. Enhanced carbamazepine degradation by the Cu-modified TiO2/Ti3C2 photocatalyst

In the present study, a hydrothermal method in a water/ethanol environment was used for the first time to obtain novel Cu/TiO2/Ti3C2 composites with high photocatalytic activity for the degradation of carbamazepine (CBZ) under simulated solar light. The Box–Behnken factorial design was coupled with Response Surface Methodology (RSM) for synthesis parameter optimisation. The effect of different synthesis parameters, including temperature, time and water/ethanol ratio, was for the first time studied in detail. The analysis of variance (ANOVA) was used to verify the adequacy of the proposed model. The water/ethanol ratio was the most influential parameter for anatase crystallite growth and the efficiency of carbamazepine degradation. The TiO2/Ti3C2 sample prepared under the optimised conditions (synthesis time of 17 h, temperature of 220 °C, and water/ethanol ratio of 58:42 v/v) revealed almost 100% of CBZ degradation within 60 min. Furthermore, the surface modification of this sample with 0.25% - 1 wt% of copper resulted in improved photocatalytic activity. For TiO2/Ti3C2 modified with 0.5% of Cu, almost complete CBZ degradation was observed in 40 min of the photodegradation process. Finally, the combination of the photodegradation process with the activation of peroxymonosulphate (PMS) by Cu-TiO2/Ti3C2 resulted in markedly improved carbamazepine degradation and reached 100% within 20 min under simulated solar light irradiation. The degradation mechanism of CBZ was proposed based on trapping experiments, which revealed that •O2− and •SO4− are the main oxidising species involved in carbamazepine degradation. Moreover, the hybrid system exhibited high recyclability and stability during subsequent photodegradation cycles.