Efficient PPCPs degradation by self-assembly Ag/Ti3C2@BiPO4 activated peroxydisulfate with microwave irradiation: Enhanced adsorptive binding and radical generation

A hybrid nanocomposite (Ag/Ti3C2@BiPO4) synthesized by an electrostatic self-organizing method for peroxydisulfate (PDS) activation to degrade pharmaceuticals and personal care products (PPCPs) under microwave irradiation (MW) was developed. Degradation and mineralization efficiencies of 99.4 % and 71.5 % for bisphenol A at initial concentration of 20.0 mg/L in 5.0 min operation were achieved in the proposed system. Other kinds of PPCPs including ciprofloxacin, diclofenac, sulfamethoxazole, benzophenone-3 and diethyltoluamide could also be effectively degraded. The two-dimensional (2-D) layered Ti2C-based material Ti3C2 significantly facilitated charge transfer, the separation of electron-hole pairs and production of radicals. Additionally, Ti3C2 incorporation also provided more active species being involved in MW-assisted PDS activation. Density functional theory calculation confirmed that PDS was more easily adsorbed by Ag/Ti3C2@BiPO4 than Ag@BiPO4, favoring PDS activation to produce more radicals for PPCPs removal. Evidences from radical scavenger trials and electron paramagnetic resonance analysis collectively suggested that sulfate radicals and hydroxyl radicals contributed significantly to PPCPs degradation. The main degradation pathways of investigated PPCPs were also clarified with the detected intermediate products. Meanwhile, the eco-toxicity effect of intermediate products of PPCPs on fish, daphnid, and green algae calculated using ecological structure activity relationship software showed that they were much less harmful or not toxic. This work opens up a new perspective on the applications of MXene-based 2-D materials for fast and highly efficient catalytic activation of PDS to degrade PPCPs under MW irradiation.