Emerging pollutant degradation processed by a novel 3D printed monolith: Performance evaluation and mechanisms

In the current study, a novel Cu@PLA monolith was prepared by 3D printing technology to activate persulfate (PS) for ciprofloxacin (CIP) removal. This study focuses on the development of a 3D catalyst from a commercial filament with a 73 wt.% Cu composition. The monolith design was a cylinder with an internal mesh, adopted to improve the fluid dynamics of the process. Continuous-flow reactor experiments were conducted to investigate the effects of different operating parameters on CIP removal. Our findings indicated that the immersion of Cu@PLA monolith in an alkaline solution for 15 min activated the surface of the catalyst owing to the increase in Cu at% and the Cu 2p signal observed in XPS. After this process, the PS dose was optimised to 0.5 mM to achieve 90 % of CIP degradation. The other parameters were pH 0 = 5, flow rate = 0.22 mL/min, Tª = 25°C and CIP = 1.3 ppm. The performance in long-term experiments (7 days) was excellent, with a slight efficiency decrease from the first hours (90 %) to 84 % at the end of the experiment. Moreover, the degradation mechanisms and transformation pathways were elucidated by scavenging tests and liquid chromatography/mass spectrometry, respectively. Finally, the feasibility of the system was demonstrated in real water matrices.