Robust Photocatalytic MICROSCAFS ® with Interconnected Macropores for Sustainable Solar-Driven Water Purification

• Published in: International journal of molecular sciences 2024-06, Vol.25 (11), p.5958
• Main Authors: Vale, Mário, Barrocas, Beatriz T, Serôdio, Rita M N, Oliveira, M Conceição, Lopes, José M, Marques, Ana C
• Format: Article
• Language: English
• Subjects: Azo Compounds - chemistry; Catalysis; Cellulose; Ethylenediaminetetraacetic acid; Germany; heterogeneous photocatalysis; Kinetics; macroporosity; Mass spectrometry; Massachusetts; Methylene blue; Microspheres; Particle size; Pharmaceutical industry; Photocatalysis; Photochemical Processes; Photolysis; Polyvinyl alcohol; Porosity; Silicon Dioxide - chemistry; sol–gel; Sunlight; titania; Titanium - chemistry; Water Pollutants, Chemical - chemistry; Water pollution; Water Purification - methods
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25115958

Advanced oxidation processes, including photocatalysis, have been proven effective at organic dye degradation. Tailored porous materials with regulated pore size, shape, and morphology offer a sustainable solution to the water pollution problem by acting as support materials to grafted photocatalytic nanoparticles (NPs). This research investigated the influence of pore and particle sizes of photocatalytic MICROSCAFS on the degradation of methyl orange (MO) in aqueous solution (10 mg/L). Photocatalytic MICROSCAFS are made of binder-less supported P25 TiO NPs within MICROSCAFS , which are silica-titania microspheres with a controlled size and interconnected macroporosity, synthesized by an adapted sol-gel method that involves a polymerization-induced phase separation process. Photocatalytic experiments were performed both in batch and flow reactors, with this latter one targeting a proof of concept for continuous transformation processes and real-life conditions. Photocatalytic degradation of 87% in 2 h (batch) was achieved, using a calibrated solar light simulator (1 sun) and a photocatalyst/pollutant mass ratio of 23. This study introduces a novel flow kinetic model which provides the modeling and simulation of the photocatalytic MICROSCAFS performance. A scavenger study was performed, enabling an in-depth mechanistic understanding. Finally, the transformation products resulting from the MO photocatalytic degradation were elucidated by high-resolution mass spectrometry experiments and subjected to an in silico toxicity assessment.