Synthesis of hierarchically porous perovskite-carbon aerogel composite catalysts for the rapid degradation of fuchsin basic under microwave irradiation and an insight into probable catalytic mechanism

3D hierarchically porous perovskites LaFe_0.5M_0.5O₃-CA (M = Mn, Cu) were synthesized by a two-step method using PMMA as template and supporting with carbon aerogel, which were characterized with SEM, TEM, XRD, XPS and FT-IR spectroscopy. The as-prepared composites were used in microwave (MW) catalytic degradation of fuchsin basic (FB) dye wastewater. Batch experiment results showed that the catalytic degradation of FB could be remarkably improved by coating with CA. And LaFe_0.5Cu_0.5O₃-CA exhibited higher catalytic performance than LaFe_0.5Mn_0.5O₃-CA, which had a close connection with the activity of substitution metal ion in B site of the catalysts. The FB removal fit pseudo-first-order model and the degradation rate constant increased with initial pH value and MW powder while decreases with initial FB concentration. All catalysts presented favorable recycling and stability in the repeated experiment. Radical scavenger measurements indicated that hydroxyl radicals rather than surface peroxide and hole played an important role in the catalytic process, and its quantity determined the degradation of FB. Furthermore, both Cu and Fe species were involved in the formation of active species, which were responsible to the excellent performance of the LaFe_0.5Cu_0.5O₃-CA/MW system. Therefore, LaFe_0.5Cu_0.5O₃-CA/MW showed to be a promising technology for the removal of organic pollutants in wastewater treatment applications.