Titanium dioxide coated carbon foam as microreactor for improved sunlight driven treatment of cotton dyeing wastewater

© 2019 Elsevier Ltd The reckless discharge of untreated industrial wastewater into the environment has caused serious pollution. Sunlight driven degradation with assistance of catalysts is a promising strategy for removing contaminants from water. TiO2 nanoparticles have been successfully immobilized on melamine foam via a biomimetic polydopamine coating strategy followed by a carbonization treatment. The obtained carbonized TiO2 nanoparticles-coated melamine foam inherited the porous structure from pristine melamine foam and had a high loading density of TiO2 nanoparticles on the foam fibrils. The binding interaction between TiO2 nanoparticles and melamine foam was enhanced by carbonization. The carbonized 3D framework of melamine foam improved the thermal stability of TiO2 nanoparticles and prevented TiO2 nanoparticles from aggregation. The carbonized TiO2-coated melamine foam maintained the porous structures of melamine foam and can act as a microreactor for color removal from the dyeing wastewater. The carbonized TiO2-coated melamine foam demonstrated the prominent photocatalytic activity on Rhodamine B degradation, with 16 times higher than the non-carbonized counterpart, with 98% of Rhodamine B removed after 60 min of irradiation. More importantly, the carbonized TiO2-coated melamine foam removed 90% of dyes in the traditional dyeing wastewater after 120 min under simulated sunlight irradiation, which shows 20 times higher photocatalytic performance than TiO2 nanoparticles for treating traditional dyeing wastewater. The remarkable photocatalytic performance of the carbonized TiO2-coated melamine foam is attributed to the combination of both high light absorption of nitrogen doped carbonized foam and the efficient charge carrier separation promoted by the carbon layer, which inhibited the recombination of electron-hole pairs in TiO2. The TiO2-coated carbon foam can be used as a microreactor, which has promising practical applications in clean production and environmental remediation.