A controllable floating pDA-PVDF bead for enhanced decomposition of H2O2 and degradation of dyes

Fe species/biochar fiber composite (FCF) has become one of promising materials for wastewater treatment via heterogeneous photo-Fenton reaction. However, the powdered form always suffers from inefficient recovery and inherent iron loss, limiting their practical application. Herein, we provide an alternative polydopamine (pDA)-modified PVDF bead as excellent photo-Fenton support for immobilizing FCF by phase inversion, which not only limits the loss of iron ions, but also promotes the H2O2 decomposition. Moreover, these beads can float on the wastewater due to their inner structure, favoring the harvest of light. Thanks to these unique characteristics, these beads displayed almost 100% of decolorization in self-designed flowing dyes wastewater systems. Particularly, the self-floating beads structure makes catalysts be easily recovered and maintains long-term high activity, which significantly eliminates the inherent challenge of powdered catalyst (e.g. FCF) based degradation process. This work provides an "easily applicable platform" for large-scale applications of powdered photo-Fenton catalyst in wastewater treatment.