Structuring core–shell micro-reactor with binary complexes interface and selective passing surface towards enhancing photo-Fenton degradation

Fenton-based multi-component catalysts show great potential in water treatment due to the designable electron transfer structure, but balancing the requirements of recycling and degradation efficiency is still a formidable challenge. Herein, a novel core–shell structured cellulose-based microgel with solid titanium dioxide (TiO2) shell and highly dispersed ferroferric oxide (Fe3O4) in the core, were fabricated by Pickering emulsion and in-situ mineralization. The meticulously designed structure endowed microgel with selective passing surface that allowed the proton and oxidant to pass through, but selectively prevent the diffusion of contaminants to interior. And the enhanced photo-Fenton degradation via binary complexes interface between TiO2 shell and highly dispersed Fe3O4 exhibited removal rate of as high as 0.123 min−1 and 0.053 min−1 in decomposing methylene blue and tetracycline, respectively. Moreover, the degradation of contaminants occurred on the surface of microgel, markedly reducing the consumption of oxidant compared with the previous work of hydrogel immobilized catalyst. Due to the double protection provided by solid shell and hydrogel network, the as-prepared core–shell structured microgel maintained highly effective degradation after 5 rounds cyclic test. This study opens up a new avenue to develop highly efficient Fenton-based catalytic system with good recyclability, promoting its application in the wastewater treatment.