Development and testing of alginate/C3N4porphyrin bead as a self-initiated Fenton photocatalyst for highly efficient atrazine removal

Abstract

Fenton reaction has been widely used for the efficient treatment of organic wastewater. However, its applications are limited by such key factors as a requirement of a workable pH < 3. In this study, we developed, tested, and optimized the alginate/C3N4porphyrin bead (alginate/C3N4por) as a recyclable photocatalyst in a photocatalysis-self-Fenton process to overcome these limitations. Porphyrin-modified C3N4 (C3N4por) was used as an H2O2 donator, while Fe(III) nodes served as a Fenton reagent. The as-prepared floating alginate/C3N4por bead utilized the light source as a driving force for the catalysis. Under visible light irradiation for 6 h, the model pollutant atrazine was degraded by 70.96 %, demonstrating better photocatalytic performance than alginate/C3N4 beads. This improvement was attributed to the higher H2O2 yield of C3N4por. The alginate/C3N4por bead showed better photocatalytic activity even after four consecutive cycles and could easily be recovered for reuse. Furthermore, Fe(III)/Ca(II) bimetallic alginate bead exhibited better photocatalytic activity and a higher content of •OH radicals than the Ca(II) monometallic alginate beads, due to the ability of Fe(III) nodes to serve as a Fenton reagent. The influences of light sources, and commonly existing matters (namely SO42−, Cl−, CO32−, NO3−, and humic acid) were investigated. Moreover, the alginate/C3N4por bead demonstrated good photocatalytic performance in a simulated natural environment without the addition of extra H2O2, with an atrazine removal percentage of up to 96.3 % after 3-h irradiation. These findings indicated the great potential of alginate/C3N4por beads in practical applications.