Floatable 3D Sponge@SBC-Induced Dual-Pathway-Activated Persulfate for Microcystis aeruginosa Inactivation

Harmful algal blooms have become a global environmental problem. Persulfate-based advanced oxidation processes (PS-AOPs) are a good method for controlling the algal bloom emergency. However, the practical application of PS-AOPs is hindered by the low efficiency and difficult recovery of the powdered catalysts in actual water. To address this challenge, a novel floatable 3D sponge@SBC composite (sponge@SBC1-300) was synthesized using biochar through a simple coating process. The sponge@SBC1-300 showed excellent mechanical stability and catalytic performance in PS-AOPs, achieving 97.7% removal of Microcystis aeruginosa in 250 mins. Good stability and repeatability with a 90.1% removal efficiency after four reuse times were observed. In addition, in the actual river and lake water samples, M. aeruginosa can be effectively inactivated (87.9%). Dual mechanisms, including free-radical (SO4•–, •OH, and •O2–) and nonradical (1O2 and electron transfer) pathways, were found to participate in M. aeruginosa inactivation. Based on the observations of changing cellular morphologies, membrane permeability, and antioxidant system of M. aeruginosa, it was suggested that the generated reactive oxygen species could inactivate algae cells by attacking cell membranes and damaging their antioxidant systems.