A novel strategy for efficient capture of intact harmful algal cells using Zinc oxide modified carbon nitride composites

The development of safe and efficient materials to remove harmful algae is continuing to be a major challenge in controlling cyanobacterial blooms in eutrophication waters. Herein, we present a novel strategy that combines Zinc oxide (ZnO) with carbon nitride composites to efficiently collect the intact Microcystis aeruginosa cells. The influence of different dosages of g-C 3 N 4 precursors were assessed and the synthesized catalysts were characterized. The results revealed that 93.0 % of algae cells were removed by the ZnO/CN (2:1) system within 10 min at a dose of 4.0 g L −1 . Regardless of the variation in initial cell density, the final removal efficiency reached >90.0 %. The integrity of the algal cell membrane was observed by K + release and intracellular organic matter such as MC-LR during the removal process, which were further verified by SEM images. The Zeta potential values indicated that the improved effectiveness may be attributed to the electrostatic attraction and coagulation by ZnO/CN. The removal mechanism of ZnO/CN was revealed through charge neutralizing flocculation and the different types of flocculants were compared. The present work provides a new insight in using ZnO nanoparticles modified carbon-based composites in treating cyanobacterial blooms.