Adsorption-photocatalysis functional expanded graphite C/C composite for in-situ photocatalytic inactivation of Microcystis aeruginosa

In this study, efficient adsorption-photocatalysis functional expanded graphite covered carbon layer composites (shorted for AP-EGC) with graphitic carbon nitride (g-C₃N₄ shorted for C) and nitrogen-phosphorus codoped titanium dioxide (NP-TiO₂, shorted for T) coating was successfully prepared, which has been named as AP-EGC-CT. It was used for in-situ remediation of harmful algae polluted water. It is shown that the AP-EGC-CT composites exhibit a worm-like structure which can be manipulated by the expanded graphite substrate, and g-C₃N₄ can tune their photoelectric property. Of all the composites, the AP-EGC-CT with 5 wt% g-C₃N₄ exhibits the best adsorption-photocatalytic inactivation performance under visible light irradiation, and presents a total removal efficiency of 98.5% after 2 h reaction. The photocatalytic inactivation behavior can be well described by the Modified Chick-Watson model and Hom model. It has been demonstrated that the photocatalytic oxidation can destroy cell structure, disturb cellular metabolism and realize inactivation of algal cells, and that the hole is the major reactive oxygen species. It has been found that these composites can simultaneously remove the algal cells and MC-LR with high efficiency, holding substantial promise in remediating algae pollution in eutrophic water.