Efficient elimination of the pollutants in eutrophicated water with carbon strengthened expanded graphite based photocatalysts: Unveiling the synergistic role of metal sites

Metal sites (Ni, Bi or Ag) were introduced into carbon strengthened expanded graphite (CEG) based photocatalysts, and performed as a novel strategy to enhance the elimination of Microcystis aeruginosa and microcystinLR from water. Results show that metal doping can efficiently improve the adsorption of harmful algae and enhance the photocatalytic activities in inactivation of harmful algae and degradation of MC-LR. Among the CEG catalysts, Ni-CEG can achieve the highest removal rate up to 90.6% for algal cells with 5 h visible light irradiation, while Bi-CEG catalyst provides the best performance for MC-LR degradation with the removal rate of 80.9% in 6 h visible light irradiation. In general, considering the coexistence of algal cells and microcystin-LR, BiCEG is proved to be an excellent candidate for the remediation of eutrophicated waters since it can achieve the efficient removal of both harmful algae and MC-LR. DFT calculations indicate that metal doping can transform the photocatalysts into n-type semiconductor, and provide the mid-gap state. In addition, the partial charge density distribution near Fermi level was mainly composed by the metal dopants, which can enhance the interaction with harmful algae and MC-LR.

Automated summary

Metal doping significantly enhances the efficiency of photocatalysts in removing harmful algae and microcystinLR, with Ni-CEG showing the best performance for algal removal and Bi-CEG for MC-LR degradation. DFT calculations suggest that metal doping transforms the photocatalysts into n-type semiconductors with mid-gap states, enhancing interaction with harmful algae and MC-LR.