Efficient degradation of bisphenol A with MoS2/BiVO4 hetero-nanoflower as a heterogenous peroxymonosulfate activator under visible-light irradiation.

Photocatalyst activated peroxymonosulfate (PMS) under visible-light irradiation to construct a photo-Fenton system has shown great application prospect for environmental remediation. In this study, MoS2/BiVO4 heterojunction nanoflowers were successfully synthesized by hydrothermal method and used to activate PMS under visible-light to achieve highly efficient degradation of bisphenol A (BPA). The constructed heterojunction showed excellent catalytic activity, which was attributed to the synergistic effect of effective separation of charge carriers and PMS activation. In the MoS2/BiVO4/PMS/vis system, 2-MoS2/BiVO4 (2-MB) exhibited the highest degradation rate constant for BPA (0.1747 min-1), which was 91.9 times of pure MoS2 and 38.0 times of pure BiVO4, respectively. The electron paramagnetic resonance (EPR) and radical quenching experiments demonstrated that the oxidative degradation of BPA was mainly participated by SO4-, OH, 1O2 and h+ active species. Through the analysis of energy band structure and element valence state of photocatalyst and the identification of reaction intermediates, the degradation mechanism and degradation pathways were proposed. In addition, MoS2/BiVO4 heterojunction showed high catalytic ability for various organic pollutants (herbicides, pesticide intermediates, antibiotics and dyes), and common anions (Cl-, SO42- and NO3-) and humic acid (HA) had little effect on its degradation efficiency. This study has provided a new solution for the use of heterojunction photocatalysts for visible-light assisted PMS activation to achieve highly efficient degradation of organic pollutants.