Highly efficient degradation of iohexol on a heterostructured graphene-analogue boron nitride coupled BiMoO photocatalyst under simulated sunlight.

Iohexol (IOH), as a typical iodinated X-ray contrast media (ICMs) with potential threat to human health, is difficult to be removed with the conventional wastewater treatment methods. In this work, new boron nitride coupled BiMoO layered microspheres (BN/BiMoO) composites were applied to remove IOH from water via photocatalytic degradation. The degradation constant k of IOH over 3.5 wt% BN/BiMoO was 0.016 min, which was 3.2 times that of BiMoO (0.005 min). The degradation rate of IOH on 3.5 wt% BN/BiMoO reached 92% in 150 min. The enhanced photocatalytic activity of BN/BiMoO can be attributed to the heterojunction between BN and BiMoO. The matched type-I band alignment heterojunction of two semiconductors prominently improved the charge separation. Based on the trapping experiments, holes and superoxide radicals were proved to be the main active species for photocatalytic IOH degradation. Besides, the degradation products of IOH were analyzed by LC-HRMS and the possible degradation mechanism of IOH was also proposed in this work.