Carbon-nitride-based micromotor driven by chromate-hydrogen peroxide redox system: Application for removal of sulfamethaxazole

In this study, a Janus Fe/C3N4 micromotor driven by a chromate-hydrogen peroxide (Cr(VI)/H2O2) redox system was developed and its movement was analyzed. The motion of the micromotor was tracked via nanoparticle tracking analysis (NTA) and the corresponding diffusion coefficients (D) were determined. The NTA results revealed that D = 0 in water in the absence of additives (Cr(VI) or H2O2). The addition of H2O2 resulted in an increase in D from 0 to 12 x 10(6) nm(2) s(-1), which further increased to 20 x 10(6), 26.5 x 10(6), 29 x 10(6), and 44 x 10(6) nm(2) s(-1) with the addition of 0.5, 1, 2, and 5 ppm of Cr(VI), respectively. Cr(VI) alone did not efficiently propel the Fe/C3N4-based micromotor. Therefore, it was proposed that the Cr(VI)/H2O2 redox system generates O-2, which plays a major role in the movement of the C3N4-based micromotor. In addition, the formation of reactive species, such as center dot OH and O-1(2), was confirmed through electron spin resonance experiments. The reactive species efficiently degraded sulfamethaxazole (SMX), an organic pollutant, as demonstrated through degradation studies and product analyses. The effects of various parameters, such as H2O2 concentration, Cr(VI) concentration, and initial pH on the movement of micromotor and degradation of SMX were also documented. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

A Fe/C3N4 Janus micromotor driven by a Cr(VI)/H2O2 redox system was developed in this study, with O-2 generated by the redox system playing a crucial role in the movement of the micromotor. Reactive species efficiently degraded the organic pollutant SMX, as confirmed by degradation studies and product analyses. Various parameters such as H2O2 concentration, Cr(VI) concentration, and initial pH were found to affect the movement of the micromotor and the degradation of SMX.