Degradation of 1,4-dioxane by heterogeneous photocatalysis and a photo-Fenton-like process under fluorescent light

ABSTRACT

The overall objective of this study was to develop cost-effective treatment processes for 1,4-dioxane removal that were safe and easy to scale up. Degradation of 1,4-dioxane was conducted and compared for the first time by heterogeneous photocatalysis and a photo-Fenton-like process under cool white fluorescent light in mild conditions, using two types of commercial nanoparticles–titanium dioxide (TiO₂) and nanoscale zero-valent iron (nZVI), respectively. Both types of nanoparticles removed >99.9% of 1,4-dioxane in a short period of time. Hydroxyl radicals (·OH), superoxide radicals (·O₂^-), and hydrogen peroxide (H₂O₂) were detected in both degradation processes; photogenerated holes (h⁺) were critical in the degradation of 1,4-dioxane by the photocatalytic process using TiO₂. 1,4-Dioxane can be degraded at pH 7 in TiO₂/light system and at pH 3 in nZVI/light system, and faster degradation of 1,4-dioxane at even higher concentration was achieved in the former system. Increase in light intensity accelerated 1,4-dioxane degradation, which followed first order kinetics in both systems. In wastewater effluent, the removal of 1,4-dioxane was slower than that in deionised water, which likely reflected the complex compositions of the wastewater effluent. Under combined UVA and visible light illumination, a two-stage degradation process was proposed for 1,4-dioxane for the first time by TiO₂ nanoparticles; this study also demonstrated for the first time 1,4-dioxane degradation by the photo-Fenton-like process using nZVI. The cost-effective solutions using commercial nanoparticles under fluorescent light developed in this study can be potentially applied to treat water contaminated by high concentrations of 1,4-dioxane in large-scale.

GRAPHICAL ABSTRACT

KEYWORDS:

• 1,4-dioxane
• nanoparticles
• heterogeneous photocatalysis
• photo-Fenton-like
• fluorescent light

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The data that support this study will be shared upon reasonable request to the corresponding author.

Additional information

Funding

This research was supported by the SEED Grants from the Advanced Coal and Energy Research Centre and the Material Technology Centre at SIUC; and the Interdisciplinary Materials Research, Research Experience for Undergraduates, funded by National Science Foundation, No., 1757954. Thanks are also given to the National Ground Water Association for funding recommendation.