Insights into enhanced oxidation of benzophenone-type UV filters (BPs) by ferrate(VI)/ferrihydrite: Increased conversion of Fe(VI) to Fe(V)/Fe(IV)

Boying Liu; Shengnan Zhang; Mingzhu Liu; Siyu Cao; Ruijuan Qu; Zunyao Wang

doi:10.1016/j.scitotenv.2023.168860

Insights into enhanced oxidation of benzophenone-type UV filters (BPs) by ferrate(VI)/ferrihydrite: Increased conversion of Fe(VI) to Fe(V)/Fe(IV)

Sci Total Environ. 2024 Feb 20:912:168860. doi: 10.1016/j.scitotenv.2023.168860. Epub 2023 Nov 29.

Authors

Boying Liu¹, Shengnan Zhang¹, Mingzhu Liu¹, Siyu Cao², Ruijuan Qu¹, Zunyao Wang³

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, China.
² School of Resources and Environmental Engineering, Anhui University, Anhui, Hefei 230601, China.
³ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, China. Electronic address: wangzy@nju.edu.cn.

PMID: 38040358
DOI: 10.1016/j.scitotenv.2023.168860

Abstract

In this work, the oxidation performance of a new ferrate(VI)/ferrihydrite (Fe(VI)/Fh) system was systematically explored to degrade efficiently six kinds of benzophenone-type UV filters (BPs). Fe(VI)/Fh system not only had a superior degradation capacity towards different BPs, but also exhibited higher reactivity over a pH range of 6.0-9.0. The second-order kinetic model successfully described the process of BP-4 degradation by heterogeneous Fh catalyzed Fe(VI) system (R² = 0.93), and the presence of Fh could increase the BP-4 degradation rate by Fe(VI) by an order of magnitude (198 M^-1·s^-1 v.s. 14.2 M^-1·s^-1). Remarkably, there are higher utilization efficiency and potential of Fe(VI) in Fe(VI)/Fh system than in Fe(VI) alone system. Moreover, characterization and recycling experiments demonstrated that Fh achieved certain long-term running performance, and the residual Fe content of solution after clarifying process meet World Health Organization (WHO) guidelines for drinking water. The contributions of reactive species could be ranked as Fe(V)/Fe(IV) > Fe(VI) > •OH. Fe(IV)/Fe(V) were the dominant species for the enhanced removal in the Fe(VI)/Fh system, whose percentage contribution (72 %-36 %) were much higher than those in Fe(VI) alone system (5 %-17 %). However, the contribution of Fe(VI) in oxidizing BP-4 should not be underestimated (20 %-56 %). These findings reasonably exploit available Fh resources to reduce the relatively high cost of Fe(VI), which offers a proper strategies for efficient utilization of high-valent iron species and may be used as a highly-efficient and cost-effective BPs purification method.

Keywords: Benzophenone; Catalytic oxidation; Fe(V)/Fe(IV) species; Ferrate; Ferrihydrite.