Boosting Fe(III)/Fe(II) cycling under visible-light-driven TiO2-based membrane with electron-deficient center for wastewater decontamination
Qingfei Zhao, Zhenpeng Guo, Zhonghua Wu, Shuyuan Dong, Ronghao Kang, Siyu Jian, Shuhui Guan, Ting Zhang, Zhenfeng Bian
Abstract
The advanced oxidation process (AOP) based on hydroxyl radical ( • OH) has garnered increasing attention in water purification and wastewater treatment . However, producing • OH by activating hydrogen peroxide (H 2 O 2 ) encounters the challenges associated with the sluggish kinetics of Fe(II) regeneration. Herein, we developed a carambola-like catalyst of boron (B)-doped TiO 2 mesocrystals-based iron catalyst (Fe-B-MST), which served as a photocatalyst to modulate the regeneration of Fe(II) in photo Fenton-like systems. We successfully used the electrospinning method to gain membrane and realised the remediation of different industrial wastewater. The Fe-B-MST catalyst exhibits excellent efficiencies in the oxidative degradation of 4-chlorophenol (4-CP) pollutants, effectively facilitating the production of • OH while minimising the formation of toxic byproducts, with the first-order kinetic constant ( k = 2.372 min −1 ) being approximately 6.1 times greater than that without B doping, and 19.8 times greater than that observed with commercial TiO 2 . Theoretical calculations and related physicochemical characterisation reveal that B occupies an interstitial site in titania, conferring a sufficiently high valence band potential, making it thermodynamically favourable for H 2 O 2 oxidation and weakening its interaction with • OH, consequently increasing higher reactivity toward the targeted organic pollutant . The B doping facilitates electron transfer , promotes rapid reduction of Fe(III) to Fe(II), and further enhances • OH production via a photo Fenton-like reaction. The oxidation reaction stoichiometry efficiencies were quantified for different organics and calculated to be in the range of 7.70–24.20 % in Fe-B-MST/H 2 O 2 vis. system, representing an enhancement of 1.18–1.54 times compared to Fe-MST/H 2 O 2 vis. , alongside the utilisation efficiency of H 2 O 2 ( η ) of Fe-B-MST/H 2 O 2 vis. is 1.37–1.67 fold greater than that of Fe-MST/H 2 O 2 vis. after 30 min of reaction. This study expands our understanding and provides valuable insights into applying photocatalysis for enhanced wastewater treatment .