Degradation of dyes by peroxymonosulfate activated by ternary CoFeNi-layered double hydroxide: Catalytic performance, mechanism and kinetic modeling

Hanxuan Zeng; Weiqiu Zhang; Lin Deng; Jinming Luo; Shiqing Zhou; Xia Liu; Yong Pei; Zhou Shi; John Crittenden

doi:10.1016/j.jcis.2018.01.016

Degradation of dyes by peroxymonosulfate activated by ternary CoFeNi-layered double hydroxide: Catalytic performance, mechanism and kinetic modeling

J Colloid Interface Sci. 2018 Apr 1:515:92-100. doi: 10.1016/j.jcis.2018.01.016. Epub 2018 Jan 4.

Authors

Hanxuan Zeng¹, Weiqiu Zhang², Lin Deng³, Jinming Luo², Shiqing Zhou⁴, Xia Liu⁵, Yong Pei⁵, Zhou Shi¹, John Crittenden²

Affiliations

¹ Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, Hunan 410082, PR China.
² Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, GA 30332, United States.
³ Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, Hunan 410082, PR China; Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, GA 30332, United States. Electronic address: lindeng@hnu.edu.cn.
⁴ Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, Hunan 410082, PR China; Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, GA 30332, United States.
⁵ Department of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University, Xiangtan 411105, PR China.

PMID: 29331784
DOI: 10.1016/j.jcis.2018.01.016

Abstract

Ternary CoFeNi-layered double hydroxide (CoFeNi-LDH) was synthesized and initially applied to activate peroxymonosulfate (PMS) for the degradation of Congo red (CR) and Rhodamine B (RhB). The results show that the CoFeNi-LDH/PMS system can efficiently degrade nearly 100% of 20 mg/L CR or 20 mg/L RhB within 6- and 10-min reaction times, respectively. And the catalyst exhibits higher degradation efficiency on CR than on RhB under identical conditions, which is confirmed by electron clouds of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) performed by DFT calculations. Quenching tests reveal that SO₄^- is the dominant active species participating in the degradation process. Mechanism investigation demonstrates that Co(II)-Co(III)-Co(II) cycle is responsible for activating PMS to generate radicals for dyes degradation. A dynamic kinetic model is successfully developed to simulate the concentration profiles of CR and RhB degradation in CoFeNi-LDH/PMS system. The empirical second order rate constants between SO₄^- and CR (k_SO4-/CR), HO and CR (k_OH/CR), SO₄^- and RhB (k_SO4-/RhB), HO and RhB (k_HO/RhB) are determined to be 2.47 × 10⁷, 3.44 × 10⁶, 8.39 × 10⁶ and 2.62 × 10⁷ M^-1s^-1, respectively. In addition, toxic assessment using ECOSAR program suggests that the overall toxicity of CR and RhB decreased after treatment with CoFeNi-LDH/PMS system. Repeating tests and application of CoFeNi-LDH in different water sources give us adequate confidence that the as-synthesized CoFeNi-LDH is favorable for the purification of dye-contaminanted waters in practical.

Keywords: CoFeNi-layered double hydroxide; Degradation; Heterogeneous catalysis; Kinetic modeling; Peroxymonosulfate activation.