Catalytic ozonation of an imidazole ionic liquid via Fe3O4/ZnO nanocomposites: Performance, products and reaction mechanism. Issue 6 (December 2022)

• Record Type: Journal Article
• Authors: Tian, Jie; Wei, Junyan; Liang, Yeping; Guo, Ruixue; Li, Beibei; Qu, Ruijuan; Zhou, Dongmei; Wang, Zunyao; Sun, Ping
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 6(2022)
• Publication Date: 2022-12
• Subjects: Fe3O4/ZnO -- Ozone -- [HMIM]Br -- Catalytic mechanism -- Degradation products; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108726
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: This study aimed to investigate the catalytic performance of Fe3 O4 /ZnO in the ozonation of 1-hexyl-3-methyl imidazolium bromide ([HMIM]Br). The Fe3 O4 /ZnO composite was prepared by a quick and convenient two-step coprecipitation method, and the optimum mass ratio of Fe3 O4 :ZnO was determined as 1:8. The structure, surface morphology, and chemical composition of the Fe3 O4 /ZnO composites were studied by characterization methods. The degradation efficiency of [HMIM]Br reached 96% in 5 min in catalytic ozonation with the Fe3 O4 /ZnO composite, an increase of 20% compared with ozonation alone. Moreover, the pseudo-first-order rate constant was 1.5 times higher than ozonation alone. With the increase in the catalyst dosage, the degradation efficiency of [HMIM]Br first improved and then decreased, and the optimum dosage was 0.25 g/L. The increase in pH value and the introduction of Cu 2+ effectively promoted the catalytic ozonation of [HMIM]Br with Fe3 O4 /ZnO, while the reducing inorganic ions inhibited the ozonation reaction. Different water matrices had little influence on the catalytic performance of Fe3 O4 /ZnO. Radical scavenging and EPR experiments showed that hydroxyl radicals (OH), superoxide radicals (O2 - ) and singlet oxygen ( 1 O2 ) were the main active species in this system. Meanwhile, product identification showed that the degradation of [HMIM]Br mainly included hydroxylation, imidazole ring cleavage and bond cleavage. Toxicity prediction illustrated that the catalytic ozonation of [HMIM]Br could effectively reduce its toxicity. The efficiency, toxicity, reusability, and stability experiments suggested that the developed catalyst, Fe3 O4 /ZnO composite, had promising prospects in catalytic ozonation. Graphical Abstract: ga1 Highlights: Fe3 O4 /ZnO with effective catalytic performance for the ozonation of [HMIM]Br was prepared by a coprecipitation method. OH, O2 -, and 1 O2 were the main reactive oxygen species in catalytic ozonation. Fe3 O4 /ZnO had good application potential and stability in ozone catalysis. Hydroxylation, imidazole ring cleavage, bond cleavage and bromate formation were the main degradation pathways. Catalytic ozonation could effectively reduce toxicity of [HMIM]Br.