Comparative removal of imidacloprid, bisphenol‐S, and azithromycin with ferrate and FeCl₃ and assessment of the resulting toxicity

Abstract

BACKGROUND: Emerging micro-pollutants (EMPs) in water have received much attention due to their potential hazards to human health and ecological security. Ferrate has been researched in recent years to remove both particulate and dissolved impurities (including EMPs) from water, and its promising performance has been attributed to the high oxidation capacity and coagulation functions. However, limited research has compared ferrate with coagulation alone in the treatment of EMPs, which is one of the major objectives of this study. RESULTS: Three emerging micro-pollutants (EMPs), imidacloprid (IMP), bisphenol-S (BS), and azithromycin (AZM) were chosen for this study. In all cases, ferrate outperformed to ferric chloride in the removal of the EMPs. For a given ferrate dose of 0.05 mM, 99% of BS, 85% of AZM, and 78% of IMP were removed for a start concentration of 10 ∼g L −1. However, if the start concentration was 1000 ∼g L −1 , removal efficiency was decreased to 82% for BS, 62% for AZM, and 22% for IMP. pH 5 was favorable to the EMP removal by ferrate for the study conditions. Although higher removals of IMP, BS, and AZM were achieved by ferrate in comparison to those by ferric chloride, only 20% DOC removal was achieved by the ferrate. The formation of various oxidation products in the degradation process resulted in the disparity of the solution toxicity; that of BS was reduced but those of IMP and AZM increased after ferrate treatment. Nevertheless, the toxicity of ferric chloride treated samples was all increased. CONCLUSION: Ferrate has higher efficiency comparing with FeCl 3 to remove IMP, BS, and AZM. Degradation of the EMPs by ferrate was more efficient in acidic conditions (pH 5) and at the EMPs' lower initial concentrations for the given conditions. IMP was more resistant to the ferrate treatment compared to BS and AZM under the same conditions. Overall, 20% DOC reduction was achieved by ferrate for pH 5. Finally, the toxicity of BS can be reduced but those of IMP and AZM were increased after ferrate treatment, whilst the toxicity of ferric chloride treated samples was all increased.

A Review on Methods for the Elimination of Imidacloprid: 2018–2022

“…Thus oxidation can be considered as a preferred mechanism for imidacloprid removal. However, the removal using ferrate leads to more toxic by‐products than imidacloprid and ferrates themselves which is the main limitation of the reported study [74] …”

“…However, the removal using ferrate leads to more toxic by-products than imidacloprid and ferrates themselves which is the main limitation of the reported study. [74] Cui et al, in 2020 developed a peroxymonosulphate activation-based (PMS) method for the degradation of imidacloprid d. For this purpose, water treatment residuals having iron content were utilized as a precursor for the preparation of activation reactor (HWTRs) via hydrothermal method. The degradation process was carried out by considering the varying peroxymonosulphate concentration, activator dosage, water composition and pH among which the maximum degradation of 97.7 %was found using 0.5 g L À 1 of HWTRs and 1.5 mM PMS under acidic conditions.…”

Removal of neonicotinoids present in secondary effluents by ferrate(VI)-based oxidation processes

“…In addition, Fe(VI) could attack to the N-nitro moiety of CLO, THM, and IMI, causing the substitution of the -NO2 group by hydrogen. Previous investigations have proposed that the disproportionate N-N bond of nitrite and amino groups attached to the imidazole ring of IMI can be weakened by an electron transfer oxidation reaction with Fe(VI), leading to the release of NO3 - (Zhang and Jiang 2021;Wang et al 2022). However, the low reactivity of IMI indicates that the Nnitro group is less reactive than the thiazole ring.…”

A Novel Natural Iron-Rich Tourmaline Activated Bisulfite System for the Efficient Degradation of Aqueous Imidacloprid

“…Numerous studies have reported technologies for the removal of IMI, including adsorption, , Electro-Fenton oxidation, , photocatalytic oxidation, − ferrate oxidation, , and persulfate oxidation. − Among them, persulfate-based advanced oxidation processes (AOPs) have been vastly studied for organic wastewater treatment due to the fact that the SO 4 •– generated in the persulfate oxidation process had a higher standard redox potential (SO 4 •– : 2.5–3.1 eV) and a prolonged half-life (30–40 μs) compared to • OH. − Nevertheless, considering the cost factor caused by the persulfate-based AOPs, there are still non-negligible limitations in their practical applications. In contrast, bisulfite (BS) has the advantages of low cost, low toxicity, and high activity .…”

“…Numerous studies have reported technologies for the removal of IMI, including adsorption, 6,7 Electro-Fenton oxidation, 8,9 photocatalytic oxidation, 10−12 ferrate oxidation, 13,14 and persulfate oxidation. 15−17 Among them, persulfate-based advanced oxidation processes (AOPs) have been vastly studied for organic wastewater treatment due to the fact that the SO 4…”