Highly toxic iodinated products would form in oxidation and disinfection of iodine-containing water. Variation of iodinated aromatic products in ferrate [Fe(VI)] oxidation of phenolic compounds (phenol, bisphenol A (BPA), and p-hydroxybenzoic acid (p-HBA)) in iodine-containing water was investigated. At pH 5.0, oxidation of phenolic compounds was inhibited by competitive reaction of ferrate with I–, and no formation of iodinated aromatic products was detected. Almost all I– was converted into nontoxic IO3 –. At pH 7.0, 8.0, and 9.0, HOI formed in ferrate oxidation of I– and further reacted with phenols, with the formation of iodinated aromatic products. Mass spectrometry analysis showed that both kinds and contents of iodinated aromatic products were raised with the increase in solution pH and the content of I–, and these iodinated aromatic products were further oxidized by ferrate. Ferrate deprived iodine from iodinated aromatic products and transferred highly toxic organic iodine into nontoxic IO3 –. An electron-donating substituent (alkyl) increased the reactivity of phenol with ferrate and HOI and facilitated ferrate oxidation of iodinated phenols. An electron-drawing substituent (carboxyl) decreased the reactivity of phenol with ferrate and HOI and hindered the further oxidation of iodinated aromatic products. A kinetic model about the variation of phenol, BPA, and p-HBA in reaction with ferrate in iodine-containing water was developed, and the oxidation profile of phenolic compounds could be satisfactorily predicted at various iodide concentrations.
Membrane fouling is one of the main obstacles impacting ultrafiltration (UF) membranes for water purification. Herein, it was found that a hydrophilic layer that is composed of a ferric floc formed in the reduction of ferrate coated on the membrane during the ultrafiltration of river water, and this layer is effective for attenuating membrane fouling. The newly formed ferric (hydro)oxide particles aggregated with natural organic matter (NOM) of the source water and then deposited on the membrane surface forming a negatively charged, porous, and hydrophilic prefiltration layer. This layer was beneficial for rejecting transphilic dissolved organic carbon (DOC), resulted in the accumulation of external membrane foulants, and alleviated internal membrane fouling. The membrane flux improved by 2.8 times, and the membrane fouling resistance decreased by 0.36 times after preoxidation with 1.5 mg/L of ferrate. Meanwhile, the performance of the membrane rejection was enhanced by this layer as well. DOC and UV 254 were eliminated by 41% and 67% at the condition of 2.0 mg/L ferrate preoxidation coupled with UF. A model analysis suggested that intermediate and standard pore blocking were enhanced after ferrate preoxidation, while cake layer fouling was substantially attenuated. The ferric prefiltration layer can be back-washed for the recovery of membrane flux and be repeatedly generated through ferrate preoxidation. The combination of ferrate preoxidation with UF takes full advantage of the oxidizability of ferrate and the aggregation/adsorption potential of ferric (hydro)oxides by the reduction of ferrate.
Anthracite is globally used as a filter material for water purification. Herein, it was found that up to 15 disinfection byproducts (DBPs) were formed in the chlorination of anthracite-filtered pure water, while the levels of DBPs were below the detection limit in the chlorination of zeolite-, quartz sand-, and porcelain sandstone-filtered pure water. In new-anthracite-filtered water, the levels of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonia nitrogen (NH3–N) ranged from 266.3 to 305.4 μg/L, 37 to 61 μg/L, and 8.6 to 17.1 μg/L, respectively. In aged anthracite (collected from a filter at a DWTP after one year of operation) filtered water, the levels of the above substances ranged from 475.1 to 597.5 μg/L, 62.1 to 125.6 μg/L, and 14 to 28.9 μg/L, respectively. Anthracite would release dissolved substances into filtered water, and aged anthracite releases more substances than new anthracite. The released organics were partly (around 5%) composed by the μg/L level of toxic and carcinogenic aromatic carbons including pyridine, paraxylene, benzene, naphthalene, and phenanthrene, while over 95% of the released organics could not be identified. Organic carbon may be torn off from the carbon skeleton structure of anthracite due to hydrodynamic force in the water filtration process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.