Understanding the Importance of Periodate Species in the pH-Dependent Degradation of Organic Contaminants in the H₂O₂/Periodate Process

Abstract

Although periodate-based advanced oxidation processes have been proven to be efficient in abating organic contaminants, the activation properties of different periodate species remain largely unclear. Herein, by highlighting the role of H4IO6 –, we reinvestigated the pH effect on the decontamination performance of the H2O2/periodate process. Results revealed that elevating pH from 2.0 to 10.0 could markedly accelerate the rates of organic contaminant decay but decrease the amounts of organic contaminant removal. This pH-dependent trend of organic contaminant degradation corresponded well with the HO· yield and the variation of periodate species. Specifically, although 1O2 could be detected at pH 9.0, HO· was determined to be the major reactive oxidizing species in the H2O2/periodate process under all the tested pH levels. Furthermore, it was suggested that only H4IO6 – and H2I2O10 4– could serve as the precursors of HO·. The second-order rate constant for the reaction of H2I2O10 4– species with H2O2 was determined to be ∼1199.5 M–1 s–1 at pH 9.0, which was two orders of magnitude greater than that of H4IO6 – (∼2.2 M–1 s–1 at pH 3.0). Taken together, the reaction pathways of H2O2 with different periodate species were proposed. These fundamental findings could improve our understanding of the periodate-based advanced oxidation processes.

Novel Insights into the Mechanisms of Periodate-Based Pretreatment in Enhancing Short-Chain Fatty Acids from Waste Activated Sludge

“…It was first proved that • OH and • O 2 – could be generated in the PI-pretreatment anaerobic fermentation system without any activator. IO 4 – was considered to be the dominant periodate species at pH < 8, which accorded with the acidogenic fermentation system. IO 4 – can act as an electron acceptor like H 2 O 2 ; we therefore hypothesized that reactive species such as • OH and • O 2 – might be generated as an intermediate during the electron transfer process between the electron donors in WAS (e.g., Fe(III)) and PI.…”

“…− was considered to be the dominant periodate species at pH < 8, 37 which accorded with the acidogenic fermentation system. IO 4 − can act as an electron acceptor like H 2 O 2 ; 16 we therefore hypothesized that reactive species such as • OH and • O 2 − might be generated as ) could be generated after the addition of PI into WAS and how these species can be produced in the future.…”

Enhanced anaerobic digestion of waste activated sludge with periodate-based pretreatment

“…Previous studies have recorded that PI was rapidly consumed with minor residual and stoichiometrically converted to IO 3 − (nontoxic) in the PI-based treatment system [ 12 , 50 ]. The environment-friendly end product of PI (i.e., IO 3 − ) was also a critically attractive reason for PI-based AOPs [ 51 , 52 ]. A limitation of the present work was the inevitable chemical inputs.…”

Naproxen as a Turn-On Chemiluminescent Probe for Real-Time Quantification of Sulfate Radicals

“…First, various AOPs with single ROS responsible for the oxidation of organic compound were employed to determine the values of Φ CL for the reactions of NAP with different ROS [i.e., Fe(IV), Co(IV), Mn(V), and HO • ]. To be specific, the activation of periodate by Fe(II) process [Fe(II)/ periodate process], 45 the activation of PMS by Co(II) process [Co(II)/PMS process], 22 the activation of PMS by Mn(II) assisted by 1,10-phenanthroline monohydrochloride monohydrate process [Mn(II)/Phen/PMS process] 46 and the Fenton process [Fe(II)/H 2 O 2 process], 47 and the activation of periodate by H 2 O 2 process (H 2 O 2 /periodate process) 48 were selected to determine the Φ CL of the reactions of NAP with Fe(IV), Co(IV), Mn(V), and HO • , respectively. All the selected AOPs could achieve complete removal of NAP rapidly (Figure S7), suggesting the high reactivity of Fe(IV), Co(IV), Mn(V), and HO • toward NAP.…”