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Wang C, Zhou S, Wang X, Tan W, Feng X. Photocatalytic activation of sulfite by maghemite (γ-Fe 2O 3) for iohexol degradation and alleviation effect of HCO 3- on water acidification. Environ Pollut 2024; 346:123557. [PMID: 38355082 DOI: 10.1016/j.envpol.2024.123557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/27/2024] [Accepted: 02/10/2024] [Indexed: 02/16/2024]
Abstract
Photo-catalyzing sulfite (S(IV)) for the generation of sulfate radical (SO4•-) has emerged as a novel advanced oxidation process (AOP) recently. However, both the potential of soil minerals as effective photocatalysts and the process of water acidification due to S(IV) oxidation have been overlooked. Herein, maghemite (γ-Fe2O3), a typical soil iron oxide with excellent photocatalytic reactivity like hematite and magnetic-collectible property like magnetite, was successfully used to activate S(IV) for iohexol degradation under visible light irradiation. As a result, 91.3% of iohexol was eliminated within 15 min at 0.1 g/L maghemite and 0.5 mM S(IV) under neutral conditions. The influencing factors, including initial pH, catalyst dosage, S(IV) amount, co-existing substances and water matrix, were systematically investigated. The maghemite/S(IV)/vis system exhibited superior performance in iohexol degradation at a wide pH range (3-10). It was found that the released proton via S(IV) oxidation led to severe water acidification. Interestingly, a low dose of HCO3- could evidently resist water acidification with little influence on iohexol elimination. Radical quenching experiments and electron spin resonance (ESR) analysis confirmed that SO4•-, •OH and •O2- were involved in iohexol abatement with SO4•- being the dominant reactive species. Compared with hydrogen peroxide, persulfate and peroxymonosulfate, the established maghemite/S(IV)/vis system achieved much more remarkable degradation performance. Furthermore, the reactivity of the catalyst was not obviously reduced even after 10 runs of reaction. This study expands the application of soil iron oxide mineral in S(IV) activation in water treatment and proposes an approach to regulate water acidification in S(IV)-based AOP.
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Affiliation(s)
- Cheng Wang
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs of the People's Republic of China, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Shuijing Zhou
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs of the People's Republic of China, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Xiaoming Wang
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs of the People's Republic of China, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Wenfeng Tan
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs of the People's Republic of China, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Xionghan Feng
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs of the People's Republic of China, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
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Zeng J, Zhang M, Qin X, He Y, Liu X, Zhu Y, Liu Z, Li W, Dong H, Qiang Z, Lian J. Quenching residual H 2O 2 from UV/H 2O 2 with granular activated carbon: A significant impact of bicarbonate. Chemosphere 2024; 354:141670. [PMID: 38462184 DOI: 10.1016/j.chemosphere.2024.141670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/06/2024] [Accepted: 03/06/2024] [Indexed: 03/12/2024]
Abstract
UV/H2O2 has been used as an advanced oxidation process to remove organic micropollutants from drinking water. It is essential to quench residual H2O2 to prevent increased chlorine demand during chlorination/chloramination and within distribution systems. Granular activated carbon (GAC) filter can quench the residual oxidant and eliminate some of the dissolved organic matter. However, knowledge on the kinetics and governing factors of GAC quenching of residual H2O2 from UV/H2O2 and the mechanism underlying the enhancement of the process by HCO3- is limited. Therefore, this study aimed to analyse the kinetics and influential factors, particularly the significant impact of bicarbonate (HCO3-). H2O2 decomposition by GAC followed first-order kinetics, and the rate constants normalised by the GAC dosage (kn) were steady (1.6 × 10-3 L g-1 min-1) with variations in the GAC dosage and initial H2O2 concentration. Alkaline conditions favour H2O2 quenching. The content of basic groups exhibited a stronger correlation with the efficiency of GAC in quenching H₂O₂ than did the acidic groups, with their specific kn values being 8.9 and 2.4 min-1 M-1, respectively. The presence of chloride, sulfate, nitrate, and dissolved organic matter inhibited H2O2 quenching, while HCO3- promoted it. The interfacial hydroxyl radical (HO•) zones were visualised on the GAC surface, and HCO3- addition increased the HO• concentration. HCO3- increased the concentration of persistent free radicals (PFRs) on the GAC surface, which mainly contributed to HO• generation. A significant enhancement of HCO3- on H2O2 quenching by GAC was also verified in real water. This study revealed the synergistic mechanism of HCO3- and GAC on H2O2 quenching and presents the potential applications of residual H2O2 in the H2O2-based oxidation processes.
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Affiliation(s)
- Jinfeng Zeng
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China; Hydrology and Water Resources Monitoring Center for Ganjiang Upstream Watershed, 8 Zhang-jia-wei Road, Ganzhou, 341000, China
| | - Miao Zhang
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China; Guyang Water Conservancy Agricultural Machinery Management Service Station, Zhenjiang, 212100, China
| | - Xinxin Qin
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China
| | - Yi He
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China
| | - Xinyue Liu
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China
| | - Yichun Zhu
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China
| | - Zuwen Liu
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China; National-local Joint Engineering Laboratory of Water Engineering Safety and Efficient Utilization of Resources in Poyang Lake Watershed, Nanchang Institute of Technology, Nanchang, 330099, China
| | - Wentao Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China
| | - Huiyu Dong
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China
| | - Junfeng Lian
- Jiangxi Provincial Key Laboratory of Water Ecological Conservation at Headwater Regions, Jiangxi University of Science and Technology, 1958 Ke-jia Road, Ganzhou, 341000, China.
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Jung EH, Eom J, Brauner CJ, Martinez-Ferreras F, Wood CM. The gaseous gastrointestinal tract of a seawater teleost, the English sole (Parophrys vetulus). Comp Biochem Physiol A Mol Integr Physiol 2020; 247:110743. [PMID: 32531535 DOI: 10.1016/j.cbpa.2020.110743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 02/07/2023]
Abstract
There has been considerable recent progress in understanding the respiratory physiology of the gastrointestinal tract (GIT) in teleosts, but the respiratory conditions inside the GIT remain largely unknown, particularly the luminal PCO2 and PO2 levels. The GIT of seawater teleosts is of special interest due to its additional function of water absorption linked to HCO3- secretion, a process that may raise luminal PCO2 levels. Direct measurements of GIT PCO2 and PO2 using micro-optodes in the English sole (Parophrys vetulus; anaesthetized, artificially ventilated, 10-12 °C) revealed extreme luminal gas levels. Luminal PCO2 was 14-17 mmHg in the stomach and intestinal segments of fasted sole, considerably higher than arterial blood levels of 5 mmHg. Moreover, feeding, which raised intestinal HCO3- concentration, also raised luminal PCO2 to 34-50 mmHg. All these values were higher than comparable measurements in freshwater teleosts, and also greater than environmental CO2 levels of concern in aquaculture or global change scenarios. The PCO2 values in subintestinal vein blood draining the GIT of fed fish (28 mmHg) suggested some degree of equilibration with high luminal PCO2, whereas subintestinal vein PO2 levels were relatively low (9 mmHg). All luminal sections of the GIT were virtually anoxic (PO2 ≤ 0.3 mmHg), in both fasted and fed animals, a novel finding in teleosts.
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Nunes AR, Holmes APS, Sample V, Kumar P, Cann MJ, Monteiro EC, Zhang J, Gauda EB. Bicarbonate-sensitive soluble and transmembrane adenylyl cyclases in peripheral chemoreceptors. Respir Physiol Neurobiol 2013; 188:83-93. [PMID: 23727159 DOI: 10.1016/j.resp.2013.05.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 05/09/2013] [Accepted: 05/13/2013] [Indexed: 12/17/2022]
Abstract
Stimulation of the carotid body (CB) chemoreceptors by hypercapnia triggers a reflex ventilatory response via a cascade of cellular events, which includes generation of cAMP. However, it is not known if molecular CO2/HCO3(-) and/or H(+) mediate this effect and how these molecules contribute to cAMP production. We previously reported that the CB highly expresses HCO3(-)-sensitive soluble adenylyl cyclase (sAC). In the present study we systematically characterize the role of sAC in the CB, comparing the effect of isohydric hypercapnia (IH) in cAMP generation through activation of sAC or transmembrane-adenylyl cyclase (tmAC). Pharmacological deactivation of sAC and tmAC decreased the CB cAMP content in normocapnia and IH with no differences between these two conditions. Changes from normocapnia to IH did not effect the degree of PKA activation and the carotid sinus nerve discharge frequency. sAC and tmAC are functional in CB but intracellular elevations in CO2/HCO3(-) in IH conditions on their own are insufficient to further activate these enzymes, suggesting that the hypercapnic response is dependent on secondary acidosis.
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Affiliation(s)
- Ana R Nunes
- Department of Pediatrics, Johns Hopkins Medical Institutions, Baltimore, MD 21287-3200, USA
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