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Kaolin Particles Assisting Dissolved Manganese Oxidation by Chlorination in Water Treatment
https://orcid.org/0000-0001-9505-6813
https://orcid.org/0000-0003-1193-7088
Poor Mn(II) oxidation by chlorination raises concerns about elevating residual Mn(II) levels in treated tap water. Using kaolin (KA) particles to absorb colloidal manganese oxides (MnO x ), we proposed an assisting strategy to improve the Mn(II) oxidation in conventional chlorination process. Both kinetic and underlying mechanisms of Mn(II) oxidation by KA assisting chlorination (Cl2@KA) were investigated. Without adding KA, chlorination alone (a Cl2/Mn ratio of 5:1, [Cl2] of 1.85 and 6.9 mg/L) poorly oxidized Mn(II), with Mn(II) oxidation rates <20% after 120 min. When KA was added from 6.7 to 18.5 NTU, the Mn(II) oxidation rates increased to 28–57 and 57–87% for the low and high [Mn(II)]0 of 0.37 and 1.38 mg/L, respectively. The Mn(II) oxidation kinetics of Cl2@KA followed an autocatalytic model, where the chlorination with KA assistance and high [Mn(II)]0 increased the noncatalytic k 1 and autocatalytic k 2 rate constants. KA attracted newly formed MnO x colloids via electrostatic attraction to form KA adsorbing MnO x particulates (KA@MnO x ), which enhanced the autocatalytic effect of MnO x toward free Mn(II). After chlorination, KA@MnO x showed significant increases in the Mn 2p atomic concentrations from undetectable to 5.63%. The KA@MnO x surface was dominated by Mn(III) oxides (∼60–70%) rather than MnIVO2. From a bench-scale experiment with KA assisting chlorination–coagulation/sedimentation–filtration, this process effectively removed >90% soluble Mn(II) in the solution to a level <0.05 mg/L, when the conventional chlorination alone could not achieve the same goal.
Kaolin Particles Assisting Dissolved Manganese Oxidation by Chlorination in Water Treatment
https://orcid.org/0000-0001-9505-6813
https://orcid.org/0000-0003-1193-7088
Poor Mn(II) oxidation by chlorination raises concerns about elevating residual Mn(II) levels in treated tap water. Using kaolin (KA) particles to absorb colloidal manganese oxides (MnO x ), we proposed an assisting strategy to improve the Mn(II) oxidation in conventional chlorination process. Both kinetic and underlying mechanisms of Mn(II) oxidation by KA assisting chlorination (Cl2@KA) were investigated. Without adding KA, chlorination alone (a Cl2/Mn ratio of 5:1, [Cl2] of 1.85 and 6.9 mg/L) poorly oxidized Mn(II), with Mn(II) oxidation rates <20% after 120 min. When KA was added from 6.7 to 18.5 NTU, the Mn(II) oxidation rates increased to 28–57 and 57–87% for the low and high [Mn(II)]0 of 0.37 and 1.38 mg/L, respectively. The Mn(II) oxidation kinetics of Cl2@KA followed an autocatalytic model, where the chlorination with KA assistance and high [Mn(II)]0 increased the noncatalytic k 1 and autocatalytic k 2 rate constants. KA attracted newly formed MnO x colloids via electrostatic attraction to form KA adsorbing MnO x particulates (KA@MnO x ), which enhanced the autocatalytic effect of MnO x toward free Mn(II). After chlorination, KA@MnO x showed significant increases in the Mn 2p atomic concentrations from undetectable to 5.63%. The KA@MnO x surface was dominated by Mn(III) oxides (∼60–70%) rather than MnIVO2. From a bench-scale experiment with KA assisting chlorination–coagulation/sedimentation–filtration, this process effectively removed >90% soluble Mn(II) in the solution to a level <0.05 mg/L, when the conventional chlorination alone could not achieve the same goal.
Kaolin Particles Assisting Dissolved Manganese Oxidation by Chlorination in Water Treatment
https://orcid.org/0000-0001-9505-6813
https://orcid.org/0000-0003-1193-7088
Poor Mn(II) oxidation by chlorination raises concerns about elevating residual Mn(II) levels in treated tap water. Using kaolin (KA) particles to absorb colloidal manganese oxides (MnO x ), we proposed an assisting strategy to improve the Mn(II) oxidation in conventional chlorination process. Both kinetic and underlying mechanisms of Mn(II) oxidation by KA assisting chlorination (Cl2@KA) were investigated. Without adding KA, chlorination alone (a Cl2/Mn ratio of 5:1, [Cl2] of 1.85 and 6.9 mg/L) poorly oxidized Mn(II), with Mn(II) oxidation rates <20% after 120 min. When KA was added from 6.7 to 18.5 NTU, the Mn(II) oxidation rates increased to 28–57 and 57–87% for the low and high [Mn(II)]0 of 0.37 and 1.38 mg/L, respectively. The Mn(II) oxidation kinetics of Cl2@KA followed an autocatalytic model, where the chlorination with KA assistance and high [Mn(II)]0 increased the noncatalytic k 1 and autocatalytic k 2 rate constants. KA attracted newly formed MnO x colloids via electrostatic attraction to form KA adsorbing MnO x particulates (KA@MnO x ), which enhanced the autocatalytic effect of MnO x toward free Mn(II). After chlorination, KA@MnO x showed significant increases in the Mn 2p atomic concentrations from undetectable to 5.63%. The KA@MnO x surface was dominated by Mn(III) oxides (∼60–70%) rather than MnIVO2. From a bench-scale experiment with KA assisting chlorination–coagulation/sedimentation–filtration, this process effectively removed >90% soluble Mn(II) in the solution to a level <0.05 mg/L, when the conventional chlorination alone could not achieve the same goal.
Kaolin Particles Assisting Dissolved Manganese Oxidation by Chlorination in Water Treatment
Hua, Lap-Cuong (Autor:in) / Tsai, Ming-Han (Autor:in) / Weng, Chia-Yu (Autor:in) / OuYang, Ruei-Ci (Autor:in) / Huang, Chihpin (Autor:in)
ACS ES&T Engineering ; 3 ; 398-406
10.03.2023
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Oxidation of Dissolved Manganese in Natural Waters
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Chlorination‐Filtration for Iron and Manganese Removal
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Iron and Manganese Removal by Free Residual Chlorination
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