Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution
A very low concentration of manganese (Mn) in water is a critical issue for municipal and industrial water supply systems. Mn removal technology is based on the use of manganese oxides (MnO<sub>x</sub>), especially manganese dioxide (MnO<sub>2</sub>) polymorphs, under differe...
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MDPI AG
2023-02-01
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| Series: | International Journal of Molecular Sciences |
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| author | Magdalena M. Michel Mostafa Azizi Dorota Mirosław-Świątek Lidia Reczek Bogumił Cieniek Eleonora Sočo |
| author_facet | Magdalena M. Michel Mostafa Azizi Dorota Mirosław-Świątek Lidia Reczek Bogumił Cieniek Eleonora Sočo |
| author_sort | Magdalena M. Michel |
| collection | DOAJ |
| description | A very low concentration of manganese (Mn) in water is a critical issue for municipal and industrial water supply systems. Mn removal technology is based on the use of manganese oxides (MnO<sub>x</sub>), especially manganese dioxide (MnO<sub>2</sub>) polymorphs, under different conditions of pH and ionic strength (water salinity). The statistical significance of the impact of polymorph type (akhtenskite ε-MnO<sub>2</sub>, birnessite δ-MnO<sub>2</sub>, cryptomelane α-MnO<sub>2</sub> and pyrolusite β-MnO<sub>2</sub>), pH (2–9) and ionic strength (1–50 mmol/L) of solution on the adsorption level of Mn was investigated. The analysis of variance and the non-parametric Kruskal–Wallis H test were applied. Before and after Mn adsorption, the tested polymorphs were characterized using X-ray diffraction, scanning electron microscope techniques and gas porosimetry analysis. Here we demonstrated the significant differences in adsorption level between MnO<sub>2</sub> polymorphs’ type and pH; however, the statistical analysis proves that the type of MnO<sub>2</sub> has a four times stronger influence. There was no statistical significance for the ionic strength parameter. We showed that the high adsorption of Mn on the poorly crystalline polymorphs leads to the blockage of micropores in akhtenskite and, contrary, causes the development of the surface structure of birnessite. At the same time, no changes in the surfaces of cryptomelane and pyrolusite, the highly crystalline polymorphs, were found due to the very small loading by the adsorbate. |
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| last_indexed | 2024-03-11T07:24:01Z |
| publishDate | 2023-02-01 |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-dbf3fd98b5c4428295ea31b7a4b4af912023-11-17T07:48:36ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-02-01245444810.3390/ijms24054448Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water SolutionMagdalena M. Michel0Mostafa Azizi1Dorota Mirosław-Świątek2Lidia Reczek3Bogumił Cieniek4Eleonora Sočo5Institute of Environmental Engineering, Warsaw University of Life Science, 02-787 Warsaw, PolandInstitute of Environmental Engineering, Warsaw University of Life Science, 02-787 Warsaw, PolandInstitute of Environmental Engineering, Warsaw University of Life Science, 02-787 Warsaw, PolandInstitute of Environmental Engineering, Warsaw University of Life Science, 02-787 Warsaw, PolandInstitute of Materials Engineering, University of Rzeszow, 35-310 Rzeszow, PolandDepartment of Inorganic and Analytical Chemistry, Faculty of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, PolandA very low concentration of manganese (Mn) in water is a critical issue for municipal and industrial water supply systems. Mn removal technology is based on the use of manganese oxides (MnO<sub>x</sub>), especially manganese dioxide (MnO<sub>2</sub>) polymorphs, under different conditions of pH and ionic strength (water salinity). The statistical significance of the impact of polymorph type (akhtenskite ε-MnO<sub>2</sub>, birnessite δ-MnO<sub>2</sub>, cryptomelane α-MnO<sub>2</sub> and pyrolusite β-MnO<sub>2</sub>), pH (2–9) and ionic strength (1–50 mmol/L) of solution on the adsorption level of Mn was investigated. The analysis of variance and the non-parametric Kruskal–Wallis H test were applied. Before and after Mn adsorption, the tested polymorphs were characterized using X-ray diffraction, scanning electron microscope techniques and gas porosimetry analysis. Here we demonstrated the significant differences in adsorption level between MnO<sub>2</sub> polymorphs’ type and pH; however, the statistical analysis proves that the type of MnO<sub>2</sub> has a four times stronger influence. There was no statistical significance for the ionic strength parameter. We showed that the high adsorption of Mn on the poorly crystalline polymorphs leads to the blockage of micropores in akhtenskite and, contrary, causes the development of the surface structure of birnessite. At the same time, no changes in the surfaces of cryptomelane and pyrolusite, the highly crystalline polymorphs, were found due to the very small loading by the adsorbate.https://www.mdpi.com/1422-0067/24/5/4448environmental engineeringgroundwater treatmentadsorptionMnO<sub>2</sub> polymorphsakhtenskitebirnessite |
| spellingShingle | Magdalena M. Michel Mostafa Azizi Dorota Mirosław-Świątek Lidia Reczek Bogumił Cieniek Eleonora Sočo Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution International Journal of Molecular Sciences environmental engineering groundwater treatment adsorption MnO<sub>2</sub> polymorphs akhtenskite birnessite |
| title | Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution |
| title_full | Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution |
| title_fullStr | Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution |
| title_full_unstemmed | Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution |
| title_short | Significance of MnO<sub>2</sub> Type and Solution Parameters in Manganese Removal from Water Solution |
| title_sort | significance of mno sub 2 sub type and solution parameters in manganese removal from water solution |
| topic | environmental engineering groundwater treatment adsorption MnO<sub>2</sub> polymorphs akhtenskite birnessite |
| url | https://www.mdpi.com/1422-0067/24/5/4448 |
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