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Open AccessArticle

Morphological Features and Sorption Performance of Materials Based on Birnessite Exposed to Various Reductive Conditions

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Institute of Chemistry, Far Eastern Branch of Russian Academy of Sciences, Pr. 100-letiya Vladivostoka 159, Vladivostok 690022, Russia
2
School of Natural Sciences, Far Eastern Federal University, Sukhanova Str. 8, Vladivostok 690091, Russia
*
Author to whom correspondence should be addressed.
Colloids Interfaces 2018, 2(4), 70; https://doi.org/10.3390/colloids2040070
Received: 9 November 2018 / Revised: 4 December 2018 / Accepted: 6 December 2018 / Published: 9 December 2018
The article is devoted to the evolution of structural, morphological, and sorption characteristics of layered manganese oxide (birnessite) under various conditions close to the real operating regime of the sorbents for radioactive waste processing. To identify the phase composition in the birnessites, we implemented XRD analysis, while SEM and temperature-programmed reduction (TPR) were used to study morphological and redox features of the materials, respectively. Structural changes after various kinds of treatment of birnessites were tracked using low temperature nitrogen sorption. Sorption characteristics were assessed under static and in dynamic conditions on the efficiency of Sr2+ removal from simulated seawater. TPR combined with kinetic analysis revealed the decrease of particle sizes in the birnessites after repeated use in sorption-regeneration cycle and reduction with hydrazine. Despite the fact that the porous structure of the materials remains preserved, the surface morphology of birnessite changes drastically depending on the reducing agent. Hydrazine treatment increases the sorption performance of the birnessite followed by degradation of mechanical properties, thus, preventing such sorbent from repeated use. Kinetic analysis of TPR allows quantifying differences in morphology and porous structure of manganese oxide materials. The specific surface area, amorphous surface structure, and accessibility of Mn+3 sites are the most important factors for birnessite sorption performance. View Full-Text
Keywords: H2-TPR; seawater; Sr-90; birnessite; kinetic analysis; cubic splines H2-TPR; seawater; Sr-90; birnessite; kinetic analysis; cubic splines
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Portnyagin, A.; Egorin, A.; Golikov, A.; Tokar, E.; Mayorov, V.; Didenko, N.; Mashtalyar, D.; Sokol’nitskaya, T.; Avramenko, V. Morphological Features and Sorption Performance of Materials Based on Birnessite Exposed to Various Reductive Conditions. Colloids Interfaces 2018, 2, 70.

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