Antimony oxidation and sorption behavior on birnessites with different properties (δ-MnO2 and triclinic birnessite). (March 2019)

• Record Type: Journal Article
• Authors: Sun, Qian; Cui, Pei-Xin; Liu, Cun; Peng, Shi-Meng; Alves, Marcelo Eduardo; Zhou, Dong-Mei; Shi, Zhen-Qing; Wang, Yu-Jun
• Is Part Of: Environmental pollution. Volume 246(2019)
• Page Start: 990
• Page End: 998
• Publication Date: 2019-03
• Subjects: Antimony -- δ-MnO2 -- Triclinic birnessite -- Sorption -- Oxidation -- Edge sites; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.12.027
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Birnessites are abundant naturally occurring minerals with high sorption and oxidation capacity that could therefore play an important role in antimony (Sb) migration and transformation. There are various types of birnessites in the environment. However, little is known about the similarities and differences in Sb oxidation and sorption on birnessites with different properties. In this study, the behavior of Sb oxidation and sorption on two contrasting birnessites (δ-MnO2 and triclinic birnessite (TrBir)) were investigated via batch and kinetic experiments and various spectroscopic techniques. Our results showed that the reaction mechanisms between Sb and the two birnessites were similar. The edge sites of birnessites were responsible for Sb(III) oxidation. Mn(IV) was reduced to Mn(III) and Mn(II), bound with birnessites and released to the solution, respectively. Because of the rapid rate of electron transfer of adsorbed Sb(III) to birnessites, the only Sb species on δ-MnO2 after the oxidation reaction was Sb(V). Sb(V) was adsorbed at the edge sites of birnessites by replacing the OH group of birnessites, forming corner-sharing complexes with birnessites. However, the Sb sorption and oxidation capacities of the two birnessites were significantly different. Poorly-crystallized δ-MnO2 exhibited a much higher oxidation and sorption capacity than well-crystallized TrBir because the former had many more edge sites than the latter. This study reveals the general mechanism of the reaction between Sb and birnessite and indicates that birnessite with a high number of edge sites would exhibit a huge capacity in Sb oxidation and sorption. Graphical abstract: Image 1 Highlights: The reaction mechanisms between Sb and the two birnessite (δ-MnO2 and TrBir) are similar. The edge sites of birnessite were responsible for Sb(III) oxidation and Sb(V) sorption. Sb(V) was adsorbed at the edge sites of birnessite, forming corner-sharing complexes with birnessite. δ-MnO2 was much reactive than TrBir in Sb oxidation and adsorption due to the many more edge sites of δ-MnO2 . Abstract : The general reaction mechanism between Sb and birnessite and the key properties of birnessite affecting the reaction were revealed.