These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: [Investigation on the oxidation behaviors and kinetics of sulfide by cryptomelane].
    Author: Li Q, Yu Y, Zhao YL, Zhu LJ, Feng XH, Liu F, Qiu GH.
    Journal: Huan Jing Ke Xue; 2011 Jul; 32(7):2102-8. PubMed ID: 21922837.
    Abstract:
    As one of the common manganese oxide minerals in supergene environment, cryptomelane affects the migration, transformation and environmental fate of sulfur in soil. In this work, oxidation process of sodium sulfide solution by cryptomelane was investigated without oxygen gas. The species and concentration of oxidation products of sulfide in solution were determined by spectrophotometry and ion chromatography, and the crystal structures and micro-morphologies of solid oxidation products of sulfide were characterized by XRD and SEM. The influence of solution temperature, pH value of solution, manganese average oxidation state (AOS) and the amount of added cryptomelane on the initial oxidation rate of S2- was studied. It was observed that the oxidation products of sulfide were S2O3(2-), SO3(2-), SO4(2-) and S, and S was the main one for that the total transformation rate of S2- to S2O3(2-), SO3(2-) and SO4(2-) was below 13.4%. The initial oxidation rate of S2- follows a pseudo-first-order law. Oxidation rate increased with elevating reaction temperature, decreasing pH value of solution and the increase of the amount of added mineral. The oxidation capacity of cryptomelane increased with the increase of Mn(III) content, and the initial oxidation rate constants (K(obs)) of S2- were 0.220 3 min(-1) and 0.1729 min(-1) when cryptomelane was applied with AOS about 3.81 and 3.98, respectively. During the redox process, cryptomelane was reduced to Mn(OH)2, which could be oxidized into Mn3O4, by O2 in air, and Mn3O4 was further transformed into MnOOH likely due to the reaction of surface-adsorbed water on manganese oxide and O2 and Mn3O4.
    [Abstract] [Full Text] [Related] [New Search]