| Title |
Order of osakaite-namuwite-lahnsteinite formation during alkalization of sulfate solutions |
| ID_Doc |
18817 |
| Authors |
Delcheva, Z; Stanimirova, T; Petrova, N |
| Title |
Order of osakaite-namuwite-lahnsteinite formation during alkalization of sulfate solutions |
| Year |
2023 |
| Published |
|
| Abstract |
Experiments with dropwise alkalization of a 0.1 M ZnSO4 solution with 1M NaOH were carried out to establish the formation order of Zn-hydroxy-sulfate minerals (osakaite, namuwite, and lahnsteinite). During the controlled alkalization with 1M NaOH of a 0.1M ZnSO4 solution, namuwite (osakaite), lahnsteinite and wulfingite are successively formed. The obtained precipitates were characterized by powder X-ray diffraction (XRD) and SEM-EDS methods. The formation conditions and regions of stability of osakaite and namuwite are at near circumneutral pH (6.5-7), while lahnsteinite is stable at high pH (11-12). This explains the wider distribution of namuwite and osakaite in nature. The isomorphic substitution of Zn2+ cation with Cu2+ in the hydroxide layer of the Zn-hydroxy-sulfate minerals during controlled alkalization was studied using mixed 0.1M ZnSO4 + CuSO4 solution (molar ratio Zn:Cu = 4:1 and 1:1). During controlled alkalization of mixed Zn-Cu sulfate solutions, 25% copper cations are isomorphic incorporated in the namuwite (osakaite) and lahnsteinite structures. It was determined that this Cu2+ content is the upper limit of the isomorphism and corresponds to the occupation of 1/3 of octahedral positions. |
| PDF |
https://doi.org/10.52215/rev.bgs.2022.83.2.51
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