1
|
Zaia DAM, de Carvalho PCG, Samulewski RB, de Carvalho Pereira R, Zaia CTBV. Unexpected Thiocyanate Adsorption onto Ferrihydrite Under Prebiotic Chemistry Conditions. ORIGINS LIFE EVOL B 2020; 50:57-76. [PMID: 32266585 DOI: 10.1007/s11084-020-09594-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 03/10/2020] [Indexed: 02/02/2023]
Abstract
The most crucial role played by minerals was in the preconcentration of biomolecules or precursors of biomolecules in prebiotic seas. If this step had not occurred, molecular evolution would not have occurred. Thiocyanate is an important molecule in the formation of biomolecules as well as a catalyst for prebiotic reactions. The adsorption of thiocyanate onto ferrihydrite was carried out under pH and ion composition conditions in seawater that resembled those of prebiotic Earth. The seawater used in this work had high Mg2+, Ca2+ and SO42- concentrations. The most important result of this work was that ferrihydrite adsorbed thiocyanateata pH value (7.2 ± 0.2) that usually does not adsorb thiocyanate. The high adsorptivity of Mg2+, Ca2+ and SO42-onto ferrihydrite showed that seawater ions can act as carriers of thiocyanate to the ferrihydrite surface, creating a huge outer-sphere complex. Kinetic adsorption and isotherm experiments showed the best fit for the pseudo-second-order model and an activation energy of 23.8 kJ mol-1forthe Langmuir-Freundlich model, respectively. Thermodynamic data showed positive ΔG values, which apparently contradict the adsorption isotherm data and kinetic data that was obtained. The adsorption of thiocyanate onto ferrihydrite could be explained by coupling with the exergonic SO42- adsorption onto ferrihydrite. The FTIR spectra showed no difference between the C≡N stretching peaks of adsorbed thiocyanate and free thiocyanate, corroborating the formation of an outer-sphere complex. All the results demonstrated the importance of the artificial seawater composition for the adsorption of thiocyanate and for understanding prebiotic chemistry.
Collapse
Affiliation(s)
- Dimas A M Zaia
- Departamento de Química, Laboratório de Química Prebiótica-LQP, Universidade Estadual de Londrina, Londrina, PR, CEP 86 057-970, Brazil.
| | - Paulo C G de Carvalho
- Departamento de Química, Laboratório de Química Prebiótica-LQP, Universidade Estadual de Londrina, Londrina, PR, CEP 86 057-970, Brazil
| | - Rafael B Samulewski
- Departamento de Química, Laboratório de Química Prebiótica-LQP, Universidade Estadual de Londrina, Londrina, PR, CEP 86 057-970, Brazil
| | - Rodrigo de Carvalho Pereira
- Departamento de Química, Laboratório de Química Prebiótica-LQP, Universidade Estadual de Londrina, Londrina, PR, CEP 86 057-970, Brazil
| | - Cássia Thaïs B V Zaia
- Departamento de Ciências Fisiológicas, Laboratório de Fisiologia Neuroendocrina--LaFiNen, Universidade Estadual de Londrina, Londrina, PR, CEP 86 057-970, Brazil
| |
Collapse
|
2
|
Villafañe-Barajas SA, Baú JPT, Colín-García M, Negrón-Mendoza A, Heredia-Barbero A, Pi-Puig T, Zaia DAM. Salinity Effects on the Adsorption of Nucleic Acid Compounds on Na-Montmorillonite: a Prebiotic Chemistry Experiment. ORIGINS LIFE EVOL B 2018; 48:181-200. [PMID: 29392543 DOI: 10.1007/s11084-018-9554-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 01/08/2018] [Indexed: 10/18/2022]
Abstract
Any proposed model of Earth's primitive environments requires a combination of geochemical variables. Many experiments are prepared in aqueous solutions and in the presence of minerals. However, most sorption experiments are performed in distilled water, and just a few in seawater analogues, mostly inconsistent with a representative primitive ocean model. Therefore, it is necessary to perform experiments that consider the composition and concentration of dissolved salts in the early ocean to understand how these variables could have affected the absorption of organic molecules into minerals. In this work, the adsorption of adenine, adenosine, and 5'AMP onto Na+montmorillonite was studied using a primitive ocean analog (4.0 Ga) from experimental and computational approaches. The order of sorption of the molecules was: 5'AMP > adenine > adenosine. Infrared spectra showed that the interaction between these molecules and montmorillonite occurs through the NH2 group. In addition, electrostatic interaction between negatively charged montmorillonite and positively charge N1 of these molecules could occur. Results indicate that dissolved salts affect the sorption in all cases; the size and structure of each organic molecule influence the amount sorbed. Specifically, the X-ray diffraction patterns show that dissolved salts occupy the interlayer space in Na-montmorillonite and compete with organic molecules for available sites. The adsorption capacity is clearly affected by dissolved salts in thermodynamic terms as deduced by isotherm models. Indeed, molecular dynamic models suggest that salts are absorbed in the interlamellar space and can interact with oxygen atoms exposed in the edges of clay or in its surface, reducing the sorption of the organic molecules. This research shows that the sorption process could be affected by high concentration of salts, since ions and organic molecules may compete for available sites on inorganic surfaces. Salt concentration in primitive oceans may have strongly affected the sorption, and hence the concentration processes of organic molecules on minerals.
Collapse
Affiliation(s)
- Saúl A Villafañe-Barajas
- Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México
- Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México
| | - João Paulo T Baú
- Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina, Londrina, PR, 86051-990, Brazil
| | - María Colín-García
- Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México.
| | - Alicia Negrón-Mendoza
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México
| | - Alejandro Heredia-Barbero
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México
| | - Teresa Pi-Puig
- Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Cd. Mx., México
| | - Dimas A M Zaia
- Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina, Londrina, PR, 86051-990, Brazil.
| |
Collapse
|