『Abstract
Amino acids are ubiquitous in the Earth's surface environments
as reactive biological molecules produced by every living thing
including bacteria. To evaluate the effects of amino acids on
mineral dissolution and to reveal the mechanism by which they
interact with the mineral surface, we performed dissolution experiments
of X-ray amorphous silica in solution containing 0.1 mmol Na with
10.0 mmol amino acids such as cysteine, asparagine, serine, tryptophan,
alanine, threonine, histidine, lysine and arginine in near-neutral
solutions. Dissolution experiments in solutions of 0.1, 1.0 and
10.0 mmol NaCl without amino acids were also conducted as amino-free
controls. The results of this study indicate that basic amino
acids such as histidine, lysine and arginine can interact more
strongly with the negatively charged surface of amorphous silica
than other non-basic amino acids due to their greater dissociation,
thus forming cationic species. This electrostatical interaction
enhanced dissolution rates of amorphous silica by approximately
one order of magnitude compared with amino acid-free controls.
In contrast, no significant effect on the dissolution rates of
amorphous silica was observed in solutions containing cysteine,
asparagine, serine, tryptophan, alanite and threonine because
of lesser interaction with the surface of amorphous silica.
Key Words: Amino acids; Amorphous silica; Biological molecule;
Dissolution rate; Mineral dissolution』
Introduction
Experimental methods
Materials
Dissolution experiments
Analysis
Results and discussion
Effect of pH and concentrations of Na
Effect of amino acids
Conclusions
Acknowledgments
References