 |
Article dans une revue
Bio-dissolution of colloidal-size clay minerals entrapped in microporous silica gels
Abstract : Four colloidal-size fractions of strongly anisotropic particles of nontronite (NAu-2) having different ratios of basal to edge surfaces were incubated in the presence of heterotrophic soil bacteria to evaluate how changes in mineral surface reactivity influence microbial dissolution rate of minerals. To avoid any particle aggregation, which could change the reactive surface area available for dissolution, NAu-2 particles were immobilized in a biocompatible TEOS-derived silica matrix. The resulting hybrid silica gels support bacterial growth with NAu-2 as the sole source of Fe and Mg. Upon incubation of the hybrid material with bacteria, between 0.3% and 7.5% of the total Fe included in the mineral lattice was released with a concomitant pH decrease. For a given pH value, the amount of released Fe varied between strains and was two to twelve-fold higher than under abiotic conditions. This indicates that complexing agents produced by bacteria play an important role in the dissolution process. However, in contrast with proton-promoted NAu-2 dissolution (abiotic incubations) that was negatively correlated with particle size, bacterial-enhanced dissolution was constant for all size fractions used. We conclude that bio-dissolution of nontronite particles under acidic conditions seems to be controlled by bacterial metabolism rather than by the surface reactivity of mineral.
https://hal-unilim.archives-ouvertes.fr/hal-00654622
Contributeur : Claire Douady Connectez-vous pour contacter le contributeur
Soumis le : jeudi 22 décembre 2011 - 14:49:31
Dernière modification le : mercredi 20 octobre 2021 - 01:31:09
Contributeur : Claire Douady Connectez-vous pour contacter le contributeur
Soumis le : jeudi 22 décembre 2011 - 14:49:31
Dernière modification le : mercredi 20 octobre 2021 - 01:31:09
