test_moissonnage_selune
type: Agent

Precipitation kinetics of Mg-carbonates, influence of organic ligands and consequences for CO2 mineral sequestration
type: Distribution
access URL: https://pastel.hal.science/pastel-00806512
format: HTML
issued: 2026-05-11T19:53:05.940446
modified: 2026-05-11T19:53:05.896989

Precipitation kinetics of Mg-carbonates, influence of organic ligands and consequences for CO2 mineral sequestration
type: Dataset
contact point: Organization
  fn: CCSD
keyword: infoeu-reposemanticsdoctoralthesis
keyword: microscopie-a-force-atomique
keyword: co2-mineral-sequestration
keyword: sequestration-minerale-du-co2
keyword: sdustusciences-of-the-universe-physicsearth-sciences
keyword: magnesite
keyword: experimental-geochemistry
keyword: geochimie-experimentale
keyword: hydromagnesite
keyword: croissance-cristalline
keyword: crystal-growth
keyword: theses
keyword: atomic-force-microscopy
landing page: https://pastel.hal.science/pastel-00806512
description: Forming magnesium carbonate minerals through carbonation of magnesium silicates has been proposed as a safe and durable way to store carbon dioxide, with a possibly high potential to offset anthropogenic CO2 emissions. To date however, chemical reactions involved in this process are facing strong kinetic limitations, which originate in the low reactivity of both Mg-silicates and Mg-carbonates. Numerous studies have focused on the dissolution of Mg-silicates, under the questionable hypothesis that this step limits the whole process. This thesis work focuses instead on the mechanisms and rates of formation of magnesium carbonates, which are the final products of carbonation reactions. The first part of the work is dedicated to studying the influence on magnesite precipitation kinetics of three organic ligands known to accelerate Mg-silicates dissolution rates : oxalate, citrate and EDTA. With help of mixed-flow reactor experiments performed between 100 and 150°C, we show that these ligands significantly reduce magnesite growth rates, through two combined mechanisms: (1) complexation of Mg2+ cations in aqueous solution, which was rigorously estimated from a thermodynamic database established through a critical review of the literature, and (2) adsorption of ligands to a limited number of surface sites, leading to a decrease of the precipitation rate constant. The observed growth inhibition is maximal with citrate. We then used hydrothermal atomic force microscopy to probe the origin of the documented growth inhibition. Our observations show that citrate and oxalate interact with the crystal growth process on magnesite surface, modifying the shape of growth hillocks as well as the step generation frequency through spiral growth. We also show that the ligands adsorb preferentially on different kink-sites, which is probably related to their different structures and chemical properties. We propose that the stronger magnesite growth inhibition caused by citrate is related t…
identifier: NNT: 2012PEST1128
issued: 2026-05-11T19:53:05.918797
language: fr
modified: 2026-05-11T19:53:05.918802