title: Magnesium hydroxide extracted from a magnesium-rich mineral for CO2 sequestration in a gas-solid system.
abstract: Magnesium hydroxide extracted from magnesium-bearing minerals is considered a promising agent for binding CO2 as a carbonate mineral in a gas-solid reaction. An efficient extraction route consisting of hydrothermal treatment on serpentine in HCl followed by NaOH titration for Mg(OH)2 precipitation was demonstrated. The extracted Mg(OH)2 powder had a mean crystal domain size as small as 12 nm and an apparent surface area of 54 m2/g. Under one atmosphere of 10 vol% CO2/N2, carbonation of the serpentine-derived Mg(OH)2 to 26% of the stoichiometric limit was achieved at 325 degrees C in 2 h; while carbonation of a commercially available Mg(OH)2, with a mean crystal domain size of 33 nm and an apparent surface area of 3.5 m2/g, reached only 9% of the stoichiometric limit. The amount of CO2 fixation was found to be inversely proportional to the crystal domain size of the Mg(OH)2 specimens. The experimental data strongly suggested that only a monolayer of carbonates was formed on the crystal domain boundary in the gas-solid reaction, with little penetration of the carbonates into the crystal domain.
authors.affiliation: Department of Chemical Engineering and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Pao-Chung
authors.initials: PC
authors.lastname: Lin
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Huang
authors.forename: Ching-Ta
authors.initials: CT
authors.lastname: Hsiao
authors.forename: Hsisheng
authors.initials: H
authors.lastname: Teng
mesh_terms: D017632:Asbestos, Serpentine / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D005740:Gases; D008276:Magnesium Hydroxide / Q000737:chemistry*
chemical_list: D017632:Asbestos, Serpentine; D005740:Gases; D002245:Carbon Dioxide; D008276:Magnesium Hydroxide