title: Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent.
abstract: The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (<2 wt% non-calcium impurities, according to ICP-MS analysis). Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6∙H2O). Based on its ability to adsorb Ni2+, as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.
authors.affiliation: Department of Offshore, Process and Energy Engineering, Cranfield University.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Georgakopoulos
authors.affiliation: School of Applied Chemical and Environmental Sciences, Sheridan College Institute of Technology and Advanced Learning; rafael.santos@alumni.utoronto.ca.
authors.forename: Rafael M
authors.initials: RM
authors.lastname: Santos
authors.affiliation: School of Engineering, University of Guelph.
authors.forename: Yi Wai
authors.initials: YW
authors.lastname: Chiang
authors.affiliation: Carbon Systems Engineering, Centre for Combustion, Carbon Capture and Storage, Cranfield University.
authors.forename: Vasilije
authors.initials: V
authors.lastname: Manovic
mesh_terms: D000327:Adsorption; D002119:Calcium Carbonate / Q000138:chemical synthesis*; D007220:Industrial Waste / Q000032:analysis*; D017641:Zeolites / Q000138:chemical synthesis*
chemical_list: D007220:Industrial Waste; D017641:Zeolites; D002119:Calcium Carbonate