Hydroxyapatite Coatings on Calcite Powder for the Removal of Heavy Metals from Contaminated Water

An approach for the remediation of heavy metal-contaminated wastewater that is gaining increasing attention is the application of hydroxyapatite (HAP)-based particles. HAP is conventionally synthesized through wet chemical precipitation of calcium and phosphate ions, although later studies have focu...

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Bibliographic Details
Published in:Water (Basel) 2021-06, Vol.13 (11), p.1493
Main Authors: Gibert, Oriol, Valderrama, César, Martínez, María M., Darbra, Rosa Mari, Moncunill, Josep Oliva, Martí, Vicenç
Format: Article
Language:English
Subjects:
Aquifers
Calcite
Calcite crystals
Calcium influx
Calcium ions
Calcium phosphates
Carbonates
Chemical precipitation
Chemicals
Contamination
Energy consumption
Ethanol
Groundwater
Heavy metals
Hydroxyapatite
Investigations
Ion exchange
Metal industry wastewaters
Metals
Mineral industry
Mining industry
Powders
Sonication
Sorption
Wastewater
Wastewater pollution
Wastewater treatment
Water pollution
Zinc
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Summary:An approach for the remediation of heavy metal-contaminated wastewater that is gaining increasing attention is the application of hydroxyapatite (HAP)-based particles. HAP is conventionally synthesized through wet chemical precipitation of calcium and phosphate ions, although later studies have focused on HAP synthesis from solid calcite contacted with a phosphate solution under ambient conditions. This synthesis route can allow saving soluble Ca-chemicals and, thus, make the process more cost-efficient. The aim of this study was to coat natural calcite powder with a layer of HAP for the removal of Zn and Cu from contaminated water. For this purpose, a HAP layer was synthesized on calcite particles, characterized using several complementary techniques and evaluated for the removal of Zn and Cu from synthetic solutions. Sorption kinetics and equilibrium isotherms, as well as the effect of sonication of the synthesized sample on its sorption performance, were determined. The results showed that calcite particles were efficiently coated with a HAP layer with high capacity in removing Zn and Cu from acidic solutions, with a qmax of 34.97 mg/g for Zn (increased to 37.88 g/mg after sonication of the sample) and 60.24 mg/g for Cu (which hardly varied with sonication). The mechanisms behind the sorption of Zn and Cu onto HAP, inferred from pH changes, the relation between metal uptake and Ca2+ release and XRD analysis, included surface complexation, ion exchange and precipitation of new Zn- and Cu-containing phases.
ISSN:2073-4441
2073-4441
DOI:10.3390/w13111493