Circular economy approach for the development of niobium nano-adsorbents

Circular economy approach for the development of niobium nano-adsorbents

• Autor
• Rafael Gomes Andrade
• Co-autores
• Giovani Pavoski , William Leonardo da Silva , Denise Crocce Romano Espinosa
• Resumo

• Niobium (Nb) is a metal of significant commercial importance for Brazil, as it holds approximately 98% of the world's reserves. Niobium can be sourced from primary (ores) and secondary (mining tailings) sources. Columbite is a naturally occurring mineral that may be present in mining tailings. A circular economy process is proposed to recover Nb from columbite as a secondary source and obtain raw material for the synthesis of nano-adsorbents. Initially, columbite was characterized, followed by pre-treatment with NaOH at columbite:NaOH ratios of 5:5, 5:4, and 5:3. The effects of temperature (25–95°C) and time (15–180 min) on the process were evaluated. Subsequently, leaching was performed using mineral acids (H₂SO₄, HCl, HNO₃, and H₃PO₄) and organic acids (C₂H₂O₄, C₄H₆O₅, C₄H₆O₆, and C₆H₈O₇) at acid concentrations ranging from 1 to 10 mol/L. Columbite was found to contain 24.5 wt% Nb. The best leaching performances were achieved with HCl (43.1%) and C₂H₂O₄ (86.4%). The highest Nb extraction rates were observed at temperatures of 70–80°C over 180 min. The leaching process was effective in extracting Nb, leading to its dissolution in an aqueous solution. This method allowed for the recovery of Nb in a form suitable for controlled precipitation. The extracted niobium can then be used as a raw material for the synthesis of nano-adsorbents, leveraging its chemical properties for applications in photocatalysis, purification, and separation processes.

• Palavras-chave
• Circular economy; secondary sources; columbite; niobium.
• Área Temática
• Adsorção aplicada ao meio ambiente