Gold recovery from printed circuit boards in an acidic environment: A case study in Burkina Faso

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Résumé

This study deal with a method for gold recovery from printed circuit boards (PCBs) obtained from WEEE collected in Burkina Faso. After grinding PCB samples and leaching with aqua regia, a solution rich in metal ions were obtained, containing notably 6.04 μg/g of gold, a concentration roughly 200 times higher than that of conventional gold ores. The study focused on the selective adsorption of Au3+ ions using a magnetic Fe-BTC/PpPDA MOF composite. This MOF exhibited a microporous microstructure (iodine index of about 2543.2 mg/g) and a point of zero charge (pHpzc) of 5.6, promoting electrostatic interactions in an acidic environment. Batch tests demonstrated highly efficient and selective gold adsorption, with a recovery rate exceeding 98%. The Fe-BTC/PpPDA material also enables the reduction of Au3+ ions to metallic gold, catalyzed by the amine and hydroxyl groups in the structure. After desorption of gold-loaded composite a magnetic separation allowed a good regeneration of the adsorbent, with a recovery rate of 89% after a second cycle. Infrared spectroscopy analyses confirmed the involvement of N-H and O-H functions in the adsorption and reduction mechanism of gold ions.

Mots-clés

Gold; Adsorption; WEEE; Fe-BTC/PpPDA