Catalytic selective recovery of silver from dilute aqueous solutions and e-waste leachates

• Published in: Separation and purification technology 2022-03, Vol.285, p.120303, Article 120303
• Main Authors: Ruck, Erez B., Amikam, Gidon, Darom, Yonatan, Manor-Korin, Naama, Gendel, Youri
• Format: Article
• Language: English
• Subjects: Adsorption; Capacitive-Faradaic fuel cells; Electroless deposition; Hydrogenation; Hydrometallurgy; Metals separation
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2021.120303

[Display omitted] •The new process for selective silver ions recovery from water is reported.•Ag+ ions are catalytically reduced to Ag0 by H2 on the Pt in the separation step.•The Ag0 is oxidized by air on the Pt catalyst within the regeneration step.•Both steps are performed at ambient temperature and gas pressure of 1 bar.•Ag+ ions are separated from Cu2+ ions due to higher reduction potential of Ag+. The two-step catalytic process is proposed for the recovery of silver ions from aqueous solutions. First, the Ag+-containing solution is enriched with hydrogen gas and recirculated through the Pt-loaded activated carbon (Pt/AC). The Ag+ ions are reduced into the metal particles at ambient temperature and H2 gauge pressure of 1 atmosphere. Next, the Ag particles precipitated on the Pt/AC are oxidized by air to form the pure Ag+ concentrate and to regenerate the catalyst. The process was studied using pure AgNO3 solutions at varied pH values (0.0, 1.5 and 3.9) in a batch mode system that was operated with Pt/AC particles loaded with 0.1–1.0% of Pt metal. The complete removal of Ag+ ions was achieved within