Separation and Recovery of Base Metals from Waste Streams at Low pH

Marin Florido, Daniel (2021). Separation and Recovery of Base Metals from Waste Streams at Low pH. PhD thesis The Open University.



The growing application of Ni-containing materials in new technologies, such as Electric Vehicle (EV) battery systems and in industrial products such as Ni alloys, catalysts, metal hydrides and in certain portable electronic devices creates a sustainability challenge. Ni-containing wastewaters are a source of pollution that can harm human health, and mining Ni from primary sources has a significant environmental impact. Consequently, the recovery of Ni(II) is of growing importance. Solid phase extraction technologies are regarded as some of the most effective techniques to recover metals from low concentration solutions. Some of the advantages over other methods are lower cost, easier operation, high capacity, selectivity, and efficiency. A key challenge is the selective recovery of Ni from solutions which contain other base metals (e.g., Co, Cu and Fe) at low pH.

Picolinamide was explored as a potential chelating ligand as the aromatic amine in combination with the amide group was expected to lead to stronger nickel coordination at low pH. The functionalisation of silica gel with picolinamide was investigated using a diverse range of methods. Derivatisation of (3-aminopropyl)-functionalised silica was achieved by reaction of picolinic acid and the amide-coupling agent 1,1’-carbonyldiimidazole. This new material successfully demonstrated industrially relevant nickel adsorption at low pH and the materials were characterised by FT-IR, Solid State NMR and microanalysis. The silica material was also compared with commercial chelating resins. The functionalisation of other backbones such as poly(styrene), poly(glycidyl methacrylate) and silica-polymer composites with picolinamide was also explored using a similar route. In addition, the picolinamide-functionalised silica in column conditions demonstrated the selective separation of metals such as Co(II), Cu(II), Fe(III), Li, Mn(II), Ni(II) and Zn(II). Furthermore, the silica material is capable of chromatographically separating Co(II) and Ni(II) mixtures.

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