The molecule of glutaroimidedioxime, a cyclic imidedioxime moiety that can form during the synthesis of the poly(amidoxime)sorbent and is reputedly responsible for the extraction of uranium from seawater. Complexation of manganese (II) with glutarimidedioxime in aqueous solutions was investigated with potentiometry, calorimetry, ESI-mass spectrometry, electrochemical measurements and quantum chemical calculations. Results show that complexation reactions of manganese with glutarimidedioxime are both enthalpy and entropy driven processes, implying that the sorption of manganese on the glutarimidedioxime-functionalized sorbent would be enhanced at higher temperatures. Complex formation of manganese with glutarimidedioxime can assist redox of Mn(II/III). There are about ~15% of equilibrium manganese complex with the ligand in seawater pH(8.3), indicating that manganese could compete to some degree with uranium for sorption sites.
The preparation of adsorbents with low cost, efficient adsorption and high profitability for gold recovery has important practical applications. In this work, synergistic poly (imine dioxime and amidoxime) (PDA) adsorbents were successfully prepared for gold recovery. An inexpensive engineering polyacrylonitrile (PAN) fiber is selected as the adsorbent substrate covalent binding with hydroxylamine hydrochloride to obtain PDA. The PDA surface with imine dioxime and amidoxime groups has a rich charge density and is more easily combined with gold ions through electrostatic interactions. The adsorption process of gold on PDA is a spontaneous endothermic process with monomolecular layer adsorption and the adsorption capacity increases with the increasing temperature under acidic conditions. The maximum adsorption capacity of PDA can reach 2937 mg g −1 at 25 °C and pH = 2 with an equilibrium time of 168 h. Meanwhile, excellent gold adsorption performance is also observed for PDA in simulated water treatment filler and water circulation reactor as well as interference conditions with other metal ions. Surprisingly, PDA has an ultra-low preparation cost ($ 2.54 × 10 2 kg −1 ), yet enables high-value gold (2.9 kg) for every kilogram of PDA with significant economic benefits. Therefore, this work will provide new ideas for the development of inexpensive, highly efficient, and specialized adsorbent preparation for gold recovery.
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