Simultaneous separation of nickel and copper from sulfuric acid using chelating weak base resins

BACKGROUND The management of industrial spent acids containing metals to be potentially recovered for further reuse is within the scope of circular economy principles. In particular, spent sulfuric acid solutions are usually treated by precipitation technologies, which are limited by the lack of selectivity thus affecting metal reuse. In this work, acidic effluents containing nickel (approximate to 9 g L-1), copper (approximate to 3 g L-1) and iron (approximate to 24 g L-1) in sulfuric acid media were treated with commercial chelating resins. Iminodiacetate (Purolite (R) S930Plus) and bis-picolylamine (MTS9600 (R)) resins were selected to perform the selective recovery of nickel and copper over iron, which is an impurity for further metal recovery by electrowinning. RESULTS Under the selected operation conditions (pH approximate to 2), resin MTS9600 (R) reported the best separation results with removal percentages of copper, nickel and iron of approximate to 80%, approximate to 99% and approximate to 10% respectively. The adsorption equilibrium of copper and nickel were described by the Langmuir (q(m,Cu) = 48 309 mg kg(dryresin)(-1) and K-L,K-Cu = 9.1 10(-2) L mg(-1)) and Freundlich (K-F,K-Ni = 645 (mg kg(dry resin)(-1))(L mg(-1))(1/n)) and n(Ni) = 2.29) models, respectively. Kinetic experiments confirmed that copper removal is preferential and weakly influenced by the operation conditions being described by a pseudo-first-order model. On the contrary, nickel kinetics that followed a pseudo-second order are strongly affected by reducing both the pH and the solid-liquid ratio. CONCLUSIONS The promising results confirm that resin MTS9600 (R) is an effective adsorbent for the removal of nickel and copper at strong acid conditions. More research is being conducted to analyze the resin regeneration and the selective recovery of target metals. (c) 2020 Society of Chemical Industry