Mining from the ores is never cent percent, and the remains are rejected to tailings. These tailings are often rich in precious metals ions such as copper and acidic constituents which when let out contaminate freshwaters such as lakes, rivers, streams, and groundwater. Porous ion exchange resins with attributes of the high surface area, fast adsorption kinetics and selectivity are attractive for recovering metals like copper and adding value to the mining process.
From our previous studies, we already know that glutaraldehyde crosslinked polyethyleneimine (GA-PEI) has an excellent selectivity and affinity for copper.1-3 Here, we modified an inexpensive biotemplate, i.e., diatomaceous earth particles (DE) with GA-PEI4 and performed subsequent alkaline etching of the template to synthesize porous GA-PEI resin. The cross-section of GA-PEI modified single DE frustule was examined through focused ion beam scanning electron microscopy (FIB-SEM) and copper distribution through the whole volume of frustule was investigated using energy dispersive X-ray spectroscopy (EDX). GA-PEI resins produced after etching of the DE template were characterized for structure and morphology through scanning electron microscopy (SEM) as well as composition through X-ray photoelectron spectroscopy (XPS). The kinetics of copper ion adsorption was determined to be fast with resins achieving 75% saturation of adsorption sites in just 15 minutes, and binding capacity was evaluated through Langmuir adsorption isotherm. We also investigated the copper uptake of GA-PEI resin from its high concentration environmental solutions such as acid mine drainage from Mt Lyell in Tasmania. The results revealed that copper could be efficiently and selectively bound at pH 4 and completely eluted at pH 1. The copper recovery and regeneration capability of the GA-PEI resin was evaluated in two cycles of iteration and performance compared to two commercial resins, Purolite S930 Plus and Lewatit TP220. The results implicate great potential for using GA-PEI resins for effective recycling copper from highly copper polluted environmental solutions.
1. J. B. Lindén, M. Larsson, B. R. Coad, W. M. Skinner and M. Nydén, RSC Advances, 2014, 4, 25063-25066.
2. J. B. Lindén, M. Larsson, S. Kaur, W. M. Skinner, S. J. Miklavcic, T. Nann, I. M. Kempson and M. Nydén, RSC Advances, 2015, 5, 51883-51890.
3. S. Kaur, I. M. Kempson, J. B. Lindén, M. Larsson and M. Nydén, Biofouling, 2017, 1-11.
4. A. Nosrati, M. Larsson, J. B. Lindén, Z. Zihao, J. Addai-Mensah and M. Nydén, International Journal of Mineral Processing, 2017, 166, 29-36.