Abstract
The continuous expansion of the market demand and scale of commercial amidoxime chelating resins has caused large amounts of resin to be discarded around the world. In this study, the waste amidoxime chelating resin was reutilized as an adsorbent for the removal and recovery of Pb(II), Cu(II), Cd(II) and Zn(II) ions from aqueous solutions. The physical morphology and chemical composition of the waste amidoxime chelating resin (WAC-resin) from the factory was characterized by the elemental analyzer, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The influence of the initial metal ions concentration, contact time, temperature and the solution pH on the adsorption performance of the metal ions was explored by batch experiments. It was shown that the optimal pH was 4. Kinetic studies revealed that adsorption process corresponded with the pseudo-second-order kinetic model and the adsorption isotherm was consistent with the Langmuir model. At room temperature, the adsorption capacities of WAC-resin for Pb2+, Cu2+, Zn2+ and Cd2+ reached 114.6, 93.4, 24.4 and 20.7 mg/g, respectively.
Highlights
The rapid development of the metal mining and electronics industries has caused serious environmental pollution concerns, especially the discharge of wastewater containing heavy toxic metals [1] such as Pb, Zn, Cd, Ni, Cu, Cr, Co, etc
The amidoxime chelating resin containing both an amino (–NH2) and an oximido (=N–OH) at the same carbon atom is of broad interest, due to the fact that it can coordinate with a wide range of metal ions [2,3]
If these waste resins are not effectively treated, they will take up a lot of space, and the harmful substances leached from the waste resin will pollute the environment
Summary
The rapid development of the metal mining and electronics industries has caused serious environmental pollution concerns, especially the discharge of wastewater containing heavy toxic metals [1] such as Pb, Zn, Cd, Ni, Cu, Cr, Co, etc. In the Guangxi branch of Chalco, the amidoxime chelating resins for adsorption gallium from Bayer solution were discarded after being reused 50–60 times a month, and 225 tons of waste resin are produced and shelved each year [12]. This is extremely incompatible with the advocacy of recycling resources and carbon neutrality. In order to extend the service life of commercial amidoxime chelating resins, another part of our research was to investigate the effectiveness of waste resin as an adsorbent to remove and recover various metals from a synthetic aqueous solution containing lead, copper, zinc and cadmium ions.
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