Triazine-crosslinked polyethyleneimine for efficient adsorption and recovery of gold from wastewater

Abstract

Recovering precious gold Au(III) ions from aqueous solution not only has a large economic incentive but also bears a significant environmental impact. One longstanding challenge is to obtain fast, effective and selective Au(III) adsorption without performance degradation. In this paper, a series of novel water-insoluble triazine-crosslinked polyethyleneimines (referred as TCPEIs, s stands for the molar ratio of amino to chlorine and s = 2, 4, 6, 8, 10) are designed and synthesized as adsorbents for Au(III) recovering from waste solutions. Excitingly, TCPEIs, TCPEI6 in particular, not only have high adsorption capacity, but also exhibit an unprecedentedly high adsorption rate. Langmuir monolayer adsorption capacities of TCPEI6 were calculated as 5462 mg/g. The adsorption efficiency of 95.6 % within 10 s with a capacity of 1073.0 mg/g and the recovering rate constant is more than 10 times greater than the best Au(III) adsorbents reported so far. Such excellent adsorption performance is mainly attributed to electrostatic interaction, complexation and the mechanical stability of TCPEIs. Furthermore, TCPEIs was regenerated within one minute to completely release the adsorbed Au(III) ions and the regenerated TCPEIs was used again for adsorb Au(III) ions, showing no apparent performance degradation, demonstrating the very attractive prospect for TCPEI6 in precious metal ion recovery.