Removal of metal ions from cyanide gold extraction wastewater by alkaline ion-exchange fibers

Abstract

The metal cyanide complex ions of gold extraction wastewater consume extra cyanide and compete with gold for adsorption on activated carbon during wastewater recycling. Therefore, the removal of metal cyanide complex ions from gold extraction wastewater is of great significance. In this study, polypropylene (PP) fibers were used to prepare strong acylated alkaline ion-exchange fibers (SAA-IEFs) using a polymer graft monomer method that achieved excellent adsorption of metal cyanide complex ions from gold extraction wastewater. The properties of the SAA-IEFs were characterized via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). Adsorption experiments were conducted to study the adsorption performance and to verify the adsorption mechanism. The results show that the highest adsorption efficiencies of the SAA-IEFs for zinc and copper cyanide complex ions were 85.5% and 91.2%, respectively, and these performances were obtained when the SAA-IEF concentration was 50 g/L and pH was 10. The adsorption efficiency of the cyanide complexes in practical wastewater reached 92% at a concentration of 30 g/L. The desorption and regeneration results indicate that the adsorption capacity of the SAA-IEFs remained high after nine cycles. Moreover, an adsorption mechanism is proposed, and the adsorption process is best modeled using the Freundlich isotherm and pseudo-second-order kinetic model. These results indicate that chemisorption plays a dominant role in the adsorption process. Overall, SAA-IEFs are a promising, efficient, and cost-effective adsorbent for metal cyanide complex ion adsorption from gold extraction wastewater.