Extraction of Gold from the Leachate of Copper Anode Slime by Quaternary Ammonium Rice Husk Lignin

Abstract

ABSTRACT Extraction of gold by adsorption is being concerned because of easy operation, low cost and non-pollution for the present. Lignin and its derivatives are considered to be the most promising adsorbent due to abundance and environmental friendliness. In this work, gold was extracted from the leachate of copper anode slime by quaternary ammonium rice husk lignin (QARHL). QARHL was synthesized and characterized by Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS) and Thermogravimetric Analysis and Differential Scanning Calorimetry (TG-DSC). The influence of adsorption time, dosage of adsorbent and temperature on adsorption were investigated. The adsorption mechanism of QARHL for gold was explored by Scanning Electron Microscope (SEM), FTIR and X-ray Diffractometry (XRD). The results showed that QARHL had excellent thermostability and contained a large number of quaternary ammonium groups and hydroxyl groups. The saturated adsorption capacity reached 220.70 mg•g-1 and the time of equilibrium was 120 min. The adsorption was easy to occur spontaneously and obeyed the models of pseudo-second order and Langmuir. AuCl4- was reduced to Au(0) by phenolic hydroxyl after ion exchange. The new process could be used to recovery gold from gold-containing raw materials without pretreatment. It is possible to extract gold effectively, economically and environmentally friendly.