Producing gold nanoparticles from loaded activated carbon and its separation with carbon fiber film formation at the oil/water interface in the acetone-water-sodium chloride system

Due to the wide spread applications of gold in medicine, electronic computational industries, catalysts, and its special application in biological researches and more over by attention to high cost and complicated production of gold nanoparticles (AuNPs) and in the other hand, the importance of substituting the environmental pollutants such as cyanide compounds in most commonly processes of gold recovery from ores and concentrates, finding a simple, economic and environmental way to achieve AuNPs has to be considered. Because of its large surface area, activated carbon (AC) is used in extracting gold. In this research work a new way has been mentioned for production and separation of AuNPs from loaded AC. By heating loaded AC in the air at 300 for 30 min, gold metal nanoparticles were produced on the surfaces of AC with reducing the gold cyanide complex. The detachment of the AuNPs from AC surfaces was done by two ways: 1. Abrasion of AC by NaCl 2. Using ultrasound; the separation of the detached AuNPs from AC granules abraded by NaCl was done based on the difference between AC and gold density and using water and oil mixture. Effect of abrasion time, salt to carbon weight ratio and pre-washed loaded AC conditions on the amount of gold recovered from loaded AC was evaluated in abrasion method. In a novel approach, separation of carbon from gold-containing aqueous solution was done by addition of acetone in mixture and forming carbon microfibers film at the oil/water interface. Acid washing was done to remove impurities after separating carbon from gold-containing solution. As a result, relatively pure AuNPs were obtained after acid washing.

Keywords:

gold nanoparticles , loaded activated carbon , gold separation from carbon , carbon separation from aqueous solution , abrasion