Regeneration of waste activated carbon after extracting gold with steam under microwave heating: Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology (RSM) technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 °C, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m²/g, with total pore volume of 1.242 cm³/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.