Iranian Journal of Chemical Engineering (IJChE)

Abstract Activated carbons are extremely versatile adsorbents for major industrial significance, especially for metal ions recovery from wastewaters. In this study, the activated carbon prepared from the hard shell of apricot stones, an agricultural solid, which was used for the gold recovery from gold-plating wastewater is investigated. Activated carbon was produced by chemical activation with phosphoric acid. Recovery parameters such as adsorbent dose, the particle size of the activated adsorbent, pH and the agitation speed of mixing were studied. The equilibrium data fit well with the Freundlich isotherm model. A Langmuir isotherm model has been used to obtain thermodynamic parameters. The results showed that under the optimum operating conditions, more than 98 per cent of the gold was recovered by activated carbon after only 3 hours. It was found that the activated hard shell of apricot stones could be used as an effective adsorbent for gold recovery from wastewaters.

Abstract The application of the Taguchi analysis to the experimental results of the extraction of gold (III) ions by a three-phase W/O/W emulsion liquid membrane system has been studied. Experiments were performed using alkaline aqueous sodium sulfite as the internal phase and LK-80 as a novel emulsifier for the first time in emulsion liquid membrane technology. The effects of various operational and compositional parameters were studied. Results showed that nearly all of the Au (III) ions in the aqueous phase were extracted in a few minutes. The analysis determined the effects and contribution of each of the parameters on the extraction efficiency, interaction between the parameters and also the optimum parameters to achieve the best extraction efficiency. The analysis showed that the pH of the external phase with a contribution of 65% is the highest, and the concentration of carrier with a contribution of 2% is the least effective in the final system response.