Abstract
We report a novel recovery system of gold (Au) that is one of noble metals contained in the electronics scraps, utilizing tannin gel particles. Tannin gel particles were prepared by cross-linking process of the condensed tannin (wattle tannin), which is ubiquitous and inexpensive natural material having a lot of hydroxyl groups. The adsorption mechanism of gold onto the tannin gel particles was investigated in detail. The adsorption of gold takes place through the reduction of trivalent gold ions to metallic gold on the surface of tannin gel particles, which is accompanied by the oxidization of hydroxyl groups of tannin gel simultaneously. Additionally, it is found that the maximum adsorption capacity of gold is about 8000mg-Au/g-dry gel, an extremely high value. The present investigation shows the properties of tannin gel particles on gold adsorption from the view point of XRD analysis and FT-IR spectrum observation and gives a possibility of its application to the efficient novel recovery system of gold.
