Metal Recovery using Tannin Resin- An Alternative for the Treatment of Electronic Waste

Electronic wastes are produced from all discarded electronic materials, such as computers, cell phones, printers and televisions. With the great generation of this solid residue, it became necessary to study an environmentally suitable technique, able to recycle the metals generated by it. In this study, black wattle tannin resin was used as a potential alternative for the treatment of this waste due to its metal adsorption capacity. Black wattle resin was synthesized by using different pH values (3, 4, 5 and 6) and particle sizes (80, 100, 140 and 200 mesh) from the standard solution of AgNO3 and solid silver dissolved into HNO3 solution. Absorption technique was used for the quantification of Ag+ from samples. It was observed that pH values closer to neutrality (5 - 6) favor a greater adsorption of Ag+ ion as well as smaller particle sizes (granulometry of 140 - 200 mesh). From the tests of atomic absorption, a high yield of the silver adsorption by the tannin was verified, becoming the resin a viable adsorbent, as much for its efficiency, as for being a vegetal compound which does not promote the degradation of natural resources.