Removal of chromium (VI) by polymetallic nanoparticles synthesized from printed circuit boards

In this work, obsolete printed circuit boards were used as raw material for polymetallic nanoparticles synthesis (NP-PCIs), which were used in the Cr(VI) removal from aqueous system. The NP-PCIs are mainly constituted by Cu, also containing Fe and Zn in smaller amounts. The Cr(VI) removal by NP-PCIs is dependent of the pH system, since the Cr(VI) removal amount decreased from approximately 70 to 2% with the pH increase from 2 to 12. The pH of the system plays an important role in the Cr(VI) removal mechanism. At pH 2 there is mainly a reduction from Cr(VI) to Cr(III) by NP-PCIs mostly. At pH 8, the Cr(VI) and Cr(III) are adsorbed by oxide and/or hydroxide species present in NP-PCIs. Given the results, it can be concluded that NP-PCIs, synthesized by a sustainable route, were effective in removing Cr(VI) in aqueous media, presenting reductive and adsorbent processes as a removal mechanism. (author)