Synthesis of polymetallic nanoparticles from spent lithium-ion batteries and application in the removal of reactive blue 4 dye

In this study inedited polymetallic nanoparticles were synthesized from electronic wastes of spent lithium-ion batteries (PN-LIB) and applied in the removal of the dye reactive blue 4 (RB4). Initially, the extraction of metals from batteries was performed using HCl/HNO3 (3:1 v/v). Subsequently, the PN-LIB were synthesized via chemical reduction with NaBH4. The PN-LIB showed spherical shape and size smaller than 50 nm, being constituted by Cu, Co, Ni, and Mn. The surface area was estimated at 92.29 m2 g−1 and the volume and average size of pores in 0.25 cm3 g−1 and 5.84 nm, respectively. The X-Rays diffractogram presented characteristic peaks of the Cu0. The PN-LIB were applied in the removal of the RB4 dye, in which the effects caused by the variables initial pH, dose of PN-LIB and initial concentration of dye in the removal process were evaluated. There was no significant effect of initial pH on the RB4 removal, since, a natural increase of this parameter occurred in the system and maintained at pH about 8.5. The rate of removal increases with the increase in the dose of PN-LIB and with the reduction of the initial concentration of dye. The experimental data were adjusted to the kinetic model of pseudo-second order and the Langmuir isotherm model, with a maximum capacity of removal, was calculated as being equal to 344.83 mg g−1. The molecular absorption spectra in the UV/Vis region and the infrared spectra indicated that two phenomena happen, adsorption and degradation of the dye.