Metal Recovery from Multi-elementary Electroplating Wastewater Using Passion Fruit Powder

Abstract

Electroplating wastewaters are composed of a mixture of metallic ions. The process commonly applied to treat these residues generates a large amount of toxic sludge and does not allow metal recovery. In this context, the use of an adsorption technique to separate the metallic ions from the wastewater and recuperate it by desorption was proposed. For the process to be more environmentally interesting, a solid residue from the agro-industry was used as an adsorbent: the powder of passion fruit shells. The adsorbent was characterized by SEM, TEM, BET, FTIR, and pH-PZC. The adsorption experiments were carried out in monoelementary solution of Ni2+, Cu2+, and Zn2+—to analyze the fit to the kinetic and isotherms models—and in the multi-elementary electroplating wastewater. The desorption was evaluated with three eluents. The results obtained show the effectiveness of the process in mono- and multi-elementary solutions, reaching an adsorption capacity of 44.82 mg g−1 for Ni2+, 1.10 mg g−1 for Cu2+, and 0.20 mg g−1 for Zn2+ on the wastewater. The three ions showed a better fit to the Freundlich isotherm model. Zn2+ was adjusted to pseudo-second order, Cu2+ to Elovich model, and Ni2+ to pseudo-first order. It was possible to recover more than 99% of Zn2+ and Ni2+, and 45% of Cu2+ using acid eluent. Therefore, the method proposed in this study was effective to recover the metallic ions in electroplating wastewater, opening up the possibility of treating these wastes in an eco-friendly way. Graphical Abstract: [Figure not available: see fulltext.].