Insight into Limited Recoveries in Printed Circuit Board Leaching: Evidence of Gold Adsorption Loss to Polymeric Particles

Abstract

Sustainable resource utilization ultimately depends on total recovery during recycling operations. PCB leach pulp for target metal recovery contains ceramic and polymeric particles resistant to reagent attack. The investigation herein shows the physicochemical behavior of five polymeric particles namely green, red, black, white, and blue in gold chloride complex [AuCl4]− solution. Gold concentration change was monitored over time to study how the gold solution interacted with the polymeric particles and how the interaction conforms to known adsorption isotherm and kinetic models. The black and green polymeric particles have the highest adsorption per unit mass to about 1.81 mg/g and 2.18 mg/g, respectively. Four adsorption kinetic models evaluated for insight on the adsorption mechanism observed show Elovich and pseudo-second-order (PSO) models fit the kinetic data best compared to other models with correlation coefficients of 0.9867 and 0.9863, respectively. Of the seven adsorption isotherm models evaluated, Sips model shows best fit for the isotherm data with correlation coefficients of 0.9727 and 0.9328 for green and black particles, respectively. Isotherm and kinetic model analyses of the experimental data indicated physisorption and chemisorption as driving mechanism of the interaction between PCB polymeric particles and gold chloride complex aliquot. Graphical Abstract