A new reutilization strategy of waste printed circuit board nonmetal powders for constructing superhydrophobic coatings

Copper leaching from ultrasonically treated milled waste printed circuit boards: investigation of parameters optimization and kinetics

Waste printed circuit boards (WPCBs) encompass abundant metals (gold, silver, and copper), along with other harmful materials including brominated epoxy resins, plastics, and heavy metals (lead, mercury, and cadmium). Direct burning and landfilling of WPCBs may cause severe health issues and impair the environment. Therefore, sustainable treatment of WPCBs is necessary to recover valuable metals and remove hazardous materials before disposal. The present work investigates the separation of copper-rich metallic fractions from the WPCBs by the combination of hammer milling and ultrasonic irradiation. Initially, discarded mobile phone PCBs are pre-processed and shortened into 1 × 1 cm2. Downscaled WPCBs are fed into the hammer mill to obtain the fine ground powder. The Powdered WPCBs are further processed through ultrasonic treatment to acquire metal-rich fraction. XRD, SEM-EDS, and ICP/AAS analysis revealed that the current technique can efficiently separate the metal-rich fraction without using toxic solvents. Results show the enhancement of copper fraction from 42.73 to 87 wt. % after ultrasonic treatment of WPCBs ground powder. Further, nitric acid leaching has been implemented to metal-rich fractions, and the parameters have been optimized for copper leaching with the assistance of response surface methodology (RSM) of the design of experiments (DOE). Quantitative dissolution (98.96%) of copper occurred using 3.5 M nitric acid within 3 h at 30 °C with 50 GPL pulp density and 500 rpm agitation speed. Finally, the kinetics of the leaching process were studied to conform the kinetics model. Moreover, the activation energy for diffusion (19.075 kJ/mole) and reaction kinetics model (13.29 kJ/mole) has also been calculated. The low energy consumption due to room temperature pre-treatment and effective leaching ensures the industrial feasibility of the proposed process.

High Value-Added Reutilization of Waste-Printed Circuit Boards Non-Metallic Components in Sustainable Polymer Composites

The reutilization non-metallic components from a waste-printed circuit board (WPCB) has become one of the most significant bottlenecks in the comprehensive reuse of electronic wastes due to its low value and complex compositions, and it has received great attention from scientific and industrial researchers. To effectively address the environmental pollution caused by inappropriate recycling methods, such as incineration and landfill, extensive efforts have been dedicated to achieving the high value-added reutilization of WPCB non-metals in sustainable polymer composites. In this review, recent progress in developing sustainable polymer composites based on WPCB non-metallic components was systematically summarized. It has been demonstrated that the WPCB non-metals can serve as a promising reinforcing and functional fillers to significantly ameliorate some of the physical and chemical properties of polymer composites, such as excellent mechanical properties, enhanced thermal stability, and flame retardancy. The recovery strategies and composition of WPCB non-metals were also briefly discussed. Finally, the future potentials and remaining challenges regarding the reutilization of WPCB non-metallic components are outlined. This work provides readers with a comprehensive understanding of the preparation, structure, and properties of the polymer composites based on WPCB non-metals, providing significant insights regarding the high value-added reutilization of WPCB non-metals of electronic wastes.