Copper Recovery by Waste derived Alkali-Activated Sorbent

The global use of Electric and Electronic Equipment (EEE) is extensively increasing in our everyday life and over the years, across different sectors. This trend inevitably leads to a growing Waste from Electric and Electronic Equipment (WEEE), and if left untreated or mismanaged, it may represent a serious environmental concern due to its content of hazardous components. However, WEEE also represents a valuable secondary source of critical and strategic raw materials. Among them, Printed Circuit Boards (PCBs) are very rich in copper (Cu), a strategic element, representing the 40 %(w/w) of the selected e-waste. Through proper treatment and recovery processes, copper can be efficiently extracted from WEEE, offering both significant environmental advantages and substantial economic benefits by reducing the need for primary mining and supporting a more circular economy. Among the available treatments, hydrometallurgical recovery is a versatile technique, which often includes an adsorption step following leaching stages. Adsorption is particularly advantageous due to its high recovery efficiency, rapid extraction time, strong enrichment capability, operational simplicity, and low cost. Moreover, it can be performed using a wide range of sorbents with diverse properties, including silica- and carbon-based materials, green alternatives, and polymeric compounds. Accordingly, waste-derived alkali-activated based materials, obtained by mixing ladle steel slag (Calcetek) with selected retarding admixtures following a procedure developed by Opigeo srl (European Patent extension demand n°. 25179514.2.), was used in this study as adsorbent. The resulting material was used in powder form, maximizing in this way the surface to volume ratio, and was contacted with different initial copper concentrations, ranging from 1 mM to 300 mM in order to study the sorbent capacity and behaviour. The experiments were conducted in batch at room temperature for 90 minutes under stirring conditions (450 rpm), using 50 mL of solution and 2 grams of sorbent. The adsorption capacity showed very promising results also at high initial concentrations, reaching 5 mmol/g of adsorbed copper. The materials were also characterized using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX), and X-ray Diffraction (XRD).