Direct copper electrowinning from iron-rich e-waste leachates without prior iron removal

• High Fe²⁺ concentrations reduce copper deposition rates and current efficiency. • High Fe²⁺ concentrations do not affect copper sheet and purity. • It is unnecessary to separate Fe²⁺ to produce high-quality copper sheets. • Current density is the most critical factor for optimizing copper sheet formation. • Successful scale-up test with 100% copper sheet formation and 99.9% purity. • Electrolysis is a viable method for copper recovery from bioleaching leachates. Electronic waste bioleaching generates leachates rich in copper and ferrous iron, which conventionally require iron removal before copper electrowinning because Fe²⁺ impairs current efficiency and deposit purity. A systematic investigation confirmed that direct-current electrowinning of copper from such iron-rich leachates is feasible without any iron-removal step, thereby simplifying the hydrometallurgical process. Key operational parameters (0–26.4 g L -1 Fe²⁺, 5–15 g L -1 Cu²⁺, current density 25–275 A m², temperature 25–55 °C, flow rate 1–3 min⁻¹) were systematically varied in a Taguchi design to assess their effects on copper deposition rate, current efficiency, deposit morphology, and cathode purity. Increasing Fe²⁺ content drastically lowered current efficiency (from 80–95% to 15–60%) and slowed the copper deposition rate. However, high copper purity (≈99.9%) and a uniform sheet morphology were preserved as long as continuous cathode sheet growth was favored. A predictive model was developed to define the operating boundaries for copper sheet formation as a function of current density and Cu²⁺ concentration, and it was experimentally validated. In a 25 L pilot electrowinning test, 100% cathode sheet coverage was achieved at 75 A m -2 and 25 °C using a leachate containing 15 g L -1 Cu²⁺ and 26.4 g L Fe²⁺, yielding a deposit with 99.9% Cu purity and only 0.01% Fe. These results confirm that high-purity copper can be directly electrowon from highly ferrous solutions under optimized low-current-density conditions. By eliminating the iron-removal step, this approach significantly simplifies the hydrometallurgical flowsheet and could enable low-cost, decentralized e-waste recycling where simplicity is prioritized over maximum energy efficiency. The recovery of copper from electronic waste (e-waste) poses a major challenge for sustainable resource management, particularly when leachates contain high concentrations of Fe²⁺. Conventional hydrometallurgical routes require iron removal before electrowinning, increasing chemical and operational complexity, waste generation, and cost. Despite the technological maturity of copper electrowinning, studies addressing direct copper recovery from iron-rich leachates remain scarce due to concerns regarding current efficiency, deposit purity, and morphology. As bioleaching and circular metallurgical systems gain industrial relevance, the development of electrowinning processes compatible with high-Fe²⁺ leachates has become essential for process simplification and environmental sustainability. This work demonstrates, for the first time, the direct electrowinning of copper from ferrous-rich leachates without the need for prior iron separation, achieving 99.9% copper purity and compact sheet morphology under optimized low-current-density conditions. Through the systematic application of a Taguchi experimental design, the study identifies operational boundaries that ensure smooth sheet deposition in solutions containing up to 26.4 g L⁻¹ Fe²⁺. The resulting empirical model predicts conditions required for industrially relevant sheet formation and is validated through a successful semi-industrial scale-up test. These findings redefine the operational limits of copper electrowinning under iron interference, demonstrating that purity and morphology are preserved when process parameters are properly optimized. The novelty lies in the integration of experimental design, mechanistic insight, and scale-up validation to establish a simplified, iron-tolerant electrowinning process. This approach eliminates the conventional iron-removal step, thereby reducing reagent consumption, operational costs, and waste generation, while maintaining high product quality. From an industrial perspective, this methodology offers a low-cost, scalable solution for decentralized and small-scale e-waste treatment plants, particularly when coupled with bioleaching in closed-loop systems. Overall, this study advances sustainable hydrometallurgy by demonstrating that direct electrowinning from Fe²⁺-rich solutions is both technically feasible and environmentally advantageous, supporting the development of resilient and circular strategies for the recovery of critical metals from e-waste.