Cradle-to-Gate Life-Cycle Assessment of a Waste Printed Circuit Board-Derived Adsorbent: Production Impacts Normalized by Heavy-Metal Adsorption Capacity

A cradle-to-gate life-cycle assessment (LCA) was conducted for an activated adsorbent produced from the non-metallic fraction (NMF) of waste printed circuit boards. The primary production reference was 1 kg of dry activated non-metallic fraction (ANMF) produced. Cradle-to-gate production impacts were subsequently normalized using previously reported equilibrium adsorption capacities for Pb2+, Cu2+, and Zn2+ to obtain performance-normalized production impacts per kilogram of theoretical metal uptake. Environmental impacts were quantified using the ReCiPe 2016 Midpoint (H) method together with cumulative energy demand (CED). Production of 1 kg of ANMF resulted in a climate change (CC) impact of 5.77 kg CO2-eq and a CED of 140.03 MJ. After adsorption-capacity normalization, the CC impacts were 8.44, 31.35, and 43.05 kg CO2-eq kg−1 metal uptake, while the corresponding CED values were approximately 205, 761, and 1045 MJ kg−1 metal uptake for Pb2+, Cu2+, and Zn2+, respectively. Commercial activated carbon (AC) exhibited slightly lower production impacts, but its lower representative Pb2+ adsorption capacity resulted in substantially higher normalized production burdens. These normalized indicators represent cradle-to-gate production impacts scaled by adsorption performance and do not include wastewater-treatment use-stage operations, regeneration, or management of spent adsorbent. The results demonstrate that adsorption performance substantially influences the interpretation of production-related environmental burdens and should therefore complement conventional mass-based assessment of adsorbents.