Determination of Heavy Metal and Platinum Group Concentrations in Spent Automotive Catalysts from Common Iranian Vehicles

This study provides the first systematic baseline assessment of Platinum Group Metals (PGMs: Pt, Pd, Rh) and associated toxic heavy metals (Pb, Cd, Zn, Ni, Cr) in spent automotive catalytic converters (SACCs) from Iran's most prevalent vehicles. The unique composition of the Iranian fleet, dominated by a mix of older licensed European models and modern domestic and imported cars, creates a distinct SACC waste stream whose characteristics are largely undocumented. Samples from eight common models were systematically collected, prepared, and analyzed using Inductively Coupled Plasma–Mass Spectrometry (ICP–MS) and X-ray Fluorescence (XRF). The results reveal significant inter-model variability, directly linked to vehicle age and technology. A clear technological transition was observed, from older, Pt-dominant catalysts (e.g., Peugeot ۴۰۵, with total PGMs up to ۴,۸۵۰ mg/kg) to newer, Pd-dominant, and lower-loading designs (e.g., Mazda ۳, ~۱,۲۵۵ mg/kg). Critically, SACCs from older, high-volume models were found to be a particularly rich secondary PGM resource. Concurrently, significant concentrations of hazardous metals were quantified, with lead (Pb) reaching up to ۷۵۰ mg/kg in older models—a legacy of past leaded gasoline use—and zinc (Zn) exceeding ۲,۰۰۰ mg/kg across all samples. These findings underscore the dual nature of SACCs in the Iranian context: a high-value "urban ore" for critical metals and a hazardous waste stream requiring stringent environmental management. This foundational dataset provides the crucial evidence base needed to develop a tailored national SACC recycling strategy, one that can harness the economic opportunity of PGM recovery while mitigating the environmental risks posed by toxic metal contaminants, thereby advancing circular economy principles in the region.

کلیدواژه ها:

Spent automotive catalyst ، heavy metals ، platinum group metals ، Iran ، Recycling ، Urban mining