Chemical Treatment of X-Ray Film Waste: Silver Recovery and PET Base Recycling via Pyrolysis

Abstract

Radiology departments generate significant quantities of medical waste, specifically discarded X-ray films, which pose environmental risks due to their heavy metal content and non-biodegradable components. Managing this waste is crucial to prevent toxic leaching and to recover valuable resources that are often lost through conventional disposal. This study addresses these challenges through a dual-purpose integrated treatment protocol focusing on high-purity silver recovery and the recycling of the polyethylene terephthalate (PET) base. Silver recovery was analyzed using two chemical approaches: acid leaching with nitric acid (HNO₃) and alkaline stripping with sodium hydroxide (NaOH). Stoichiometric analysis demonstrated that the alkaline method achieved a significantly higher silver yield of 31.29 g/kg, compared to 21.08 g/kg for the nitric acid method. Although nitric acid exhibited faster reaction kinetics, the sodium hydroxide approach proved more efficient and environmentally sustainable. Following silver extraction, the remaining PET base was processed through thermal pyrolysis to produce high-value liquid hydrocarbon fuel. Analytical results showed carbon chain distributions ranging from C₆ to C₂₀, closely resembling the profile of commercial gasoline. This research establishes a sustainable circular economy framework for managing hazardous radiological waste. By optimizing resource recovery through the alkaline-pyrolysis pathway, the study offers a viable solution to minimize environmental impacts while maximizing the economic value of medical waste materials.