Sustainable valorization of pineapple leaf waste into biocompatible activated carbon for biomedical and food applications

Agricultural waste valorization offers a sustainable pathway for producing functional carbon materials. We report a scalable method for converting pineapple leaf-derived activated carbon (PLAC) via controlled pyrolysis, followed by ethylenediaminetetraacetic acid (EDTA)-assisted chelation to reduce residual heavy metals. Comprehensive physicochemical and biosafety assessments were conducted to evaluate the potential applicability of the material in food-contact and biomedical applications. Inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS) confirmed that toxic regulated heavy metals (Pb, Cd, As, and Hg) and polycyclic aromatic hydrocarbons (PAHs) were below detectable limits after purification. However, trace amounts of Cu remained measurable. In vitro assays using rat intestinal epithelial (IEC-6) and human gastric epithelial (GES-1) cells demonstrated high cytocompatibility, minimal lactate dehydrogenase release, and negligible apoptotic activity. Oral exposure in Sprague-Dawley rats (up to 100 mg/kg) showed no significant changes in body weight, organ coefficients, serum biochemical markers (GOT, GPT, creatinine), inflammatory cytokines (IL-6, TNF-α, IL-10), or histopathology of the liver, kidney, and ileum. These findings demonstrate that integrating controlled pyrolysis with EDTA-assisted purification and alginate-based formulation provides an effective strategy for reducing toxic regulated heavy metals to below the analytical detection limits under the tested conditions while supporting favorable in vitro and acute in vivo biosafety. The study demonstrates the potential of PLAC as a sustainable and biocompatible carbon material for future food-contact and biomedical applications, while further long-term safety evaluations remain necessary.