Anthocyanin based agricultural wastes as bio-adsorbents for scavenging radioactive iodide from aqueous environment

Abstract To provide an alternative solution for radioactive iodine remediation, mangosteen pericarps, red onion peels, red dragon fruit peels, and passion fruit rinds (anthocyanin-based adsorbents) were successfully employed for iodide (I-) removal from aqueous solution with minimal processing. The adsorption results revealed that 0.5 g/L of mangosteen pericarps and red onion peels removed up to 90% of 10 mg/L I- within 30 min. For both adsorbents, the experimental and the predicted Langmuir isotherms adsorption capacity (qmax) were over 70 mg/g. Anthocyanin quantification revealed that the quantity of vacuole pigments coincided with I- adsorption capacity across different adsorbents. O+, as part of the flavylium cation in anthocyanin, attracted I- via electrostatic force, and the adsorption was controlled by ion-exchange. The computational radial distance was predicted to be ∼3.28 A. Further characterization by UV-visible spectrometry, FTIR, EDX, XPS, and XAS supported the claim of flavylium cation in anthocyanin as the main I- adsorbing functional group. Thus, the anthocyanin-based materials from agriculture waste can be used sustainably to remove radioactive I- from nuclear power facilities, water treatment plants and for environmental remediation.