FT-IR and Functional Group Characterization of Aloe barbadensis and Cymbopogon citratus Extracts for Potential Heavy Metal Biosorption

Heavy metal toxicity poses significant health and environmental risks due to the persistent, bioaccumulative, and non-biodegradable nature of the metals cadmium (Cd), chromium (Cr), and lead (Pb). These metals can damage vital organs, disrupt metabolic processes, and induce oxidative stress, inflammation, and tissue injury. Consequently, the search for safe, affordable, and eco-friendly remediation strategies has increased, with growing interest in plant-based biosorbents. This study investigated the FT-IR and classical functional group characterization of Aloe barbadensis and Cymbopogon citratus extracts for heavy metal biosorption. Classical qualitative tests were used for the identification of functional groups responsible for metal binding, including the sodium hydrogen carbonate test for carboxylic acids, the 2,4-dinitrophenylhydrazine (2,4-DNP) test for ketones, the sodium hydroxide plus heat test for amides, the Hinsberg test for amines, and the Lucas test for alcohols. Fourier Transform Infrared (FT-IR) spectroscopy was employed to confirm the results. The findings revealed the presence of carboxylic acids in both extracts, while ketones and amides were detected only in C. citratus. Secondary amines and secondary alcohols were identified in A. barbadensis, whereas C. citratus contained primary amines and tertiary alcohols. These functional groups serve as active sites for binding metal ions. through chelation, ion exchange, and complexation mechanisms. The results suggest that both extracts, particularly C. citratus have strong potential as affordable and eco-friendly biosorbents for the removal of heavy metals.