Biosorption ability of starfruit (Averrhoa carambola L.) in removing cadmium and lead in contaminated water samples

Abstract

Starfruit (Averrhoa carambola L.) is a common fruit found in the tropics, particularly in the Philippines. Due to it having chelating agents in its fruit composition, the study determined the ability of unripe and ripe starfruits to filter heavy metals, cadmium Cd2+ (aq) and lead Pb2+ (aq), in contaminated water samples. Twenty water samples were prepared during the study, where ten samples were contaminated with Cd2+ (aq), and the other ten samples with Pb2+ (aq). 15% unripe starfruit solutions were introduced to five Cd2+- and five Pb2+-contaminated samples, and ripe starfruit solutions were introduced to the remaining samples. Findings revealed that both Cd2+ (aq) and Pb2+ (aq) were significantly reduced when the starfruit extract was introduced to the contaminated samples. It was also found out that the biosorption abilities of unripe and ripe starfruits were comparable with each other, and that starfruit filtered more Pb2+ (aq) than Cd2+ (aq). Thus, starfruit is capable of removing significant amounts of heavy metals, thereby indicating metal ion concentration reduction. Studies are recommended to investigate further this ability of starfruit.