Demetallization of heavy metals in clam, corbicula fluminea utilizing catalytic chelation technique

Abstract

Malaysian clams can be contaminated with heavy metals which are cumulative poison through long term ingestion. Currently, there is no commercial technology has been developed for the removal of these heavy metals from contaminated clams especially C. fluminea species. Therefore, the main objective for this study is to develop method to remove these heavy metals from clams until achieve the permissible limit set by Malaysia Food Regulation 1985 (MFR) and Commission Regulation of EU (2006). In this study, three types of chelating agents were used which are trisodium citrate, sodium acetate, and disodium oxalate. Meanwhile, three types of catalysts supported on Al₂O₃, which are CaO, MgO, and BaO were used. Heavy metals analyse conducted using Flame Atomic Absorption Spectroscopy (FAAS). The results showed that initial concentration of Pb, Ni, and Cd were 28.73±6.06 (μg/g), 67.36±3.29 (μg/g), and 24.875±0.35 (μg/g) respectively. The optimization chelation technique showed that 300 mg/L of trisodium citrate gave the highest percentage removal of studied heavy metals which were 67.50% (9.34±0.75 µg/g) of Pb, 75.45% (16.54±1.29 µg/g) of Ni, and 74.63% (6.31±0.35 µg/g) of Cd. Then, the addition of catalyst to chelation technique improved the removal of heavy metals in C. fluminea. Therefore, among the three-catalyst studied, CaO/Al₂O₃ calcined at 1000°C gave the highest percentage removal of heavy metals which were 93.11% (1.98±0.32 µg/g) of Pb, 98.65% (0.91±0.18 µg/g) of Ni, and 96.10% (0.97±0.24 µg/g) of Cd, with stirring at 29.50±0.50ºC for 1 hour. Therefore, this study showed that catalytic chelation technique at optimum conditions could enhance the removal of heavy metals in C. fluminea to achieve the permissible limit set by MFR and EU.