Demetallization of toxic and heavy metals in clam, Paphia Textile utilizing catalytic chelation technique

Abstract

This research was carried out to study the toxic and heavy metals removal like lead (Pb), cadmium (Cd) and nickel (Ni) from Paphia textile. Three types of chelating agents, namely trisodium citrate, sodium acetate and disodium oxalate and three types catalysts supported on Al₂O₃ namely MgO, CaO and BaO were used. The demetallization treatment screening carried out at a 400 mg/L, one hour treatment time and treatment temperature of 32.5 ± 0.5°C on Paphia textile, revealed trisodium citrate was the most potential chelating agent. Metals concentration were analysed using Flame atomic absorption spectroscopy (FAAS). The initial concentration of Pb, Ni and Cd in Paphia textile were found to be 1.05±0.18 μg/g, 0.83±0.21 μg/g and 0.56±0.02 μg/g respectively. The results on the optimization chelation technique showed that 400 mg/L of trisodium citrate gave the highest percentage removal of toxic and heavy metals with Pb 84.69% (0.16±0.05 μg/g), Ni with 78.60% (0.18±0.08 μg/g) and Cd with 41.96% (0.33±0.01 μg/g). Among the three catalysts studied, CaO/Al₂O₃ catalysts at an optimum calcination temperature of 1000°C, in the presence of trisodium citrate, gave the highest percentage removal with 87.79% (0.13±0.15 μg/g) of Pb, 83.56% (0.14±0.11 μg/g) of Ni and 76.43% (0.13±0.01 μg/g) of Cd. This study showed that catalytic chelation technique at optimum conditions able to remove further the toxic and heavy metals compared to chelation technique from P. textile to achieve permissible limits set by Malaysian Food Regulation (Cd and Ni: 1.00 μg/g; Pb: 2.00 μg/g) and EU Regulation (Cd and Ni: 1.00 μg/g; Pb: 1.50 μg/g).