Demetallization of toxic and heavy metals in squid, D. Sibogae utilizing catalytic chelation technique

Abstract

Malaysian squid were exposed to contamination of toxic and heavy metals. Continuous uptake of food containing heavy metals may affects human health. Therefore, this study was done to reduce percentage of heavy metals in squid since there is no technology has been developed in removing heavy metals in squid. In this study, the concentration of heavy metals (Ni and Cd) in muscle of D. Sibogae were determined. Squid samples were bought from Pasar Awam Taman Universiti in which the squid used were originated from Mersing with size range of 5.5 to 7.5 inch. From this study, the initial concentration of heavy metals found before treatment were 0.4565 and 0.358 µg/g for Ni and Cd respectively. The concentration of heavy metals contain were below permissible limit recommended by Malaysia Food Regulation (1985). Concentrations of chelating agent (trisodium citrate) used in this study were 300, 400, 500, 600, 700 and 800 ppm. After treatment, it was found that the optimum concentration of chelating agent used was 600 ppm with percentage of removal for Ni and Cd were 55.64% and 93.97 % respectively. After treatment for 1 hour, percentage removal of Ni and Cd were 73.67 % and 88.03 % respectively. To enhance the performance of chelation process, catalyst was added in which the catalyst used was CaO supported on Al₂O₃. Using catalytic chelation technique, the percentage removal of Ni and Cd were 89.64 % and 94.95% respectively. It was proven that catalytic chelation technique will give more percentage removal of heavy metals compared to chelation technique itself. From characterization, XRD analysis depicted the active sites were due to the presence of orthorhombic Al₂O₃, monoclinic CaAl₄O₇/CaO.2Al₂O₃ and cubic Ca₁₂Al₁₄O₃₃ species. BET surface area study illustrated the surface area of 33.22 m²/g. Finally, FTIR analysis concluded that CaO/Al₂O₃ catalyst at 1000^oC treatment showed total removal of metal precursor’s species.