Removal Of Cadmium From Crude Polysaccharides Of Scallop Viscus

Scallop viscera polysaccharide is a bioactive compound with good activities, such as improve immunity, antioxidation and anticoagulant. But the cadmium content of this polysaccharide is very high. How to effectively remove this heavy metal becomes the key factor for the utilization of the scallop polysaccharide.The content of cadmium, chromium, mercury and lead in each organs of scallop were investigated. The scallop viscera polysaccharide (SVP) was isolated from viscera of scallop and the transformation of heavy metal content during the extraction process was monitored. Various methods including ion exchange, dialysis, and physical adsorption were performed to remove cadmium from SVP. The single factor experimental and response surface experiment were adopted to optimum the factor parameters during cadmium (Cd) remove from SVP. Experimental results show that the Cd content in scallop viscera is 5.98mg/kg and it is the most serious comtaiminaed organ. The yield of SVP is 28.1%, total sugar content is 14.78%, cadmium content is 33.38mg/kg. The cation exchange resin was proved to be the most suitable material to remove cadmium and the removal rate can achieve 90.72%. The result of single factor experiment showed that the optimum conditions as:initial concentration of 20 mg/mL, Resin amount is 4g, pH value is 5, adorption time is 10 min with elution speed of 120 r/min and temperature is 30 ℃. Box-Behnken design was used to evaluate the effects of three independent variables of SGP concentration, pH value and adsorption time. The optimized conditions to maximize the Cd removal rate were as follows:SGP concentration at 17.07mg/mL, pH value at 4.92 and adsorption time with 11.73 min. The experimental value of the removal rate (95.38%) at these optimum conditions was found in perfect agreement with the value predicted by model (95.65%).