Speciation Analysis Of Several Metals In Seaweed

With the development of industry, a large amount of heavy metals have been poured into the ocean in various ways, resulting in a continuous increase of heavy metals in waters. Considering the biosorption of heavy metal by algae, it would be a potential danger to the algae safety. Additionally, the biological activity, toxicity and exploitability of trace metal elements depend on not only their total concentrations, but also chemical speciation. Hence, element speciation analysis of heavy metals is of important significance to algae safety research.On the basis of systematic study on the adsorption of heavy metals such as C2+, Pb2+by algae species, existing form of heavy metals elements in algae was also investigated. The main contents and conclusions are listed as follows:1. The influence of kelp varieties and other metals on the adsorption of Cd and Pb.It was investigated that the adsorption of cadmium and lead with four species of Laminaria japonica and the influence of calcium, magnesium, zinc to the adsorption of two heavy metals. Under the same metal concentration, the adsorption capacity of four species showed considerable differences. The adsorption capacity increased because of seawater supplemented with more metals.There are different metals in seawater, and the adsorption capacity of different metal is different. The different heavy metals are affected each other. The change trend is different because of various metals content and species of Laminaria japonica.2. Adsorption kinetics of Cd and Pb in algae:The adsorption kinetics of Cd and Pb in Laminaria japonica and sargassum were researched in this experiment and the results showed that there was a fast adsorption process. Fast adsorption time is between 20 and 30 minute and then reached the adsorption equilibrium.Adsorption kinetics curve of metals in Laminaria japonica and Sargassum can be simulated by Pseudo-two-level model. The adsorption capacity is related to the species of algae, processing mode and metal type. 3. Existing form of several metals in Sargassum and Laminaria japonica.Different components were obtained with solvent extraction, and they are fat-soluble ingredient, water decocated ingredient, acid extracted ingredient, alkaline extracted ingredient and residue. The content of metals in the five ingredients was determined by atomic absorption spectrophotometry. Under the detection line, there was no metal in fat-soluble ingredient, and the other four ingredients have various amounts of metals.Ca:Calcium content in Laminaria japonica is higher than Sargassum. Ca in Laminaria japonica exists in alkali extraction and ethanol precipitation ingredient, residue and exudate. Ca content in the three parts occupy 65.08% of the total Ca. Ca content of Sargassum in acid extracted and aqueous alcohol solution ingredient is higher the several previous.Mg:Mg content in Laminaria japonica is lower than that in Sargassum. Mg in Laminaria japonica mainly exists in exudates of water decocated ingredient, and it occupy 55.92%. In Sargassum, Mg contents in four parts are relatively higher than that of others, and they are residue, alkaline extracted and alcohol precipitation ingredient, dialysis solution and exudates.Zn:Zn content in Laminaria japonica is lower than that in Sargassum. Zn in Laminaria japonica which mainly dissolve in water component occupy 51.3%, among them 33.03% exists in exudates. Zn in Sargassum mainly exists in four parts and they are dialysis solution, exudates, residue and acid extracted-aqueous alcohol solution ingredient.Pb:Pb content in Laminaria japonica is lower than that in Sargassum. Pb in Laminaria japonica mainly exists in alkaline extracted ingredient, and it occupy 48.2%.44.13% Pb in Sargassum mainly exists in water extracted ingredient.