Removal Of Cadmium Ions From Aqueous Solution By Adsorption

Through the static experiment and membrance reactor, the adsorption behaviour of Cadmium onto treated alga biomass Undaria pinnatifida which was artificially cultured in Dalian and adsorption behaviour of fluorion on calcination product of Mg-Al-Fe hydrotalcite compound were studied in this paper. The reactor comprises adsorbent and membrane was studied in order to provide valid data for its industrial application.Within the test range (initial concentration 2-10 mg/L, adsorbent doze 0.05-0.5 g, pH 2-6), biosorption capacity for Cadmium ions showed an increase with an increasing in initial ions concentration and decreasing in biosorbent doze. The optimized condition of pH value for Cadmium is 5.0, while contact time is about 80 min. At equilibrium, the maximum uptake by Undaria pinnatifida was 8.755 mg/g for cadmium. The results for cadmium fit well to the Temkin isotherm. Pseudo-second-order model described the sorption kinetic of cadmium ions better than pseudo-first-order and intra-particle diffusion kinetic model.Then the mechanisms of adsorption have been discussed. The response relationships between alginates and CaCl2, the existence form of cadmium in aqueous solution and FTIR were considered.In EDTA-Cd complex system, adsorption behavior of cadmium was investigated considering different molar ratio of EDTA-Cd, different pH. Aqueous EDTA can strongly compete with the bacterial surface for aqueous Cd, and the presence of aqueous EDTA significantly diminishes Cd adsorption onto treated alga biomass Undaria pinnatifida. Chemical equilibrium modeling was used to estimate the extent of Cd adsorption. The observed adsorption behavior is in excellent agreement with chemical equilibrium modeling.The final part aims at developing a simple and practical methods to study the effect of a submerged membrane adsorption hybrid system. When the Cadmium solution concentration is 1.0mg/L and the volume is 8 L with 3.0 g alga biomass Undaria pinnatifida it needs 150 min to meet the emission standard which is 0.1 mg/L was studied in the continuous systems;The first-order kinetic is more approximate to the adsorption behaviour of fluorion onto the calcination product of Mg-Al-Fe hydrotalcite compound. According to the results of the experiment we can provide some effective operational data for the system.