Adsorption Of Yeast Immobilized By Alginatesodium-Gelatin-PVA Embedding Method On Heavy Metal

With the rapid development of China’s industry, the speed of heavy metal pollution has become increasingly accelerated. Heavy metals such as lead and cadmium have a strong biological toxicity, and these heavy metals are relatively stable under normal environment that can not be degraded in a short time. The heavy metal ions can accumulate in living creatures through the food chain, they are difficult to discharge and cause greater harm to the organism. The traditional method to deal with heavy metal wastewater is complicated, and it is easy to cause secondary pollution, and the immobilized microorganism technology has become the focus of research because of its high adsorption efficiency and low cost. In this paper, the adsorption ability of heavy metals by immobilized yeast on sodium alginate gelatin and polyvinyl alcohol was studied.According to the embedding conditions (diameter, density, mechanical strength and mass transfer performance) of the fixed materials to choose better conditions, then using the blank pellets on the adsorption of lead and cadmium as the evaluation index, through the orthogonal experiment, wo know the best ratio is 2% sodium alginate and 0.5% gelatin and 2% polyvinyl alcohol. Under these conditions, the preparation of immobilized blank pellets adsorption rate for lead and cadmium were 68.72% and 66.35%.After using the best ratio obtained immobilized yeast pellets, scanning electron microscope analysis, the folding surface of the immobilized yeast and the internal net space are favorable for the growth of microorganisms, which provide the necessary basis for the adsorption of heavy metal ions by immobilized pellets.This paper use pH, heavy metal ion initial concentration, yeast amount, environmental temperature and adsorption time as the control factors, to carry out experimental study on the immobilization yeast adsorption of heavy metals under different environmental conditions.The results showed that the immobilized yeast optimum adsorption conditions for pH=5, the initial concentration of heavy metal was 120mg/L, the amount of yeast 10g/L, temperature 25, time 120min.Using immobilized yeast, yeast, and blank pellets adsorption of lead, cadmium in optimal conditions, the results showed that the immobilized yeast adsorption effect were better than that of immobilized yeast and blank pellets.To explore a simple mechanism by immobilized yeast beads adsorption of Pb2+ and Cd2+, the quasi second stage reaction kinetics model is better than the pseudo first order kinetic model that can describe the adsorption behavior of the immobilized yeast well on Pb2+ and Cd2+.The quasi second stage reaction kinetics model fit the R2 were 0.9934 and 0.9977. Langmuir isotherm model can more accurately describe the adsorption performance of immobilized yeast on heavy metal lead and cadmium than the Freundlich isotherm model. Langmuir isothermal model fit the R2 were 0.9914 and 0.9942.