Biosorption effect of Pb(II)and Cd(II)on baker's yeast in single and double heavy metal ions systems

The given paper is to present our study on the biosorption effect and the mechanism of Pb~(2+)and Cd~(2+)ions on autoclaved bak- er's yeast in single and double heavy metal ions systems.Autoclaved baker's yeast was chosen as biosorbent,then the kinetic process and isotherm effect were studied in the different ion systems of Pb~(2+)and Cd~(2+).The experimental results show that the biosorption of Pb~(2+)on baker's yeast proves always more effective than that of Cd~(2+)in dif- ferent systems at the same initial heavy metal ion concentration.Un- der the experimental conditions,the isotherm biosorption of baker's yeast to the single system of Pb~(2+),Cd~(2+)and the double system of Pb~(2+)-Cd~(2+)are well conformed with the Langmuir model,with the maximum absorption quantities (q_(max))being 0.414 9 mmol/g, 0.346 8 mmol/g and 0.488 5 mmoL/g,respectively.SEM/EDS analysis proves that Pb~(2+)and Cd~(2+)ions are absorbed by the baker's yeast tissues.It can also be found that it is the toxicity of heavy ions to yeast tissues make the tissues distorted and broken,which can probably be attributed to the response to the second biosorption pro- cess after the absorption took place some time later.In addition,the autoclaved baker' s yeast proves to have favorable biosorption effect on Pb~(2+)and Cd~(2+).The toxicity of the two heavy metal ions,when put into spot combination and competition is expected to be helpful substances that affect the total biosorption in the double system of pb~(2+)-Cd~(2+).