Abstract: This paper studies the bacterial adsorption and desorption of cadmium ions and other heavy metal ions. The test results showed that the appropriate adsorption time of cadmium ions by the bacteria is 60 min. Infrared spectral analysis indicates that the amide, hydroxyl and carbonyl functional groups of polysaccharides and proteins on cell surface play a key role in the adsorption process. Further experimental results show that pretreatment of 0.1 mol/L NH₄OH solution on cell can significantly increase the bacterial adsorption capacity for Cd²⁺, Ni²⁺ and Pb²⁺;0.02 mol/L HCl solution can make more than 96% of the heavy metal ions to be desorbed from the microbial cell, and after desorption, the bacteria can be reused.

Key words: Microbial bacteria, Heavy metal ions Infrared, Spectroscopy, Adsorption, Desorption