Mechanisms of metal biosorption are complicated and not fully understood. Key factors controlling and characterizing the mechanisms are:
-The types of biological ligands available for metal sequestering
-The status of the biomass: living /non living
-The chemical, stereochemical and coordination characteristics of the targeted metals-metal species.
- The properties of metal solution such as the pH, the presence of competing co-ions etc.
Microorganisms possess an abundance of functional groups that can passively adsorb metal ions. The term adsorption is representative for biosorption, can be used as a general term and includes several passive i.e. non-metabolic mechanisms :