Biofilm Polymer for Biosorption of Pollutant Ions

Abstract The utilization of biofilm as an adsorbent of pollutant ions is one of the promising technologies for water contamination treatment. An understanding of biofilm adsorption property is therefore essential to predict how biofilm contributes to mobility and bioavailability of pollutant ions in the environments. The aim of this study is investigating adsorption properties of biofilm, i.e., existing in the biofilm polymer and clarifying the ability of biofilm as an adsorbent in the biosorption of pollutant ions. The biofilms applied in this study are natural biofilms formed on the surface of stones collected from Lake Biwa. The characterization of the biofilm polymer is revealed by electrophoretic mobility measurements and acid-base titrations. To clarify the ability of biofilm for biosorption of pollutant ions, we study the adsorption kinetics of lithium ion to biofilms formed in winter and spring. The followings are observed as results of this study: 1) both negative and positive charged sites exist on biofilm polymer; 2) the ion adsorption by biofilm polymer is a physicochemical process where the electrostatic interaction between ion and the charged sites in biofilm polymers is a main driving force; 3) the adsorbing ion promotes ions desorption from biofilms through ion exchange mechanism; 4) the biofilms components change seasonally and appear to affect the ability of biofilms to adsorb ions. From all of similar studies, this study is the first one investigating utilization of natural biofilms formed in different seasons for biosorption of heavy metal ion i.e., lithium ion. This study also reveals that biofilm may become a promising adsorbent for pollutant ions.