Speciation of inorganic mercury ions using bacterial cells

Abstract

The adsorption of soluble inorganic mercury ions from aqueous solutions on the external membrane of both lyophilized bacterial cells and living cells was studied as a function of solution pH, adsorption time, amount of adsorbent, concentration of mercury ions, and sample volume. Desorption studies were also performed using also both types of cells. Loaded membranes and the amount of the unadsorbed ions were measured by electrothermal atomic absorption spectrometry (ETAAS) and/or gamma spectrometry. The ²⁰³Hg radiotracer (t_1/2= 46.6 d) was used to monitor recoveries in gamma spectrometry. The adsorption process was adapted to develop a method for the speciation of the Hg^II and Hg^I ions. Speciation is possible because mercury ions can be selectively retained by the bacterial external membrane depending on the solution pH.