A Comparative Study of Two Indigenous Bacterial Biosorbents for Mercury Removal from Aqueous Solutions

In the present study, the capability of dried indigenous biomass of Vibrio and Oceanimonas, was assessed and compared for mercury biosorption from aqueous solutions. It was found that both of the biosorbents reached equilibrium after 60 min of contact although the mercury sorption capacity of Vibrio was significantly more. Its sorption capacity increased from 9 to 83 mg/g biomass by increasing the initial metal concentration from 10 to 100 mg/L although the efficiency decreased from 90 to 83%. The changes in the pH of the medium had a great impact on the Hg2+ adsorption capacities of the bio sorbents. The maximum mercury bio sorption capacities were obtained under pH value of 6. The kinetic studies revealed that the pseudo-second order model described Hg2+biosorption than the pseudo-firs order, for both of the bio sorbents better. The equilibrium isotherms showed that the Langmuir model described the mercury bio sorption by dried Vibrio better whereas the Freundlich was a dominant model for mercury bio sorption by Oceanimonas. According to the Langmuir model, the maximum mercury sorption capacities were achieved 193 and 113 mg/g biomass, respectively. Therefore, due to its high efficiency and high availability, the use of Vibrio as mercury biosorbent was a good alternative in mercury removal from water.