Metal ion adsorption onto bacteria-mineral composites

Adsorption onto mineral and bacterial surfaces affects the fate of aqueous metal(loid)s but there is currently a poor understanding of adsorption onto mixtures of these two sorbents. This thesis used chemical analyses and imaging to track selenate and copper adsorption by iron oxide-Escherichia coli composites during Fe(II)aq addition. No selenate adsorbed onto E. coli under the conditions in this study. Selenate adsorption onto composites was reduced compared to iron oxide. Surface complexation models (SCMs) suggested that the reduction in selenate adsorption was due to masking of iron oxide sites and aggregation of the mineral over time. Copper adsorbed primarily to the cells under the conditions in this study; however, some removal was due to co-precipitation within the iron oxide. SCMs overestimated copper removal as they did not account for masking of bacterial sites. In conclusion, metal(loid) removal is significantly affected by the presence of sorbent mixtures and redox processes.