Adsorption of phosphate on goethite: An undergraduate research laboratory project

Adsorption experiments are rarely included in undergraduate general chemistry laboratories, even though this phenomenon is of great importance from both applied and theoretical points of view. We present a laboratory experiment on the adsorption of phosphate on goethite (an iron oxide, α-FeOOH) as a case study that opens the doors to the discussion of surface properties, interfaces, acid-base equilibrium, molecular structure, and solid state chemistry, among other topics. We also describe a pedagogical implementation of this experiment that allows students to work cooperatively.