New paper explores the roles of pH and dissolved silicate on the adsorption and desorption of phosphate in the presence of ferric iron oxyhydroxides

Phosphorus (P), in the form of aqueous phosphate, is an essential nutrient for the growth of plants and algae. Because it often limits or colimits primary production in freshwater and nearshore marine systems, phosphate enrichment can result in eutrophication and algal blooms. A major process driving phosphate enrichment is the desorption of phosphate from mineral surfaces, in particular those of ferric iron oxyhydroxides. Adsorption and desorption of phosphate can further be modulated by other aqueous anionic species, including arsenate, bicarbonate, sulfate, and silicate, that compete with phosphate for mineral binding sites. Among phosphate’s anionic competitors, dissolved silicate is ubiquitous in aquatic environments. The results presented in the new paper by Sabur Abdus, a former PhD student in ERG, show that the competitive effect of silicate on phosphate adsorption is strongly dependent on pH and the molar Si:P ratio. As a representative ferric iron oxyhydroxide mineral goethite was used.  For more details, visit 10.1021/acsearthspacechem.1c00197.