Effects of pH and Dissolved Silicate on Phosphate Mineral-Water Partitioning with Goethite

Release of sorbed phosphate from ferric iron oxyhydroxides can contribute to excessive algal growth in surface water bodies. Dissolved silicate has been hypothesized facilitate desorption by competing for mineral sites. Here, we conducted and adsorption experiments with goethite under a wide pH range (3–11), both individually (P or Si) simultaneously plus Si). The entire experimental data set was successfully reproduced the charge distribution multisite complexation (CD-MUSIC) model. Phosphate highest acidic conditions gradually decreased near-neutral alkaline conditions. Maximum adsorption, contrast, occurred conditions, peaking around 10. competitive effect on negligible becoming more pronounced elevated molar Si:P ratios (>4). In subsequent experiment, increasing monitored, presence absence dissolved silicate. While, as expected, observed during transition fraction remained irreversibly bound goethite. Even at high pH, did not affect desorption, implying that kinetic factors prevented displacing binding