Proton interaction in phosphate adsorption onto goethite.
The adsorption of phosphate on goethite is generally modeled by assuming a simple ligand exchange reaction with surface hydroxyl groups. This study investigates the binding forms of phosphate on goethite by evaluating the proton interaction and surface charge change during phosphate adsorption. It is found that OH(-) release stoichiometry increases with phosphate coverage, which suggests that different mechanisms predominate at different phosphate loadings. It demonstrates that surface binding changes from monodentate complexation to bidentate complexation with increasing surface phosphate coverage. The net OH(-) release accompanying this transformation is best interpreted with a 2pK(a) multisite model.
Zhong
Bin
B
Division of Environmental Science & Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576.
Stanforth
Robert
R
Wu
Shunnian
S
Chen
J Paul
JP
D000327:Adsorption; D058085:Iron Compounds / Q000737:chemistry*; D008903:Minerals; D008956:Models, Chemical; D010710:Phosphates / Q000737:chemistry*; D011522:Protons
D058085:Iron Compounds; D008903:Minerals; D010710:Phosphates; D011522:Protons; C094886:goethite