Molecular-Scale Study of Aspartate Adsorption on Goethite and Competition with Phosphate

• DOI: 10.1021/acs.est.5b05450
• Publication Date: 2016-02-12T16:56:02Z
• Authors: Yanli Yang; Shengrui Wang; Yisheng Xu; Binghui Zheng; Jingyang Liu
• Keywords: Aspartic Acid; Minerals; Molecular Structure; Osmolar Concentration; Water; Hydrogen-Ion Concentration; 01 natural sciences; Phosphates; Solutions; Spectroscopy, Fourier Transform Infrared; Adsorption; Iron Compounds; 0105 earth and related environmental sciences

Knowledge of the interfacial interactions between aspartate and minerals, especially its competition with phosphate, is critical to understanding fate transport amino acids in environment. Adsorption reactions play important roles mobility, bioavailability, degradation phosphate. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements density functional theory (DFT) calculations were used investigate structures their relative contributions single-adsorbate systems. Our results suggest three dominant mechanisms for aspartate: bidentate inner-sphere coordination involving both α- γ-COO(-), outer-sphere complexation via electrostatic attraction H-bonding NH2 goethite surface hydroxyls. The mainly governed by pH less sensitive changes ionic strength concentration. phosphate significantly reduces adsorption capacity on goethite. Whereas affected presence aspartate, including diprotonated monodentate, monoprotonated bidentate, nonprotonated structures. process facilitates removal bioavailable from soil solution as well sediment pore water overlying water.