Competition and surface conditioning alter the adsorption of phenolic and amino acids on soil minerals

作者：Gao J^*; Jansen B; Cerli C; Helmus R; Mikutta R; Dultz S; Guggenberger G; Kalbitz K

来源：European Journal of Soil Science, 2017, 68(5): 667-677.

DOI：10.1111/ejss.12459

Adsorptive interactions of organic molecules with soil minerals often impair their bioavailability. However, little is known about the adsorption behaviour of phenolic and nitrogenous compounds on different minerals and their mutual interaction with respect to competition and surface conditioning (i.e. surface modification induced by preceding adsorption of the other class of compounds). Therefore, batch adsorption experiments were done to study the interaction between phenolic acids (PAs; salicylic acid, Sal; syringic acid, Syr; ferulic acid, Fer; vanillic acid, Van) and amino acids (AAs; lysine, Lys; glutamic acid, Glu; leucine, Leu; phenylalanine, Phe) during adsorption on goethite and Ca2+-montmorillonite at pH6 by applying adsorbate concentrations of 0.01, 0.05 and 0.1mm. Larger adsorption of PAs was observed on goethite than montmorillonite, whereas the phyllosilicate was a better adsorbent for AAs than the oxide. Among all tested PAs, Sal was preferentially adsorbed on both minerals. For the AAs, Glu was preferentially adsorbed on goethite and Lys on montmorillonite. The AAs were more competitive than PAs and partially suppressed the adsorption of PAs on both minerals. The adsorption of PAs or AAs on both minerals was enhanced by surface conditioning with the other group, with larger effects for goethite than montmorillonite. For goethite, surface conditioning by PAs enhanced the adsorption of AAs more (by 97-161%) than did AAs for PAs (9-48%). The results support the hypothesis that pre-adsorption of one class of organic compound can enhance the retention of another class. This suggests that adsorbed organic matter on soil mineral phases might be subject to a self-strengthening effect.
Highlights
Phenolic acids (PAs) were preferentially retained on goethite.
Amino acids (AAs) were preferentially retained on montmorillonite.
AAs were more competitive than PAs for adsorption sites on both minerals.
Pre-adsorption of one class of compound can enhance the retention of another class.

• 出版日期2017-9