Integrated investigations on the adsorption mechanisms of fulvic and humic acids on three clay minerals

Interaction of Natural Organic Matter with Layered Minerals: Recent Developments in Computational Methods at the Nanoscale

“…Zhang et al [68] also noted that the higher concentration of iron cations in vermiculite facilitated ligand exchange and cation bridging of carboxyl and hydroxyl functional groups, thus improving adsorption capacity. Finally, Chorover [78] and Jokic [79] have looked at the role of synthetic manganese oxides in stabilizing dissolved organic matter (DOM) and concluded that although they are not as good at adsorbing DOM as other metal oxides or clays, they have a large capacity for fractionating DOM at their surfaces.…”

“…The role of iron and aluminum oxides, which are adsorbed onto clay particles, is known to play a part in MUC stabilization [68,[82][83][84][85], although the mechanisms for stabilization have not been determined. Zhang et al [68] also noted that the higher concentration of iron cations in vermiculite facilitated ligand exchange and cation bridging of carboxyl and hydroxyl functional groups, thus improving adsorption capacity.…”

“…Kennedy and Wagner [3] have recently argued that smectite is particularly important in governing carbon preservation in marine sediments. Zhang et al [68] noted that pH increases in clay suspensions after fulvic acid (FA)/humic acid (HA) adsorption suggesting that ligand exchange occurred and FA/HA-clay complexes formed. This was particularly noted for the 2:1 type clay minerals such as smectite and vermiculite, which have surface complexed cations.…”

“…While spectroscopic methods have been used to investigate the structure of NOM adsorbed on mineral surfaces [66][67][68][69][70][71][72][73][74], using simple organic acids as proxies for NOM can provide valuable insight into possible adsorption mechanisms [75,76]. Carboxylic functional groups are particularly relevant, not only to NOM but also as ligands responsible for binding and transporting potentially toxic elements, owing to many mineral surfaces carrying areas of net positive charge and poly-carboxylate species bridging between these surfaces and dissolved metals during flocculation processes.…”

Adsorption of Natural Organic Matter (Nom) in Peat Water by Local Indonesia Tropical Clay Soils

“…The Freundlich isotherm model is proposed for both monolayer and multilayer adsorption on the heterogeneous adsorbent surface. Activation process of the ALPC by immersing it in a strong acid (HCl) might change the clay mineral's structure, and created more heterogeneous adsorption sites and increased its specific surface [33]. The kF values obtained from NOM adsorption onto the LCP and the ALCP were 12.6 and 14.91, respectively, while if compared with other studies, which using nanomaterials and carbon materials as adsorbents, their kF values obtained were in a range of 100-200 [34], [35].…”