The acidobasic and complexation properties of humic acids Study of complexation of Czech humic acids with metal ions

Fabrication and Characterisation of Novel Natural <i>Lycopodium clavatum</i> Sporopollenin Microcapsules Loaded <i>In-Situ</i> with Nano-Magnetic Humic Acid-Metal Complexes

“…Significant peaks corresponding to the phenyl, hydroxyl, carboxyl, and the other substituents have been observed. The broad peak at 3431 cm It was reported that the origin of HA substances and their pre-treatments affects the sorption capacity of metal ions [48]. Figure 3 shows the FTIR of HA-Zn complex prepared by ion-exchange method.…”

Soil humic acids may favour the persistence of hexavalent chromium in soil

“…In fact, one of the most significant properties of HAs or/and HA-like substances is their ability to interact with xenobiotics to form complexes of different solubility and chemical and biochemical stability. HAs can therefore affect the uptake, bioavailability, transport, fixation and toxicity of xenobiotics in the environment (Borges et al, 2005;Campitelli et al, 2006;Lubal et al, 1998). This paper focuses on the elucidation of interactions of Cr(VI) with standard HAs under sub-neutral conditions using three complementary analytical methods: UV-Visible (UV-Vis) spectroscopy, X-ray absorption spectroscopy (EXAFSdExtended X-ray Absorption Fine Structure, and XANESdX-ray Absorption Near Edge Structure) and Differential Pulse Stripping (DPS) voltammetry.…”

Role of complex equilibrium in the shape-selective performances of MgO/MCM-22 catalysts prepared by complexing impregnation

“…However, in fact, a small fraction of free Mg 2+ might still be able to diffuse into the pores of MCM-22 during the impregnation. The free Mg 2+ cation was originated from the equilibrium between ligand and Mg 2+ during the complexing impregnation [17,18]. It was also found that the complex equilibrium between ligand and metal ion was mainly affected by the pH value of the impregnation system [19,20].…”

“…Most of the acidic sites on the external surface of MCM-22 zeolite could be covered when MgO/MCM-22 catalysts were prepared using complexing impregnation method, whereas the pore size could not be adjusted effectively by this way. It is well known that the existence of complexing equilibrium between metal ion and ligand during complexation process results in the presence of partial free metal ion [17,18]. Meanwhile, the complexing equilibrium between the metal ion and ligand could be affected by a number of factors, such as the pH values of the complexation system [19,20].…”