Complexation of Antimony with Natural Organic Matter: Performance Evaluation during Coagulation-Flocculation Process

Abstract

The presence of natural organic matter (NOM) in drinking water sources can stabilize toxic antimony (Sb) species, thus enhancing their mobility and causing adverse effects on human health. Therefore, the present study aims to quantitatively explore the complexation of hydrophobic/hydrophilic NOM, i.e., humic acid (HA), salicylic acid (SA), and L-cysteine (L-cys), with Sb in water. In addition, the removal of Sb(III, V) species and total organic carbon (TOC) was evaluated with ferric chloride (FC) as a coagulant. The results showed a stronger binding affinity of hydrophobic HA as compared to hydrophilic NOM. The optimum FC dose required for Sb(V) removal was found to be higher than that for Sb(III), due to the higher complexation ability of hydrophobic NOM with antimonate than antimonite. TOC removal was found to be higher in hydrophobic ligands than hydrophilic ligands. The high concentration of hydrophobic molecules significantly suppresses the Sb adsorption onto Fe precipitates. An isotherm study suggested a stronger adsorption capacity for the hydrophobic ligand than the hydrophilic ligand. The binding of Sb to NOM in the presence of active Fe sites was significantly reduced, likely due to the adsorption of contaminants onto precipitated Fe. The results of flocs characteristics revealed that mechanisms such as oxidation, complexation, charge neutralization, and adsorption may be involved in the removal of Sb species from water. This study may provide new insights into the complexation behavior of Sb in NOM-laden water as well as the optimization of the coagulant dose during the water treatment process.

Three Reactions, One Catalyst: A Multi‐Purpose Platinum(IV) Complex and its Silica‐Supported Homologue for Environmentally Friendly Processes

“…Other literature data showed better ligand activity of para‐substituted pyridine in sorption processes of Pt(IV) compared to ortho‐substituted aminopyridine . In addition, according to our measurements, the presence of hydrophobic disiloxane moiety enhanced the affinity of the ligand for Pt(IV), as other studies have revealed for hydrophobic ligands, such as humic acid, which forms stronger complexes with Sb than hydrophilic ligands …”

“…[49] In addition, according to our measurements, the presence of hydrophobic disiloxane moiety enhanced the affinity of the ligand for Pt(IV), as other studies have revealed for hydrophobic ligands, such as humic acid, which forms stronger complexes with Sb than hydrophilic ligands. [50] For comparison, the complex formation ability of these ligands with PdCl 2 and RuCl 2 (DMSO) 4 was studied using the Hildebrand-Benesi method, and the found stability constants are also summarized in SCHEME 1 Chemical structures of the ligands used in this study Table 1. It can be observed that the affinity for Pd(II) was better in the case of model ligands compared with the siloxane ones, but the para-substituted pyridyl ligands still gave better results in each mini-series.…”

Interaction of Arsenic Species with Organic Ligands: Competitive Removal from Water by Coagulation-Flocculation-Sedimentation (C/F/S)

“…These model organic ligands that is, HA and SA had been widely used to simulate different water characteristics. Moreover, these model substances were obtained from commercial sources and have been widely used to provide consistent experimental conditions [29,30,31]. Prior to the binding and coagulation experiments, the total organic carbon (TOC) contents for HA and SA (10 mg L −1 each) were analyzed to be 4.17 and 2.40 mg C/L, respectively.…”

“…The organic ligand bound As was characterized by calculating the difference between total and free As species in water. The procedure was previously described in detail elsewhere [31,33]. Furthermore, the bonding features of pristine HA, SA and As(III, V) species as well as As-organic ligands composite complexes and FC composite flocs were determined using Fourier Transform Infrared Spectroscopy (FT/IR-4700, spectroscopy; JASCO Analytical Instruments, Easton, PA, USA).…”

Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes

“…The chelating effect of FAs can reduce the cation-positive charge and facilitate the migration of micronutrients to the plant. On the other hand, the lack of knowledge on interactions and complexing properties of FAs or other fractions of soil organic matter can pose a risk of heavy metal migration [16,17] and stabilize toxic species in drinking water [18,19]. Translocation of heavy metals to plants can increase the risk of food-chain contamination [20].…”