Rational Design of an Ion-Imprinted Polymer for Aqueous Methylmercury Sorption

Abstract

Methylmercury (MeHg+) is a mercury species that is very toxic for humans, and its monitoring and sorption from environmental samples of water are a public health concern. In this work, a combination of theory and experiment was used to rationally synthesize an ion-imprinted polymer (IIP) with the aim of the extraction of MeHg+ from samples of water. Interactions among MeHg+ and possible reaction components in the pre-polymerization stage were studied by computational simulation using density functional theory. Accordingly, 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT), acrylic acid (AA) and ethanol were predicted as excellent sulfhydryl ligands, a functional monomer and porogenic solvent, respectively. Characterization studies by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) revealed the obtention of porous materials with specific surface areas of 11 m2 g−1 (IIP–MBI–AA) and 5.3 m2 g−1 (IIP–MBT–AA). Under optimized conditions, the maximum adsorption capacities were 157 µg g−1 (for IIP–MBI–AA) and 457 µg g−1 (for IIP–MBT–AA). The IIP–MBT–AA was selected for further experiments and application, and the selectivity coefficients were MeHg+/Hg2+ (0.86), MeHg+/Cd2+ (260), MeHg+/Pb2+ (288) and MeHg+/Zn2+ (1510), highlighting the material’s high affinity for MeHg+. The IIP was successfully applied to the sorption of MeHg+ in river and tap water samples at environmentally relevant concentrations.

Using Carbon Paste Electrode Modified with Ion Imprinted Polymer and MWCNT for Electrochemical Quantification of Methylmercury in Natural Water Samples

“…The first cathodic peak, peak C1 at −0.48 V, represents the reduction in MeHg to methylmercury radical CH 3 Hg·, then, the second cathodic peak, peak C3 at −0.69 V, represents the reduction in CH 3 Hg· to Hg. It is worth noting that CH 3 Hg· can be disproportionate to (CH 3 Hg) 2 within a short time [ 14 ]; these reactions occur on the electrode surface during deposition. During the anodic scan, the stripping peak current correspondent to peak C1 is not observed; instead, one notices the presence of an anodic peak A2 at more positive potential, around 0.21 V, which indicates the oxidation of Hg to Hg 2+ .…”

“…The present work reports the development and application of a highly selective and sensitive sensor for the quantification of MeHg. The sensor was developed using a carbon paste electrode modified with an imprinted polymer, which is highly selective toward MeHg (this was reported in our previous study [ 14 ]) and multi-walled carbon nanotubes-MWCNTs (which increase the charge transfer on the electrode surface). The electrochemical determination of MeHg was conducted by differential pulse stripping voltammetry (DPSV).…”

2-Mercaptobenzimidazole-functionalized chitosan for enhanced removal of methylene blue: Batch and column studies

“…For rubidium recovery, Guerra et al [39] used organoclays for the immobilization of MBI. Recently, Mesa et al [40] reported the immobilization of 2-MBI onto ion-imprinted acrylic acid-based polymer and the removal of methylmercury. Different techniques were used for immobilizing 2-mercaptobenzimidazole on chitosan-based sorbents, including impregnation mediated by acetone [41], or chemical grafting [42].…”

Screening of synthesis conditions for the development of a radium ion-imprinted polymer using the dummy template imprinting approach

“…Computational simulations or spectroscopic methods (e.g. UV-vis, FTIR or RMN) have already been used to preselect the best monomers candidates and template/monomer ratio for molecular or ion-imprinted polymers synthesis [39][40][41]. However, carrying out theoretical calculations and reliable modelings require specific knowledge.…”