Introducing an alternate conjugated material for enhanced lead(II) capturing from wastewater

CaFu MOF as an efficient adsorbent for simultaneous removal of imidacloprid pesticide and cadmium ions from wastewater.

104 MHz surface acoustic wave sensors, functionalized with two polypyrrole (PPy) imprinted polymers, were designed for lead ion detection in liquid media. The main difference between the two ionic imprinted polymers (IIP) is related to the nature of the chelating agent: L-Cysteine (L-Cys) for the former and acrylic acid (AA) for the latter. Performances of the IIPs based sensors were compared in terms of sensitivity, limits of detection (LOD), dissociation constants and selectivity. The gravimetric results indicated that both designed sensors can detect picomolar concentrations of lead ions. These values are, in fact, significantly inferior to the World Health Organization (WHO) maximum accepted limit in drinking water, and among the lowest LODs ever reported in the literature. The relevant dissociation constants, calculated from the most appropriate fits of the calibration curves, were estimated at: Kd $_{\textsf {1}} = (\textsf {1.1} \pm \textsf {0.4})\times \textsf {10}^{-\textsf {10}}$ M and Kd $_{\textsf {2}}= (\textsf {1.1} \pm \textsf {0.8})\times \textsf {10}^{-\textsf {5}}$ M for L-Cys-IIP/Pb2+ and Kd $_{\textsf {1}}= (\textsf {1.1} \pm \textsf {0.3})\times \textsf {10}^{-\textsf {13}}$ M and Kd $_{\textsf {2}}= (\textsf {5.9} \pm \textsf {1.8}) \times \textsf {10}^{-\textsf {10}}$ M for AA-PPy-IIP/ Pb2+, thus confirming the strong binding between the designed IIPs and lead ions. Selectivity tests were investigated with mercury, cadmium, copper, zinc, and nickel divalent ions, which largely coexist with lead ions in soils, rivers, and wastewaters.

Design of L-Cysteine and Acrylic Acid Imprinted Polypyrrole Sensors for Picomolar Detection of Lead Ions in Simple and Real Media

A biomimetic, ion-imprinted polymer (IIP) was prepared by electropolymerization of pyrrole at the surface of gold electrodes decorated with vertically grown ZnO nanorods. The vertical growth of the nanorods was achieved via an ultrathin aryl monolayer grafted by reduction of diazonium salt precursor. Pyrrole was polymerized in the presence of L-cysteine as chelating agent and Hg2+ (template). Hg2+-imprinted polypyrrole (PPy) was also prepared on a bare gold electrode in order to compare the two methods of sensor design (Au-ZnO-IIP vs. Au-IIP). Non-imprinted PPy was prepared in the same conditions but in the absence of any Hg2+ template. The strategy combining diazonium salt modification and ZnO nanorod decoration of gold electrodes permitted us to increase considerably the specific surface area and thus improve the sensor performance. The limit of detection (LOD) of the designed sensor was ~1 pM, the lowest value ever reported in the literature for gold electrode sensors. The dissociation constants between PPy and Hg2+ were estimated at [Kd1 = (7.89 ± 3.63) mM and Kd2 = (38.10 ± 9.22) pM]. The sensitivity of the designed sensor was found to be 0.692 ± 0.034 μA.pM-1. The Au-ZnO-IIP was found to be highly selective towards Hg2+ compared to cadmium, lead and copper ions. This sensor design strategy could open up new horizons in monitoring toxic heavy metal ions in water and therefore contribute to enhancing environmental quality.

https://www.mdpi.com/2076-3417/10/19/7010/pdf

High Performance Zinc Oxide Nanorod-Doped Ion Imprinted Polypyrrole for the Selective Electrosensing of Mercury II Ions

Spectroscopic characterization and binding interaction of heavy metal onto the surface receptor of the azobenzene: DFT and experimental approach

104 MHz surface acoustic wave (SAW) sensors functionalized with new anthracene derivates were designed for the detection of lead ions (Pb2+) in liquid media. On the basis on quantum chemical calculations, three anthracene molecules have been synthetized and tested: 4-(9-anthrylmethoxy) benzyl[4-(9-anthrylmethoxy)phenyl]sulfone (BPS-AN); 9-{[4-({[4-(9 anthrylmethoxy) phenyl]sulfanyl}methyl)]methyl] anthracene (TDP-AN) and 2,2-bis(4 anthracenylmethoxy-1,1′-biphenyl (BP-AN). Gravimetric results indicate that the affinity of BPS-AN towards Pb2+ ions is superior to that of TDP-AN and BP-AN, confirming thus the computational approach. The designed BPS-AN SAW sensor has a sensitivity of [7.2 ± 4.6]×108 [°/M], a limit of detection (LOD) of 22 pM, and displayed very high affinity to lead ions with an apparent dissociation constant Kd of order of (1.1 ± 2.7) × 10−10. Selectivity was investigated by both gravimetry and DFT calculation. Results indicate that the designed sensor is more sensitive to lead cations than copper and mercury ones. A tetrabutylphosphonium (TBP) lactate ionic liquid (IL) solution was used to regenerate the SAW sensor, permitting its further reuse a dozen times without degrading the BPS-AN recognition layer.

S. Bouquillon

Papers

Anthracene based surface acoustic wave sensors for picomolar detection of lead ions. Correlation between experimental results and DFT calculations