A Novel Colorimetric Chemosensor Based on Ferene-S-Conjugated Silver Nanoparticles for Selective Recognition of Fe2+

Ferene is the most commonly used chromogenic agent for the determination of serum iron in blood. In this work we have successfully synthesized Ferene-S-conjugated silver nanoparticles (Ferene-S-AgNPs) for the first time characterized by UV-visible, Fourier-Transform Infrared Spectroscopy (FTIR), and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry techniques. Particle size of the synthesized nanoparticles was determined by atomic-force microscopy and scanning electron microscopy techniques with size ranges from 10–90 nm in diameter. Ferene-S-AgNPs were explored for their chemosensing potential with various metal ions such as Sb3+, Pb2+, Ca2+, Fe2+, K+, Co2+, Ba2+, V5+, Cu+, Cd2+, Hg2+, Ni2+, Cu2+, Fe3+, Mg2+, Mn2+, Al3+, and Cr3+. Ferene-S-AgNPs were found to show selective quenching effects and slight bathochromic shifts to the surface plasmon resonance absorption band after treatment with Fe2+. Furthermore, the developed chemosensor also exhibited substantial selectivity towards Fe2+ in the presence of other competitive ions. We observed that Ferene-S-AgNPs mimic the selectivity of the parent compound of Ferene towards Fe2+. The system obeyed Beer’s law over concentration ranges of 110–190 nM. The detection limit was found to be 110 nM.

Electrochemical Determination of Lead & Copper Ions Using Thiolated Calix[4]arene-Modified Screen-Printed Carbon Electrode

This study used a thiolated calix[4]arene derivative modified on gold nanoparticles and a screen-printed carbon electrode (TC4/AuNPs/SPCE) for Pb2+ and Cu2+ determination. The surface of the modified electrode was characterised via Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used for the detection of Pb2+ and Cu2+ under optimum conditions. The limit of detection (LOD) for detecting Pb2+ and Cu2+ was 0.7982 × 10−2 ppm and 1.3358 × 10−2 ppm, respectively. Except for Zn2+ and Hg2+, the presence of competitive ions caused little effect on the current response when detecting Pb2+. However, all competitive ions caused a significant drop in the current response when detecting Cu2+, except Ca2+ and Mg2+, suggesting the sensing platform is more selective toward Pb2+ ions rather than copper (Cu2+) ions. The electrochemical sensor demonstrated good reproducibility and excellent stability with a low relative standard deviation (RSD) value in detecting lead and copper ions. Most importantly, the result obtained in the analysis of Pb2+ and Cu2+ had good recovery in river water, demonstrating the applicability of the developed sensor for real samples.

Synthesis of N2, N6-bis(5-methylthiazol-2-yl)pyridine-2,6-dicarboxamide fluoroscent sensor for detection of Cu2+ and Ni2+ Ions

This article reports an amide based Chemosensor used for selective detection of divalent Cu+2 and Ni+2 ions via Fluorescence turn off. The selective sensing ability of Chemosensor was investigated in presence of different metal ions Mg2+, Ag+, Fe2+, K+, Cu2+, Ni2+, Hg2+, Pb2+, Mn2+, Pd2+, Cd2+ and Mn3+ as competitive ions. The receptor i. e. Chemosensor formed complexes with metal ions in 1:1 stoichiometric ratio. The detection limit and binding constant calculated as 1.92×10–4 and 1.4×10–4 M and 2.16×103 M−1 and 3.09×103 M−1 for Cu2+ and Ni2+ions respectively. The complexes were characterized by UV/visible, FT-IR, 13C NMR and 1H NMR spectroscopy. Further the structure and Crystallinity were calculated by P-XRD spectral analysis. The crystallinity found to be 65.27 and 67.87% respectively

Removal of Barium from Solution by Natural and Iron(III) Oxide-Modified Allophane, Beidellite and Zeolite Adsorbents

Efficient capture of barium (Ba) from solution is a serious task in environmental protection and remediation. Herein, the capacity and the mechanism of Ba adsorption by natural and iron(III) oxide (FeO) modified allophane (ALO), beidellite (BEI) and zeolite (ZEO) were investigated by considering the effects of contact time, temperature, pH, Ba2+ concentration, adsorbent dosage, the presence of competitive ions and adsorption–desorption cycles (regenerability). Physicochemical and mineralogical properties of the adsorbents were characterized by XRD, FTIR, SEM with EDX and N2 physisorption techniques. The Ba2+ adsorption fitted to a pseudo-first-order reaction kinetics, where equilibrium conditions were reached within <30 min. BEI, ALO and ZEO with(out) FeO-modification yielded removal efficiencies for Ba2+ of up to 99.9%, 97% and 22% at optimum pH (pH 7.5–8.0). Adsorption isotherms fitted to the Langmuir model, which revealed the highest adsorption capacities for BEI and FeO-BEI (44.8 mg/g and 38.6 mg/g at 313 K). Preferential ion uptake followed in the order: Ba2+ > K+ > Ca2+ >> Mg2+ for all adsorbents; however, BEI and FeO-BEI showed the highest selectivity for Ba2+ among all materials tested. Barium removal from solution was governed by physical adsorption besides ion exchange, intercalation, surface complexation and precipitation, depending mainly on the absorbent type and operational conditions. BEI and FeO-BEI showed a high regenerability (>70–80% desorption efficiency after 5 cycles) and could be considered as efficient sorbent materials for wastewater clean-up.

Arsenic removal from water by Zr-γ- FeOOH nanoparticles

Zr-γ-FeOOH nanoparticle adsorbent for As(V) and As(III) removal was prepared by a chemical co-precipitation method. Compared with γ-FeOOH, the addition of Zr enhanced the adsorptive capacities of As(V) and As(III). The maximum adsorptive capacities for As(V) and As(III) were 69.81 and 94.25 mg/g, respectively (rate Fe:Zr =1:0.5) at pH= 7.0. The adsorption data accorded with Langmuir and Freundlich isotherms. The adsorption of As(III) by Zr- γ-FeOOH was found to be effective in wide pH range of 6–8. Competitive ions hindered the adsorption according to the decreasing sequence phosphate, sulfate, ammonium, chloride, magnesium and calcium. The high adsorptive capability and good performance on other aspects make the Zr-γ- FeOOH nanorods a promissing adsorbent for the removal of As(V) and As(III) from groundwater.