One-step electrochemical deposition of Polypyrrole–Chitosan–Iron oxide nanocomposite films for non-enzymatic glucose biosensor

One-step electrodeposition method of Polypyrrole–Chitosan–Iron oxide (Ppy–CS–Fe3O4) nanocomposite films (Ppy–CS–Fe3O4NP/ITO) has been developed for the fabrication of advanced composite coatings for biosensors applications. The FESEM and EDX results provide the evidence of successful incorporation of Fe3O4 into Ppy–CS molecules. The presence of Fe3O4 nanoparticles in the nanocomposite films was further confirmed by the XRD and XPS spectrums. The fabricated electrode Ppy–CS–Fe3O4 NP/ITO shows a fast amperometric response with high selectivity to detect glucose non-enzymatically with improved linearity (1–16 mM) and the detection limit of (234 μM) at a signal-to-noise ratio (S/N=3.0)

Nano-zinc oxide fibers: Synthesis, characterization, adsorption of acid blue 92 dye, isotherms, thermodynamics and kinetics

Surface water is significantly contaminated by different dyes and pigments around the world due to rapid industrialization, especially textile/dyeing. Bangladesh's export-driven textile industry has grown dramatically over the past few decades, severely contaminating the nearby waterways. In this study, nano-zinc oxide was synthesized through precipitation method in the presence of PEG 400. SEM, XRD, and FTIR techniques were used to characterize the synthesized ZnO and revealed that it was pure, fiber-like, and essentially wurtzite. Nano-ZnO was used to remove the ionic dye acid blue 92 (AB 92) from aqueous solution in order to test its effectiveness as an adsorbent. The effects of pH, adsorbent dosage, AB 92 concentration, and contact time were investigated in order to optimize the adsorption process. According to correlation coefficients (R2) and the Redlich-Peterson model's fitting, the adsorption process followed the Freundlich isotherm at higher temperature and the Langmuir isotherm at lower temperature. The adsorption process was found to be endothermic and spontaneous. For adsorption thermodynamics, ΔH was found to be +20.32 kJmol-1, and ΔG was varied from −1.86 to −3.84 kJmol-1 as the temperature increased from 291 to 317 K. The adsorption kinetics exhibited pseudo second order. The Temkin isotherm and Elovich kinetic models suggested that the process was chemisorption. The nano-ZnO showed tremendous re-usability as an adsorbent for the removal of AB 92. The results are suggesting for designing nano-ZnO-based methods to remove organic pollutants efficiently from industrial effluents for ecological and sustainable development. The mechanism of formation of nano-ZnO fiber and adsorption of anionic dye on nano-ZnO are also explored

The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials

<p>A series of azo-ester linked mesogen containing liquid crystalline acrylate compounds <b>C1-C6</b> having different terminal groups (–F, –Cl, –Br, –OCH₃, –OC₂H₅ and –OC₃H₇) were successfully synthesised and characterised. The chemical structure, purity, thermal stability, mesophase behaviour and optical property of the synthesised compounds were investigated by different instrumental techniques. X-ray crystal structure showed that compounds <b>C1</b>, <b>C4</b> and <b>C5</b> exhibited more stable <i>E</i> configuration with two bulky group in the opposite side of the N=N double bond motifs. The fluoro-substituted derivative (<b>C1</b>) is connected by the R¹₂(5) type of C–H…O hydrogen bond motifs whereas the molecules of <b>C4</b>, and <b>C5</b> are connected to each other by means cyclic R²₂(8) type of C–H…O hydrogen bond motifs. Thermogravimetric study revealed that the investigated compounds exhibited excellent thermal stability. All the compounds showed enantiotropic liquid crystal (LC) phase behaviour and the mesophase formation was greatly influenced by the terminal substituents. Alkoxy (–OCH₃, –OC₂H₅ and –OC₃H₇) substituted compounds exhibited greater mesophase stability than those of halogen (–F, –Cl and –Br) terminated derivatives. UV-vis spectroscopic study revealed that the investigated compounds exhibited a broad absorption band around 300–420 nm with absorption maximum (<i>λ</i>_max) of nearly 370 nm.</p