Investigation of structural, morphological, and electrical conductivity study for understanding transport mechanisms of perovskite CH3NH3HgCl3.

Along with morphological and structural studies, the temperature and frequency dependence of the electrical and dielectric properties of the CH3NH3HgCl3 (MATM) compound was investigated and analyzed. SEM/EDS and XRPD analyses proved the purity, composition, and perovskite structure of the MATM. DSC analysis reveals the existence of an order-disorder phase transition of a first-order type at about 342 ± 2 K and 320 ± 1 K (heating and cooling, respectively), attributed to the disorder of [CH3NH3]+ ions. The overall results of the electrical study provide arguments for the ferroelectric nature of this compound and aim to broaden the current knowledge on the thermally activated conduction mechanisms of the studied compound via impedance spectroscopy. The electrical investigations have shown the dominant transport mechanisms in different frequency and temperature ranges, proposing the CBH model in the ferroelectric phase and the NSPT model in the paraelectric phase. The temperature dependence of the dielectric study reveals the classic ferroelectric nature of the MATM. As for the frequency dependence, it correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes.

Enhanced Storage Performance of PANI and PANI/Graphene Composites Synthesized in Protic Ionic Liquids.

Polyaniline (PANI) was synthesized using oxidative polymerization in a mixture of water with pyrrolidinium hydrogen sulfate [Pyrr][HSO4], which is a protic ionic liquid PIL. The obtained PANI (PANI/PIL) was compared with conventional PANI (PANI/HCl and PANI/HSO4) in terms of their morphological, structural, and storage properties. The results demonstrate that the addition of this PIL to a polymerization medium leads to a fiber-like morphology, instead of a spherical-like morphology, of PANI/HSO4 or an agglomerated morphology of PANI/HCl. In addition, PAN/PIL exhibits an improvement of the charge transfer kinetic and storage capability in H2SO4 1 mol·L-1, compared to PANI/HCl. The combination of PANI/PIL and graphene oxide (GO), on the other hand, was investigated by optimizing the PANI/GO weight ratio to achieve the nanocomposite material with the best performance. Our results indicate that the PANI/PIL/GO containing 16 wt% of GO material exhibits a high performance and stability (223 F·g-1 at 10 A·g-1 in H2SO4 1 mol·L-1, 4.9 Wh·Kg-1, and 3700 W·Kg-1 @ 10 A·g-1). The obtained results highlight the beneficial role of PIL in building PANI and PANI/GO nanocomposites with excellent performances for supercapacitor applications.

Removal of toxic heavy metals from river water samples using a porous silica surface modified with a new ß-ketoenolic host.

A new hybrid adsorbent material for the efficient removal of heavy metals from natural real water solutions (Moroccan river water samples) was prepared by the immobilization of a new conjugated ß-ketoenol-pyridine-furan ligand onto a silica matrix. The thermodynamical properties including pH, adsorption isotherms, competitive adsorption, selectivity and regeneration were studied to investigate the effect of ketoenol-pyridine-furan-silica (SiNL) on the removal of Zn(II), Pb(II), Cd(II) and Cu(II) from aqueous solutions. An increase in adsorption as a function of pH and fast adsorption was reached within 25 min. The maximum sorption capacities for Zn(II), Pb(II), Cd(II) and Cu(II) were 96.17, 47.07, 48.30 and 32.15 mg·g-1, respectively. Furthermore, the material proved to be very stable - its adsorption capacity remained greater than 98% even after five cycles of adsorption/desorption. Compared to literature results, this material can be considered a high-performing remediation adsorbent for the extraction of Zn(II) from natural real water solution.

Organically modified silica with pyrazole-3-carbaldehyde as a new sorbent for solid-liquid extraction of heavy metals.

A new chelating matrix, SiNP, has been prepared by immobilizing 1.5-dimethyl-1H-pyrazole-3-carbaldehyde on silica gel modified with 3-aminopropyl-trimethoxysilane. This new chelating material was well characterized by elemental analysis, FT-IR spectroscopy, cross polarization magic angle spinning solid state 13C-NMR, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore size, and scanning electron microscopy (SEM). The new product exhibits good chemical and thermal stability as determined by thermogravimetry curves (TGA). The new prepared material was used as an adsorbent for the solid-phase extraction (SPE) of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions using a batch method, prior to their determination by flame atomic adsorption spectrometry. The adsorption capacity was investigated using kinetics and pH effects. Common coexisting ions did not interfere with separation and determination.