Chromium speciation,selective extraction and preconcentration by alumina-functionalised 2-pyridenecarboxyladehyde thiosemicarbazone

A method is proposed and explored for speciation of Cr(III) and Cr(VI), selective extraction and preconcentration in various water samples based on dynamic and static techniques. Three newly designed alumina phases-physically adsorbed-2-pyridenecarboxyladehyde-thiosemicarbazone [Al-2PC-TSC (I–III)] were synthesised and characterised. Stability tests and application of [Al-2PC-TSC (I–III)] as inorganic ion exchangers and chelating solid sorbents for various metal ions were studied and evaluated. The distribution coefficient and separation factors of chromium species versus other interfering metal ions were determined to examine the incorporated selectivity into these alumina phases. Quantitative recovery of Cr(VI) was accomplished by [Al-2PC-TSC (I–III)] at pH = 1.0 while Cr(III) was found to be quantitatively recovered on these sorbents at pH = 7.0 with minimal or no interference between these two species under the studied buffering conditions. Selective solid phase speciation and preconcentration of Cr(III) and Cr(VI) in various real water samples were successfully performed and accomplished via a micro-column, with 200 as a preconcentration factor. Selective speciation of Cr(VI) and Cr(III) via preconcentration from seawater and industrial water samples by alumina phases in pH = 1 was found to give percentage recovery values of Cr(VI) in the range 93.5–97.3 ± 3.0–5.0% and 94.0–97.5 ± 3.0–4.0%, for seawater and industrial water samples, respectively.     

Ab initio study of Ba+Arn (n = 1–4) clusters: spectroscopic constants and vibrational energy levels

This study is interested in the illustration of ab initio potential energy curves for Ba⁺Ar_n (n = 1–4) clusters. The electronic structures of these molecules are calculated using [Ba²⁺] and [Ar] non-empirical core pseudo-potentials complemented by the core polarisation operators for both atoms, which allow the consideration of core valence correlation effects. The structure and stabilities of Ba⁺Ar_n (n = 1–4) clusters are investigated. These molecules are treated as one-electron active system. Spectroscopic constants and vibrational energy levels have been derived from their potentials. The analysis of the geometric forms, basing on the potential energy curves and the spectroscopic constants, clearly shows the importance of rare gas induced dipole. We also show that the dipolar interactions can influence the coupling between atoms.     

Radiation synthesis of porous calcium silicate aerogel derived from polyacrylamide hydrogel as thermal insulator

Journal of Sol-Gel Science and Technology - In this article, the first aerogels synthesis through cross-linked polyacrylamide (PAAm) hydrogel was reported through the use of gamma irradiation...     

Solvothermal synthesis of EDTA-functionalized magnetite-carboxylated graphene oxide nanocomposite as a potential magnetic solid phase extractor of p-phenylenediamine from environmental samples

The use of carboxylated graphene oxide (CGO) in the removal of organic pollutants from aquatic life is a recent and significant issue. In this study, EDTA-functionalized magnetite-carboxylated graphene oxide nanocomposite (EDTA-MCGO) was first used for the adsorptive removal of p-phenylenediamine (PDA) from industrial wastewaters. Based on the great surface area of the magnetic nanocomposite and the huge number of carboxyl groups from CGO and EDTA, multiple interactions to adsorb PDA can be anticipated. The maximum adsorption capacity of EDTA-MCGO was 994.75?mg g^?1 at pH 7.8 and this value was decreased to 94.7% after seven cycles. The adsorption process was spontaneous and fits the pseudo-second-order kinetic model. PDA strongly deposited on the EDTA-MCGO surface via different electrostatic interactions and hydrogen bonding. The PDA removal efficiency from different environmental wastewaters was 98.6?±?0.6%. All the results demonstrate that the EDTA-MCGO nanocomposite is a potential magnetic extractor of aromatic contaminants from aquatic life.GRAPHICAL ABSTRACT     

Single Crystals of Mixed-Cation Copper-Based Perovskite with Trimodal Bandgap Behavior

Two-dimensional (2D) hybrid perovskites with novel functionalities and structural diversity are a perfect platform for emerging optoelectronic devices such as photodetectors, light-emitting diodes, and solar cells. Here, we demonstrate that excess concentration of Cesium bromide (CsBr) is key to the formation of easily exfoliated 2D Cs₂Cu(Cl/Br)₄ perovskite crystal. Furthermore, by employing this trick to 2D perovskite MA₂Cu(Cl/Br)₄ (MA=methylammonium), we achieve a phase-pure easily exfoliated 2D mixed-cation (MA/Cs)₂Cu(Cl/Br)₄ perovskite crystal, which exhibits reduced bandgap (1.53 eV) with ferromagnetic behavior and photovoltaic property. The resultant mixed-cation structured device reveals enhanced efficiency compared to all MA and all Cs counterparts. These findings demonstrate the importance of cation-engineering in developing innovative materials with novel properties.     

Acrylation of pre-irradiated polypropylene and its application for removal of organic pollutants

Reactive extrusion of pre-irradiated polypropylene (PP) at different doses of gamma radiation was studied in the presence of different concentrations of acrylic acid monomer (AAc). Preliminary investigations study the feasibility or removal of organic pollutants. The optical properties and surface morphology of the grafted polypropylene were observed by FT–IR, UV/vis and scanning electron microscopy (SEM). The affinity of this membrane to the basic dye was found to be increased with increase in the dose of gamma irradiation and the ratio of acrylic acid monomer (AAc).     

Biocompatible hydrogel for cartilage repair with adjustable properties

Synthesis of hydrogel at mild conditions is considered one most important challenge, especially if the hydrogel will be used for hosting bioactive materials or drugs. The procedure of hydrogel preparation should have no effect on the properties of the hosted materials. Hyaluronic acid (HA) was modified by adding dialdehyde groups to its structure to facilitate formation of hydrogel at very mild conditions. Dialdehyde HA (DHA) was prepared through oxidation of HA using sodium metaperiodate as oxidizing agent. The prepared DHA was characterized by Fourier‐transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) and aldehyde content. A hydrogel was prepared using different chitosan/DHA molar ratio and fixed amount of glutaraldehyde at 25°C. The prepared hydrogel has tunable properties and pores size depending on the chitosan/DHA molar ratio. Sodium diclofenac was loaded on the hydrogel as a model drug. The hydrogel was characterized by FTIR spectroscopy, swelling rate, gel fraction, drug release profile, and cytotoxicity. The results obtained indicated that the properties of the prepared hydrogel, including gelling time, gel fraction, swelling, pores size, and drug release profile are highly tuned depending on the chitosan/DHA molar ratio. The drug loading efficiency was in the range of 70% to 85%. The cytotoxicity results reveal that the prepared hydrogel has a very low toxicity in presence and absence of sodium diclofenac.     

Synthesis and Antiproliferative Activity of Some Newly Synthesized Pyrazolopyridine Derivatives

Russian Journal of General Chemistry - A series of pyrazolopyridine derivatives is synthesized from emyl-4-amino-6-memyl-1-(mphtha[1,2-d]-[1,3]tmazol-2-yl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylate...     

Synthesis of Novel Bis(pyrido[2,1‐a]isoquinolines) Linked to Aliphatic or Aromatic Core via Ether Linkage

A synthesis of novel bis(pyrido[2,1‐a]isoquinoline‐1,3‐dicarbonitriles) by the multicomponent reaction of 2‐(6,7‐dimethoxy‐3,4‐dihydroisoquinolin‐1‐yl)acetonitrile with the corresponding bis(aldehydes) and malononitrile in the presence of basic catalysts was reported.