Synthesis, Modification, and Application of Mesoporous Materials Based on Mcm-41

The purpose of the investigation carried out in this research work was to synthesize mesoporous materials based on MCM-41 with high surface areas, large pore sizes, narrow pore size distributions, and high thermal, hydrothermal, and mechanical stabilities. This was completed by following the same procedures reported for the fabrication of the MCM-41 but with alterations in the surfactants and the additives used, and the reaction conditions employed such as the pH, the temperature, and aging time. Moreover, we aimed to modify these synthesized mesoporous materials with different functional groups of interest and evaluate their abilities in adsorption and separation of transition and heavy metal ions, and radioactive materials from aqueous medium. The functionalization of these mesoporous materials was done using different methods in order to maximize the number of groups on the surface and inside the pores. Different techniques such as infrared (IR), solid-state 29Si and 13C nuclear magnetic resonance (NMR), X-ray powder diffraction (XRD), thermal gravimetric analyses (TGA), and scanning and transmission electron microscopes (SEM and TEM) were used to confirm the production of the desired products. The surface area, pore size and pore size distribution were determined using the surface area analysis (BET) method. The surface properties (e.g., number of groups on the surface) of these materials were determined by the adsorption of a proper probing molecule. The adsorption and separation abilities of these modified materials for the transition and heavy metal ions, and radioactive materials in aqueous solution were performed in the pH range from 2 to 8 at room temperature. The equilibrium concentration of the metal ions were determined using lead analysis test kit for the lead and using ultraviolet-visible (UV-Vis), inductive couple plasma (ICP), and atomic absorption spectroscopy (AAS) for the rest of materials.Findings and Conclusions: The synthesized mesoporous materials possess high surface areas, large pore sizes, narrow pore size distributions, and high thermal, hydrothermal, and mechanical stabilities. The modified mesoporous materials were found to have high selectivity and capacity in the adsorption and separation of the transition and heavy metal ions in the aqueous solution. In addition, they showed great selectivity and capacity for the adsorption and separation of the radioactive materials in aqueous medium.Chemistry Departmen

catena-Poly[diquinolinium [[diaqua­cobaltate(II)]-μ-cyclo­tetra­phosphato] hexa­hydrate]

The cyclo­tetra­phosphate anion, [P4O12]4−, forms the title complex with cobalt(II) and quinolinium, {(C9H8N)2[Co(P4O12)(H2O)2]·6H2O}n. In the complex anion, the CoII ion, lying on an inversion center, is surrounded by four phosphate O atoms and two water mol­ecules in a slightly distorted octa­hedral geometry. The crystal structure consists of anionic ribbons of formula {[Co(P4O12)(H2O)2]2−}n extending along [100]. A network of O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds consolidates the crystal packing

Tris(1,10-phenanthroline)cobalt(II) bis­(perrhenate) monohydrate

In the title compound, [Co(C12H8N2)3][ReO4]2·H2O, the CoII atom is coordinated by three 1,10-phenanthroline ligands in a distorted octa­hedral arrangement. In the crystal, the components are linked by O—H⋯O, C—H⋯O and aromatic π–π stacking [shortest centroid–centroid separation = 3.659 (5) Å] inter­actions

2-Amino-3-nitro­pyridinium perrhenate

In the title mol­ecular salt, (C5H6N3O2)[ReO4], the cations and tetrahedral anions are linked by trifurcated N—H⋯(O,O,O) and bifurcated N—H⋯(O,O) hydrogen bonds, as well as weak C—H⋯O inter­actions. This results in alternating corrugated inorganic and organic layers in the crystal

A Facile and Convenient Synthesis of some Novel Hydrazones, Schiff’s Base and Pyrazoles Incorporating Thieno[2,3-b]thiophenes

A facile and convenient synthesis of some novel hydrazones, schiff’s base and pyrazoles from thieno[2,3-b]thiophene derivatives 1 have been achieved in high yields assisted by microwave and classical methods. The structures of all the title compounds have been elucidated by elemental analysis, IR, MS, 1H-NMR and 13C-NMR. Generally, these findings represent a new class of sulfur and nitrogen moieties that should also be of interest as new materials

Scope of partial least-squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles

Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst need to measure the chiral purity, i.e., when one of the enantiomers is present in the sample in very low concentrations. In this report, we explore the scope of a multivariate chemometric technique based on unfolded partial least-squares regression, as a mathematical tool to solve this quite frequent difficulty. This technique was applied to obtain quantitative results from partially overlapped chromatographic profiles of R- and S-ketoprofen, with different values of enantioresolution factors (from 0.81 down to less than 0.2 resolution units), and also at several different S:R enantiomeric ratios. Enantiomeric purity below 1% was determined with excellent precision even from almost completely overlapped signals. All these assays were tested on the most demanding condition, i.e., when the minor peak elutes immediately after the main peak. The results were validated using univariate calibration of completely resolved profiles and the method applied to the determination of enantiomeric purity of commercial pharmaceuticals.Fil: Padro, Juan Manuel. Universidad Nacional de la Plata. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Osorio Grisales, Jaiver. Universidad Nacional de la Plata. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arancibia, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Olivieri, Alejandro Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de la Plata. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Cyclohexylammonium nitrate

In the title salt, C6H14N+.NO3_, the cyclohexyl ring adopts a chair conformation. The ammonium group occupies an equatorial position and the crystal struture is stabilized by intermolecular N—H� � �O hydrogen-bonding interactions, resulting in a three-dimensional network

Method for the fast determination of bromate, nitrate and nitrite by ultra performance liquid chromatography–mass spectrometry and their monitoring in Saudi Arabian drinking water with chemometric data treatment

A rapid, sensitive and precise method for the determination of bromate (BrO3(-)), nitrate (NO3(-)) and nitrite (NO2(-)) in drinking water was developed with Ultra performance Liquid Chromatography-Mass Spectrometry (UPLC-ESI/MS). The elution of BrO3(-), NO3(-) and NO2(-) was attained in less than two minutes in a reverse phase column. Quality parameters of the method were established; run-to-run and day-to-day precisions were <3% when analysing standards at 10µgL(-1). The limit of detection was 0.04µg NO2(-)L(-1) and 0.03µgL(-1) for both NO3(-)and BrO3(-). The developed UPLC-ESI/MS method was used to quantify these anions in metropolitan water from Saudi Arabia (Jeddah, Dammam and Riyadh areas) and commercial bottled water (from well or unknown source) after mere filtration steps. The quantified levels of NO3(-) were not found to pose a risk. In contrast, BrO3(-) was found above the maximum contaminant level established by the US Environmental Protection Agency in 25% and 33% of the bottled and metropolitan waters, respectively. NO2(-) was found at higher concentrations than the aforementioned limits in 70% and 92% of the bottled and metropolitan water samples, respectively. Therefore, remediation measures or improvements in the disinfection treatments are required. The concentrations of BrO3(-), NO3(-) and NO2(-) were mapped with Principal Component analysis (PCA), which differentiated metropolitan water from bottled water through the concentrations of BrO3(-) and NO3(-) mainly. Furthermore, it was possible to discriminate between well water; blend of well water and desalinated water; and desalinated water. The point or source (region) was found to not be distinctive

Lead Contamination in Selected Foods from Riyadh City Market and Estimation of the Daily Intake

This study was carried out to determine lead contamination in 104 of the representative food items in the Saudi diet and to estimate the dietary lead intake of Saudi Arabians. Three samples of each selected food items were purchased from the local markets of Riyadh city, the capital of Saudi Arabia. Each pooled sample was analyzed in triplicate by ICP-AES after thorough homogenization. Sweets (0.011–0.199 μg/g), vegetables (0.002–0.195 μg/g), legumes (0.014–0.094 μg/g), eggs (0.079 μg/g), meat and meat products (0.013–0.068 μg/g) were the richest sources of lead. Considering the amounts of each food consumed, the major food sources of lead intake for Saudi can be arranged as follows: vegetables (25.4%), cereal and cereal products (24.2%), beverages (9.7%) sweets (8.2%), legumes (7.4%), fruits (5.4%) milk and milk products (5.1%). The daily intake of lead was calculated taking into account the concentration of this element in the edible part of the daily consumption data which were derived from two sources, (a) the KSA food sheet provided by the Food and Agriculture Organization (FAO) and (b) from questionnaires distributed among 300 families in Riyadh city. The results showed that the daily intakes of lead according to the two sources are 22.7 and 24.5 μg/person/day respectively, which are lower than that mentioned by The Joint Expert Committee on Food Additives (JECFA), whereas it is comprabale with that of other countries