Oxidic systems from some organometallic precursors

The oxidation of ethylene glycol with Co(II), Ni(II) and Fe(III) nitrates in dilute acid solutions was investigated. The Co(II)/Fe(III) and Ni(II)/Fe(III) heteropolynuclear coordination compounds, having as ligand the oxidation product of ethylene glycol, were both prepared. Under specific working conditions, the oxidation of ethylene glycol to glyoxylic acid takes place, which is coordinated to Ni(II), Co(II) and Fe(III) cations as glyoxylate anion (C2H2O4 2- ), with simultaneous isolation of the corresponding heteropolynuclear coordination compound in both cases. The semi-empirical (PM7) structural investigations of the monomeric units and the thermal analysis (TG, DTG and DSC) of the heteropolynuclear coordination compounds, which are precursors of mixed oxides, are briefly presented

Long bonds in radical cations of sorbitol and mannitol

The quantum chemical analysis (RM1 semiempirical method) of sorbitol and mannitol in their radical cation states reveals C-C long bonds with lengths around 2.1 or 2.2 Å. In some cases, the stabilities of these long bonds appear to be related with the intensities of the corresponding peaks found in the mass spectra of these hexitols

Water Quality Survey of Streams from Retezat Mountains (Romania)

The Retezat Mountains, located in the Southern Carpathians, are one of the highest massifs in Romania and home of the Retezat National Park, which possesses an important biological value. This study aimed at the investigation of water quality in creeks of the Southern Retezat (Piule-Iorgovanul Mountains) in order to provide information on pollutants of both natural and anthropogenic origin, which could pose a threat for the human health. Heavy metal and other inorganic ion contents of samples were analyzed with on-site and laboratory measurements to estimate water quality. The samples were investigated using microwave plasma - atomic emission spectrometry to quantify specific elements, namely aluminium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead and zinc. The results were compared with the European Union and Romanian standards regarding drinking water and surface water quality. The studied heavy metals have been found to be in very low concentrations or under the method’s detection limit. Thus, in the microbasin corresponding to the sampling points, there seems to be no heavy metal pollution and, from this point of view, the samples comply as drinking water according to the European Union and Romanian recommendations. Our findings confirm that the Retezat Mountains are still among the least contaminated regions in Europe and that the ecosystem and the human health is not negatively influenced by water quality problems

A spectroscopic and semiempirical quantum chemical study of copper (II) phthalocyaninate

Copper(II) phthalocyaninate (CuPc) was studied using both the PM3 and PM7 semiempirical molecular orbital methods, and the results were compared with its XRD, FTIR and Raman experimental properties

Ecological survey of Padiș area, Romania

A couple of stream water samples from the Padiș tourist area (Romania) were analyzed using the chemical methods stipulated in the Romanian Pharmacopoeia in order to establish their content of heavy metals and other ions, both cations and anions. Additionally, the samples were investigated using microwave plasma – atomic emission spectrometry (MPAES) to quantify specific elements, namely aluminium, barium, cobalt, chromium, copper, manganese, molybdenum, nickel, lead, strontium and zinc. The cation levels found were compared with the Romanian and international standards regarding surface and drinking water quality

Non-ambient FTIR study of thermally treated seashells

A large quantity of waste seashells (millions of tons) is discarded annually after mollusc consumption, which becomes a problem for the environment worldwide as these shells are a habitat for microbes which could turn into a public health issue [1]. On the other hand, waste shell biomaterials need a small amount of energy for recycling and processing into useful products for various applications. Calcium carbonate is essential in biomineralization, where it is the primary constituent of mollusc shells, crustacean cuticles, corals etc. In its pure form, it occurs naturally, under normal temperature and pressure conditions, in three anhydrous crystalline forms, namely calcite, aragonite and vaterite [2]. At high pressures, two further forms, namely calcite II and calcite III, are formed. The most stable form of calcium carbonate at atmospheric pressure and room temperature is calcite. The presence of both calcite and aragonite is very frequent in biologically produced calcium carbonate minerals. Though aragonite is metastable in aqueous solution, it can nucleate [3]. Aragonite is found in the nacre of the shells of bivalve molluscs, which provide a protection for these animals [4]. From the study of the marine bivalve species Mercenaria mercenaria and Crassostrea gigas, Weiner et al. [5] have shown that amorphous calcium carbonate is a precursor phase of aragonite. The present study, which is part of our efforts to convert seashells into useful products like hydroxyapatite, investigates the temperature influence on the calcite and aragonite in a processed shell sample by using Fourier-transform infrared spectroscopy (FTIR)

Influence of nucleation centers upon solvothermal growth of silver nano/microcrystals

Silver nano/microcrystals were obtained at medium pressure in a microwave field by using the solvothermal synthesis. In order to evaluate the nucleation centers’ influence upon the formed crystals’ morphology, investigations were conducted using scaffolds to stimulate their heterogeneous nucleation. Therefore, besides the silver and chloride nanocrystals used as nucleation centers, SiOx type spheres were used. The results indicate that the presence of the heterogeneous nucleation centers on the SiOx scaffolds plays a crucial role in the silver nano/microcrystals morphology