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Sima M.,Romanian Academy of Sciences | Dold B.,University of Lausanne | Frei L.,Ecole Polytechnique Federale de Lausanne | Senila M.,Research Institute for Analytical Instrumentation | And 2 more authors.
Journal of Hazardous Materials | Year: 2011

Sulfidic mine tailings have to be classified as one of the major source of hazardous materials leading to water contamination. This study highlights the processes leading to sulfide oxidation and acid mine drainage (AMD) formation in the active stage of two tailings impoundments located in the southern part of the Apuseni Mountains, in Romania, a well-known region for its long-term gold-silver and metal mining activity. Sampling was undertaken when both impoundments were still in operation in order to assess their actual stage of oxidation and long-term behavior in terms of the potential for acid mine drainage generation. Both tailings have high potential for AMD formation (2.5 and 3.7wt.% of pyrite equivalent, respectively) with lesser amount of carbonates (5.6 and 3.6wt.% of calcite equivalent) as neutralization potential (ABA=-55.6 and -85.1tCaCO3/1000t) and showed clear signs of sulfide oxidation yet during operation. Sequential extraction results indicate a stronger enrichment and mobility of elements in the oxidized tailings: Fe as Fe(III) oxy-hydroxides and oxides (transformation from sulfide minerals, leaching in oxidation zone), Ca mainly in water soluble and exchangeable form where gypsum and calcite are dissolved and higher mobility of Cu for Ribita and Pb for Mialu. Two processes leading to the formation of mine drainage at this stage could be highlighted (1) a neutral Fe(II) plume forming in the impoundment with ferrihydrite precipitation at its outcrop and (2) acid mine drainage seeping in the unsaturated zone of the active dam, leading to the formation of schwertmannite at its outcrop. © 2011 Elsevier B.V.

Senila M.,Research Institute for Analytical Instrumentation | Levei E.A.,Research Institute for Analytical Instrumentation | Senila L.R.,Research Institute for Analytical Instrumentation | Oprea G.M.,Technical University of Cluj Napoca | Roman C.M.,Research Institute for Analytical Instrumentation
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2012

The mercury (Hg) concentrations were evaluated in soils and perennial plants sampled in four districts of Baia Mare city, a historical mining and ore processing center in Northwestern Romania. The results showed that the Hg concentration exceeded the guideline value of 1.0 mg kg-1 dry weight (dw) established by the Romanian Legislation, in 24% of the analyzed soil samples, while the median Hg concentration (0.70 mg kg-1 dw) was lower than the guideline value. However, Hg content in soil was generally higher than typical values in soils from residential and agricultural areas of the cities all over the world. The median Hg concentration was 0.22 mg kg -1 dw in the perennial plants, and exceeded the maximum level of Hg (0.10 mg kg-1) established by European Directive 2002/32/EC for plants used in animal feed in order to prevent its transfer and further accumulation in the higher levels of food chain. No significant correlations were found between soil Hg and other analyzed metals (Cd, Cu, Pb, Zn) resulted from the non-ferrous smelting activities, probably due to the different physicochemical properties, that led to different dispersion patterns. Copyright © Taylor & Francis Group, LLC.

Talos F.,Babes - Bolyai University | Senila M.,Research Institute for Analytical Instrumentation | Frentiu T.,Babes - Bolyai University | Simon S.,Babes - Bolyai University
Corrosion Science | Year: 2013

The dissolution and surface layer changes of new xTiO2(100-x)[4SiO2·CaO·0.3P2O5] sol-gel derived xerogels (0≤x≤20mol%) have been investigated in Kokubo's simulated body fluid (SBF). The ionic leaching rate was analysed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). ICP-AES results showed a relatively fast dissolution of titanium free sample, with a high release of phosphorous and calcium ions in the first hour of incubation while the release of silicon ions continuously increased up to 6h of immersion. The titanium dioxide addition up to 20mol% differently influences the release of phosphorus, calcium and silicon ions, i.e. TiO2 strongly stabilises the phosphorus ions, to a lesser extent the calcium ions, and has almost no effect on the silicon ions release. The structural changes were evaluated using X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The XRD results show that all samples remain mainly amorphous after immersion in SBF. The changes occurred in the surrounding of phosphorous and silicon ions are well reflected in FTIR spectra and they were correlated with the samples stability in SBF. © 2013 Elsevier Ltd.

Dan M.,Romanian Institute of Isotopic And Molecular Technology | Senila L.,Research Institute for Analytical Instrumentation | Roman M.,Research Institute for Analytical Instrumentation | Mihet M.,Romanian Institute of Isotopic And Molecular Technology | Lazar M.D.,Romanian Institute of Isotopic And Molecular Technology
Renewable Energy | Year: 2015

Fir wood wastes were used to produce crude bio-ethanol by two methods: simultaneous saccharification and fermentation (SSF) and acid hydrolysis followed by the fermentation of the acid hydrolyzate. The main components of crude bio-ethanol are ethanol and acetic acid. In addition, low concentrations of a wide range of alcohols, acids, esters, ethers and aldehydes are also present. Ethanol concentration is higher in the SSF process than in the acid hydrolysis: 43.69g/L compared to 37.53g/L, respectively. Opposite to ethanol concentration, the acetic acid concentration is higher in the acid hydrolysis process: 16.36g/L compared to 10.24g/L, respectively. The crude bio-ethanol was used to produce hydrogen by catalytic steam reforming. The tested catalysts were the common Ni/Al2O3 and two rare earth oxides promoted Ni catalysts: Ni/La2O3-Al2O3 and Ni/CeO2-Al2O3 prepared by successive wet impregnation. The characterization techniques revealed that the addition of rare earth oxides improves the Ni dispersion and the reducibility of the promoted catalysts. The best feed rate which assures the optimal ratio between conversion and catalyst deactivation is 0.8mL/min bio-ethanol. The addition of extra oxide (La2O3 and CeO2) to the support improves the ethanol conversion especially at 250°C, but no significant effect on the acetic acid conversion was observed. At 250°C the ethanol conversion is almost 90% for Ni/La2O3-Al2O3 and Ni/CeO2-Al2O3, but the acetic acid conversion is below 30% for all catalysts. At 350°C both ethanol and acetic acid present maximum conversion. At this temperature the best hydrogen production is obtained for Ni/La2O3-Al2O3 due to better ethanol conversion and better selectivity for hydrogen formation. At 350°C the promoted catalysts are stable for 4h time on stream, different degrees of deactivation being obtained at lower temperatures. © 2014 Elsevier Ltd.

Senila M.,Research Institute for Analytical Instrumentation | Levei E.A.,Research Institute for Analytical Instrumentation | Senila L.R.,Research Institute for Analytical Instrumentation
Chemistry Central Journal | Year: 2012

Background: The metals bioavailability in soils is commonly assessed by chemical extractions; however a generally accepted method is not yet established. In this study, the effectiveness of Diffusive Gradients in Thin-films (DGT) technique and single extractions in the assessment of metals bioaccumulation in vegetables, and the influence of soil parameters on phytoavailability were evaluated using multivariate statistics. Soil and plants grown in vegetable gardens from mining-affected rural areas, NW Romania, were collected and analysed.Results: Pseudo-total metal content of Cu, Zn and Cd in soil ranged between 17.3-146 mg kg-1, 141-833 mg kg-1 and 0.15-2.05 mg kg-1, respectively, showing enriched contents of these elements. High degrees of metals extractability in 1M HCl and even in 1M NH4Cl were observed. Despite the relatively high total metal concentrations in soil, those found in vegetables were comparable to values typically reported for agricultural crops, probably due to the low concentrations of metals in soil solution (Csoln) and low effective concentrations (CE), assessed by DGT technique. Among the analysed vegetables, the highest metal concentrations were found in carrots roots. By applying multivariate statistics, it was found that CE, Csoln and extraction in 1M NH4Cl, were better predictors for metals bioavailability than the acid extractions applied in this study. Copper transfer to vegetables was strongly influenced by soil organic carbon (OC) and cation exchange capacity (CEC), while pH had a higher influence on Cd transfer from soil to plants.Conclusions: The results showed that DGT can be used for general evaluation of the risks associated to soil contamination with Cu, Zn and Cd in field conditions. Although quantitative information on metals transfer from soil to vegetables was not observed. © 2012 Senila et al.; licensee Chemistry Central Ltd.

Senila M.,Research Institute for Analytical Instrumentation
Journal of Environmental Health Science and Engineering | Year: 2014

Background Lead (Pb) is a toxic element that occurs in elevated concentrations in soils, mostly as a result of anthropogenic activities. This study assess the Pb bioavailability in soils from two areas with different contamination level using Diffusive Gradients in Thin-Films (DGT) technique, single extractions and metal contents of vegetables grown on contaminated soils. Results In the area situated far from mining and smelting activities, the pseudo total Pb concentration (12 - 51 mg kg-1 dw) was found to be comparable to that normally found in unpolluted areas. In the area from the vicinity of the Pb smelter very high concentrations of pseudo-total Pb (850 - 9300 mg kg-1 dw) were found. The average concentrations of Pb accumulated in onion, garlic, carrot, and parsley grown on this contaminated soils were 18, 48, 38 and 91 mg kg-1 dw, respectively, and represent a risk factor for the consumers. Conclusions The present study demonstrates the utility of DGT technique for the assessment of Pb bioavailability, since, generally, better correlations are obtained between the effective Pb concentration and Pb concentration in vegetables than for bioavailable Pb determined by chemical extractions and Pb concentration in vegetables.

Cadar O.,Research Institute for Analytical Instrumentation | Paul M.,Research Institute for Analytical Instrumentation | Roman C.,Research Institute for Analytical Instrumentation | Miclean M.,Research Institute for Analytical Instrumentation | Majdik C.,Babes - Bolyai University
Polymer Degradation and Stability | Year: 2012

(Lactic acid, ethylene glycol, malonic or succinic acid) copolymers [(LA-EG-MA) and (LA-EG-SA) copolymers] were synthesized with different monomer feed ratios by direct polycondensation. The copolymers were characterized in terms of various properties such as acid value and number average molecular weight. The aerobic biodegradation under controlled composting conditions of commercially available and laboratory synthesized poly(l-lactic acid) (PLA) and synthesized copolymers was carried out according to ISO 14855-1:2005. The biodegradability of tested materials was found to be strongly dependent on the lactic acid content, ranging from 94% (method A) and 104% (method B) to 43% (method A) and 46% (method B) over the 110-days of the 50°C composting. © 2011 Elsevier Ltd. All rights reserved.

Senila M.,Research Institute for Analytical Instrumentation | Tanaselia C.,Research Institute for Analytical Instrumentation | Rimba E.,Babes - Bolyai University
Carpathian Journal of Earth and Environmental Sciences | Year: 2013

The aim of this study was to investigate the effects of Dryopteris filix-mas L., one of the indigenous fern species from Romania, and of a known As-hyperaccumulator, Peris cretica L., on As bioavailability at the roots-soil interface. The ferns were grown in pot experiments on two composite soils collected from two localities from north-western Romania, containing 108 mg kg-1 dw and respectively 230 mg kg-1 dw total As. The Diffusive Gradient in Thin-films (DGT) technique was used to study the root-available As in soils, by measuring DGT-labile As fraction before and after plants grown. The R ratios between labile As concentration measured by DGT and As in soil solution were calculated and two different behaviors were observed for the two ferns: in rizosphere of Pteris cretica L., R increased after plants grown, which indicate a greater proportion of As in labile form, probably due to the As solubilisation by fern roots, while contrary, in the rizosphere of Dryopteris filix-mas L. this ratio decreased. Also, was observed that higher organic carbon (in its dissolved form) and phosphorous in soil enhanced As biovailability. Pteris cretica L. accumulated higher concentrations of As in the aboveground part, the translocation factor being about 7.5, but for Dryopteris filix-mas L. this factor was <1, thus this cannot be considered As-hyperaccumulator. This study has also confirmed that DGT technique is a sensitive tool for the evaluation of As mobility changes in the rizosphere of plants.

Ardelean I.,Babes - Bolyai University | Lupsor S.,Babes - Bolyai University | Rusu D.,Research Institute for Analytical Instrumentation
Physica B: Condensed Matter | Year: 2010

xMnO·(100-x)[As2O3·TeO2] glass system, with 0≤x≤50 mol %, was prepared and investigated by FT-IR and Raman spectroscopies in order to determine its structure and the changes induced by the increasing of MnO content. The results offered by FT-IR and Raman spectroscopies suggest a structure formed by AsO3, TeO4 tbp and TeO3 tp units. The presence of MnO2 units was confirmed by FT-IR spectra only for high concentration of MnO. © 2010 Elsevier B.V. All rights reserved.

Torok Z.,Babes - Bolyai University | Ozunu A.,Babes - Bolyai University | Cordos E.,Research Institute for Analytical Instrumentation
Environmental Engineering and Management Journal | Year: 2011

Technological accidents caused the loss of many human lives, the major pollution of the environment and significant financial losses. These accidents can be categorized in three major classes: fires, explosions and toxic releases. The prevention of technological accidents can be made in two ways, on one hand with technological improvements, on the other hand with legislative regulations. According to EU legislation Land-Use Planning is necessary and essential study for Seveso-type sites. Four years after the adhesion of Romania to the EU there is still missing a common risk analysis methodology which could be used for Land-Use Planning purpose. This paper (part one) opens a series of three papers proposing a risk assessment methodology and guidance limits for the estimation of physical effects of fires (in part one), and calculation of safety distances for Land-Use Planning for Seveso-type sites. With this purpose, different case studies were considered with technological accidents involving flammable hazardous materials. In this first part heat radiations from different types of fires were studied and physical effects and safety distances were calculated. Several methodologies applied in the EU member states were approached, while the proposed methodology is based on the results of this research.

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