Cecilia Roman

A novel analytical system with a capacitively coupled plasma microtorch and a gold filament microcollector for the determination of total Hg in water by cold vapour atomic emission spectrometry

A novel, miniaturized analytical system of high sensitivity and precision based on atomic emission in a capacitively coupled plasma microtorch (13.56 MHz, 20 W, 200 mL min−1 Ar) equipped with a gold filament microcollector and a microspectrometer was investigated for total Hg determination in water. The method is based on cold vapour generation using SnCl2 and preconcentration on the microcollector followed by thermal desorption for 5 s and emission measurement at 253.652 nm. The microcollector consists of a gold filament of 80 μm diameter, 24 cm length and 43 turns encapsulated in a quartz capillary of 2.5 mm i.d., 4 mm o.d. supplied at 1.5 A. Due to very low thermal inertia, the fast, direct heating of the filament provides a high flow rate of Hg vapour toward plasma and hence sensitivity of the analytical system in the sub-ng L−1 Hg range. The optimal working conditions and figures of merit of the system are presented for Hg determination in drinking and river water, leachate of polyethylene terephthalate bottles and food packaging of biodegradable materials. At concentrations in the range of 0.06–57.4 ng L−1 the precision was 0.9–7.0%. The detection limit in solution was 0.02 ng L−1, while the absolute value was 0.5 pg. Validation of the system was carried out by analyzing a certified groundwater (ERM-CA615) that gave a recovery of 101 ± 2% for the certified concentration of 37.0 ± 0.4 ng L−1. The novel system can be prototyped as a substitute for existing systems based on atomic fluorescence or absorption.

Characterisation of soil quality and mobility of Cd, Cu, Pb and Zn in the Baia Mare area Northwest Romania following the historical pollution

The paper presents a characterisation of the soil quality and mobility of Cd, Cu, Pb and Zn in the Baia Mare city, northwest Romania, historically polluted with airborne particulate matter resulted from non-ferrous ores processing. Although the impact of the ores smelters on the environment is relatively limited today, Baia Mare is still a highly polluted site with Cd, Pb, Cu and Zn. The concentration ranges of metals in soil were (mg kg−1): 1.9-25.4 Cd, 87.7-9880 Pb, 78.3-962 Cu, 109-11500 Zn, of which in (%): 1.3-80; 2.2-40; 2.0-34 and 0.3-21 as mobile species in 0.005 mol L−1 diethylenetriaminepentaacetic acid (DTPA). Baia Mare is more polluted with Cu, Pb and Zn than Copsa Mica and Cu, Pb than Zlatna, other smelter centres in Romania. Also, pollution is higher compared to similar centres in Europe. Cd, Pb and Cu are the most severe contaminants as available species for plants and should be considered in the soil remediation strategy. The PCA on metal contents following aqua regia mineralisation and DTPA extraction allowed the identification of anthropogenic origin from three sources associated with the Flotation Station (residual species), Cuprom plant (Cu, Cd and Zn mobile species) and Romplumb plant (Pb mobile species). The car traffic as anthropogenic source does not modify the pollution pattern caused by industrial activity since no association between Pb and Zn was found. On the other hand, an affinity between Cd and Zn as well as between Cu and Pb were also identified. A particular case is that of Cu, for which the PCA revealed an interference of polluters. Statistics are in agreement with the distribution maps of contaminants.

Mercury in soil and perennial plants in a mining-affected urban area from Northwestern Romania.

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.

The Autohydrolysis of Albies Alba Wood Using Adaptive Neural Fuzzy Interference System Mathematical Modeling

In this work, autohydrolysis pretreatment of Albies alba wood was conducted to obtain a liquid fraction, which contains hemicellulosic fraction recovered as sugars and byproducts, and a solid phase, which contains cellulose and lignin. The influence of temperature (180°C, 190°C, and 200°C) and pretreatment time (5, 10, and 15 minutes) on the compounds resulting in liquid and in solid fractions were studied. The software ANFIS Edit Matlab 7.0 was used to develop a fuzzy neural model that reproduces the experimental results of the dependent variables with errors less than 10%. The optimum of solubilized components in liquid fraction has been obtained at 190°C and 10 minutes pretreatment time. The proposed ANFIS model and the neuro-fuzzy modeling demonstrate performance of prediction on the autohydrolysis of wood process.

Optimized Removal of Methylene Blue from Aqueous Solution using a Commercial Natural Activated Plant-Based Carbon and Taguchi Experimental Design

ABSTRACT This study presents the results obtained for methylene blue removal on a commercial natural activated plant-based carbon using a simple and fast method. The optimum adsorption conditions were 200 mg/L initial methylene blue concentration, pH 1 in the initial solution, 0.5 g quantity of commercial natural activated plant-based carbon, 300 min contact time, <0.5 mm particle size of commercial natural activated plant-based carbon, and 75 rpm stirring rate. Analysis of variance indicated that the most significant parameter for methylene blue removal was the quantity of commercial natural activated plant-based carbon. Also, the results showed that the quantity of commercial natural activated plant-based carbon was the most significant parameter for methylene blue removal (24% contribution), while contact time was the least significant parameter (6% contribution). Langmuir and Freundlich isotherms suggested a favorable adsorption of methylene blue by commercial natural activated plant-based carbon, while the Dubinin–Radushkevich isotherm indicated a chemisorption process involved in methylene blue removal.