-contaminated soils and groundwater. Tech Rep. TE-97-01, GWRTAC, Pittsburgh, Pa, USA, GQRTAC-E series (1997).
. M.I. Kuhlman, T.M. Greenfield, Simplified soil washing processes for a variety of soils, J. Hazard. Mater. 66 (1999) 31-45.
. M. Udovic, D. Lestan, EDTA and HCl leaching of calcareous and acidic soils polluted with potentially toxic metals: remediation efficiency and soil impact, Chemosphere 88 (2012)718–724.
. M.H. Lee, I.S. Paik, W.H. Do, I.S. Kim, Y.S. Lee, S.H. Lee, Soil washing of As-contaminated stream sediments in the vicinity of an
Silvia Zichová, Adriána Brisudová and Svetlana Hrouzková
Single drop microextraction technique uses microamounts of organic solvents. Simplicity, low cost, low environmental impact, compatibility with chromatographic systems as well as its applicability to different matrices are main advantages of single drop microextraction. This technique has become frequently used for the extraction of a broad scope of compounds for numerous analytical applications. This review provides an overview of the existing single drop microextraction modes of realisation and the main scope is devoted to the optimization of parameters influencing the efficiency. The state of the art is discussed on the basis of examples selected from representative application areas. Extraction parameters for toxic organic compounds extraction and microdrop stability were evaluated.
Aurel Tăbăcaru, Mariana Buşilă, Viorica (Ghisman) Pleşcan and Viorica Muşat
In our recent studies, we have investigated the tunability of optical properties of zinc oxide nanoparticles (ZnO NPs) through surface modification with organosilane surfactants. In the present paper, the effect of ZnO NPs modified with variable amount of 3-(trimethoxysilyl)propylmethacrylate (MPS) surfactant was investigated toward the photocatalytic degradation of methylene blue (MB), using two different UV light sources emitting at 254 nm and 365 nm. While the maximum photodegradation efficiency of 63% was reached by ZnO NPs loaded with the highest concentration of MPS upon exposure at 254 nm, in the case of UV exposure at 365 nm an opposite photodegradation trend was observed. Actually, a significant photodegradation efficiency of 95% was recorded by the unmodified ZnO, followed by ZnO NPs modified with 2% MPS for which the photodegradation efficiency amounted to 80%, thus highlighting their best photocatalytic performance.
Habibat Faith Chahul, Gloria Ihuoma Ndukwe and David Ogwu Ogwu
The dissolution of aluminum alloy AA 1060 in 0.5 M and 1.0 M HCl was investigated using thermometric measurements. The reaction number of the aluminum coupons varied linearly with the concentration of the acid. Addition of Napoleonaea imperialis seed extract to the dissolving aluminium coupons lowered the reaction number in both concentrations of HCl by inhibiting the dissolution process. The inhibition efficiency of Napoleonaea imperialis seed extract was enhanced to a considerable extent in the presence of iodide ions with the synergistic parameter S > 1. The adsorption of Napoleonaea imperialis extract on the aluminium surface best aligned with the Langmuir adsorption isotherm model. The values of the free energy, ΔGadsfor the adsorption process revealed the process to be spontaneous and physisorptive.
Field trials of a MgO-Lime-CaCl2-HCl filter has been carried out to test the operation of the filter during actual user conditions. Water quality parameters like pH, TDS, Ca, Mg hardness, total alkalinity, SO4-2, Cl- were found to be within permissible limits in the water obtained from the filter except nitrate, whose concentration was above permissible limits in the raw ground water itself. The dosage of HCl had to be adjusted and fixed in the field trials. In comparison to the laboratory trials conducted earlier it was found that during the field trials there was on an average 6% reduction in the fluoride removal efficiency of the filter. Operational user problems of filter were found and were addressed in the village.
P. Natkański, P. Kuśtrowski, A. Kochanowski, A. Białas, Z. Piwowarska and M. Michalik
Thermal stability and pollutant adsorption efficiency of nanocomposites consisted of clay and polymeric quaternary ammonium salts
Polymer/layered silicate nanocomposites based on polymeric quaternary ammonium salts (ionenes) intercalated into the interlayer galleries of montmorillonite were synthesized. Zeta potential measurements were conducted to determine the amount of ionenes required to neutralize the negative charge of clay. The composition and structure of the obtained nanocomposites were examined by elemental analysis, ATR-FTIR and XRD. High dye sorption capacity was observed for the composite containing ionene 6,2.
Mioara Drobota, Alexandru Trandabat and Marius Pislaru
This paper reports the modification of a polyester film surface in air plasma at room temperature. In order to evaluate the efficiency of the plasma treatment, the modified surface of the PET films was characterized by contact angle and ATR-FTIR spectroscopy.
Habibat F. Chahul, David T. Orhemba and Taiwo A. Gbadamosi
The inhibition of mild steel corrosion in 1.0 M HCl and 0.5 M H2SO4 by Cissus populnea stem extract was investigated using weight loss measurements in the temperature range of 303 – 333 K. Results from the study revealed that Cissus populnea stem extract inhibited the corrosion of mild steel in both acid media. Inhibition efficiency of the stem extract increased with increase in the extract concentration but decreased with immersion time. The kinetics of the reaction aligned with a first order type. Thermodynamics investigations showed that Cissus populnea extract is adsorbed on the steel surface through physical interactions, and the adsorption process was endothermic and spontaneous. Langmuir, Freundlich and Temkin isotherm models best described the adsorption mechanism of the stem extract on the steel surface.
The adsorption and inhibitive behavior of gums obtained from Mangifera indica tree was investigated at 303-333 K using weight loss and linear polarization measurements. The results obtained from both measurements showed that Mangifera indica gums inhibited the corrosion of mild steel in 1.0 M HCl. Linear polarization measurements revealed Mangifera indica gums to inhibit both the anodic and cathodic reactions on the surface of the mild steel thereby functioning as a mixed-type inhibitor. Adsorption behavior of the gums were approximated by the isotherm models of Langmuir, Freundlich and Temkin. The adsorption mechanism derived from the trend in inhibition efficiency as a function of temperature as well as kinetic and activation parameters signified Mangifera indica gums adsorbed on the surface of the mild steel through the mechanism of physisorption and that the adsorption process was exothermic and spontaneous.
Phosphorus removal in wastewater treatment plant is carried out by chemical precipitation, advanced biological treatment or a combination of both. One of the biggest problems with high concentration of phosphorus in water environment is eutrophication. Activated sludge flocs have a heterogeneous structure, which consist of a variety of microorganisms. Filamentous bacteria are normally present in the activated sludge and have ability to assimilation of phosphorus. In this study phosphorus accumulation by isolated filamentous bacteria from activated sludge foam was present.