The present study deals with the problem of soil contamination risk assessment for a region being
actively impact by the routine production of Kremikovtzi metallurgical plant near Sofia, Bulgaria.
Although the production is now cancelled, the soil pollution is present and needs careful
assessment. The application of self-organizing maps classification strategy of Kohonen makes it
possible to identify: a/ pollution sources in the region of interest; b/ spatial patterns of similarity of
polluted sites and the reason for the specific pollution.
Artificial neural networks (ANNs) are being used increasingly to predict water variables. This study
offers an alternative approach to quantify the relationship between time of chlorination in potable
water (due to convectional treatment procedure) and chlorination by-products concentration
(expressed as carbon and bromine) with an ANN model, i.e., capturing non-linear relationships
among the water quality variables.
Thus, carbon and bromine concentrations in potable water (the second chosen due to the toxicity of
brominated trihalomethanes, THMs) were predicted using artificial neural networks (ANNs) based
mainly on multi-layer perceptrons (MLPs) architecture. The chlorination (detention) time as much as
58 hours in Athens distributed network, comprised the input variables to the ANNs models.
Moreover, to develop an ANN model for estimating carbon and bromine, the available data set was
partitioned into training, validation and test set. In order to reach an optimum amount of hidden
layers or nodes, different architectures were tested. The quality of the ANN simulations was
evaluated in terms of the error in the validation sample set for the proper interpretation of the results.
The calculated sum-squared errors for training, validation and test set were 0.056, 0.039 and 0.060
respectively for the best model selected.
Comparison of the results showed that a two-layer feed-forward back propagation ANN model could
be used as an acceptable model for predicting carbon and bromine contained in potable water
In this article, the technical feasibility of various commercial adsorbents (activated carbon,
clinoptilolite, and their mixture) for removal of Cr(total) ions from waste printing developer has been
represent. Experimental tests were performed in laboratory batch mode. The adsorption data were
analyzed using the Freundlich, Langmuir and Dubinin-Kaganer-Radushkevich (DKR) isotherm
models. It was found that the Freundlich isotherm gave better results than the Langmiur and DKR
models, with the corresponding correlation coefficients (R2): 0.981, 0.996 and 0.997 for mixture
(NZ+AC), AC and NZ, respectively. The adsorption capacities of Cr(total) ions followed the order:
(NZ+AC)>AC>NZ. The adsorption efficiencies of Cr(total) ions removal were 38.5 to 39.9%. Due to
easy availability and good efficiency, the mixture of clinoptilolite and activated carbon is an ideal
adsorbents for removal of Cr(total) ions from waste printing developer.
Water hyacinth Eichhornia crassipes was found to have biosorption capacity for cationic dyes,
malachite green and methylene blue from aqueous solutions. To evaluate the biosorption capacity
and characteristics, the effect of solution pH, initial dye concentration, temperature, dose of
biosorbent loading, contact time and shaking rate were investigated in a batch mode. Biosorption
was increased with the increasing temperature for both studied dyes. The Langmuir and Freundlich
adsorption models were used for mathematical description of the sorption equilibrium. Equilibrium
data was fitted well to the Langmuir model in the studied concentrations (1-200 mg L-1) at 293 and
313 K. Based on the Langmuir isotherm plots the maximum biosorption capacity values were
calculated to be 44.64 mg g-1 for malachite green and 42.55 mg g-1 for methylene blue at 313 K.
Various thermodynamic parameters such as ΔGo, ΔHo, and ΔSo were evaluated with results
indicating that this system was an endothermic spontaneous reaction and kinetically suited to
Various pollutants (e.g. boron and hexavalent chromium) are introduced into the aquatic
environment from a variety of industrial operations causing damages to environment and
affecting human health. Boron in irrigation water is of particular interest because it can have
beneficial or toxic effect on plants, depending on its concentration. Pollution of the environment
with hexavalent chromium (Cr(VI)) and associated toxicity to microorganisms, plants, animals
and humans is of major concern. Indeed, chromium in environmentally significant
concentrations is found near to tanneries and involves large volumes of wastewater. One of the
most effective remediation technologies used for the removal of B(III) and Cr(VI) from aquatic
systems and wastewater is their sorption on metal oxide surfaces. However, in order to
understand better the mechanisms involved and improve the efficiency of remediation
technologies further fundamental studies are needed. The present study is focused on the
adsorption of H3BO3 and CrO42- onto Fe(O)OH at various ionic strengths (I = 0.0, 0.1 and 1.0 M
NaClO4), under normal atmospheric conditions, at 22 ± 3 oC and pH 8. Additionally,
competitions studies were carried out to investigate the ion-exchange mechanism and compare
the individual affinities of H3BO3 and CrO42- for Fe(O)OH. The concentration of H3BO3 and
CrO42- in solution was determined spectrophotometrically by means of azomethine-H and DPC
(1,5-diphenylcarbazide), respectively. The results obtained indicate that the release of Cr(VI)
and therefore its concentration in solution increases as the amount of B(III) is increased in the
sorption system. This phenomenon is due to the replacement of Cr(VI) ions by ions B(III) on the
surface of Fe(O)OH. Evaluation of the experimental data results in a value for the competition
constant which is equal logK= -3.5 ± 0.2, indicating that the adsorbent surface has greater
affinity for Cr(VI) than for B(III) species. The formation constant for the Cr(VI)-Fe(O)OH surface
complex is calculated to be logßCr= 7.9 ± 0.2.
The procedure for the reliable determination of Be in natural waters by ETAAS was elaborated.
Various modifiers (EDTA, Ca(NO3)2, Mg(NO3)2, Pd(NO3)2 and the mixture of Pd(NO3)2 and
Mg(NO3)2) for the determination of beryllium was examined. The applicability of the selected
Mg(NO3)2 as the appropriate and generally used modifier for the determination of Be in the different
types of natural waters by ETAAS has been confirmed. The accuracy of the method was verified by
analyzing of the certified reference material of drinking water ("Trace Metals in Drinking Water"). The
real drinking waters and waste waters with the reference values of Be concentration, spiked tap
water, mineral waters and model river water were utilized for the determination of Be. Using
Mg(NO3)2 for modification, the detection limit of 0.07 μg L-1, the quantification limit of 0.22 μg L-1 and
characteristic mass of 3.7 pg of Be were obtained. The recovery was in the range 95–111% and (%)
RSD value was less than 8%.
This work is first report showed that supported TiO2 NPs on alumina could act catalytic activity on
peroxyoxalate chemiluminescence system. In this work the catalytic effect of supported Titanium
dioxide nanoparticles (TiO2 NPs) on the trichloroperoxy oxalate – hydrogen peroxide (PO-CL)
reaction is investigated. Supported TiO2 nanoparticles exhibited the better CL catalysis activity than
SnO and Carbon nanotubes. Supported TiO2 nanoparticles catalyze the chemiluminescence
reaction between TCPO (bis-(2,4,6-trichlorophenyl) oxalate) and H2O2 and produce a strong CL
signal in the presence of triazinyl dye derivative as fluorophore. The CL signal intensity was linear
with the hydrogen peroxide concentration in the range of 5 to 1000 nmol ml-1 with a detection limit of
1.2 nmol ml-1 and regression coefficient was 0.992 (n=4). The relative standard deviations for
measurement of 300 and 500 nmol ml-1 hydrogen peroxide were 2.2 and 3.4%, respectively(n=4).
Hydrogen peroxide concentration in river water was 8.7 nmol ml-1 with RSD=5.4%(n=3).
Chelating resins based on immobilised oxines are attractive solid-phase extraction (SPE) materials
in the analysis of trace metals from environmental samples. The most common immobilisation
procedure for bonding oxines to silica supports is time-consuming and incompatible with “green
chemistry” regulations. In this work, a rapid, environmentally friendly chemical transformation to
attach oxines (i.e. 8-hydroxyquinoline) to silica surfaces is reported. The chelating resin produced by
the procedure described here maintains the chemical configuration (including the spacer arm
separating the reactive groups from the matrix) and is identical to that obtained with the traditional
method. The resin showed satisfactory capacity exchange and excellent performance as a SPE
material for on-line sample preparation (preconcentration and matrix elimination) of some transition
metals before their determination by ICP-OES. The applicability of this SPE material was tested by
analysing Cu, Co, Zn, Ni and Pb in the range of 50-300 ng ml-1 from a synthetic matrix simulating
sediment. The recovery values ranged from 100% for Zn to 70% for Ni. The system was used with
optimised parameters to analyse these ions in different sediment reference materials. The results
showed good agreement with certified values.
Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures of polychlorinated
n-alkanes with carbon-chain lengths from C10-C13 and chlorine content between 49 and 70%. They
are produced by chlorination of n-alkanes and do not occur naturally. Because of their physical
properties (viscosity, flame resistance) they are used in many different applications, such as
lubricant additives, PVC plasticizers and flame retardants in paints, adhesives and sealants. Among
the chlorinated paraffin mixtures, SCCPs have the highest potential for release into the environment,
because of their higher vapour pressure and water solubility (about 10-100 times higher than for
SCCPs can reach the environment through production, storage or use, as well as through leeching,
runoff and volatilization from contaminated areas. Despite the fact that they are one of the most
challenging groups of compounds to quantify and analyze, SCCPs have been detected in biota and
humans, as well as a variety of environmental matrices such as sediments and air. SCCPs have
also been detected in remote places such as the Arctic (Reth et al., 2006) and dated sediment
cores, suggesting long-range atmospheric transport and persistence in the environment. SCCPs
have been found to be toxic to aquatic and soil organisms, fish and there is some evidence of
carcinogenicity. This paper reviews the current state of knowledge and highlights the need for further
research in order to improve future monitoring efforts.
Nowadays, the scientific community has focused and prioritised research on “emerging pollutants”.
The term “emerging pollutants” stands for the substances that are released in the environment for
which currently no regulations are established for their environmental monitoring. Their occurrence is
reported worldwide in a range of aquatic environments, such as lakes, rivers, freshwater
catchments, estuaries, reservoirs and marine waters. Nevertheless, due to their large number
(ranging in an order of thousands), only few of these compounds are toxicologically evaluated.
Published data concerning occurrence and potential toxicological effects is limited. The
contamination source of the aquatic environment is mainly the effluents from the sewage treatment
plants (STPs). Reliable methods are available for residue analysis of these pollutants down to low ng
L-1 levels. However, an urgent need is highlighted for the investigation (primarily in environmental
media and following in biological ones) of the toxicity and transformation pathways of all emerging
pollutants. The aims of this mini-review are to briefly present: (a) the major classes of emerging
pollutants; (b) the reasons why these substances constitute an environmental issue; and (c)
developments and applications of environmental analysis in this field.