Featured research (6)

The aim of the present study is the effective application of chemometric approach to the elemental composition of a data set of ten ethereal oil plant materials. The contents of 28 essential and toxic mineral elements at main, minor and trace level are determined in each sample by means of direct solid sampling electrothermal vapourization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) and are subjected to hierarchical and non-hierarchical cluster analysis and principal component analysis. Z-transformation of the raw data, Ward’s method of linkage and squared Euclidean distance as similarity measure are used in order to discover appropriate linkage between the plant materials and between the chemical parameters characterizing them. Thus, the investigated plant samples are classified, depending on their chemical composition. On the other hand, the mineral elements are categorized into several patterns which are related to the specific soil characteristics.
The efficiency of a material based on the plant Thymus vulgaris L. for Cu(II) removal from aqueous solutions is investigated. The estimation of optimal parameters influencing the Cu(II) adsorption was studied by the batch method. Optimum pH value was found to be about 4. Kinetic of Cu(II) adsorption was very fast. Equilibrium experimental data were fitted to linear isotherm and kinetic models. It was established that the Langmuir isotherm most adequately described the adsorption process. The possibility for desorption was also studied. The results showed that the investigated biosorbent has good potential for removal of Cu(II) from contaminated wastewaters.
The objective of the present study is the characterization of an adsorbent plant material based on Hypericum perforatum L. and the investigation of its feasibility for the removal of Cu2+ ions from aqueous solutions. XRD, TGA, FTIR, SEM and low-temperature nitrogen adsorption were used for the analytical characterization of the material. Particle size distribution and slurry pH of the investigated material were also determined. The effect of contact time, solution acidity and initial metal concentration on the adsorption of Cu(II) ions was studied by means of the batch method. Desorption studies have also been performed. Equilibrium experimental data were fitted to the linear Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacity was calculated and it was concluded that the material could be used as an effective biosorbent for the removal of copper ions from aqueous media.
The present study aims at removal of hexavalent chromium from aqueous solution using manganese ferrite (MnFe 2 O 4) nanoparticles. The investigated material was obtained by solution combustion method using starting reagents Mn(NO 3) 2 .4H 2 O and Fe(NO 3) 3 .9H 2 O (as oxidizers) and citric acid (as a re-ducer). Nanoparticles of MnFe 2 O 4 were characterized by X-ray diffraction and scanning electron microscopy. The porous structure of the studied material was investigated by low-temperature nitrogen adsorption. Batch adsorption experiments were performed to evaluate the effect of various parameters, such as contact time, acidity of initial solutions and chromium concentration. Pseudo-first order, pseudo-second order and intraparticle diffusion models were used to analyze kinetic data. Equilibrium experimental data are fitted to linear Langmuir and Freundlich adsorption models. The Langmuir isotherm most adequately describes the adsorption process. The maximum adsorption capacity was calculated. The results indicate that investigated material is a suitable ad-sorbent for removing Cr(VI) from wastewater, but additional modification of manganese ferrite nanoparticles is planned for further experiments to increase their adsorption capacity.C
Chemical processes that could occur in the anode chamber of an electrolytic cell divided by a semi-permeable membrane when direct current passes through a water solution of weak mineralization are described. The interest concerns the possibility of a formation of chemical substances with strong oxidative action as O2 and H2O2, due to nascent oxygen. These substances can destroy the structure of pathogenic bacteria and viruses. The preservation of these properties for a long period of time without specific storage requirements makes the anolyte cheap and effective disinfection and therapeutic means.

Lab head

Paunka Vassileva
  • Institute of General and Inorganic Chemistry

Members (2)

Albena K. Detcheva
  • Bulgarian Academy of Sciences
Lidia Petkova Ivanova
  • Bulgarian Academy of Sciences