The parameters which influence the removal of different zinc (Zn) species: Zn2+, Zn(II)–EDTA and Zn(II)–citrate from aqueous solutions by nanoparticles of zerovalent iron (nZVI) were investigated at environmental relevant pH values. Untreated, surface modified and silica-fume supported nZVI were applied at different iron loads and contact times to Zn solutions, which were buffered to pH 5.3, 6.0 and 7.0. The results revealed that pH, the type of nZVI, the iron load, the contact time, and the Zn species all had a significant influence on the efficiency of removal. Zn2+, Zn(II)–EDTA and Zn(II)–citrate were the most effectively removed from aqueous solutions by untreated nZVI. Zn2+ removalwas governed mainly by adsorption onto precipitated iron oxides. Complete removal of Zn2+ and Zn(II)–citrate was obtained at all pH values investigated. The removal of strong Zn(II)–EDTA complex was successful only at acidic pH,which favored degradation of Zn(II)–EDTA. Consequently, the released Zn2+ was completely removed from the solution by adsorption onto iron oxides.
COBISS.SI-ID: 27431207
In this study the mineralogical and geochemical characteristics of Lake Dojran surficial (0-5, 5-10, 10-15 cm) sediments were studied in order to determine their suitability for use as potential raw material in balneotherapeutic treatments. X-ray powder diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS) analyses were performed, and thereupon chemical index of alteration (CIA) and enrichment factor (EF) values were calculated. The XRD results revealed close association of sediment mineralogy with the prevailing metamorphic, volcanic and igneous rocks of the region surrounding Lake Dojran. CIA values of around 67 % suggest a moderate degree of weathering in the lake catchment area. According to the EF value results, surficial Lake Dojran sediments are little enriched with Co, Cr, Cu, Pb, and Zn, moderately enriched with Au, Ni and Sb, moderately severely enriched with Au, severely enriched with Sb and very severely enriched with As. This elemental enrichment likely originates from various different geogenic (geological background and polymetallic mineralization) and anthropogenic (tourism, traffic, coatings, untreated wastewater discharge and agrochemicals) sources. The abundances of the major elements, trace elements and rare earth elements (REEs) were almost constant, changing very little throughout the surficial (0-5, 5-10, 10-15 cm) sediments. Comparison of sediment trace element concentrations with consensus-based threshold effect concentration (TEC) and probable effect concentration (PEC) values showed that lake biota may be under threat of contamination with As, Cu and Ni. Given the present results, we cannot recommend/confirm the application of Lake Dojran dark mud sediment in balneotherapeutic treatments.
COBISS.SI-ID: 1176158
A fuzzy sets decision support system is proposed for geotechnical site investigation. The system considers parameters such as geology and soil variability that affect the required number of soundings to adequately characterize a site. It permits also to consider vagueness and lack of information. On the basis of available qualitative and quantitative information, the system allows estimating, for common projects, the number of site soundings. Monte Carlo simulations of entry ranges, where each point has a uniform probability distribution, permit to arrange the output in form of histograms fitted with probability functions. The cases presented show that the fuzzy inference system can be used as a systematic decision support for engineers dealing with site characterization.
COBISS.SI-ID: 17710614
In the study the dry end of the soil water characteristic curve (SWCC) was used to estimate the specific surface area (SSA) of 90 engineering soil samples, using the Tuller and Or (2005) model. The results of SSA obtained by measurements using a WP4T dew point potentiometer were compared with those obtained by means of traditional BET (Brunauer, Emmett, and Teller) surface area and the methylene blue (MB) techniques. An analysis of the results discussed in terms of the representative literature data showed that the SWCC method could provide a reliable estimation of the specific surface area in the case of fine grained inorganic soils with a total specific surface area greater than 5 m2/g. A Hamaker constant with a value of 6 × 10− 20 J was found to be a good approximation, in the case of SSA calculations. The study also shows that karstic clay — terra rossa exhibits specific behavior which was not investigated in detail in the study, but clearly shows that further research is needed in order to modify the Tuller and Or (2005) model to a wider range of engineering soils with more complex mineralogical composition and texture.
COBISS.SI-ID: 6328417
The Port of Koper, one of the biggest and the most important ports in the Northern Adriatic Sea, is constantly faced with the problems caused by the accumulation of marine sediments inside the port, disturbing some of the portʼs crucial operations. However, these sediments can be viewed as a potential raw material and, in order to define the best way of using them in the civil-engineering field, an extensive research project has been launched. The preliminary results of this project are presented and discussed in the paper. So far the project has given two main results: first, the concentrationof heavy metals in the aqueous leachates is low and, secondly, intheir present state, the sediments are too wet, so that there are only limited possibilities for drying them out naturally. For this reason additional technological treatment will be needed.
COBISS.SI-ID: 1972071