The degradation of cyanide by anodic electrooxidation using different anode materials

Cyanides are very popular electrolytes used in metal electroplating, metal ore processing, chemical and electrochemical applications. Due to wide utility of these technologies cyanides become increasingly harmful effluent, which has to be treated. One of the best ways to degrade cyanides is an anodic electrooxidation. In this work the destruction of free cyanide on platinum, titanium and stainless steel (SS) electrodes has been investigated. It was determined that anode material greatly influences the process of cyanide electrooxidation. The best results were obtained by using the Pt electrode. This kind of anode allows us to reduce CN^? concentration from 0.1 M to 0.06 M during the first hour of electrolysis at a current density of 200 A m^?2, with a current efficiency up to 80%. To substitute expensive Pt anodes Ti electrodes covered with nanolayers of Pt were prepared and used for the anodic oxidation of cyanide ions. An effect of a thickness of Pt layer and temperature of an electrolyte solution were studied. It was established that using platinized Ti electrodes the current efficiencies of electrooxidation of cyanides of about 60% can be obtained. The usage of chloride ions to facilitate the destruction of cyanide was also studied.     

Transfer of natural and anthropogenic radionuclides to ants, bryophytes and lichen in a semi-natural ecosystem

Few data are available to quantify the transfer of both natural and anthropogenic radionuclides to detritivorous invertebrates to facilitate estimation of the internal dose to such biota in models used to assess radiation exposure. To enhance the available data, activity concentrations of ¹³⁷Cs, ⁴⁰K, ⁹⁰Sr, ^239?+?240Pu, ²⁴¹Am, ²³⁵U and ²³⁸U were measured in ants (Formicidae) and corresponding undisturbed soil collected from the Zlatibor mountain in Serbia and ant/soil concentration ratios (CR) calculated. The ²⁴¹Am concentration ratios for ants were fourfold higher than those calculated for ants in a previous study whereas they are similar to the more numerous data previously reported for a range of detritivorous invertebrates in other studies. CR values for ¹³⁷Cs in ants were similar to the few other reported values and slightly lower than those for a range of detritivorous invertebrates. Those for ^239?+?240Pu were slightly higher than those for ants in two other studies but they were close to upper limit of a range of data reported for detritivorous invertebrates. All the CR values will be included in a future revision of the ERICA Tool database and will particularly improve the information available for uranium.     

Managing occupational injuries records in Slovenia from 1948 to 2008

The aim of this study is to examine and compare all publicly accessible data on occupational injuries in Slovenia in the period from 1948 to 2008, obtained either from archives or websites. The data obtained from five different sources which have been formally collecting and presenting data on occupational injuries in Slovenia (Labour Inspectorate of the Republic of Slovenia – LIRS, Institute of Public Health of the Republic of Slovenia – IPHRS, International Labour Organization – ILO, Statistical Office of the Republic of Slovenia – SORS, and issues of the Journal of Occupational Safety and Fire Safety) were reviewed and managed. Since the early 1960s, there has been a significant decrease of fatal and non-fatal occupational injuries in Slovenia. Problems related to gathering and interpreting data on occupational injuries are also discussed with special emphasize on diversity of models used for occupational injuries data collecting. The results of the 60-year-long retrospective study can also be of assistance for professionals involved in planning, implementing and controlling the national policy and/or regional policies on safety and health at work.     

Canopy leaching of nutrients and metals in a mountain spruce forest

Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg²⁺, Ca²⁺, and K⁺ in decaying biomass and co-transport of Ca²⁺ and K⁺ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO₃^?) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of ?13.9 and 16.4 mmol m^?2 yr^?1 for NH₄⁺ and organic N, and ?0.33 and 0.22 mmol m^?2 yr^?1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (～90%) originated from microbial DRP and NH₄⁺ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m^?2 yr^?1), and greatest for Mn (0.9 mmol m^?2 yr^?1) due to leaching from decaying tissue by acidic precipitation.     

Cancer risk assessment after exposure from natural radionuclides in soil using Monte Carlo techniques

Purpose  

The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like ²³⁸U, ²³²Th, ⁴⁰K, and ²²⁶Ra on the territory of Bela Crkva, Serbia. Although receiving doses are low from sources like natural radionuclides in soil, because of stochastic effects of ionizing radiation, risk for developing cancer exists and can be quantified.     

Monitoring of nitrates in drinking water from agricultural and residential areas of Podravina and Prigorje (Croatia)

Nitrates are the most common chemical pollutant of groundwater in agricultural and suburban areas. Croatia must comply with the Nitrate Directive (91/676/EEC) whose aim is to reduce water pollution by nitrates originating from agriculture and to prevent further pollution. Podravina and Prigorje are the areas with a relatively high degree of agricultural activity. Therefore, the aim of this study was, by monitoring nitrates, to determine the distribution of nitrates in two different areas, Podravina and Prigorje (Croatia), to determine sources of contamination as well as annual and seasonal trends. The nitrate concentrations were measured in 30 wells (N?=?382 samples) in Prigorje and in 19 wells (N?=?174 samples) in Podravina from 2002 to 2007. In Podravina, the nitrate content was 24.9 mg/l and 6 % of the samples were above the maximum available value (MAV), and in Prigorje the content was 53.9 mg/l and 38 % of the samples above MAV. The wells were classified as correct, occasionally incorrect and incorrect. In the group of occasionally incorrect and incorrect wells, the point sources were within 10 m of the well. There is no statistically significant difference over the years or seasons within the year, but the interaction between locations and years was significant. Nitrate concentrations’ trend was not significant during the monitoring. These results are a prerequisite for the adjustment of Croatian standards to those of the EU and will contribute to the implementation of the Nitrate Directive and the Directives on Environmental Protection in Croatia and the EU.     

The applicability of different waste materials for the production of lightweight aggregates

The applicability of different waste materials for the production of lightweight aggregates has been studied. The following waste materials were investigated: silica sludge, superfluous clay in the quarry, waste glass, and residue from the polishing process of different types of stone. SiC and MnO₂ were selected as foaming agents. Feldspar containing minerals and scrap glass were added in order to lower the softening point of the waste materials. The granules were prepared by mixing together finely ground waste with one or both of the selected foaming agents. The granules were then fired at different temperatures above the softening point of the glassy phase within the temperature range from 1150 to 1220 °C, where the foaming agent degasses, and the resulting gasses remain trapped in the glassy structure. The foaming process was observed by hot-stage microscopy. The properties of the so-obtained granules, such as their apparent density and compressive strength, were determined, and their microstructures were evaluating using SEM and polarizing microscopy.With the addition to clay of polishing residue from granite-like rocks, after firing at 1220 °C homogeneously porous granules with a density down to 0.42 g/cm³ were obtained, whereas with the addition to waste silica sludge of polishing residue from granite-like rocks and waste glass with a foaming agent, after firing at 1220 °C densities from 0.57 to 0.82 g/cm³ were obtained.     

Driving under the influence of alcohol and the effects of alcohol prohibition—Case study in Serbia

Objective: The purpose of this study is to provide an overview of the prevalence of driving under the influence of alcohol (DUI) according to day of the week, specific roads (urban/rural), daytime or nighttime, and vehicle category. In addition, this study examines how the prohibition of selling alcoholic drinks in shops and supermarkets (not in restaurants) after 10 p.m. has affected the prevalence of DUI.

Method: Breath alcohol concentration (BrAC) was collected from all drivers through police checkpoints at 54 locations in Serbia. In this study, 17,945 drivers were tested in urban areas and 19,507 in rural areas. The relationship between DUI during the prohibition on alcohol sales in Belgrade and other large cities in Serbia was determined using logistic regression.

Results: On average, every 100th driver in traffic in Serbia was DUI (0.99%). This study shows that the 0 blood alcohol concentration (BAC) limit for motorcyclists does not have an influence on DUI. Moreover, motorcyclists represent the category with the highest share of DUI, with a statistically significantly larger difference compared to drivers of other vehicle categories. These results may be a consequence of the fact that a large number of drivers drive both motorcycles and other vehicle categories (cars or mopeds), so the different BAC limits for nonprofessional drivers may create confusion about the legal BAC limit.

Conclusions: This study suggests that the required legal BAC limit for nonprofessional drivers should be the same. The prohibition of selling alcoholic drinks in Belgrade after 10 p.m. does not decrease the prevalence of DUI.