No abstract

An important tributary of the Danube River, the Olt River, was characterized in its middle and lower catchment in terms of volatile organic compounds (1,2 -dichloroethane and perchlorethylene) and volatile aromatic hydrocarbons (benzene, toluene and xylene isomers) to better assess their transfer in the environmental compartments (air, water, sediment and biota). A fugacity based calculation model was applied to establish the bio-concentration factors (BCFs) that relates the compounds concentration from sediment-, water- or air- to the biota based on experimental data. Thus, conclusive suggestions can be achieved for a rapid preliminary risk assessment as support tool for the preventive measures in the contaminated areas resulting from accidental chemical discharges or continuous pollution. For thus, water and sediment samples were collected and analyzed by gas chromatography for the selected compounds, the results being applied as input data for the model. The modeling revealed the tendency of the investigated compounds to transfer from water section to air. Simulated values obtained for section sediment as validation tool, are comparable and compatible with the values obtained by analytical measurements, and thus a rapid estimation of the pollution level in the environmental compartment of interest can be achieved based on a limited number of analytical measurements. Thus, by applying the fugacity model to estimate a pollution footprint, conclusive indications for a rapid environmental risk assessment can be achieved.

The paper describe the sonochemical degradation of organochlorine compounds (Trichloroethylene, Tetrachloroethene and 1, 1, 2-Trichloroethane) from aqueous solutions. The experiments was realized with two types of equipment: ultrasound bath UCD-150 and sonotrode UP 200 Ht. The experimental results showed high efficient removal for all three compounds: Tetrachloroethene 93.8%, 1, 1, 2-Trichloroethane 92.9% and Trichloroethylene 86.6% in bath ultrasound treatment after 50 min. The ultrasound efficiency treatment depend by the sonotronde diameter. The degradation of Trichlorethylene and 1, 1, 2 -Trichloroethane is much better for sonotrode with 14 mm diameter (92.1% respectively 92.7%) than for sonotrode with 40 mm diameter (71.9% and 61.6%), while for Tetrachloroethene values were very close, 88.7% respectively 89.4% for the same above mentioned diameters.

With a crystal lattice structure first characterized in the 1970s, NASICON sodium-based superionic conductors have recently found renewed interest as solid electrolytes in sodium-ion and seawater flow batteries due to their exceptional ionic conductivity being on the same scale as liquid electrolytes. Since sodium ions in the crystal lattice move among interstitial positions through site-specific bottlenecks, the overall conductivity is strongly dependent on the NASICON composition. In this work, we report on the synthesis protocols and processing parameters of Na3Zr2Si2PO12 prepared from Na2CO3, SiO2, ZrO2, and NH4H2PO4 precursors by the conventional solid-state reaction (SSR) route. We critically evaluated important observations made in the extended literature on the topic including: (i) the importance of precursor particle size concerning the SSR synthesis, focusing on effective ball-milling protocols; and (ii) the onset of excess zirconia contamination, expanding on the effects of both thermal and pressure processing—the latter often overlooked in the available literature. In approaching the cryogenic regime, the dataset availability concerning ionic conductivity and dielectric permittivity measurements for NASICON was extended, starting from elevated temperatures at 200 °C and reaching into the very low temperature zone at −100 °C.

The potential of using ultrasonic irradiation and microbiological treatment for the removal bis(1-chloro-2-propyl) ether from aqueous solutions has been investigated. Experiments were performed in a continuous bioreactor, 3500 mL volume, and in an ultrasonic bath respectively, using frequencies of 38+1kHz and applying a power of 30 W. Under these conditions, the sonochemical conversion of ether was found to be superior to the biological one. The ultrasound method was improved by air bubbled into liquid bulk solution and it was found that the main part of bis(1-chloro-2-propyl) ether destruction takes place in the close vicinity of the ultrasound source. These experiments showed the usefulness of the applications of ultrasound to the wastewater treatment processes.