In this paper, the kinetics of polyphenols extraction from spruce bark (Picea abies) under ultrasounds action was investigated. Studies were performed in order to express the effect of some specific parameters (as: ultrasounds, surface contact between solvent and solid, extraction time and temperature) on the total phenolic content (TPC). Experiments were performed in the presence and absence of ultrasounds, using different contact surfaces between solvent and solid, for times from 5 to 75min and temperatures of 318, 323 and 333K. All these factors have a positive influence on the process, enhancing the extraction rate by recovering higher amounts of polyphenols. The process takes place in two stages: a fast one in the first 20-30min (first stage), followed by a slow one approaching to an equilibrium concentration after 40min (second stage). In these conditions, the second-order kinetic model was successfully developed for describing the mechanism of ultrasound-assisted extraction of polyphenols from P. abies bark. Based on this model, values of second-order extraction rate constant (k), initial extraction rate (h), saturation concentration (Cs) and activation energy (Ea) could be predicted. Model validation was done by plotting experimental and predicted values of TPC's, revealing a very good correlation between the obtained data (R(2)>0.98).

Abstract:The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a great deal of interest. Selective catalytic reduction (SCR), noble metal and transition metal oxide based catalysts have been investigated at both the laboratory and plant scale with this objective. A review article published in 2006 covers the progress in the elemental mercury (Hg el ) catalytic oxidation area. This paper brings the review in this area up to date. To this end, 110 papers including several reports and patents are reviewed. For each type of catalyst the possible mechanisms as well as the effect of flue gas components on activity and stability are examined. Advantages and main problems are analyzed. The possible future directions of catalyst development in this environmental research area are outlined.

Methane, discovered in 1766 by Alessandro Volta, is an attractive energy source because of its high heat of combustion per mole of carbon dioxide. However, methane is the most abundant hydrocarbon in the atmosphere and is an important greenhouse gas, with a 21-fold greater relative radiative effectiveness than CO2 on a per-molecule basis. To avoid or limit the formation of pollutants that are dangerous for both human health and the atmospheric environment, the catalytic combustion of methane appears to be one of the most promising alternatives to thermal combustion. Total oxidation of methane, which is environmentally friendly at much lower temperatures, is believed to be an efficient and economically feasible way to eliminate pollutants. This work presents a literature review, a statu quo, on catalytic methane oxidation on transition metal oxide-modified ceria catalysts (MOx/CeO2). Methane was used for this study since it is of great interest as a model compound for understanding the mechanisms of oxidation and catalytic combustion on metal oxides. The objective was to evaluate the conceptual ideas of oxygen vacancy formation through doping to increase the catalytic activity for methane oxidation over CeO2. Oxygen vacancies were created through the formation of solid solutions, and their catalytic activities were compared to the catalytic activity of an undoped CeO2 sample. The reaction conditions, the type of catalysts, the morphology and crystallographic facets exposing the role of oxygen vacancies, the deactivation mechanism, the stability of the catalysts, the reaction mechanism and kinetic characteristics are summarized.

Aromatic volatile organic compounds (VOCs) proved to have enhanced polluting behavior upon the atmosphere and human health. Their catalytic destruction is an alternative for environmental pollution reduction in the case of gaseous emissions with low contents of VOC. In this paper, an experimental study is presented, concerning the conversion of benzene and its mono-halogenated derivatives on SCR-DeNOx (V 2 O 5 -WO 3 /TiO 2 ) commercial catalyst, specific for the reduction process of nitrogen oxides. The catalytic oxidation was carried out at temperatures ranged between 423 0 K -623 0 K in different reaction environments (air, water vapors and halogenated acids) and for low concentrations of aromatic organic pollutants (< 100 ppm). The catalytic conversion of aromatic organic volatile compounds increases with temperatures and is influenced by the presence of water vapors and halogenated acids. It can reach values of above 75%, for a temperature of 623 0 K. The reaction of catalytic oxidation is incomplete and leads to CO formation.

The purpose of the present study is the comparative investigation of the calcium cations removal from aqueous solutions using two strong acid cationic resins recommended during the last years for water softening. The performances of the two resins were evaluated by the means of the cationic exchange capacity and the retention degree of the calcium cations. The evaluation of the two resins behaviour in the ion exchange process was performed by the means of the FTIR spectra recorded on the resins before and after being used in the calcium cations exchange process. By reporting to the Purolite C100E resin regarded as benchmark, one can state that the Pure Resin PC002 can be considered as a viable alternative for the water softening processes, but a prior economical analysis should be performed regarding the costs reported to the usefulness and benefits.

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This paper presents the influence of spruce bark (Picea abies) particle size and size distribution on the separation of polyphenols, using a green extraction process (ultrasound-assisted extraction-UAE), in order to highlight the kinetic mechanism. Experiments were performed at 50 °C, for 45 minutes, using ethanol-water (70% v/v) as solvent. The considered particle size fractions were: 0.25, 0.315, 0.4, 0.5, 0.63 and 1 mm. The crude extracts were assessed using the Folin Ciocalteu method for total polyphenols content (TPC) and high-performance thin layer chromatography (HPTLC) for identifying simple phenolic acids and tannins. The study points out that particle size significantly influences the UAE process in terms of separated polyphenols and kinetic mechanism as well. From the particles with the lowest size, the highest amounts of simple phenolic acids (sinapic acid, p-coumaric acid) and tannins (catechin) were obtained. Extraction kinetics was estimated using a second order model. Results showed a good prediction of this model for the extraction kinetics in all the experiments (R 2 > 0.911), which gave the possibility to estimate the concentration of polyphenols at saturation (C s), the rate constant (k) and the initial rate (h). All these parameters were affected by the particle size and size distribution of spruce bark.

The photocatalytic degradation of Alcian Blue 8 GX, a copper phthalocyanine cationic dye, has been investigated in aqueous solutions both in heterogeneous and homogeneous systems. Initial colour removal rates in different conditions were calculated in both cases. Influence of amounts of H 2 O 2 and FeCl 3 was studied and compared for the two photocatalytic systems. Finally, some conclusions regarding the efficiency of the two photocatalytic processes were established.