1,472 research outputs found
Analytical solution of the Langmuir-based linear driving force model and its application to the adsorption kinetics of boscalid onto granular activated carbon
No full textThe application of intraparticle diffusion models is generally difficult because of complex mathematical structure. The linear driving force (LDF) approach reduces the mathematical effort and provides a reasonable approximation of the intraparticle diffusion theory. In this work, an exact analytical solution of a LDF equation based on the Langmuir equilibrium model (LLDF) was derived. The LLDF model depends on three unknown parameters, namely the adsorbed amount at equilibrium, the maximum adsorbent capacity and the mass transfer coefficient. The LLDF model was used for analyzing the adsorption kinetics of boscalid onto granular activated carbon. The experimental results at equilibrium showed that the maximum adsorption capacity of activated carbon for boscalid and the Langmuir equilibrium constant of the process were 167 mg g−1 and 0.53 L mg−1, respectively. The LLDF equation was successfully applied to the kinetic data, allowing the evaluation of the mass transfer coefficient of boscalid (8.4 × 10−3 h−1). The LLDF model has general validity for describing intraparticle diffusion-adsorption onto porous media and its reliability can be assessed by a simple graphical method
Thermal- and MnO2-Activated Peroxydisulfate for Diuron Removal from Water
No full textIn this work, a peroxydisulfate (PDS)-based advanced oxidation process was used for removing diuron from water. The effect of heat and MnO2 as PDS activators was explored. It was found that diuron degradation obeyed zero-order kinetics in the presence of heat-activated PDS. The relative contribution of MnO2 to the diuron degradation decreased with the increasing temperature. At the highest temperature investigated, T = 55 °C, complete diuron removal was achieved in less than 75 min. A kinetic model for describing the rate of diuron degradation was proposed and successfully applied to the experimental data
Some remarks on “A critical review of the estimation of the thermodynamic parameters on adsorption equilibria. Wrong use of equilibrium constant in the Van't Hoof equation for calculation of thermodynamic parameters of adsorption” - Journal of Molecular Liquids 273 (2019) 425–434
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Adsorption of Amoxicillin onto Organo-Modified Zeolitic Tuff
No full textIn this work, the ability of surface modified zeolite (SMZ), obtained by ion exchange of phillipsite-rich tuff with HDTMA (hexadecyltrimethylamm onium)-Br or HDTMA-Cl, to adsorb amoxicillin was investigated. The effect of surfactant modification was explored by contacting the tuff with HDTMA solutions at different concentrations (50-200% of the zeolite's external cation exchange capacity). It was found that for the higher surfactant concentration used the formation of a surfactant bilayer (compact for HDTMA-Br, patchy HDTMA-Cl) occurs. The results of the adsorption experiments showed that SMZ exhibited a higher adsorption capacity (especially at low solute concentrations) and a faster adsorption rate for amoxicillin than the unmodified tuff. The interaction between amoxicillin and the adsorbents was mainly ascribed to electrostatic forces
Oxidation of organic pollutants over MnO2 in cold water assisted by peroxydisulfate
No full textMnO2 can be used in advanced oxidation processes to activate peroxydisulfate (PS) and generate reactive species such as sulfate radicals (SO4 center dot-), hydroxyl radicals (center dot OH) and singlet oxygen (1O2) for the abatement of organic water contaminants. Alternatively, one can use MnO2 as particulate oxidant which, in contrast to PS, is active already at low temperatures. This low-temperature activity is particularly attractive for in situ groundwater treatment. The roles of PS and MnO2 as oxidant and catalyst, respectively, may invert: MnO2 functions as primary oxidant and PS works as re-oxidant of reduced Mn-oxides. In this way, the limited oxidation capacity of particulate MnO2 can be overcome. So far, such reaction systems have not been extensively explored.In the present study, the degradation of 4-hydroxybenzoic acid (HBA) by PS + MnO2 was studied under various experimental conditions, by varying reaction temperature (15-45 degrees C), reagent concentrations, and water matrix. Both PS and MnO2 alone have the ability to effect the oxidation of HBA. In the co-presence of PS and MnO2, a fast removal of HBA from water was achieved even at low temperatures (half-life of HBA about 0.5 h with 2.4 g L-1 MnO2 at 25 degrees C), owing to a synergic effect between the two components.Quenching experiments indicate that the primary HBA oxidation step is a heterogeneous reaction on the MnO2 surface rather than a homogeneous reaction driven by SO4 center dot-or 1O2, as frequently reported in literature. This is in line with results from the PS driven oxidation of perfluorooctanoic acid which is not significantly enhanced in the presence of MnO2
The history of the Romano famili and "Angelo, tyran de Padoue" by Victor Hugo.
No full textreservedVictor Hugo, nel dramma Angelo, tyran de Padue, ricama tre diverse epoche storiche: i primi decenni dell’Ottocento, a lui contemporanei; la metà del Cinquecento, prescelta per lo svolgimento dell’azione drammatica; il tardo Medioevo evinto dai personaggi principali che compongono il racconto. Tuttavia, l’interesse storico e prettamente romantico verso il periodo medievale assume in quest’opera una rilevanza primaria. Tra le tante casate del nord Italia nominate dall’autore nell’opera, una su tutte sembra essere davvero simbolica. Particolarmente interessante è stato comprendere come la storia della famiglia da Romano costituisca il fulcro della costruzione drammaturgica. Ezzelino III e Cunizza da Romano sono elevati a emblema della poetica romantica e divengono funzionali al messaggio politico e sociale dell’autore.Victor Hugo, in his play Angelo, tyran de Padue, embroiders three different historical epochs: the first decades of the 19th century, contemporary with him; the middle of the 16th century, chosen for the unfolding of the dramatic action; and the late Middle Ages evoked by the main characters in the story. However, the historical and purely romantic interest in the medieval period takes on primary importance in this work. Of the many northern Italian lineages named by the author in the work, one in particular seems to be truly symbolic. It was particularly interesting to understand how the history of the da Romano family forms the core of the dramaturgical construction. Ezzelino III and Cunizza da Romano are elevated to emblems of romantic poetics and become functional to the author's political and social message
Michael Angelo Caruso, international author, consultant, and speaker on Campus
No full textTollefson, Elizabeth. (2013). Michael Angelo Caruso, international author, consultant, and speaker on Campus. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/223386
Combination of MnO2 and persulfate as oxidants for degradation of water pollutants at low temperatures
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