A tányérszám hatása szakaszos desztilláció feldolgozó kapacitására egy-és kétkolonnás műveletek esetén = Influence of number of trays on the processing capacity of batch distillation with a single and two columns

Kétkolonnás szakaszos desztillációs művelet első, kisebb oszlopának tányérszáma változtatásának hatásátvizsgáltuk szimulációval aceton visszanyerésérejelentőseneltérő összetételű aceton-víz elegyekből. Célunk a feldolgozókapacitás maximalizálása volt genetikus algoritmussal. A kétkolonnás műveletet összehasonlítottuk egy olyan egykolonnás művelettel, amikor a szétválasztáshoz a nagyobb kolonnát használtuk változatlanvagya kétkolonnás művelet össz-tányérszámára megnövelt tányérszámmal

Investigating the processing capacity of batch distillation by applying a second, smaller column

Increasing the processing capacity is important, especially in the pharmaceutical industry, where a given amount of waste solvent must be processed in a specific time period, else the remaining amount of waste solvent must be incinerated, which results in organic solvent loss and considerable environmental impact. In this paper, the possibility of increasing the processing capacity of batch distillation by using a second, already available, smaller batch column in addition to the original one is studied. The size of the columns is not changed during the calculations performed. Two case studies are presented. In the first one (Mixture 1), acetone, in the second one (Mixture 2), acetic acid must be recovered in high purity from their aqueous mixtures by operating either the larger column only or both columns simultaneously. The smaller column serves for preliminary separation, and its main-cut (Mixture 1) or residue (Mixture 2) is further processed in the larger one. The goal of this work is to maximise the processing capacity of the two-column process with the same recovery as in the single-column process. Both processes are modelled with a professional flow-sheet simulator. For the single-column process, the only independent variable is the reflux ratio. For the two-column process, the independent variables are the reflux ratios of both columns and the amount of intermediate product (distillate or residue) of the first column transferred to the second one. The ranges of the independent variables are determined by sensitivity studies for different charge compositions (20–50-80 mass% acetone or acetic acid), and each case is optimised by a genetic algorithm coupled to the flow-sheet simulator. It is also shown in this work that the processing capacity maximum of the two-column process is not always at the equality of the processing times of the two columns

Többkomponensű ipari hulladék-oldószerelegy szakaszos desztillációs szétválasztása = Separation of a multicomponent, industrial waste-solvent mixture by batch distillation

Egy négykomponensű ipari hulladékoldószer-elegy feldolgozását vizsgáltuk, melynek komponensei: A, B, C és D. A B komponens regenerálását a gyárban (hagyományos) szakaszos desztillációval valósítják meg. Célunk az ipari szétválasztási művelet tanulmányozása a ChemCAD folyamatszimulátorral, illetve a modell validálása laboratóriumi kísérlettel. Megállapítottuk, hogy a jelenleginél lényegesen magasabb B kinyerés lenne elérhető speciális desztillációs módszer, például szakaszos heteroazeotróp desztilláció alkalmazásával

Melt stabilization of PE with natural antioxidants: Comparison of rutin and quercetin

The stabilization effect of a flavonoid type natural antioxidant, rutin, was compared to that of quercetin in polyethylene. Additive concentrations changed between 0 and 500 ppm in several steps and also 1000 ppm Sandostab PEPQ phosphorus secondary stabilizer was added to each compound. Stabilization efficiency was determined by changes in vinyl group content, melt flow rate, oxygen induction time, color and the consumption of the secondary antioxidant during multiple extrusions. The results showed that rutin is as efficient melt stabilizer as quercetin used as reference. On the other hand, rutin has a deteriorating effect on the stability of the polymer at small concentrations and partially decomposes during processing. The comparison of bond dissociation enthalpies indicated that the substitution of the hydroxyl group in the ring C of quercetin by saccharide moieties increases their value, but the small increase does not influence the efficiency of the stabilizer. FTIR and DSC measurements indicated the interaction of the natural antioxidant and the phosphonite secondary stabilizer, and the development of interactions was confirmed by molecular modeling. Mainly hydrogen bonds and aromatic, π electron interactions develop between the hydroxyl groups in ring A and the POC group of the phosphonite, as well as between the aromatic rings of PEPQ and the flavonoids, but they do not influence the stabilization efficiency of the antioxidants

Melt stabilization of polyethylene with dihydromyricetin, a natural antioxidant

Experiments have been carried out to compare the stabilization effect of two flavonoid type natural antioxidants, dihydromyricetin (DHM) and quercetin (Q) in polyethylene (PE). Additive concentrations changed between 0 and 500 ppm in several steps and 1000 ppm Sandostab PEPQ phosphorus containing secondary stabilizer was also added to each compound. Both antioxidants are very efficient stabilizers for PE, sufficient melt stability was achieved already at 50 ppm DHM content. At small concentrations dihydromyricetin proved to be more efficient melt stabilizer and it protected the secondary antioxidant better than quercetin. In spite of its better efficiency in melt stabilization, polymers containing DHM had the same residual stability as those prepared with quercetin. Accordingly, the larger efficiency does not result from the larger number of active phenolic hydroxyls in the molecule, but from interactions with the phosphorous secondary stabilizer that is stronger or at least different for DHM than quercetin. In spite that DHM is a white powder, it gave the polymer a brownish color which became deeper with increasing number of extrusions and additive content. Nevertheless, both natural antioxidants can be used efficiently for the stabilization of polymers in applications in which color is of secondary importance

Solvation and Protonation of Coumarin 102 in Aqueous Media - a Fluorescence Spectroscopic and Theoretical Study

The ground and excited state protonation of Coumarin 102 (C102), a fluorescent probe applied frequently in heterogeneous systems with an aqueous phase, has been studied in aqueous solutions by spectroscopic experiments and theoretical calculations. For the dissociation constant of the protonated form in the ground state, was obtained from the absorption spectra, for the excited state dissociation constant was obtained from the fluorescence spectra. These values were closely reproduced by theoretical calculations via a thermodynamic cycle – the value of also by calculations via the Förster cycle - using an implicit-explicit solvation model (polarized continuum model + addition of a solvent molecule). The theoretical calculations indicated that (i) in the ground state C102 occurs primarily as a hydrogen bonded water complex, with the oxo group as the binding site, (ii) this hydrogen bond becomes stronger upon excitation; (iii) in the ground state the amino nitrogen atom, in the excited state the carboxy oxygen atom is the protonation site. A comprehensive analysis of fluorescence decay data yielded the values kpr = 3.271010 M-1 s 1 for the rate constants of excited state protonation, and kdpr = 2.78108 s-1 for the rate constant of the reverse process (kpr and kdpr were treated as independent parameters). This, considering the relatively long fluorescence lifetimes of neutral C102 (6.02 ns) and its protonated form (3.06 ns) in aqueous media, means that a quasi-equilibrium state of excited state proton transfer is reached in strongly acidic solutions