Volume 10 (2008): Issue 1 (March 2008)

A method of monitoring sewage sludge pyrolysis and gasification was proposed. Samples of sludge were pyrolysed in Ar and gasified in CO₂ in a thermobalance. The evolved gases were analysed on the calibrated MS, the samples of sludge and solid residues at different stages of the processes were subjected to elemental analysis. The identification and the quantitative characterisation of chemical reactions were performed, based on the DTG and MS profiles.

Different thermodynamic properties (the vapour density, the liquid density and the saturation pressure) were calculated by the model based on the Nakamura-Breedveld-Prausnitz equation of state (NBP EOS). Since the original form of the NBP EOS often generates inaccurate results for liquids, it was modified to describe this phase better. The calculations were realized in the subcritical region. So far, the temperature-dependent NBP EOS parameters have been obtained by special correlations. Their constants were fitted to a lot of experimental data. In this paper the equation of state temperature-dependent parameters were obtained by a new method which was based at piecewise cubic Hermite interpolating polynomials (PCHIPs). In the proposed method some experimental data (called the key ones) were used, thus reducing the experimental effort. Seven substances were chosen for the test calculations. Each of them is common in industry. The calculation results were compared with the experimental data. The new method has made an accurate description of vapour-liquid equilibrium for the considered pure substances over a wide temperature range possible.

Forced aeration of old landfills by an in situ method causes enhanced reduction of leachate indices organic load, a decrease of greenhouse gases emitted to the atmosphere and waste stabilization. The aim of the research was an experimental simulation of aerobic stabilization on landfills carried out under different conditions of leachate recirculation in lysimeters. The results were used in balancing and the kinetic analysis of the organic substance degradation.

This paper reports on a procedure which leads to the assessment of the K_G values without the need of determining the maximal rate of pressure rise by experiments. A simulation is proposed of the combustion process in its simplest form, i.e. one-dimensional propagation of the flame. Such simulation enables the burning velocity S_u to be assessed. Knowing the S_u values for different compositions of the flammable mixture makes it possible to determine the S_{u, max} value. Once the correlation between S_u,max and K_G has been established, this will enable us to assign an appropriate value of K_G to that of the maximal burning velocity. An example of such a correlation is given. It refers to flammable mixtures of a comparatively low burning velocity.

The components of fresh vegetable oils are mainly non-polar. During frying of food, complex and multistage reactions occur in the oil, which produce various polar compounds. Active carbons are characterized by small contents of polar functional groups, which are responsible for adsorbing such polar compounds. Effective purification of the used frying oils must involve the removal of the polar substances. To improve the quality of the used palm oil, an active carbon oxidized by a hydrogen peroxide treatment was used. Such a carbonaceous adsorbent improves the quality of the oil used for frying food by purifying it from colour substances, lipid hydrolysis products, oxidation products and total polar compounds.

The hydrodynamics in fluidized-bed crystallizers is studied by CFD method. The simulations were performed by a commercial packet of computational fluid dynamics Fluent 6.x. For the one-phase modelling (15), a standard k-ε model was applied. In the case of the two-phase flows the Eulerian multi-phase model with a standard k-ε method, aided by the k-ε dispersed model for viscosity, has been used respectively. The collected data put a new light on the suspension flow behaviour in the annular zone of the fluidised bed crystallizer. From the presented here CFD simulations, it clearly issues that the real hydraulic conditions in the fluidised bed crystallizers are far from the ideal ones.

The effect of pH on copper ions sorption by alginates has been investigated. The granules of the sorbent obtained from sodium alginate (type DMF, manufactured by KELCO) have been applied. By using a new method of gelation a biosorbent containing from 11.3 to 20.3% mas. of alginate has been produced. Investigations have been carried out at a constant temperature of 25°C and the pH values ranging from 3 to 5. The obtained experimental results have been described by the Langmuir equation. It has been found that with the increasing pH of the solution the maximum biosorbent sorption capacity increased.

A research into microwave vacuum drying of rapeseeds in a fixed bed on a semi-technical scale was done. The temperature and moisture distribution for a different value of microwave power and pressure were determined. The economic analysis of the drying processes, description of equipment and measurement methodology were presented, too.

The present report reports on the process of the removal of organic solvents in the polymerisation reactor, thin-layer evaporator, and twin-screw extruder for the production of the solvent-free acrylic pressure-sensitive adhesives (PSA). New applications and technical specifications stimulate the continuous development of new methods of manufacturing of non-solvent self-adhesives. The new synthesis of 100% acrylic systems includes solvent polymerisation and finally a removal of volatile organic compounds in a special extruder, polymerisation vessel or an industrial evaporator. The removal process requires controlling such relevant parameters as temperature, pressure and volatile organic compounds concentration.

The RP-TLC method was used to determine the dissociation constant of chrysin (5,7-dihydroxyflavone) in methanol-aqueous (1:1 v/v) solutions. In this method the pK value was quantified on the basis of retention data and a retention model. The accuracy of determining the model parameters was analysed using the following statistical criteria: the sum of the squared differences between the experimental and theoretical data, approximation of standard deviation, and the Fisher test. Besides, in this work the potentiometric method was used. Investigations were carried out at ionic strength I=0.1 at T= 298 K. The dissociation constant were determined using the Rossotti method as well as the numerical method based on the procedures of non-linear curve fitting using Microsoft Excel Solver and the user-defined function. It has been found that the differences in the evaluated pK values were relatively small and did not exceed 1.2%.

The Anaerobic Digestion Model no 1 (ADM1) has been implemented to simulate batch fermentation. The pH changes and inhibition of the fermentation have been studied. The model has been used to investigate the effects of substrate composition and concentration as well as the composition of the microorganism population on the course of fermentation. The overload of a reactor has been discussed.

The work proposes a new method of hydrophobization of limestone powder from stearic acid vapour or stearic acid ether solution. The obtained product is characterised by all properties typical of water-resistant materials. The evaluation of these properties has been carried out according to Polish Standard PN-G-11020 and analysed with research methods originally used for powder technique.

The adsorption model for an accurate prediction of the analyte retention in the normal - phase liquid chromatography with a binary mobile phase has been proposed. This model was derived using a thermody-namically consistent modified competitive Langmuir isotherm. The performance of the proposed equation was compared with two retention models reported in literature. All models were verified for different NP-LC systems by use of three criteria: the sum of squared differences between the experimental and theoretical data, approximation of the standard deviation and the Fisher test.

Platinum, both alone and with a low and high amount of chromium as an additive supported on alumina, was studied as a catalyst. These catalysts were examined in the removal of the carbonizate as a model material. It was found that the 2Cr/Al₂O₃ catalyst showed a significant increase in the catalytic activity as compared to 20Cr/Al₂O₃. An addition of platinum was found to cause a decrease of activity.

Growth kinetics of vitamin C crystals during the batch mass crystallization process in L(+)-ascorbic acid - methanol - ethanol - water system was determined. The linear growth rate values were estimated on the basis of the product crystal size distributions. The kinetic model of the continuous process in a MSMPR crystallizer was adopted for the batch mode description according to Nyvlt's conception, taking the sizedependent growth (SDG) rate effects into consideration. The kinetic parameter values were determined with a Rojkowski hyperbolic SDG model. A good compatibility between the experimental product crystal population density distributions and the SDG model predictions was observed. The interpretation of the kinetic data was presented and discussed.

Fractional penetration through four fibrous filters was determined experimentally at various air velocities. To describe the data obtained for multilayer sets of filters composed of up to nine layers of the same filter, the axial dispersion model was applied. This model predicts a non-exponential decrease of aerosol penetration with a filter thickness increase. The dispersion model contains two parameters, λ and D^x, which were evaluated on the basis of the experimental data. For the first time ever the axial dispersion coefficients, D^x, in fibrous filters were determined.

Alkyl substituents in position 1 of the imidazole ring distinctly affect the hydrophobic properties of the molecule and strengthen its basicity. Hence, 1-alkylimidazoles have been used as extractants of a number of metal ions. Again, a methyl substituent in position 2 of the imidazole ring raises by an order of magnitude the basicity. At the same time, the substituent impedes the formation of the 2-alkylimidazole complexes with metal ions due to the steric effect.

By the substitution of alkyl groups in position 1 or 2 of the imidazole ring it is possible to program the extraction properties of extractants and to control the selectivity of extraction.

Extraction of several chloro compounds from water has been examined. As the extracting liquid the 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆], which is common hydrophobic ionic liquid, was used. Additionally, extraction of selected chlorinated compounds from tert-butylmethylether (MTBE) was investigated. The obtained results show the usefulness of [BMIM][PF₆] to remove the organic impurities from water, particularly at the concentration range inappropriate for biological purification plants.