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Polish Journal of Chemical Technology (v.11, #4)

TiO2 modified by ammonia as a long lifetime photocatalyst for dyes decomposition by Julia Choina; Diana Dolat; Ewelina Kusiak; Magdalena Janus; Antoni W. Morawski; (pp. 1-6).
Ammonia-modified TiO2 (TiO2/N), prepared in a pressure reactor was used as the well- active and longlife photocatalyst for the azo dye (Reactive Red 198) decomposition. The effect of aeration and the different value of the pH of the reaction medium on the photocatalytic degradation of Reactive Red 198 in water has been investigated. It has been reported that the degradation is greatly influenced by the reaction pH and the faster decomposition of azo dye took place at pH 3.5. When the solution was acidic, a larger amount of azo dye on the positively charged surface of TiO2 photocatalysts was adsorbed. From the obtained results it can be seen that the effectiveness of the decolourisation of the solution was faster by using the nitrogen-modified TiO2.

Keywords: photocatalysis; nitrogen-modified TiO2lifetime

Thermal decomposition of acrylic pressure-sensitive adhesives by Zbigniew Czech; Robert Pełech; Krzysztof Zych; (pp. 7-12).
The general aim of this article is to review the state of knowledge on pressure-sensitive adhesives (PSAs) and pyrolysis. Recent research data in the field of pyrolysis gas- chromatography (Py-GC) analysis of acrylic PSAs are presented. First, PSA characteristics and applications, pyrolysis (including Py-GC) as an analytical method, and system solutions, are described. The latest scientific achievements in the analysis of thermal degradation products of acrylic PSAs are then presented.

Keywords: acrylic and methacrylic copolymers; pressure-sensitive adhesives; pyrolysis; thermal degradation products; analysis and identification

Kinetics of the continuous reaction crystallization of barium sulphate in BaCl2 - (NH4)2 SO4 - NaCl - H2O system - neural network model by Krzysztof Piotrowski; Joanna Koralewska; Bogusława Wierzbowska; Andrzej Matynia; (pp. 13-19).
One of the main toxic components of post quenching salts formed in large quantities during steel hardening processes is BaCl2. This dangerous ingredient can be chemically neutralized after dissolution in water by means of reaction crystallization with solid ammonium sulphate (NH4)2 SO4. The resulting size distribution of the ecologically harmless crystalline product - BaSO4 - is an important criteria deciding about its further applicability. Presence of a second component of binary quenching salt mixture (BaCl2-NaCl) in water solution, NaCl, influences the reaction-crystallization process kinetics affecting the resulting product properties. The experimental 39 input-output data vectors containing the information about the continuous reaction crystallization in BaCl2 - (NH4)2 SO4 - NaCl - H2 O system ([BaCl2]RM = 10-24 mass %, [NaCl]RM = 0-12 mass %, T = 305-348 K and τ = 900-9000 s) created the database for the neural network training and validation. The applicability of diversified network configurations, neuron types and training strategies were verified. An optimal network structure was used for the process modeling.

Keywords: barium sulphate; sodium ions; used quenching salts; steel hardening; barium chloride; reaction crystallization kinetics; population density distribution; chemical neutralization; solid waste utilization; neural network model

Salt effect on the enthalpy of mixing of 2-propanol + acetic acid at 303.15 K by R. Tamilarasan; Sunil G. Baffna; A. Anand-Prabu; M. Dharmendira-Kumar; (pp. 20-23).
This paper presents the effect of two dissolved inorganic salts (zinc chloride, ZnCl2 and ammonium chloride, NH4Cl) on the enthalpy of mixing (HE) of 2-propanol + acetic acid binary system measured at 303.15 K using an isothermal displacement calorimeter with vapour space. A decreasing trend in the excess enthalpy of mixing values in the presence of ZnCl2 and NH4Cl indicate the endothermic behavior of this system. The Redlich-Kister equation has been used to fit the experimental HE data. The deviations from the ideal value and binary parameters were calculated and reported.

Keywords: Excess enthalpy; binary system; salt effect; 2-propanal; acetic acid

A Novel method for Thermodynamic Study on the Binding of Milk Carrier protein of BLG-A with Cr+3 by G. Rezaei Behbehania; A. Divsalar; A. A. Saboury; (pp. 24-29).
Thermodynamics of the interaction between Cr3+ with β-lactoglobulin type A (BLG-A) was investigated at pH 7.0 and 37°C by isothermal titration calorimetry. A new method to follow the effect of Cr3+ on the stability of BLG-A was introduced. The new solvation model was used to reproduce the enthalpies of BLG-A+ Cr3+ interactions over the whole range of Cr3+ concentrations. The solvation parameters recovered from the new equation are attributed to the structural change of BLG-A and its biological activity. The results obtained indicate that there is a set of two identical binding sites for Cr3+ ions with positive cooperativity. The association equilibrium constants are 14.39 and 0.49 mM-1 for the first and second binding site, respectively. The enthalpy of binding for one mole of Cr+3 ion to one mole of the binding site on BLG-A (ΔH=104.60 kJ mol-1) is obtained.

Keywords: BLG-A; Cr+3isothermal titration calorimetry; binding parameters

Catalytic oxidation of organic pollutants by Wiesław J. Parus; Wojciech Paterkowski; (pp. 30-37).

The paper presents the results of the measurements of the catalytic activity of V2O5/TiO2 and MoO3/TiO2 catalysts (8,10,12 and 15 wt % of V2O5 or MoO3 on TiO2 - anatase, respectively), prepared in our laboratory, in the complete oxidation (combustion) process of chosen volatile organic pollutants of the air such as methanol and n-butyl acetate. The activity of these catalysts was compared with the activity of industrial catalysts: supported platinum - Pt-p (0.15 wt % of Pt on γ-Al2O3) and MCA (15 wt % of CuO and 6 wt % of ZnO on γ-Al2O3). The investigations were carried out in the kinetic region (powder of the catalysts with the diameter in the range of 1.02-1.2·10-4 m) and for the chosen catalysts also in the diffusion region (the grains of the catalysts having the diameter of 2.5·10-3 m). On the basis of the obtained results the analysis of the process was performed.

It has been stated that reaction rate is well-described by the first order equation in relation to the methanol or n-butyl acetate concentration. On the basis of the obtained results in the kinetic region for all the applied catalysts the parameters of Arrhenius equation were determinated.

The comparison of the results for the kinetic region with the results for the diffusion region for the chosen catalysts allowed the calculation of the effective coefficients of diffusion. The parameters of Arrhenius equations as well as the effective coefficients of diffusion show a good correlation with the values obtained for the catalytic combustion of other organic pollutants of the air.

The measurements were carried out using a flow tubular reactor. The flow rate of the reaction mixture was kept constant 20 dm3/h (5.56·10-6 m3/s) in each test, using the space velocity of 20 s-1. It has been stated that the use of the applied catalysts led to the almost total oxidative destruction of both pollutants. Only H2O and CO2 were found as the final products of the reaction. The complete oxidation of the methanol process runs at the lower temperature than that of the complete oxidation process of n-butyl acetate. The most active at the combustion of methanol was the Pt-p catalyst. It demonstrates a comparable activity to molybdenum - titanium catalysts and the slightly lower activity than vanadium - titanium catalysts in the combustion of the n- butyl acetate process. The MCA catalyst was less active than the others in the oxidation of both compounds. The structures of the catalysts were tested using the X -ray analysis (XRD), infrared spectroscopy and scanning microscopy (SEM).

The results of the investigations show that V2O5/TiO2 and MoO3/TiO2 catalysts, especially the most active of them the 8% V2O5/TiO2 catalyst can be used in industrial systems for the purification of the air and industrial waste gases with VOCs, replacing the more expensive noble metals supported catalysts.

Keywords: catalytic oxidation of methanol and n-butyl acetate; V2O5/TiO2 and MoO3/TiO2 catalysts; macrokinetics of oxidation process

Application of central composite design for the optimization of photo-destruction of a textile dye using UV/S2O82- process by A. R. Khataee; (pp. 38-45).
The photooxidative destruction of C. I. Basic Red 46 (BR46) by UV/S2O82- process is presented. Central Composite Design (CCD) was employed to optimize the effects of operational parameters on the photooxidative destruction efficiency. The variables investigated were the initial dye and S2O82- concentrations, reaction time and distance of the solution from UV lamp. The predicted values of the photodestruction efficiency were found to be in good agreement with the experimental values (R2 = 0.9810, Adjusted R2 = 0.9643). The results of the optimization predicted by the model showed that the maximum decolorization efficiency (>98%) was achieved at the optimum conditions of the reaction time 10 min, initial dye concentration 10 mg/l, initial peroxydisulfate concentration 1.5 mmol/l and distance of UV lamp from the solution 6 cm. The figure-of-merit electrical energy per order (EEo) was employed to estimate the electrical energy consumption and related treatment costs.

Keywords: Experimental design; Response surface methodology; Decolorization; C. I. Basic Red 46; K2S2O8

Topical and prospective processes of acetoxylation by Grzegorz Lewandowski; Marcin Bartkowiak; Eugeniusz Milchert; (pp. 46-51).
The latest acetoxylation processes have been described in this work: oxidative acetoxylation of propene to allyl acetate, acetoxylation of propene to propene glycol and its acetates, acetoxylation of methyl tert-butyl ether and oxidative acetoxylation of cyclohexene by hydrogen peroxide. Acetoxylation of 1,3-butadiene, isobutene and toluene were presented together with a short description of the acetoxylation catalysts.

Keywords: acetoxylation; allyl acetate; hydrogen peroxide; propene glycol monoacetate; tert-butyl acetate; 2-cyclohexenyl acetate; tetrahydrofuran; benzyl acetate

Mixing system for highly concentrated fine-grained suspensions by Jiří Moravec; Tomáš Jirout; František Rieger; Lukáš Krátký; (pp. 52-56).
The mixing equipment for highly concentrated fine-grained suspensions must be designed differently from the equipment in which a suspension with a low concentration of the solid phase or bigger particles is mixed. It is due to the different rheological properties of the suspensions. In this work we are trying to find a suitable mixing system for a highly concentrated fine-grained suspension. The aim was to determine an effect of particular geometrical parameters of the tested mixing systems on a suspension process, especially from the energetic viewpoint. The energetic costs of all the used mixing systems were compared on the basis of the power consumption which was necessary for reaching the state of sufficient suspension movement in the whole mixed bulk. As a result, it was confirmed that multistage impellers can be used even in standard vessels (with a liquid level height equal to a vessel diameter) with a profit. During experiments, the state of sufficient movement was determined by a visual observation of the suspension at the vessel bottom, at the wall and also at the suspension level.

Keywords: Mixing; suspension; high concentration; fine particles; rheology

Destructive oxidation of ethanol in the corona discharge reactor by Wojciech Paterkowski; Wiesław Parus; Stanisław Kalisiak; (pp. 57-62).

The results of investigation of ethanol destructive oxidation (model aliphatic alcohol) in a corona discharge reactor are presented. The process was performed at the temperature of 303 K in the corona discharge generator - the reactor system manufactured in our laboratory. The process temperature was kept constant by cooling down the reactor with a stream of air. The measurements were carried out using the following process parameters: the inlet ethanol concentration in the stream of gases in the range of 0.0028 to 0.132 mol/m3 (0.128 ÷ 6.086 g/m3), the gas flow velocity in the range of 0.15-0.33 m3/h (space velocity in the range of 1220 ÷ 2680 m3/(m3R ·h)) and the power supply to the reactor ranged from 1.6 to 86.4 W. The active volume of the reactor was 1.23·10-4 m3. The phenomenological method was applied for the description of the process. It was based on the assumptions that the reaction rate can be described by the first order equation in relation to the ethanol concentration and the design equation of flow tubular reactor can be applied for the description of corona reactor. The usefulness of this model was estimated using statistical methods for the analysis of the experimental results. The Statistica 6.0 software was used for this application. The first stage of this analysis showed the dependencies between the considered variables, whereas the second stage was to find the equations describing the influence of the selected process parameters on the rate of ethanol destruction. The parameters of A and B of apparent constant rate equation given in the form of Z = A·exp(-B/P) were also determined.

The results of the investigations indicated that the applied corona discharge generator - reactor system assures a high efficiency of purification of the air and industrial waste gases contaminated by ethanol. The ethanol destruction degree of αi = 0.9 was obtained at the power supply to the reactor amounting to 650 kW/m3R per unit of its active volume. The final products of the reaction were only the harmless carbon dioxide and water vapour. It has been stated that the rate of the destructive oxidation of ethanol reaction is well described by the first order equation in relation to the ethanol concentration. Under isothermal conditions, the reaction rate also depends on the power supply to the reactor. This dependence is well described by the empirical equation Z = 3,233·exp(-82,598/P).

The obtained results also indicated that the method of destructive oxidation of ethanol in the corona discharge reactor can be useful for the removal of ethanol and probably other aliphatic alcohols from different gases. The described method of calculation of the real rate of the process can be successfully used in the design of corona discharge reactors applied for such processes.

Keywords: corona discharge reactor; destructive oxidation of ethanol; kinetics of reaction

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