Volume 12 (2010): Issue 3 (January 2010)

The photocatalytic reduction of carbon dioxide with hydrogen was studied by Temperature-Programmed Surface Reaction (TPSR). This process was carried out in a flow reactor that was especially designed and constructed for this purpose. Titanium dioxide (TiO₂, Degussa P-25) was used as supports for platinum, ruthenium and nickel catalysts. The experimental results indicated that the activity of photoreduction of CO₂ changes as follows: Ru/TiO₂ > Ni/TiO₂ > = Pt/TiO₂ > TiO₂.

A comparative study of Diels-Alder reaction between cyclopentadiene and dimethyl maleate in catalytic system is reported. The catalytic system was formed from ionic liquid which was made of N-hexylpyridinium bis(trifluoromethylsulfonyl)imide and magnesium trifluoromethanesulfonate. The yields, TONs, TOFs and endo:exo ratios were calculated. The optimal catalyst concentration was found in order to obtain the mixture of endo, exo isomers with the highest yields. Moreover recycling of the catalytic system consisting of Mg(OTf)₂ (2 mol%) and ionic liquid was performed. The distillation was noticed to be a better product removal method than extraction by organic solvent, taking into consideration both the TON and TOF values.

The results of investigations on a possible utilization of waste products formed during the production of commercial and food inorganic salts are presented. Application of wastes in the production of compound fertilizers was suggested. The work covered a full research cycle starting from laboratory tests and ending on the production implementation. Fertilizer formulas were developed on the basis of laboratory tests. A possible production of fertilizers of suggested compositions was tested on a pilot plant scale. The compound fertilizer production with the use of waste raw materials was implemented in Chemical Company Alwernia S.A. It reduced the amount of wastes directed to industrial waste site.

The aim of the studies presented in this paper was the selection of the polyurethanes synthesized from different substrates in order to obtain i) ceramic - biodegradable polymer composite and ii) polyurethane resistant to abrasive wear. The polyurethanes were obtained from the crystalline prepolymers extended by water, because it may have a beneficial effect on the toxicity of the material. The properties of PUs were investigated using infrared spectroscopy, thermogravimetry, differential scanning calorimetry and scanning electron microscopy. In all the tested polyurethanes the peak from the reactive -NCO groups was not observed, which indicates that all the substrates are fully reacted. Such polyurethanes are characterized by interesting properties with the perspective use as components of ceramic-polymer joints endoprosthesis. The designed endoprosthesis should fulfill at least three functions: load bearing function (ceramic core), fastening and stabilizing endoprosthesis to the bone (composite ceramics - biodegradable polymer) and tribologic function allowing mating with parts of the prosthesis (polyurethane layer resistant to abrasive wear).

One of the alternative methods for the treatment of animal by-products is their utilization in biological processes with a simultaneous production of energy-rich biogas. The results of the investigations of methane fermentation of animal waste are discussed in the study. The methane fermentation was carried out at 35°C. The substrates used in the experiments included poultry heads and muscle tissue. Furthermore, the fermentation residues subjected previously to hydrothermal processing were used as a substrate. The suspension of those substrates in the initial concentration range from 1 g TOC/dm³ to 11 g TOC/dm³ was used in the process. Additionally, the effect of the preliminary stage of hydrothermal substrate processing on methane fermentation efficiency was assessed. Poultry waste was subjected to thermohydrolysis at the temperature from 100°C to 300°C and pressure up to 9.0 MPa. The efficiency of the methane fermentation was estimated on the basis of biogas generated in the process. The biogas production was between 0.17 Ndm³/g TOC and 1.53 Ndm³/g TOC. In the case of poultry heads, a beneficial impact of hydrothermal processing at the temperatures from 100°C to 175°C was confirmed. For poultry meat the preliminary thermohydrolysis brought about a decrease of methane fraction in the biogas evolved. The preliminary hydrothermal processing made it possible to meet the requirements of legal regulations for the hygienization of by-products of animal origin. The obtained results allowed us to identify conditions under which the methane fermentation was carried out and which ensured a high level of methanization.

The removal of selected phenols (phenol, 4-methoxyphenol, 4-fluorophenol, 4-nitrophenol, 4-methylphenol, 4-chlorophenol, 2,4-dichlorophenol) from aqueous streams by liquid-liquid extraction is studied. Butylene and propylene carbonate - are used as green extractants. They permit to remove almost 100% of the examined phenols from feed solutions of phenol concentration about 20 g/dm³. Additionally, stripping of phenols from loaded organic phases is carried out with NaOH. The results of extraction parameters for alkylene carbonates (extraction efficency and distribution ratio) are compared with commercial solvating extractant - Cyanex 923.

The equilibrium of zinc(II) extraction from hydrochloric acid solutions with phosphonium and ammonium quaternary salts and their application as carriers in polymer inclusion membranes were studied. The most efficient was the extraction of zinc with the use of chlorides and bromide of ammonium and phosphonium salt (more than 90%). Quaternary ammonium and phosphonium chlorides and bromide are efficient extractants of zinc(II) from hydrochloric acid solutions. Two-fold molar excess of extractant over Zn(II) is necessary for efficient extraction (100%). Solvent extraction power of the extractants studied decreases with increasing hydrophobicity of the anion in the following sequence: QPCl > QPBr > QPBis > QACl > QABF₄ > QPBF₄ > QPPF₆ > QPNtf₂. A solution of 1 M H₂ SO₄ is chosen as the best stripping phase from the technological and economical point of view. Transport across polymeric inclusion membrane enables concentration of the stripping solution; however it takes a very long time.

This work presents the results of the synthesis of carbon nanotubes using the CVD method. Fe: MgO catalyst was used, also in combination with rare earth elements (gadolinium (Gd), dysprosium (Dy)), which when used alone, are not efficient as catalysts in nanotube growth. Synthesis was performed both at reduced pressure (10^-3 mbar) and atmospheric pressure, with constant parameters dependent on the process parameters.

The photocatalytic production of hydrogen over several chemical compounds based on sodium niobates and tantalates has been investigated. The photocatalysts have been prepared by an impregnation method of Nb₂O₅ and Ta₂O₅ in the aqueous solution of sodium hydroxide and then the calcination at the temperature range of 450 - 800°C. In this report, we present the study showing that of the catalysts explored, the highest photocatalytic activity was shown in a sample obtained at the temperature of 450°C and containing NaTaO₃ as a main phase.

Efficient methods of utilization of waste chloroorganic compounds coming from waste water and the waste streams formed e.g. in the production of vinyl chloride by dichloroethane method and in the production of propylene oxide by chlorohydrin method have been presented. First the separation of chloroorganic wastes by the adsorption methods has been described in the article. Three valuable methods of chlorocompounds utilization have been then discussed. The first one is isomerization of 1,1,2-trichloroethane to 1,1,1-trichloroethane as the valuable product with less toxicity than a substrate. The second method is ammonolysis of waste 1,2-dichloropropane and 1,2,3-trichloropropane. The third described method is chlorolysis. This method can be used for the utilization of all types of waste chloroorganics.

The influence of the technological parameters on the epoxidation of 1,5,9-cyclododecatriene (CDT) to 1,2-epoxy-5,9-cyclododecadiene (ECDD) by the phase-transfer catalysis method (PTC) in the presence of tungstophosphoric heteropolyacid (H₃PW₁₂O₄₀) and hydrogen peroxide as the oxidizing agent has been presented. The phase-transfer catalyst was Aliquat® 336 (methyltrioctylammonium chloride). The epoxidation of CDT to ECDD in the PTC system proceed under the relatively mild condition: low temperature, lack of solvent, short reaction time.

The effect of: the mixing velocity, the molar ratio of CDT:H₂O₂ and H₂O₂:H₃PW₁₂O₄₀, the nature of the solvent and its concentration, was studied. The most advantageous technological parameters were: the mixing rate 400 - 600 rpm, the molar ratio of CDT:H₂O₂ = 3:1 - 1.5:1, the molar ratio of H₂O₂:H₃PW₁₂O₄₀ = 200:1 - 400:1, the temperature 40 - 50°C, solvent: dichloromethane or lack of the solvent, dichloromethane concentration: 10 - 50 vol%, reaction time 35 - 50 min. The application of the above-mentioned parameters allows to achieve the yield of 44 - 47% ECDD in relation to introduced CDT.

In this work preparation and characteristic of modified nanocarbons is described. These materials were obtained using nanocrystalline iron as a catalyst and ethylene as a carbon source at 700°C. The influence of argon or hydrogen addition to reaction mixture was investigated. After ethylene decomposition samples were hydrogenated at 500°C. As a results iron carbide (Fe₃C) in the carbon matrix in the form of multi walled carbon nanotubes was obtained. After a treatment under hydrogen atmosphere iron carbide decomposed to iron and carbon and small iron particles agglomerated into larger ones.

Thermal degradation of the low density polyethylene (LDPE), polypropylene (PP) and the municipal waste plastics was investigated. The thermo-catalytic degradation of LDPE and PP was studied in the presence of the following catalysts: four different types of montmorillonite: K5, K10, K20, K30 and - for comparison - zeolites (natural - clinoptilolite, Y_Na+ and Y_H+). Thermal analyses TG-DTA-MS of polymers and polymer-catalyst mixtures were carried out in an argon flow atmosphere in isothermal and dynamic conditions. The following order was found: in lowering the reaction temperature for LDPE degradation Y_H+ > mK5 > mK20 = mK30 >mK10 > NZ > Y_Na+; for PP degradation: mK20 > mK5 = mK30 >mK10 > Y_H+ > NZ > Y_Na+. The activity tests were carried out in a stainless steel batch reactor under atmospheric pressure in a wide temperature range of up to 410°C, and using the atmosphere of argon flow. The liquid products were analysed by the GC-MS method. The hydrocarbons in the liquid products from thermal degradation of polymers were broadly distributed in the carbon fractions of C₈ to C₂₆ - for LDPE and C₆ to C₃₁ for PP.

The studies covered sugar industry. The analyses of wastes and wastefulness indicators in the sugar industry were performed in the paper. The results showed that processing of sugar beet generates the formation of huge quantities of side products and wastes. The values of indicators obtained in individual factories were very similar.

The results of preliminary research on the possibility of removing of chromium(III) and copper(II) ions from micellar solutions in MEUF were described. The effectiveness of metal ions removal in the classical UF and MEUF was compared. It was confirmed that in the classical UF the retention of metal ions is small, independent of the concentration of the feed solution. The cross-flow micellar enhanced ultrafiltration experiments showed the usefulness of this method for the separation of metal ions from micellar solutions. The retention of metal ions in MEUF process is almost total in the case of the solutions of low concentration. However, for more concentrated solutions the retention is much smaller.

The influence of technological parameters on the transformation of 1-butene-3-ol (1B3O) to bis(3-methyl-1-propene) ether (2×1B3O ether) and 3-(3-methyl-1-propene)-3-methyl-1,2-epoxypropane ether (1B3Ox1,2EB3O ether) over the TS-2 catalyst was presented. The reaction was performed in a glass reactor at atmospheric pressure and in methanol medium (protic solvent). The optimum conditions of 2×1B3O ether and 1B3Ox1,2EB3O ether obtaining were established by the mathematical method of experiments design (rotatable-uniform design) and after the analyses of the layer drawings.

The optimum conditions for biosorption of Pb(II) and Ni(II) from aqueous solution were investigated, by using living and nonliving Pseudomonas fluorescens and Bacillus pumilus isolated from wastewater treatment plant. It was found that the optimum pH for Pb(II) removal by living and nonliving cells was 6.0, while 7.0 for Ni(II) removal. At the optimal conditions, metal ion biosorption was increased as the initial metal concentration increased. The binding capacity by living cells is significantly higher than that of nonliving cells at tested conditions. The maximum biosorption capacities for lead and nickel by using Ps. fluo-rescens and B. pumilus were 77.6, 91.4 and 65.1, 73.9 mg/g, respectively. The results of bio-sorption time and desorption experiments suggested that Pb(II) and Ni(II) uptake by the living bacterial biomass might be enhanced by intracellular accumulation.