Volume 17 (2015): Issue 2 (June 2015)

In the present study, we introduce a robust modified Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method in order to examine miscible mixing within a two-blade paddle mixer. Since it has a Lagrangian nature and it is based on particles, Smoothed Particle Hydrodynamics (SPH) is an appropriate and convenient method for simulating the moving boundary problems and tracking the particles in the mixing process. The present study thus introduces a convenient SPH method for modelling the mixing process for the power-law fluids. Two geometries for the mixer are examined and the effects of the power-law index on the fluid mixing are investigated. The results show that the geometric change from circular chamber to twin chamber considerably increases the mixing rate (by at least 49%). The results also indicate that the twin chamber mixer is more efficient for the fluids with higher power-law index.

Four granular fertilisers were produced from industrial waste products, such as CaSO₄ ∙ 2H₂O and FeSO₄ ∙ 7H₂O, coniferous and deciduous sawdust mixture and municipal sewage sludge with addition of mineral fertilisers. Based on the content of organic matter, nitrogen, phosphorus and potassium and heavy metals, these granular fertilisers can be included into the group of organic-mineral fertilisers. In order to determine their manurial value, a vegetation experiment was carried out with these granular fertilisers in which spring rape and spring triticale were the test plants. The study results show that granular fertilisers increased signifi cantly the yields of test plants and their content of macroelements. The granular fertilisers containing FeSO₄ ∙ 7H₂O increased signifi cantly the yields of test plants and the contents of macroelements when compared to those with CaSO₄ ∙ 2H₂O. As affected by the granular fertilisers containing CaSO₄ ∙ 2H₂O, there was more phosphorus, calcium and sulphur in the test plants. The granular fertilisers composed of the waste products mentioned above can be a cheap source of organic matter and nutrients for plants and may reduce possibility of environmental contamination.

The soil contaminated with petroleum products must be excluded from the crops and treated to reclamation processes. Natural processes of decomposition of hydrocarbon compounds go very slow, so it is necessary to use bioaugumentation or stimulation in order to accelerate the return of the soil to high culture. In this study the effect of hydrogen peroxide on the process of cleaning soil strongly contaminated with pertochemicals was investigated. For this purpose, a pot experiment lasting 60 days was carried. The dynamics of changes in the population of filamentous fungi, yeasts and bacteria were examined and also content of aliphatic hydrocarbons (n-alkanes), monoaromatic and polycyclic aromatic hydrocarbons (PAHs). Experimental use of hydrogen peroxide in the process of biodegradation of petroleum compounds assisted in the analyzed soil led to an increase of the number of grampositive bacteria during the test. Stimulation of oil products biodegradation by hydrogen peroxide also increased by 35% decomposition efficiency of aliphatic hydrocarbons (C8-C40) and about 50% PAH’s in comparison to control samples without hydrogen peroxide. There was no influence of hydrogen peroxide on the content of monoaromatic hydrocarbons (BTEX) with respect to controls, although in the end of experiment, the total concentration decreased by about 50% compared to the initial content.

The concept of different compositional biomass is introduced to enhance the binding properties and utilize the use of different seasonal biomasses. The effect of densification on the heating values of single pure and mixed compositional biomasses is observed with and without applying special type of pretreatment named as ‘Torrefaction’. The moisture contents and bulk densities were also calculated for these briquettes. The effects of average moisture contents and bulk density (which show the swelling nature) on the heating values are also observed. The experiments have been performed on the pelletizer equipment to form briquetted biomass and bomb calorimeter was used to determine the calorific values of different briquettes. Finally, the percentage decrease in the average moisture contents of different categories of torrefied briquettes from non-torrefied briquettes were also calculated and compared.

Poly(vinyl alcohol) films were prepared with manganous chloride (MnCl₂ · 4H₂O) and glycerin as complex plasticizer. The micro morphology of pure PVA film and complex plasticizer plasticized PVA films was observed by scanning electron microscope (SEM). The interaction between complex plasticizer and PVA molecules was investigated by Fourier transform infrared spectroscopy (FT-IR). The influence of complex plasticizer on crystalline, thermal and mechanical properties of PVA films was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and tensile testing, respectively. The results showed that the complex plasticizer of MnCl₂ · 4H₂O/glycerin could interacted with PVA molecular and then effectively destroy the crystals of PVA. PVA films plasticized with complex plasticizer of MnCl₂ · 4H₂O/glycerin became soft and ductile, with lower tensile strength and higher elongation at break compared with PVA films. This is an important cause of plasticization of the complex plasticizer of MnCl₂ · 4H₂O/glycerin on PVA films.

In present study, the synergistic separation of Cr(VI) has been investigated from synthetic acidic solution containing Cr(VI), Co(II) and Ni(II) by fl at sheet supported liquid membrane (FSSLM) technique using triisooctylamine (TIOA) and tri-n-butyl phosphate (TBP) as carriers. The main goal of the study was based in the exploring of the synergistic effect of TBP on selective extraction of Cr(VI) in presence of Co(II) and Ni(II) ions. The various parameters related with membrane and aqueous solution properties were studied to identify the optimum extraction and stripping conditions of the Cr(VI) through FSSLM. In the optimum conditions, initial mass flux (J0) and separation factors (β_Cr/Co and β_Cr/Ni) were obtained as 1.49 x 10^-05 (kg/m^2.s), 382.2 and 725.3 respectively from aqueous H₂SO₄ media through Celgard 2500 (Celgard Inc., USA) polymer support. As a result, the considerable synergistic infl uence on selective transport of Cr(VI) through FSSLM using TIOA and TBP as carriers has been identifi ed.

A series of iron oxide nanocatalysts were prepared using an ultrasonically assisted co-precipitation technique. Molybdenum promoted Fe₃O₄ and Fe₂O₃ were prepared from the original materials by wet impregnation using a solution of ammonium molybdate. The catalysts were tested in the liquid phase oxidation of benzene at atmospheric pressure and at 60°C using molecular oxygen. Phenol yields between 7% and 14.5% were obtained. The major products were pyrogallol and catechol.

In this study, palladium-modified nickel foam substrate was applied to examine ethanol oxidation reaction (EOR) in 0.1 M NaOH supporting solution. An EOR catalyst was prepared by physical vapour deposition (PVD) of palladium onto Ni foam material. Temperature-dependent kinetics of the EOR were studied over the temperature range: 20-60°C by means of a.c. impedance spectroscopy and cyclic voltammetry techniques. Deposition of a noble metal additive was clearly exposed through scanning electron microscopy: SEM/EDX-supported analysis. Most importantly, this work investigated the effect of pre-deposited fullerene on nickel foam, on the catalytic (EOR) properties of such-produced Ni foam/Pd composite material.

In this study, palladium-modified nickel foam substrate was applied to examine ethanol oxidation reaction (EOR) in 0.1 The transport of cobalt(II), nickel(II), copper(II), and zinc(II) ions from chloride solutions across polymer inclusion membranes (PIMs), which 1-heptylimidazole (1̲) or 1-heptyl-2-methylimidazole (2̲) or 1-heptyl-4-methylimidazole (3̲) as the ion carrier was reported. The steric effect for carriers 2̲and 3̲decreases the transport of all ions except Cu(II). The initial fl uxes of metal ions transport across PIMs with the 1̲- 2̲decrease in the sequence: Cu(II) > Zn(II) > Co(II) > Ni(II), whereas for 3 they were Cu(II) > Zn(II) > Ni(II) > Co(II). The highest recovery values were obtained for Cu(II), this being 99 and 85% for carrier 1̲and 2̲, respectively. In both membranes the degree of deposition of the Zn(II) ions was comparable. Zn(II), Co(II) and Cd(II) ions, which form complexes with coordination numbers 4 and 6, are more easily recovered with the use of carriers 2̲and 3̲. Ni(II) ions, which form complexes with coordination number 6 only, practically remain in the feeding phase. PIMs with alkylimidazoles were characterized by non-contact atomic force microscopy.

The present study reports on the leaching of natural pigment from Mucuna pruriens for dyeing of chrome tanned leather samples. The experiments were performed at temperature (30-70°C), time (30-90 min), feed to solvent ratio (1:3-1:7) and particle size (0.25-0.75 mm) using ethanol as solvent. The influence of process variables on percentage yield has been studied and the conditions were optimized using Box-Behnken design. The optimized conditions for intensified extraction was found to occur at a temperature of 60°C, extraction time of 1 hr, for a feed to solvent ratio of 1:5 and 0.75 mm particle size. The % yield under optimized conditions was found to be 47%. The extraction results were found to agree well with the statistical model (R² = 0.9740). The colouring ability of extracted dye has been tested on wet blue goat leathers. The dyed leather exhibited a better colour value, strength and fastness properties as inferred from reflectance and visual assessment tests.

Hybrid catalysts based on the TiO₂ matrix impregnated with Nd, Eu and Yb diphthalocyanines proved effective in oxidation of sulfite ions under irradiation with light from the UV-visible range. Micro- and nano-crystalline anatase powders were used in preparation of the photocatalysts, which were applied in the form of a suspension in the water phase. The reaction yield was found to depend on the phthalocyanine sensitizer used and the conditions of TiO₂ impregnation. The best results were obtained when micro-anatase impregnated with Yb-diphthalocyanine was used.

A novel polysaccharide-based hydrogel nanocomposite was prepared using grafting of acrylic acid (AA) on to kappa-carrageenan (κC) by incorporating multi-walled carbon nanotube (MCNT). In fact, MCNTs were used as nano-sized reinforcements in the synthesized nanocomposite. Spectroscopy together with morphology proved relatively strong κC-MCNT interaction. Besides, the swelling behavior of the nanocomposite hydrogel was studied. The results showed that in the presence of MCNTs, the equilibrium swelling capacity was decreased. This can be attributed to cross-linking role and hydrophilicity nature of MCNTs. The adsorption performance of hydrogel nanocomposite was also investigated for the removal of crystal violet (CV) as a cationic dye. The effects of some important parameters such as MCNT concentration, pH and contact time on the uptake of CV solution were studied. Equilibrium adsorption isotherm data of the hydrogel exhibited better fit to the Langmuir than to the Freundlich isotherm model. According to this model, the maximum adsorption capacity of κC-based hydrogel nanocomposite was found to be 118 mg . g^-1.

The purpose of the present work was the elaboration of research methodology of the exhaustion degree of performance properties of pipes based on unsaturated polyester and glass fibers, which were manufactured by the cross winding method on a poly(vinyl chloride) core. Within the frame of the work we conducted fatigue-ageing tests being the simulation tool of the degradation process of polyester-glass pipes. Diagnosis of the composite material condition was conducted with the use of nondestructive ultrasonic testing with the application of the echo method, in which the transition time of ultrasonic wave was determined as the identifying parameter. The registered transition time of ultrasonic wave allowed the identification of the material condition during the course of pipes exploitation.

An up-flow anaerobic packed bed (UAPB) bioreactor has been designed on a laboratory-scale and used for treatment of domestic milk wastewater (MWW). The UAPB bioreactor was operated under mesophilic temperature (37-45°C) and reactor performance evaluated at various organic loading rates of MWW effluent at hydraulic retention times (HRT) of 1, 2, and 3 d based on the removal of organic matter COD, BOD, SS, pH changes and biogas production. The kinetic parameters were estimated using the experimental data to develop a reactor model. Empirical relations were generated for the characteristics like COD, BOD, and SS using modeling equations. This study proved that the UAPB reactor performance is excellent for treating domestic MWW and easily biodegradable dairy wastewater influent. Hence, this system can operate at low costs, making it suited for use in the developing countries and rural areas.

The dissolution of corn stover in alkaline solvent system composed of NaOH-H₂O₂ was reported and the separation of its ingredients combined with acid precipitation, ethanol extraction was proposed. It is proven that the residual after alkali solvent was cellulose, the filtrate by the acid precipitation of the liquor was lignin, the solid by the ethanol extraction of the liquor was hemicellulose. The optimum dissolution conditions were determined by single-factor experiment as follows: the concentration of H₂O₂ 5.0%, pH 11.5, dissolution temperature 60°C, dissolution time 3.0 h, the ratio of liquid to solid 30 mL/g. And chemical analysis were employed to determine the purity of the components separated. The structure of the components separated were identifi ed by FT-IR, SEM, XRD and NMR. The cellulose recovery yield can achieve to 84.2% and lignin recovery yield is 86.6%, the hemicellulose recovery yield is 96.7%. After recycling the solvent 3 times, the recovery yield of cellulose, lignin and hemicellulose were 82.7, 87.6 and 97.4%, and the purity of cellulose, lignin and hemicellulose were 98.0, 96.5 and 98.7%, respectively.

The conducted studies were focused on the development of the gypsum material exhibiting self-cleaning properties. To this end, the raw gypsum was mixed with unique TiO₂-based photocatalysts, previously modified by nitrogen and/ or carbon doping. The photocatalytic activity of the obtained gypsum plasters was evaluated trough the degradation of model organic compound (Reactive Red 198) under UV-vis irradiation. The impact of the photocatalysts presence on the physicochemical properties of the obtained gypsum plasters was evaluated. Furthermore, the role of non-metals presence on the photocatalytic properties of the TiO₂ was determined. It was confirmed that the addition of N,C co-modified titanium dioxide into gypsum bestows this material with self-cleaning properties. The highest dye removal rate was displayed by the gypsum plaster containing optimal amount (10 wt%) of co-modified TiO₂/N,C photocatalyst, after 20 hours of UV-vis irradiation.

Titanium dioxide thin films doped with the same amount of neodymium were prepared using two different magnetron sputtering methods. Thin films of anatase structure were deposited with the aid of Low Pressure Hot Target Magnetron Sputtering, while rutile coatings were manufactured using High Energy Reactive Magnetron Sputtering process. The thin films composition was determined by energy dispersive spectroscopy and the amount of the dopant was equal to 1 at. %. Structural properties were evaluated using transmission electron microscopy and revealed that anatase films had fibrous structure, while rutile had densely packed columnar structure. Atomic force microscopy investigations showed that the surface of both films was homogenous and consisted of nanocrystalline grains. Photocatalytic activity was assessed based on the phenol decomposition. Results showed that both thin films were photocatalytically active, however coating with anatase phase decomposed higher amount of phenol. The transparency of both thin films was high and equal to ca. 80% in the visible wavelength range. The photoluminescence intensity was much higher in case of the coating with rutile structure.

The main goal of this study was the preparation of materials containing phosphoric functionalities on the base of industrial polymer - divinyl rubber and the assessment of their removal efficiency of heavy metals from aqueous solutions. The new method concerns the oxidative chlo-rophosphorylation of divinyl rubber by PCl₃ with the following modification of obtained inter-mediates to create -PO(OH)₂, -OPO(OH)₂ groups in the polymer chain. The obtained modified polymers get some new properties such as complex formation and capability for ion exchange. The nature and distribution of phosphoric functionalities in the polymer were studied by the methods of NMRand FTIR- spectroscopy, thermal analysis and scanning electron microscopy. The sorption properties of synthesized polymers towards some cations (Cu⁺², Ni⁺², Co⁺² and Zn⁺²) from water solutions have been tested. It has been shown that the metal removal efficiency of prepared material depends on pH of medium, initial concentration and type of metal ions.

Natural gas pressure has to be reduced from medium pressure of 1.724 MPa (250 psia) to lower pressure of 0.414 MPa (60 psia) at Town Border pressure reduction Station (TBS). Currently, the pressure reduction is carried out by throttling valves while considerable amount of pressure energy is wasted. One of the equipment which could be used to recover this waste energy is the reciprocating expansion engine. The purpose of this research is to simulate one-sided reciprocating expansion engine thermodynamically for TBS pressure range. The simulation is based on first law of thermodynamics, conversation of mass and ideal gas assumptions. The model could predict in-cylinder pressure and in-cylinder temperature at various crank angles. In addition, the effects of the engine geometrical characteristics, such as intake and exhaust port area and ports timing on the Indicated work per cycle output are investigated.

This work reports on kinetics of phenol electrooxidation reaction (PhER), examined at polycrystalline Pt electrode in 0.5 M H₂SO₄ and 0.1 M NaOH supporting solutions. Important aspects of PhER kinetics were analysed based on potential-dependent, a.c. impedance-derived values of charge-transfer resistance and capacitance parameters. Special attention was also given to the influence of supporting electrolyte ions on the process of phenol oxidation (pH dependence of the PhER), in relation to an important role of anion adsorption on the Pt catalyst surface.