Volume 19 (2017): Issue 2 (June 2017)

The formation of deposits on heat exchange surfaces of combustion equipment causes a decrease in heat exchange, a decrease in power, and consequently deterioration in the economic balance of combustion equipment. The technology of French company A. I. T. DRIVEX has been developing and being applied in practice for many decades. Preventive technology is used as a mean reagent periodically injected during operation into the combustion chamber. Part of the application is always pre-prepared project resolving the location of the injection nozzles into the combustion chamber on the flue gas path. The article describes the experimental usage of reagent GEPERSUITE 2200 at the Sermaize refinery in France. The aim of the test is to evaluate the benefits and advantages of applied technology in the boiler refinery in full operation. The results clearly demonstrate that using the reagent GEPERSUITE 2200 is advantageous in terms of economic and technical properties.

Cr(VI) adsorption was studied for abundantly available low-cost lignocellulosic adsorbents in Pakistan namely, tobacco stalks (TS), white cedar stem (WCS) and eucalyptus bark (EB). Several process variables like contact time, adsorbent dose, pH, metal concentration, particle size and temperature were optimized in batch mode. EB showed high Cr(VI) adsorption of 63.66% followed by WCS 62% and TS 57% at pH 2, which is higher than most of the reported literature. Langmuir isotherm (R² = 0.999) was well fitted into the equilibrium Cr(VI) data of EB, suggesting homogeneous active sites and monolayer coverage of Cr(VI) onto the EB surface. Freundlich (R² = 0.9982) isotherm was better fitted to the equilibrium data of TS and WCS, revealing the adsorption sites with heterogeneous energy distribution and multilayer Cr(VI) adsorption. Moreover, the Cr(VI) adsorption of studied adsorbents followed the pseudo-second order kinetic model. Thermodynamic properties were investigated in two temperature ranges, i.e., T₁ (303–313 K) and T₂ (313–323 K). TS and EB showed the exothermic at T₁ and endothermic reactions at T₂ with entropy controlled adsorption at the solid-liquid interface, and WCS exhibited an opposite thermal trend with decreasing disorderness at solid-liquid interface as temperature rises. Gibbs free energy (ΔG>0) confirmed the non-spontaneous adsorption process for all studied adsorbents.

The aim of this study was to highlight the interest of using CFD technique as a diagnostic tool of a malfunctioning Solid Oxide Fuel Cells. Hydrogen starvation of a SOFC due to nitrogen dilution is one of the cell dysfunctions and can lead to its degradation. Identification of the starvation point allows to improve cell performance and establish the best conditions for degradation tests. To illustrate a potential of the CFD tool, several simulations of a single planar SOFC and its behaviour under hydrogen starvation were performed and analysed. The results showed that at lower cell voltage values of 0.3 and 0.5 V significant gradients in the electric current were noticed due to a local reduction in hydrogen concentration. The CFD analysis allowed defining desirable mass flow rate of hydrogen to SOFCs to avoid fuel starvation. The model constitutes a helpful tool for optimizing cell design and operational conditions.

In this study, ultrasonic treatment of baker’s yeast effluent was investigated in an ultrasonic homogenizer emitting waves at 20 kHz. The SnO₂/TiO₂ composites were used as a sonocatalyst to assist the sonication process. Decolorization and chemical oxygen demand (COD) removal of baker’s yeast effluent with ultrasonic irradiation was examined. The effect of the composite preparation method, the molar ratio of SnO₂/TiO₂, mixing time while the composite was prepared, the calcination temperature and time, the catalyst amount were investigated. The decolorization was higher at a 4:1 molar ratio of the SnO₂/TiO₂ composite prepared by using an ultrasonic probe and 6 min ultrasonic irradiation time. The decolorization increased, with an increase in the calcination temperature. The optimum calcination time was 60 min and catalyst amount was 0.2 g/l. According to the results, decolorization rate was 26.63% using this composite. There was no COD removal at the studied conditions.

The bottom waste obtained from bio-mass burning shows a huge variability of chemical and physical properties, depending on the kind of bio-mass, the type of a cauldron and burning parameters. The huge variability of the bottom ashes from the incineration plant and co-combustion of bio-mass makes it difficult to find any way to its management. In reality, only the bottom ashes from coal combustion and the small amount from lignite combustion are used, mainly in the building industry and in mining industry. The article presents the initial research, concerning the estimation of the properties of the bottom ashes obtained from bio-mass congestion in the fluidized-bed boiler to use them safely for the environment. To determine the influence of the tested waste on plants, a number of pot experiments have been conducted. The plants which have been used are recommended for phytotoxicity estimation, and are also used for biological reclamation.

Research treats about producing activated carbons for CO₂ capture from hazelnut shells (HN), walnut shells (WN) and peanut shells (PN). Saturated solution of KOH was used as an activating agent in ratio 1:1. Samples were carbonized in the furnace in the range of temperatures 600°C–900°C. Properties of carbons were tested by N₂ adsorption method, using BET equation, DFT method and volumetric CO₂ adsorption method. With the increase of carbonization temperature specific surface area of studied samples increased. The largest surface area was calculated for samples carbonized at 900°C and the highest values of CO₂ adsorption had samples: PN900 at 0°C (5.5 mmol/g) and WN900 at 25°C (4.34 mmol/g). All of the samples had a well-developed microporous structure.

The objective of this work was preparation of activated carbon from spent dregs for carbon dioxide adsorption. A saturated solution of KOH was used as an activating agent. Samples were carbonized in the furnace at the temperature of 550°C. Textural properties of activated carbons were obtained based on the adsorption-desorption isotherms of nitrogen at −196°C and carbon dioxide at 0°C. The specific surface areas of activated carbons were calculated by the Brunauer – Emmett – Teller equation. The volumes of micropores were obtained by density functional theory method. The highest CO₂ adsorption was 9.54 mmol/cm³ at 0°C – and 8.50 mmol/cm³ at 25°C.

In this work extrusion process were used to create thermoplastic starch and to mix obtained starch with linen, quince and apple pomace at the same time. Obtained starch beads were formed in shapes. In experimental material was determined thermal conductivity, water absorption and the solubility in water. It is possible to get the biodegradable material produced from thermoplastic starch with an addition of fruit pomace. Adding pomace and glycerine to the biodegradable material made from starch change of susceptibility on water action. In the case of materials containing pomace, glycerine addition decreases the susceptibility on water action compared to the material manufactured with pomace addition but without glycerine. In the material containing pomace, glycerine addition caused the increase of the thermal insulation time compared to the material with pomace but no glycerine in it.

This study presents a facile approach for the preparation of MoS₂ nanosheet decorated by porous titanium dioxide with effective photocatalytic activity. Mesoporous titanium dioxide nanostructures first synthesized by a hydrothermal process using titanium (III) chloride and then the MoS₂/TiO₂ were prepared through mixing of MoS₂ nanosheet with mesoporous titanium dioxide under ultrasonic irradiation. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) analysis. The results showed that the nanocomposite has mesoporous structure with specific surface area of 176.4 m²/g and pore diameter of 20 nm. The as-prepared MoS₂/TiO₂ nanocomposites exhibited outstanding photocatalytic activity for dye degradation under sunlight irradiation, which could be attributed to synergistic effect between the molybdenum disulfide nanosheet and mesoporous titanium dioxide. The photocatalytic performance achieved is about 2.2 times higher than that of mesoporous TiO₂ alone. It is believed that the extended light absorption ability and the large specific surface area of the 2D MoS₂ nanosheets in the nanocomposite, leading to the enhanced photocatalytic degradation activity.

A thermal decomposition of a cobalt-lanthanum catalyst precursor containing a mixture of cobalt and lanthanum compounds obtained by co-precipitation were studied using thermal analysis coupled with mass spectrometry (TG-MS). Studies revealed that the calcination in air at 500°C is sufficient to transform the obtained cobalt precipitate into Co₃O₄, but it leads to only partial decomposition of lanthanum precipitate. In order to obtain Co/La catalyst precursor containing La₂O₃ the calcination in air at the temperature about 800°C is required. However, it is unfavorable from the point of view of textural properties of the catalyst precursor. A strong effect of storage conditions on the phase composition of the studied cobalt-lanthanum catalyst precursor, caused by the formation of lanthanum hydroxide and lanthanum carbonates from La₂O₃ when contacting with air, was observed.

The COD removal efficiency from an instant coffee processing wastewater using electrocoagulation was investigated. For this purpose, the response surface methodology was employed, using central composing design to optimize three of the most important operating variables, i.e., electrolysis time, current density and initial pH. The results based upon statistical analysis showed that the quadratic models for COD removal were significant at very low probability value (<0.0001) and high coefficient of determination (R² = 0.9621) value. The statistical results also indicated that all the three variables and the interaction between initial pH and electrolysis time were significant on COD abatement. The maximum predicted COD removal using the response function reached 93.3% with electrolysis time of 10 min, current density of 108.3 A/m² and initial pH of 7.0, respectively. The removal efficiency value was agreed well with the experimental value of COD removal (90.4%) under the optimum conditions.

Thermally activated persulfate efficiency for the treatment of a recalcitrant high TDS wastewater was investigated. The specific character of studied wastewater was high TDS content of around 23820 mg/L and BOD5/COD ratio of 0.07. Effective operational parameters including initial pH values of 3–9, reaction temperature of 40–80°C and persulfate concentrations of 0.5–5 g/L for COD removal were investigated in batch mode experiments. Removal efficiency was pH and temperature dependent. The COD and TOC removal of 94.3% and 82.8% were obtained at persulfate concentration of 4 g/L, initial pH value of 5 and temperature of 70°C after 180 min for initial COD concentration of 1410 mg/L. The pseudo first-order kinetic model was best fitted with COD removal (R² = 0.94).

Calcium and zinc salts of dimer fatty acids (DFA-Ca and DFA-Zn) were synthesized using direct neutralization and metathesis technologies, respectively. The adduct of maleic anhydride and methyl eleostearate (MAME) was also converted to the corresponding zinc soap (C22TA-Zn) and calcium soap (C22TA-Ca) by the two different synthetic routes. Mixed Ca/Zn salts between DFA-Ca and DFA-Zn, and between C22TA-Zn and C22TA-Ca were used as thermal stabilizers for poly(vinyl chloride) (PVC). The PVC thermal stability was determined using Congo red test, discoloration test, torque rheological analysis and TGA. Dynamic mechanical properties were also tested. Results indicated that the DFA-Ca/DFA-Zn thermal stabilizer from direct neutralization technology was found to be superior to that of the metathesis product. The C22TA-Ca/C22TA-Zn thermal stabilizer from direct neutralization method had overall superior thermal stability, and displayed modulus and glass transition comparable to that of metathesis product. Direct neutralization method was more excellent and convenient than metathesis technology.

New fragrant and biodegradable starch-based films have been obtained. These films were prepared by the method of the outpour into the Teflon mould of the starch composition containing such fragrant compounds as: eugenol or α-pinene. For characterizing the final products the following properties were taken into account: the solubility in water, the absorbance of moisture from air and the length of release of the fragrant compound. The obtained starch-based films were characterized by the relatively long time of release the fragrant compound and also by the good absorbance of moisture from air. Taking into account the properties of the obtained films, they can find applications in production of appliances used in the bioactive cleaning of air. The prototype of such a product was presented in this work. The presented studies show the potential of applying these materials in the future, and thus these examinations should be developed.

The elastomeric anti-trauma pad (EA-TP) based on shear thickening fluid (STF) has been developed. Dynamic oscillatory shear experiment was conducted at constant strain amplitude of 5%. STF composed of 25% of volume fraction of 7 nm Fumed Silica, dispersed in polypropylene glycol with molar mass 400 gmol⁻¹ shows elastic properties in entire investigated range of the frequency. Ballistic tests of EA-TP with 7.62 mm × 39 mm PS bullets were performed according to the PN-V-87000:2011 standard. The studies revealed about 60% reduction of the average backface signature depth (BSD) for the EA-TP, when compared to the nowadays commonly used soft insert. The ATR-FTIR analysis confirmed slight impact of the elevated temperature and air (oxygen) on the chemical degradation of the EA-TP surface. The UV-VIS spectroscopy has allowed to notice colour deviation of the aged samples towards green and yellow, as well as lack of dye resistance to accelerated aging process. Thermographic analysis has shown no visible changes of the EA-TP surface and sub-surface during accelerated aging process. The aforementioned small changes on the surface of EA-TP did not affect the ballistic properties of composite armour. EA-TP insert maintains ballistic properties after accelerated aging process which was simulating the period of 6 years according to ASTM F1980 – 07:2002 standard.

The article describes the technology of NO_x emission abatement by SNCR method. The scope of research included CDF simulations as well as design and construction of the pilot plant and tests of NO_x reduction by urea in the plant located in industrial pulverized-coal fired boiler. The key step of research was to determine the appropriate temperature window for the SNCR process. The proposed solution of the location of injection lances in the combustion chamber enabled to achieve over a 30% reduction of NO_x. It is possible to achieve higher effectiveness of the proposed SNCR technology and meet the required emission standards via providing prior reduction of NO_x to the level of 350 mg/um³ using the primary methods.

The aim of the present study was to evaluate the impact of a rotating magnetic field (RMF) on cellular and biochemical properties of Gluconacetobacter xylinus during the process of cellulose synthesis by these bacteria. The application of the RMF during bacterial cellulose (BC) production intensified the biochemical processes in G. xylinus as compared to the RMF-unexposed cultures. Moreover, the RMF had a positive impact on the growth of cellulose-producing bacteria. Furthermore, the application of RMF did not increase the number of mutants unable to produce cellulose. In terms of BC production efficacy, the most favorable properties were found in the setting where RMF generator was switched off for the first 72 h of cultivation and switched on for the further 72 h. The results obtained can be used in subsequent studies concerning the optimization of BC production using different types of magnetic fields including RMF, especially.

In a continuing effort to realize the simultaneous hydrogen and methanol production via the auto-thermal methanol synthesis process, the effect of two different hydrogen redistribution strategies along a double-membrane reactor has been considered. A steady-state one-dimensional heterogeneous model was developed to compare two strategies applied in the operation of the auto-thermal methanol synthesis. It was found that the counter-current configuration exhibited the better performance compared to the reactor operated in the co-current mode from both the economic and environmental points of view. This superiority is ascribed to the establishment of a more favourable temperature profile along the reactor and also more hydrogen extraction from the reaction zone. Moreover, the influence of some operating variables was investigated on the performance of the auto-thermal double-membrane reactor in the counter-current configuration. The results suggest that utilizing this configuration for pure hydrogen and methanol production could be feasible and beneficial.

The electro-synthesis of poly(aniline-co-para–aminophenol) on graphite electrode was examined using cyclic voltammetry (CV) over the potential window of −0.2 V to 1 V in phosphoric acid medium, which was comprised of potassium chloride and para–Toluene sulfonic acid (pTSA) as electrolyte support. Fourier transform infrared (FTIR) spectroscopy was employed to identify the electro-synthesized copolymer while impedance techniques were used to determine charge transfer resistance (Rct) in modified and unmodified electrodes. After this, the electro-catalytic effect of the modified electrode on ascorbic acid was examined using differential pulse voltammetry (DPV) and a very strong response was observed. A negative shift of about 0.33 V was found in the peak anodic potentials for ascorbic acid. Measurement using DPV indicated a proper response by the electrode to a wide range of ascorbic acid concentrations, from 0.0001 to 0.0004 M. The peak anodic currents for increased concentrations showed a proper linear range.

In this study, UV-C light was tested as an alternative method to inactivate microorganisms in the must of ‘Regent’ red grape cultivar. The control sample containing the microorganism diluted in a physiological NaCl solution was prepared to take into consideration different conditions of liquids, such as turbidity and colour. Additionally, the changes in the composition of polyphenol compounds in the ‘Regent’ must after UV-C exposure were evaluated. The viability of yeasts (Saccharomyces cerevisiae) and bacteria (Oenococcus oeni) significantly decreased with time; however, the highest decline was noted after the first hour of exposure. The polyphenol compound content was significantly lower after UV-C treatment and this was mainly the result of anthocyanin decomposition. The total content of flavan-3-ols and hydroxycinnamic acids and derivatives increased after irradiation.