Volume 15 (2013): Issue 3 (September 2013)

Porous superhydrophobic layer of low-density polyethylene (LDPE) was created by a simple approach on the Poly(vinylidenefluoride) (PVDF) hollow fiber membranes. Acetone and ethanol mixtures with different volume ratios were used as the non-solvent on the coating surface. A 5:1 (v/v) acetone/ethanol ratio provided a porous surface with a 152° ± 3.2 water contact angle. The high contact angle could reduce membrane wettability for better carbon dioxide capture when the membrane was used as gas-liquid contactor in absorption processes. To assess the effect of the created superhydrophobic layer, the pristine and modified membranes were tested in a CO₂ absorption system for ten days. The results revealed that the absorption flux in the modified membrane was higher than that of pristine membrane.

Enzymatic depolymerisation of starch to glucose or maltose is carried out by starch- degrading amylases during a two-stage hydrolysis: liquefaction using bacterial α-amylase followed by saccharification with glucogenic (fungal amylase) or maltogenic (fungal or bacterial) amylases. As a rule, these enzymes are applied separately, following the recommendations concerning their action provided by the enzyme manufacturers. The study presents our attempts to determine the reaction conditions for a simultaneous action of liquefying and saccharifying enzymes on pre-treated potato starch. Hydrolysis was run by Liquozyme Supra, Maltogenase 4000L and San Super 360L enzymes (Novozymes) at different temperatures. During the single-stage method of starch hydrolysate production the most desirable results was obtained for the maltose hydrolysate at 80°C (51.6 DE) and for the glucose hydrolysate at 60^°C (96 DE). The analyses indicate that the application of a single-stage hydrolysis of starch to maltose or glucose makes it possible to obtain a degree of starch saccharification comparable with that obtained in the traditional two-stage hydrolysis.

The article reports sol-gel synthesis of nanosized spinel-type lithium manganese oxide LiMn₂O₄ (LMO) carried out in the presence of graphene oxide (GO) and its electrochemical lithium insertion ability. The synthesis was performed in an aqueous environment with lithium acetate and manganese acetate used as precursors and citric acid as a chelating agent. The material was characterized by X-ray diffraction, SEM microscopy, Raman spectroscopy and cyclic voltammetry. The calcination step totally eliminated graphene from the final product, nevertheless its presence during the synthesis was found to affect the resulting LiMn₂O₄ morphology by markedly reducing the size of grains. Moreover, potentials of electrochemical lithium insertion/deinsertion reactions have been shifted, as observed in the cyclic voltammetry measurements. Along with the diminished grain size the voltammetric curves of the graphene oxide-modified material exhibit higher oxidation and lower reduction peak currents. The study demonstrates that GO mediation/assistance during the sol-gel synthesis fosters more nanostructured powder and changes the electrochemical characteristics of the product

The present study investigated the effect of the surface functional groups of nanosilica on the interfacial, crystallization, and thermal stability of polyamide 6/SiO₂ (PA6/SiO₂) nanocomposite, in which nanosilica was modified in situ with both 3-triethoxysilylpropylamine and 3-methacryloxypropyltrimethoxy silane¬ (KH-550 and KH-570). The FTIR analysis results showed the chemical bonding action between the reacting amino groups of nanosilica and end carboxyl groups of polyamide 6 enhanced with increasing the ratio of KH-550 and KH-570. The XRD spectrum indicated that the crystal structure of PA6/SiO₂ nanocomposites tended to form α crystal type that was beneficial to an improvement of mechanical properties, and which was in agreement with the results of mechanical strength measurements. It was also found that crystallization temperature and crystallization rate of PA6/SiO₂ nanocomposites were lower than that of neat polyamide 6.

Studies on the currently used organophosphorus insecticides with respect to their environmental levels and effective remediation technologies for their residues in water have been considered as a source of major concern. This study was carried out to monitor the presence of organophosphorus in drinking water plants (Kafr-El-Shiekh, Ebshan, Elhamoul, Mehalt Aboali, Fowa, Balteem and Metobess) in Kafr-El-Shiekh Governorate, Egypt. Furthermore, it was carried out to evaluate the efficiency of different remediation technologies (advanced oxidation processes and bioremediation) for removing chlorpyrifos in drinking water. The results showed the presence of several organophosphorus pesticides in water sampling sites. Chlorpyrifos was detected with high frequency relative to other compounds in drinking water. Nano photo-Fenton like reagent (Fe₂O₃(nano)/H₂O₂/UV) was the most effective treatment for chlorpyrifos removal in drinking water followed by ZnO(nano)/H₂O₂/UV, Fe³⁺/H₂O₂/UV and ZnO/H₂O₂/ UV, respectively. Bioremediation of chlorpyrifos by effective microorganisms (EMs) removed 100% of the chlorpyrifos initial concentration after 23 days of treatment. There is no remaining toxicity in chlorpyrifos contaminated-water after remediation on treated rats with respect to cholinesterase activity and histological changes in kidney and liver relative to control. Advanced oxidation processes especially with nanomaterials and bioremediation with effective microorganisms can be regarded as safe and effective remediation technologies for chlorpyrifos in drinking water.

The surface modified Strychnos potatorum seeds (SMSP), an agricultural waste has been developed into an effective adsorbent for the removal of Zn(II) ions from aqueous environment. The Freundlich model provided a better fit with the experimental data than the Langmuir model as revealed by a high coefficient of determination values and low error values. The kinetics data fitted well into the pseudo-second order model with the coefficient of determination values greater than 0.99. The influence of particle diffusion and film diffusion in the adsorption process was tested by fitting the experimental data with intraparticle diffusion, Boyd kinetic and Shrinking core models. Desorption experiments were conducted to explore the feasibility of regenerating the spent adsorbent and the adsorbed Zn(II) ions from spent SMSP was desorbed using 0.3 M HCl with the efficiency of 93.58%. The results of the present study indicates that the SMSP can be successfully employed for the removal of Zn(II) ions from aqueous environment.

A study on the synthesis of esters of fatty acids of natural origin (oleic acid from rapeseed oil) and branched synthetic isostearic acid with commercially available alcohols C₈-C₉ i.e. 2-ethylhexanol (2-EH) and 3,5,5-trimethylhexanol (TMH) in the presence of selected heterogeneous catalysts containing active sulfonic groups has been made. The catalysts were obtained using ready available amorphous silicas with different textural characteristics. The influence of catalyst porosity on the catalytic properties in the esterification of fatty acids has been investigated. The effect of the synthesis temperature has also been studied. The results were compared with the results of esterification with the use of acidic ion exchange resins. It was shown that catalysts obtained on the basis of amorphous silicas are good and reusable catalysts for the esterification of fatty acids with higher alcohols

A field experiment was conducted univariate in 2008-2010 in the Variety Assessment Station in Szczecin - Dąbie. The soil on which the experience was based is made of light loamy sand (pgl). In terms of granulometric composition it includes it into the category of light soils, agricultural suitability complex IV b, good (5). The experiment included, inter alia, waste compost produced with municipal sewage sludge produced by *GWDA and ash from brown coal (waste grate). No normal ranges for heavy metals being specified in the ministerial regulations were used for environmental purposes, which are maximum 20, 500, 750, 300, 1000 and 16 mg per 1 kg dry matter for cadmium, chromium, lead, nickel, copper and mercury, respectively16 were exceeded in the sewage sludge being used to produce the compost. The field experiment design consisted of 6 fertilisation objects. A test plant was Virginia fanpetals (Sida hermaphodrita Rusby). The content of available phosphorus, potassium and magnesium in the soil, being fertilised with municipal SSC with and without an addition of high-calcium BCA, changed after three years. There was an increase in the content of available phosphorus, potassium and magnesium forms, on average by 8.5%, 16.0% and 9.0%, respectively. When analysing the chemical properties of soil before and after this study, it may be stated that respective systems of municipal sewage sludge compost and high-calcium brown coal ash application differently affected most soil richness indices. The best fertilisation effects were obtained in the system with municipal sewage sludge compost being applied at a dose corresponding to 250 kg N ∙ ha^-1 as well as with high-calcium brown coal ash at a dose corresponding to 1.5 Mg CaO ∙ ha^-1 being introduced into soil in the first year of study and at a dose corresponding to 0.75 Mg CaO ∙ ha^-1 in successive years. Fertilisation with municipal sewage sludge compost without and with addition of high-calcium brown coal ash favourably affected the preservation of soil environment stability and improvement of soil chemical composition

The kinetics of oxidation of aromatic anils to benzaldehyde and azobenzene by magnesium monoperoxyphthalate (MMPP) has been studied in aqueous acetic acid medium. The low dielectric constant of the medium facilitates the reactivity. It has been found that ionic strength of the reaction has no significant effect on rate. The added acrylonitrile has no effect on the reaction rate indicating the absence of free radical mechanism. The added Mn(II) decreases the rate of the reaction, which indicates the involvement of two-electron transfer. Highly negative ΔS^# values indicate a structured transition state. The deviation of Hammett plot is noted and a non-linear concave downward curve is obtained for the anils with substituents in the aniline moiety. The observed break in the log k_obs versus σ is attributed to the transition state whereas the non-linear concave upward curve is observed for the substituents in the benzaldehyde moiety and a non-linear concacve upward curve is observed for the substituents in the combination of aniline and benzaldehyde moiety and a suitable mechanism is proposed

The structure of liquid Sn_0.739Pb_0.261 and Sn_0.57Bi_0.43 eutectic alloys was studied by means of X-ray diffraction at several temperatures. Structure factors, pair correlation functions and the main structural parameters obtained on their basis were analyzed. We show that the structure of the Sn_0.739Pb_0.261 and Sn_0.57Bi_0.43 eutectic alloys is inhomogeneous and consists of different types of clusters. Upon heating the cluster structure undergoes topological and chemical disordering showing a significant dependence of structural parameters on temperature near the melting point

In this work, the application of the thiol-functionalized epoxy resin encapsulated on magnetic core as supports for palladium catalysts is reported. The study focuses on obtaining of heterogeneous catalysts which can be separated by magnetic field. Palladium complex catalyst [PdCl2(PhCN)2] has been heterogenized by anchoring to these supports via ligand exchange reaction. The characterization of polymeric supports and heterogenized palladium catalysts has involved research methods like time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning electron microscopy (SEM) and nitrogen BET surface area measurements. The activity and stability during long-term use of the investigated catalytic systems were tested in a Heck and hydrogenation reaction. The influence of the type of thiols used as epoxy hardeners and the morphology of the supports on the catalytic properties of epoxy-supported palladium catalysts was discussed.

The effect of two-stage thermal disintegration of sewage sludge on the particle size distribution using laser diffraction method has been studied. The sludge was sampled from municipal sewage treatment plant after each stage of disintegration. The first stage of disintegration known as homogenization proceeds at temperature of 70-90°C and pressure of 3 bar, the second stage called thermal hydrolysis was performed at temperature of 160-170°C and pressure of 6 bar. It was found that the first stage of disintegration has the strongest impact on the reduction of the sludge particle size and changes in chemical properties. The maximum size of the particles from raw sewage before disintegration was 310 μm. After first stage of the process average size of the particles was 250 μm, and during the second stage it was reduced to 226 μm. Sludge disintegration degree (DDCOD) of 59% confirms high effectiveness of the process. We established that the redox potential (Eh) of sludge effluents was changed after each step of the studied process. Furthermore, chemical oxygen demand (COD) increases which leads to the conclusion that resizing of floccules is accompanied by hydrolysis.

Approximate analytical solutions concerning lifetime of soluble solid particles in an unbounded stagnant medium have been developed by simple application of fractional half-time derivative in the Riemann-Liouville sense to express the relationship between the net surface mass flux and the concentration at the interface. The solutions start with the initial formulation of Rice and Do on the time-depletion of the radius of a spherical particle expressed through terms including the solubility parameter as the only key parameter controlling the process of dissolution. The two approximate developed solutions use different scaling and dimensionless variables: The 1^st solution is developed by an introduction of a similarity variable [xxx] while the 2^nd solution applies the classical scaling using the initial sphere radius as a length scale that leads to dimensionless radius r = R/R₀ and time τ = Dt/R₀². Both solutions provide approximate relationships close to that of Rice and Do.

Catalytic systems composed of metal chloride (InCl₃, ScCl₃, YCl₃, YbCl₃, LaCl₃, BiCl₃, ZnCl₃ and CuCl₃) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide, [C₁C₄Pyrr][NTf₂] as ionic liquid were prepared. Catalytic activity of all the systems were compared in acetalization reaction between cyclohexanone and triethyl orthoformate. 1,1-Diethoxycyclohexane were formed with high yield and the selectivity at 0°C within 5 minutes. Selected metal chlorides immobilized in ionic liquid were recycled 5 times without a decrease in their activities

Pesticide pollution is a serious problem being faced. Harmful levels of pesticides are found in the water which is used for daily purposes. In the event of such a scenario, this paper presents a working solution for bringing down the Pesticide levels in the water to safe levels by using the method of liquid-liquid extraction. The experimental liquid-liquid equilibrium data on pesticide-water-solvent ternary mixtures at a temperature of 288.15 K are presented here. The pesticide used here is a chlorinated hydrocarbon called lindane found in the water (underground, land), beverages and foods. The solvents used are Petro-ether-Chloroform (1:1), Ethylene di chloride and n-hexane. The equilibrium generation diagram, triangular diagram, tie lines and bimodal curves as well as the distribution coefficient have been determined and reported. The petro-ether-chloroform was found to be the right solvent for the separation of lindane from wastewater because of high selectivity (25.36) and distribution coefficient (4). The extraction process is simulated into ‘C’ language

The complexes of poly(ethyl methacrylate-co-N-vinyl-2-pyrrolidone) (P(EMA-co-VP)) gel with poly- (ethylene glycol) (PEG) stabilized by the hydrogen bonds were prepared. It was found that both the concentration and the molecular weight of PEG have a strong effect on the P(EMA-co-VP) gel. When PEG was introduced into the P(EMA-co-VP) gel, the glass transition temperatures (T_g) of the complexes decreases with the decreasing of PEG molecular weight. In such a system, the maximum molecular weight of PEG required for the complex formation is no more than 2000, and P(EMA-co-VP)/PEG complexes are a homogeneous amorphous phase, which was studied by FTIR, XRD, TEM, and DSC.

Self-assembly of N6-donor bis(terpyridine) ligand L with transition metal ions: Co(II), Mn(II) and Cd(II) leads to a formation of three kinds of supramolecular complexes. In the electronic absorption and emission spectra of supramolecular complexes additional bands were observed what was ascribed to the coordination of ligand molecules to metal ions. Luminescence properties of these complexes strongly depend on the kind of metal ions and counter ions. The effective blue luminescence was observed in the case of Mn(II) and Cd(II) complexes in which all N-donor atoms of ligand molecules coordinate with the metal center

The results of the studies on the influence of the phase transfer catalyst on the epoxidation of (Z,E,E)-1,5,9-cyclododecatriene (CDT) to 1,2-epoxy-5,9-cyclododecadiene (ECDD) in the H₂O₂/H₃PW₁₂O₄₀ system by a method of phase transfer catalysis (PTC) were presented. The following quaternary ammonium salts were used as phase transfer catalysts: methyltributylammonium chloride, (cetyl)pyridinium bromide, methyltrioctylammonium chloride, (cetyl)pyridinium chloride, dimethyl[dioctadecyl(76%)+dihexadecyl(24%)] ammonium chloride, tetrabutylammonium hydrogensulfate, didodecyldimethylammonium bromide and methyltrioctylammonium bromide. Their catalytic activity was evaluated on the basis of the degree of CDT and hydrogen peroxide conversion and the selectivities of transformation to ECDD in relation to consumed CDT and hydrogen peroxide. The most effective PT catalysts were selected based on the obtained results. Among the onium salts under study, the epoxidation of CDT with hydrogen peroxide proceeds the most effectively in the presence of methyltrioctylammonium chloride (Aliquat^® 336) and (cetyl)pyridinium chloride (CPC). The relatively good results of CDT epoxidation were also achieved in the presence of Arquad^® 2HT and (cetyl)pyridinium bromide

The paper presents the results of the synthesis of 2,6-dimetyhlphenol (26DMP) from o-cresol. The target compound is an important substrate for polymer chemistry. Due to a large amount of o-cresol which is generated as a by-product, during the synthesis of 2,6-dimethylphenol from phenol, the methylation of o-cresol to 2,6-dimethylphenol should be examined as a separate process. The alkylation of o-cresol was carried out in a fluidized bed of commercial iron-chromium catalyst TZC-3/1. Undesirable decomposition of methyl alcohol on the catalyst generates a number of environmentally dangerous by-products such as methane, carbon dioxide, carbon monoxide. The effect of temperature on the yield of the synthesis was investigated. The synthesis process was monitored on-line in the temperature range 310-380°C, completely covering the maximum efficiency of the process. Online analysis of the process by FTIR spectroscopy gave information about products of both methylation of o-cresol and pyrolysis of methanol. The maximum 85% yield of desired 2,6-dimethylphenol with more than 85% conversion of o-cresol was achieved at 340°C, at 1:6 molar ratio of o-cresol:methanol

Advanced silica/lignosulfonate composites were obtained using magnesium lignosulfonate and silica precipitated in a polar medium. For comparative purposes analogous synthesis was performed using commercial silica Aerosil^®200. Lignosulfonates are waste products of paper industry and their application in new multifunctional materials is of great economic interest. The composites obtained were subjected to thorough characterization by determination of their physicochemical, dispersive-morphological and electrokinetic properties. Their particle size distribution was measured, SEM images were taken, FT-IR analysis and colorimetric study were made, thermal and electrokinetic stabilities and parameters of porous structure were also determined. The results can be of interest in further application studies

The study was aimed on the determination of biodegradation rate of extruded starch carriers, with or without immobilized microorganisms in diversified storage conditions. The research was conducted on potato starch, in which Saccharomyces cerevisiae yeast cells were immobilized. Preparations with and without yeasts were than placed for 84 days in the environments of: light soil, heavy soil, compost, water and activated sludge. After 0, 7, 14, 21, 49 and 84 days of storage the preparations were perfused with water and analyzed. In the recovered samples the following tests were carried out: the force causing fracture, the elongation caused by the mentioned force, the mass and the diameter of the carrier. Due to the degradation the size and the mechanical properties of the samples were decreased. The rate of the degradation was strongly dependent on the environment of the storage. The fastest degradation of the carriers were observed for compost and heavy soil, while the slowest biodegradation was observed for the samples placed in the water environment. The rate of biodegradation was also influenced by the Saccharomyces cerevisiae yeasts. The rate of biodegradation was faster in the samples containing yeast cells, than in the extrudates without the microorganisms.

A biotechnological synthesis generated a fermentation broth containing the dissociated forms of organic compounds and residual mineral salts. An effective method of selective removal of the ionic species and organic compounds from solutions comprises nanofiltration and reverse osmosis. Ultrafiltration (UF) was used in this work as a pre-treatment method for the preparation of feed for these processes. The UF study was carried out with a real broth, which was obtained using Citrobacter freundii bacteria for the fermentation of glycerol solutions, resulting in the UF permeate with turbidity below 0.1 NTU. However, a significant decline of the permeate flux was observed during the UF process. The influence of the transmembrane pressure on the fouling intensity of used ceramic membranes was investigated. A periodical membrane cleaning was carried out by rinsing with water and a 1 wt % solution of sodium hydroxide. The applied cleaning procedures permitted to restore the initial permeate flux.