Bulgarian Chemical Communications, Volume 50, Number 4, 2018

Improved synthesis of fluconazole by using nano-SSA as a green catalyst
Original Research Article
Pages 517 – 523
L. Zamani, Z. Rezaei, S. Khabnadideh
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In our on-going interest in the preparation of new antifungal agents, our attention was focused on fluconazole because of its broad antifungal spectrum, low toxicity and excellent pharmacokinetic properties. As a part of our program to develop a new method for synthesis of fluconazole, the conditions of some reactions, especially Grignard reactions, were screened and optimized. The best situation was achieved by using nano-silica sulfuric acid as a green and mild catalyst. The high yield and comfortable isolation in each step were the advantage points in this method.


Degradation of partially absorbable surgical mesh: a chemical and mechanical study
Original Research Article
Pages 524 – 529
D. Pashkouleva, M. Kirilova-Doneva, I. Borovanska, A. A. Apostolov
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Chemical and mechanical testing of partially absorbable surgical mesh after being kept in vitro under physiological conditions for four months was performed. Differential scanning calorimetry and X-ray diffraction were used to investigate the degradation behavior and the changes in structure and crystallinity of this surgical mesh. The degradation of the copolymer poliglecaprone 25, which is a constituent of the mesh, was confirmed. The mechanical characteristics of the mesh were compared in two different directions by performing uniaxial tensile tests. A progressive loss of the tensile strength and elongation was established. Failure tests showed that the mechanical properties of the mesh are anisotropic. The lower tensile strength is in transversal direction.


Isolation and characterization of plant cell wall material from rose hip fruits
Original Research Article
Pages 530 – 537
M.H. Ognyanov, M. M. Hodzhova, N. T. Petkova, P. N. Denev, Y. N. Georgiev, M. G.Kratchanova
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In the present study, plant cell wall material from rose hip fruits was isolated as alcohol-insoluble solids. Chemical composition of the cell wall material and initial fruits (edible part) was investigated and compared. The amount of polyphenols (flavonoids), pigments, lipids, vitamin C was removed in a different extent during hot alcohol/acetone treatment. In contrary, proteins, polysaccharides and some polyphenols (condensed tannins) were co-precipitated due to the dehydration effect of alcohol, which was the main factor that restricted the extractability of ‘contaminants’. In addition, carbohydrates (mainly pectins and cellulose) were found out to be the main constituents of the ‘purified’ rose hip cell wall preparation.


Morchella esculenta (L.) growing in Bulgaria: chemical profile and hazard index
Original Research Article
Pages 538 – 544
L. Dospatliev, M. Ivanova, M. Lacheva, T. Radoukova
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Morchella esculenta (L.) Pers. (morel) is one of the most widely appreciated wild edible mushrooms. The mushroom Morchella esculenta has long been known for its medicinal properties, especially its health-promoting effects, including antioxidant activity, hepatoprotective activity, antimicrobial properties and antitumor effect. Morchella esculenta is rich in carbohydrates (79.06 g 100 g-1 dw), followed by proteins (11.19 g 100 g-1 dw), ash (7.32 g 100 g-1 dw) and fat (2.43 g 100 g-1 dw). Also moisture (89.41%), and total energy (1624.14 kJ 100 g-1 dw) were calculated. The concentrations of heavy metals: Pb (0.28 mg kg-1), Cd (0.10 mg kg-1), Cu (0.18 mg kg-1), Co (0.28 mg kg-1), Zn (0.82 mg kg-1), Ni (0.46 mg kg-1), Cr (0.28 mg kg-1), Fe (17.01 mg kg-1), and Mn (0.96 mg kg-1), were assayed in Morchella esculenta. Hazard index values were calculated for children: 1-3 years old (0.665), 3-10 years old (0.347), 10-14 years old (0.186), 14-18 years old (0.131) and for adults ˃ 18 years (0.230). According to this study, the edible wild mushroom Morchella esculenta could be used in human nutrition due to its good parameters. Heavy metal content of samples indicated that the Batak mountain is an ecologically pure region in Bulgaria, and therefore the mushrooms collected from this location could be consumed without any risk for human health.


Effect of polyphenol extract from Polygonum multiflorum Thunb. root on the storage of minced red tilapia (Oreochromis sp.)
Original Research Article
Pages 545 – 552
P. T. Q. Le, V. M. Nguyen
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This study was carried out to evaluate the effects of the polyphenol extract from Polygonum multiflorum Thunb. root on lipid oxidation and sensory characteristics of minced red tilapia (Oreochromis sp.) during frozen storage. Fresh fillets were minced in aqueous solutions of the root extract with some polyphenol concentrations of 830, 415, 277 and 208 mg GAE/L, extract solution/sample ratio of 1/20 (v/w), then stored at -20±2oC, for up to 100 days. The best oxidation inhibition results on minced fish were achieved at the highest polyphenol concentrations of 830 and 415 mg GAE/L. Significant differences (p<0.05) in all quality parameters (pH, PoV, MDA, color parameter and sensory evaluation) of treatеd and control samples (blank control and water-treated or water control) were registered during storage time. The advantages of polyphenol extract were discussed. It can extend the shelf-life of products during frozen storage and was more effective to improve qualities of minced fish, especially at a polyphenol concentration of 415 mg GAE/L. Therefore, it can be concluded that the polyphenol extract from Polygonum multiflorum Thunb. root can potentially be used as an alternative source of natural antioxidant.


Polyphenol content and antioxidant activity of aqueous/methanol extracts from different tobacco species (Nicotiana)
Original Research Article
Pages 553 – 559
M.H. Docheva, V.T. Popova,T.A. Ivanova, V.V. Nikolova, T.H.Hristeva, N.N. Nikolov
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 The aim of the study was to characterize the polyphenol contentin the leaves of different tobacco species(N. alata Link & Otto, N. rustica L., N. tabacum L.), as well as to obtain extracts enriched in phenolic acids and flavonoids, andto evaluate their radical-scavenging activity. The content of chlorogenic acid in the leaves varied from 2.44±0.21mg/g (N. rustica) to 7.10±0.50 mg/g (N. alata), and that of rutin –from 0.55±0.05mg/g (N. alata) to 10.85±0.80mg/g (N. rustica).The content of flavonoids was in the range from 0.66 ± 0.12 mg/g (N. alata) to 11.51 ± 0.8 mg/g (N. rustica).Two types of extracts were obtained using a macroporousresin– enriched in phenolic acids (PA) and enriched in flavonoids (F). Theconcentration of phenolic acids in Extracts PA was from 6.33±0.50 mg/g (N. tabacum) to 3.88±0.20mg/g(N. rustica), and the recoveryof phenolic acids –from 71 % to 86 %. Extracts Ffrom N. rustica and N. tabacum were with flavonoid content of 9.7 ±0.7mg/g and 6.15 ±0.4mg/g, respectively, and those from the two genotypes of N. alata–with only 0.43±0.09mg/g. The recovery of flavonoids was 72 ± 9 %. Extracts PA were maximally purified from flavonoids, and Extracts F – from phenolic acids. All extracts revealed high antioxidant activity, having IC50 values from 5.82 ± 0.97 μg/ml (N. rustica) to 14.56 ± 2.61 μg/ml (N. tabacum). The results from the study givegrounds forregardingthe investigated Nicotianaspecies as a promising plant material for obtaining purified natural extracts with potential use in biopharmacy.


Instabilities during electrochemical deposition of Sn-Co alloys from gluconate/sulphate electrolyte
Original Research Article
Pages 560 – 567
T. T. Valkova, I. N. Krastev
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Dull coatings with high cobalt content can be deposited from the investigated electrolyte. Depending on tin concentration, the deposition of coatings with cobalt content in the range from 0 up to 80 wt. % is possible. Electrochemical instabilities and spontaneous potential oscillations during galvanostatic deposition of Sn-Co alloys are observed and discussed.


One-pot synthesis of substituted imino- and imidazopyridines under catalyst-free conditions
Original Research Article
Pages 568 – 574
F. N. Naghiyev, A. M. Maharramov, İ. M. Akhmedov, Kh. A. Asadov, A.N. Khalilov, A. V. Gurbanov, G. Z. Mammadova, A. R. Asgarova, E. Z. Guseynov, I. G. Mamedov
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Substituted imino- and imidazopyridine derivatives were synthesized via a new one-pot, three-component reaction between benzylidenemalononitriles, malononitrile and amines under catalyst-free conditions at room temperature. When ethylenediamine was used as the amine component of the reaction, dihydro- and tetrahydroimidazopyridines were selectively obtained in good to high yields. On the other hand, the use of benzylamine led to the formation of 2- imino-1,2-dihydropyridine products. The reactions were found to tolerate the presence of electron-donating and withdrawing substituents on the benzylidenemalononitrile reactants. Products of these reactions are crystalline and can be isolated by a simple procedure at room temperature in good yields and with high purity.


Synthesis and characterization of polymeric blend membranes enhanced by monoethanolamine for CO2/CH4 separation
Original Research Article
Pages 575 – 583
A. Mushtaq, H. Mukhtar, A. M. Shariff
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Gas separation membranes for natural gas are widely used. For efficient separation of CO2/CH4, high-performance gas separating polymeric blend membranes are desired. The main objective of this study is to synthesize blend membranes for removal of CO2 from CH4 using glassy and rubbery polymers with the addition of amine. The methodology comprises various contents of polyvinyl acetate (PVAc) ranging from 5 to 20 wt% blended with polysulfone (PSU) and 10 wt% MEA in DMAc solvent used for the formation of flat sheet membranes via solution casting method. The synthesized blend membranes possessed homogenous surfaces and showed a uniform packed bed of spherical structure, as seen from FESEM images. The existence of a single glass transition temperature for different blend membranes indicated miscibility among the polymeric blends, shown by DSC analysis. Thermogravimetric analysis showed an improvement in the maximum degradation temperature with the increase in PVAc content in the membrane blends. FTIR analysis confirmed the polymer blend’s miscibility with very few spectral peak shifts. The gas permeation results concerning MEA showed that CO2 permeance increased, in PSU and PSU 80%/PVAc 20%, from 39.63% to 63.97% at 2 bar pressure. EPBM is an appropriate tool for the production of novel materials with joined characteristics that improved application properties with low-cost advantage.


Effect of MEA on the performance of polysulfone/polyvinyl acetate blend membranes
Original Research Article
Pages 584 – 591
A. Mushtaq, H. Mukhtar, A. M. Shariff
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Separation of CO2 from natural gas within the field of membrane technology has been carried out for a long time. For efficient separation of CO2/CH4, high-performance gas separating membranes are desired. The blending technique enhances the chemical and thermal stability, also taking heed in the improvement of separation properties with the economic sustainability. This research studies the perm-selective performance of polymeric blend membranes, glassy polymer (polysulfone) and rubbery polymer (polyvinyl acetate) with monoethanolamine (MEA). The polymeric amine blend membranes with enhanced properties were synthesized with different blending ratios in dimethylacetamide (DMAc) solvent. In this study, various compositions of polyvinyl acetate (PVAc) ranging from 5 to 20 wt. % were blended with polysulfone (PSU) and MEA, and were used for the formation of flat sheet membranes via evaporation method. The gas permeation results showed that the CO2 permeance increased with increasing feed pressure.


Comparative study of sunset yellow dye adsorption onto cornelian cherry stones-based activated carbon and carbon nanotubes
Original Research Article
Pages 592 – 601
F. O. Erdogan
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The objective of the study was to prepare low-cost activated carbon from cornelian cherry stones (Cornus mas L.) and compare its adsorption behavior for a food dye with that of commercial multiwalled carbon nanotubes. The cornelian cherry stones activated carbon (AC) and commercial multi-walled carbon nanotubes (MWCNT) were characterized by N2 adsorption isotherms and SEM (scanning electron microscopy). Adsorption of a food dye, sunset yellow FCF, by AC and MWCNT was examined in detail. Batch adsorption test showed that the extent of sunset yellow adsorption was dependent on dye concentration, contact time, solution temperature and adsorbent dosage. The experimental adsorption equilibrium data were compared to the Langmuir, Freundlich, Temkin and DR isotherm models and the isotherm model parameters were determined. The maximum adsorption capacity was found to be 125.3 and 43.8 mg/g for AC and MWCNT, respectively. Pseudo-first-order, pseudo-second-order and Elovich equations were fitted to the kinetic data, and the rate constants were evaluated. Thermodynamic parameters enthalpy, entropy and Gibbs free energy changes were established. Results showed that activated carbon produced from cornelian cherry stones is suitable for the adsorption of sunset yellow food dye and could be used as a low-cost effective adsorbent in the treatment of industrial wastewater..


Kinetic study and modeling of Zn2+removal from wastewater by adsorption onto multi-walled carbon nanotubes
Original Research Article
Pages 602 – 607
H.Sadegh, R. Shakibaei Lalehloo, S. M. Seyed Arabi, M. Jalili3, P. Chauhan
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Adsorption methods for the removal of Zn2+ as a toxic heavy metal ion using multi-walled carbon nanotubes (MWCNTs) as an adsorbent are presented here. SEM and FTIR techniques were used for the characterization of the MWCNTs. The relationship between the optimization factors (adsorbent dosage, contact time and initial heavy metal ion concentration) and the adsorption properties of the MWCNTs was studied. The quantity of metals adsorbed during various time intervals is the base of kinetics of adsorption. A thorough investigation was done on the modeling of kinetic curves. The results of the adsorption kinetics study showed that the adsorption of Zn2+ fitted most closely to the pseudo-second-order model (R2>0.999), and the adsorption equilibrium time was 55 min. The Langmuir isotherm model was used to fit the adsorption equilibrium data.


Synthesis, characterization and CO2 adsorption of Fe(III)-based metal-organic framework
Original Research Article
Pages 608 – 614
S. U. Rather, A. Muhammad, A. A. Al-Zahrani, T. E. Youssef, L. A. Petrov
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Iron (III)-based metal-organic framework (Fe-MOF) was synthesized via solvothermal method utilizing tritopic bridging 1,3,5-Tris(4-carboxyphenyl) benzene as a linker between metal centers. Thermogravimetric analysis revealed that weight loss in the entire temperature range corresponds to loss of desorption of adsorbed gases from pores and cavities, removal of N, N-dimethyl formamide, and framework disintegration. Specific surface area was found to be 300 m2/g and a very little rise in the isotherm at partial pressure > 0.2, indicates microporous character of the sample. Maximum CO2 adsorption capacity of Fe-MOF sample measured at room temperature and partial pressure of 0.9 atm was found to be 3.0 wt.%. Temperature increase from 298 to 343 K decreases adsorption capacity is related to Le-Chatelier's Principle. Linearity of CO2 adsorption in a Fe-MOF sample related to weak adsorption sites.


Structural change of lignin in catalytic oxidation by Co(salen)
Original Research Article
Pages 615 - 620
X.-F. Zhou
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In order to improve the catalytic performance, Co(salen) catalysis was performed on Indulin lignin. The structural changes of the lignin during the biomimetic treatment were characterized by 13C-NMR, HSQC and 31P-NMR spectroscopy. As a result of the biomimetic treatment, a decrease of β-O-4, β-β and β-5 linkage was observed, especially a cleavage of β-O-4 linkage. The fact that the condensed substructures were significantly decomposed explained the lignin degradation in-deep. In addition to these changes, the proposed route was applied to the lignin oxidation by Co(salen) catalysis based on the subtraction of phenolic hydrogen atoms.


Effect of heat absorption on Cu-water based magneto-nanofluid over an impulsively moving ramped temperature plate Original Research Article
Pages 621 – 630
M. R. Mishra, S. M. Hussain, R. Sharma, G. S. Seth
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The aim of the present paper is to explore the effects of heat absorption on а transient free convective boundary-layer flow of an electrically conducting, viscous and incompressible magneto-nanofluid over an impulsively moving vertical ramped temperature plate. Water-based nanofluids with added nanoparticles of titanium oxide, aluminium oxide and copper are taken into account. The mathematical model of the problem is obtained using the model of nanoparticle volume fraction. The governing model is solved analytically by making use of Laplace transform technique. The expressions for nanofluid velocity, nanofluid temperature, skin friction and Nusselt number were obtained for both the cases of ramped and isothermal conditions. The effects of various physical parameters on the nanofluid velocity and nanofluid temperature are shown by various graphs whereas the numerical values of skin friction and Nusselt number are presented in tables. The numerical results of the problem were compared for both ramped and isothermal conditions and it is observed that the numerical values in case of isothermal conditions are lower in magnitude as compared to ramped conditions.


Heat transfer performance of stainless steel, mild steel and aluminium target plate for various configurations of impinging air jet
Original Research Article
Pages 631 – 637
K. Jeyajothi, P. Kalaichelvi
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In spite of several studies carried out on jet impingement on a plane surface, this work describes a new approach of comparing the heat transfer characteristics when three different materials are used as a target. The heated target plates are made up of stainless steel, mild steel and aluminium and are kept at different heights (2 to 8 mm) from a nozzle with diameter ranging from 0.5 to 3 mm. Measurements were done at the stagnation point using air jets with velocity of 6.4 and 9.2 m/s. The major characteristics of a jet impinging on a plane could be shown by straightforward experiments like spreading over method. Nusselt number was calculated for various values of jet Reynolds number and it was observed that adequate cooling of the plate is attained and enhanced with an increase in Reynolds number. It was also noted that the placement of the target is critical for optimum performance in practical applications. The increment in air velocity and Reynolds number improved heat transfer while increment in nozzle height decreased the performance at the stagnation point. Furthermore, three new reliable empirical correlations were established using the experiments performed.


Study of 4-chlorophenol biological treatment using yeast and mold isolated from industrial and petroleum wastewaters (Imam Khomeini Port, Mahshahr)
Original Research Article
Pages 638 – 646
A. Alirezaei, M. Bayat, M. Alimohmmadi, S. Hashemi
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Phenolic derivatives are some of the most toxic pollutants in the environment. Chlorophenols are the most toxic pollutants of water and wastewater. Since 4-chlorophenol is a highly soluble compound in water, it is abundantly found in water and wastewater. Because of high costs, high energy consumption and in some cases environmental inconsistency of the chemical and biological removal methods, biochemical decomposition of 4-chlorophenol is very important. In the present study, 13 strains of bacteria and 6 strains of yeast and mold were purified and isolated from Shahid Tondgooyan wastewater treatment plant (Imam Khomeini Port, Mahshahr), which lasted about 15 days. Then, the ability of each microorganism isolated in the presence of 100 ppm of 4-chlorophenol was studied and two microbial species suitable for TY1 and TY2 were selected for use in a mixed microbial culture. 4-Chlorophenol decomposition was performed in the presence of 100 ppm of 4-chlorophenol. In this research, one of the most important factors affecting 4-chlorophenol degradation by mixed microbial culture including glucose concentration with 2 and 5 g/l was investigated. After examination, the microbial species suitable for TY1 and TY2 were able to completely remove 100 ppm of 4-chlorophenol, so that the TY1 strain was removed completely after 45 h and the TY2 strain after 21 h. Using a mixture of TY1 and TY2 strains (50/50) in the presence of 2 g/l of glucose, 100 ppm of 4-chlorophenol were completely removed after 18 h. Based on the 18SrRNA gene sequence analysis, the molecular identification of the two superior strains was carried out, both belonging to the genus Trichosporon. Considering the high potential of Trichosporon species, including their potential applications in increasing oil recovery and eliminating pollutants, it would be hoped that the further exploration of strains characteristics and the search for new native strains could play a crucial role in the application of native strains in the oil industry.


Research on protective method of ship electrostatic field based on metal polarization control
Original Research Article
Pages 647 – 654
Wang Xiangjun, Liu Yi, Liu Dehong
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There is the electrochemical corrosion among different metals of the ship in the seawater, of which the foremost is the electrochemical corrosion between the steel hull and the bronze propeller. In this electrochemical corrosion process, the hull is the electrochemical corrosion anode, and the propeller is the electrochemical corrosion cathode. Besides, the corrosion current from the hull to the propeller current would generate around the ship. The corrosion current would form an electrostatic field in the seawater, and field signal is easily detected by the mine and detection equipment, which can bring a great threat to the ships. In this paper, based on the research on the metal polarization curve, the potential balance method combining the anode polarization of the hull and the cathodic polarization of the propeller is proposed, to make the potential difference reduce to 0V. At this point, the corrosion current can be also greatly reduced, and the associated underwater electric field can also be eliminated. It is demonstrated that the proposed method can reduce the underwater electrostatic field indeed, and the electric field protection effect is obvious.


Optimizing final product properties and Ziegler-Natta catalyst performance with and without hydrogen in propylene polymerization by kinetic modeling
Original Research Article
Pages 655 – 671
Gh. H. Varshouee, A. Heydarinasab, A. Vaziri1, B. Roozbahani
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Kinetics of propylene polymerization with its unique complexity has the key role on final product properties, but is heavily influenced by the hydrogen amount. Hydrogen, as chain-transfer agent, gives rise to a reduction of the average molecular weight of the polymer and directly affects the final product properties; and on the other hand, based on some
theories up to a certain amount causes an increase followed by a decrease in the number of active sites. Therefore, this dual hydrogen behavior must be optimized. To date, no adequate kinetic model has been developed to predict and optimize this behavior and to simultaneously calculate the vital indices of final product properties such as melt flow index, number/weight average molecular weight, and polydispersity index. In addition to determining of the indices, by using the model some vital kinetic parameters such as activation energy, initial rate of reaction and deactivation constant can be easily calculated. The proposed model in this study was coded in MATLAB/SIMULINK software by using the polymer moment balance approach having in mind the dormant site theory as the most credible theory at the moment. The model was validated by comparison with lab experimental data and an agreement within the acceptable range of error was shown. Finally, the optimum reaction temperature and the optimum hydrogen amount according to
the used catalyst were obtained as 70°C and 18 mg hydrogen in this study.