Bulgarian Chemical Communications, Volume 50, Number 2, 2018

Waste waters of milk and cheese processing as an efficient promoter for the synthesis of 1,8-dioxo-octahydroxanthenes
Original Research Article
Pages 189 – 193
S.Fiorito, F. Epifano, F. Preziuso, V. A. Taddeo, S. Genovese
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Waste waters of agricultural and industrial processing have been recently employed to effectively promote numerous “classic” and innovative processes of synthetic organic chemistry. Such a green chemical approach allowed to bypass the use of toxic, polluting, and hazardous chemicals and in the meantime led to an increase of the commercial values of such byproducts. Xanthenes are a group of natural and semi-synthetic compounds with great pharmacological potentialities, also used for several other applications. In this paper we described a new and improved methodology for the synthesis of the title compounds using waste waters of milk and cheese processing as a solvent. 1,8-Dioxo-octahydroxanthenes were obtained in very good yields (94 – 98 %) from differently substituted aromatic aldehydes and dimedone as substrates. Although several reports about the synthesis of 1,8-dioxo-octahydroxanthenes have been published in recent years, this is the first report about the use of waste waters of agricultural and industrial processing to this aim. The findings depicted herein underline once again the great usefulness of agricultural and food industry byproducts to perform green chemical processes.


One-pot three-component synthesis of 3-[(aryl)-arylsulfanyl-methyl]-4-hydroxy-6-methylpyran-2-one
Original Research Article
Pages 194 – 197
M. Khaleghdadi, A. Hassanabadi
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A good yield in the synthesis of 3-[(aryl)-arylsulfanyl-methyl]-4-hydroxy-6-methylpyran-2-one is described involving the reaction of 4-hydroxy-6-methyl-2H-pyran-2-one with aromatic aldehydes and thiols in the presence of p-toluene sulfonic acid (p-TSA) under reflux conditions.


Detection limit and electrochemical behavior of maleic acid on a platinum electrode
Original Research Article
Pages 198 – 203
H. M. Rageh, M. M. Abou-Krisha, A. M. Abo-Bakr, M. Abd-Elsabour
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The electrochemical behavior of maleic acid (MA) on a platinum electrode was studied using cyclic voltammetric, linear sweep voltammetric and chronoamperometric techniques. The results showed that the reduction of MA on a Pt electrode is a quasi-reversible process as a result of the diffusion and the reductive potential of MA at -0.62 V (vs. Ag/AgCl). The detection limit of MA on a Pt electrode was calculated to be 1.6 × 10-5M. The anodic and cathodic current peaks of MA increased with increasing the concentration of MA from 5.00 × 10-3 to 8.89 × 10-3 M at a scan rate ranging from 20-200 mV/s. The diffusion coefficient of MA was determined to be 0.815 × 10-7 cm2.s-1. The mechanism of the produced succinic acid by electrochemical reduction of MA was discussed.


Chemical analysis of components in burned and unburned propellant powders
Original Research Article
Pages 204 –207
İ. Kara
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After firing a shot, gunshot residue (GSR) compounds containing burned and partially unburned particles are dispersed in the environment. The partially unburned GSR compounds contain elements that are ready to explode in appropriate circumstances. This can lead to serious safety problems, especially in indoor shooting ranges. In this study, the GSR compounds collected from Machine Chemistry Institute brand 9×19 mm parabellum shells were analyzed using gas chromatography/mass spectrometry (GC-MS) method. As a result of the analysis, nitroglycerin, dimethyl phthalate, 2,4-dinitrotoluene, diphenylamine, n-diphenylamine, trimethyl, 2,4-methypropyl and dibutyl phthalate compounds were detected in the GSR compounds. The changes in the amounts of these compounds depending on the number of shots wire were discussed.


New chelation products of thorium(IV) and cerium(III) with diclofenac and paracetamol analgesic drugs: Synthesis, spectroscopic, thermal stability, antimicrobial activities investigations
Original Research Article
Pages 208 – 217
F.A.I. Al-Khodir
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Four new complexes of thorium(IV) and cerium(III) with two analgesic drugs, diclofenac sodium (diclo) and paracetamol (para): [Ce(diclo)3].2H2O (1), [Th(diclo)2(OH)2].4H2O (2), [Ce(para)3(H2O)3] (3), and [Th(para)4(H2O)2] (4), were synthesized and characterized using elemental analysis, thermal analysis and FT–IR, 1H-NMR, and UV–VIS spectroscopy. The micro-analytical elemental measurements confirmed the ratio metal ions:drug for the synthesized complexes as 1:3 for complexes 1 and 3, 1:4 for complex 2, and 1:2 for complex 4. The FT-IR spectra of the para ligand νs(O–H) stretching vibration of –OH disappeared in the spectra of the complexes proving the involvement of the oxygen atom of the –OH group in the complexation after deprotonation. In case of diclo complexes, the ν(C=O) stretching vibrations of the carboxylic group were shifted in the spectra of the complexes, confirming the involvement of the –COOH group in the complexation with covalent bonding as bidentate chelation. The geometry of the Ce3+ and Th4+ ions was six-coordinated with those of both drug complexes. The nano-structured form was investigated using transmittance electron microscope (TEM)). The antimicrobial activities of the newly synthesized complexes were determined against some kinds of bacteria and fungi. All these complexes showed antimicrobial results.


A new green protocol for the synthesis of 2-substituted perimidines from hydrazones under catalyst- and solvent-free conditions
Original Research Article
Pages 218 – 222
E.Menteşe, F. Yılmaz, B. Kahveci
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A new green protocol was developed for the synthesis of 2-substituted perimidines. The protocol involves a reaction of ethoxy carbonylhydrazone with 1,8-diaminonaphthalene under solvent- and catalyst-free conditions. Simple workup procedure, economical and environmentally benign are the most advantages of the present method.


Characterization by atomic force microscopy of gold nanoparticles functionalized with azocasein for protease colorimetric enzyme assay
Original Research Article
Pages 223 – 227
Al. S. Chanachev, S. S. Simeonova, P. D. Georgiev, Tz. N. Ivanova, S. D. Petrova, K. T. Balashev
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The colorimetric assay based on surface plasmon resonance of metal nanoparticles have proved to be applicable for sensors systems in the enzyme catalysis because of its simplicity, sensitivity and low cost. The preparation of stable suspensions of gold nanoparticles (GNPs) modified with proteins is a prerequisite for their use as an analytical tool for the colorimetric spectral analysis. In this report we propose a convenient experimental procedure for reproducible production of functionalized with azocasein GNPs. The GNPs were functionalized with azocasein in a stable suspension with optimized concentration of the azocasein. A concept for the test of protease activity using modified with azocasein GNP is also proposed. In order to studying the course of the enzyme reaction we applied UV-Vis spectroscopy and we analyzed the shift of the surface plasmon resonance maxima. For characterization of the morphology and the size of functionalized with azocasein GNPs we made series of Atomic Force Microscopy (AFM) images of samples taken at the begging and at the end of the proteolytic enzyme reaction.


Optimization scheme for a typical longitudinal three-level Rankine cycle cold energy power generation system for recycling liquid gas
Original Research Article
Pages 228 – 236
Sh. Yao, L. Xu, G. Feng, L. Tang
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This study investigates an intermediate fluid vaporizer in gasification systems for liquefied natural gas floating storage regasification units. A heated longitudinal three-level Rankine cycle system that uses the cold energy of liquefied natural gas to generate power was optimized. The system was then compared to the original longitudinal three-level Rankine cycle system established under the same conditions. Results showed that under a liquefied natural gas flow of 175 t/h, the net power output and exergy efficiency of the new system increase by 10.3% and 15.3%, respectively.


Lactic acid and M(II) d-metals (Cu, Co, Mn, Cd) milli- and micro- quantities interaction: FTIR and ESI-MS analysis
Original Research Article
Pages 237 – 242
N. S. Krstić, R. S. Nikolić, V. D. Dimitrijević, D. M. Đorđević, M. N. Stanković, I. M. Krstić, M. G. Nikolić
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This study investigated the interaction of M(II) d-biometal ions (Cu, Co, Mn) and toxic Cd(II) ion with lactic acid, which is present in human body as a result of intake or as a product of biological processes, at milli- and micro-molar level, under approximately physiological conditions by FTIR and ESI-MS spectroscopy. Spectroscopic investigations showed that the lactic acid in the tested system behaves as a monodentate ligand, it comes to interact at all concentration levels, and the most pronounced interaction is in the model system with Co(II) ion.


Correlation analysis of physicochemical parameters of the ecological status: a case study of Ibar River (Serbia)
Original Research Article
Pages 243 – 249
L. M. Takić, B. Ž. Todorović, A. S. Zdravković, N. M. Elezović, N. V. Živković
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The aim of this work is to determine the mutual dependence of selected physicochemical and geochemical parameters using correlation analysis and to assess the ecological status of water quality. The goal of this method is the faster and more precise interpretation of monitoring data, identification of pollution sources, and assessment of river water quality. In this regard, we used the water quality parameters of river Ibar from the monitoring station "Raška". This station is the most representative one for determining water quality, because it is located in the middle course of the Ibar River and is under the heaviest pollutant loads. Comparative analysis showed a deviation of the measured values of biochemical oxygen demand (BOD5), total organic carbon (TOC), NH4+ and PO43- from the prescribed reference values, which indicates the presence of organic matters in the river Ibar. This water body was attributed moderate ecological status (class III), while the comparison with the limit values of priority and priority hazardous substances indicated the lack of good chemical status. Based on correlation analysis, it can be concluded that there is pluvial erosion and that oxygen regime is influenced by changes in atmospheric temperature rather than by organic pollutants.


Determination of fluoride in toothpaste and in mouthwash products by GC/FID/HS
Original Research Article
Pages 250 – 253
T.N. Rizov, S.S. Paneva
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Fluorine is imported into the human organism mainly by products for oral hygiene, toothpastes and various liquids for freshening and cleansing the oral cavity. The necessity to control its content is imposed by the requirements for safety and standardized cosmetic products production. The determination was performed by gas chromatography, flame ionization detector and automatic vapor-phase sampler “headspace” (HS). The method was based on derivatization of fluoride anions with triethylchlorsilane (TETCS) in acidic environment. The reaction was realized in the HS vials and after that triethylfluorsilane was determined by gas phase injection. The calibration of the method lies within a concentration interval of 100 – 2000 ppm for toothpaste and 50 - 1000 ppm for mouthwash products. The repeatability, expressed as relative standard deviation at optimized reaction conditions and GC determination was ± 5% for toothpaste and ± 3.5% for mouthwash products. The presented gas-chromatographic method with flame ionization detector and HS appliance enables the quick and precise detection of fluorine in cosmetic products. The method is applicable to various other environments (matrices) – foods, food supplements, drugs.


Modeling of organic Rankine cycle for suitable working fluid in HYSYS for power generation in Pakistan
Original Research Article
Pages 254 – 264
M. Ur-Rehman, M. Sh. Khurram, S. Rafiq, Sh. A. Memon, M. Ghauri, F. Jamil , M. H. Jaffery, M. Gh. Doggar
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In this study organic Rankine cycle was modeled using Aspen HYSYS 8.8 to find suitable working fluids in 9 different locations which enlightened the scope of organic Rankine cycle in Pakistan. Different working fluids, namely R141b, R21, R142b and R245fa under different solar radiation-based temperature conditions at boiler inlet are reported in this study. R21 was found as the most promising working fluid due to its relatively better work output from a 0.59 MW turbine exploiting low quality heat, as compared to above mentioned working fluids investigated in this study.


Net analyte signal-based methods for the simultaneous determination of paracetamol, propyphenazone and caffeine by UV spectrophotometry
Original Research Article
Pages 265 – 273
G. Gergov, A. Alin, P. Katsarov, V. Simeonov, D. Yankov, Y. Al-Degs
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Three different net analyte signal-based (NAS) methods - NAP CLS, HLA/GO and HLA XS were successfully applied for the determination of ternarymixtures of paracetamol (PAR), propyphenazone (PRO) and caffeine (CAF). The methods used absorbance UV-spectral data for resolving this complex system with overlapping drug spectra. A reduced five-level orthogonal design was used for the formation of a calibration set including the three compounds. The chemometric models were tested on an external validation dataset with concentrations within the calibration range. All proposed chemometric algorithms could be successfully applied for the determination of the above compounds in the pharmaceutical tablet formulation Saridon®. The obtained results showed that the NAS performance was similar compared to partial least-squares method (PLS-1). In addition, the use of the net analyte signal concept allowed the calculations of the analytical figures of merit. A moving window wavelength selection strategy was used, which significantly reduced the number of factors and improved the analytical recoveries.


Study on copper ions adsorption from aqueous solution by Emeraldine
Original Research Article
Pages 274 – 280
S. I. Lavrova-Popova, Z. L. Yaneva, G. I. Hlebarov, B. K. Koumanova
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The influence of in situ synthesized emeraldine (salt and base) on the removal of copper ions from aqueous media is discussed. Physicochemical parameters such as initial copper ion concentration, emeraldine dosage and contact time between adsorbent and Cu(II) ions in aqueous solution were studied. An assessment of the equilibrium and the kinetics of sorption of copper ions was made. The experimental results were fitted to the isotherms of Langmuir, Freundlich, Toth and Baudu. It was established that the Toth and Baudu isotherms are suitable for the case of emeraldine salt. The Langmuir model gave satisfactory correlation with the experimental results only in the low concentration range of copper ion sorption using emeraldine base. The maximum sorption capacity of emeraldine base at 50 mg.dm-3 initial copper ions concentration (qemax 7.5 mg.g-1) was higher than that of the emeraldine salt. Probably, the mechanism of copper ions sorption includes physisorption, chemisorptions, as well as intraparticle diffusion during the later stages of the process.


Insight into polymer-borate hybrid films - structural approach
Original Research Article
Pages 281 – 285
H. Hristov, M. Nedyalkova, V. Simeonov
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Transparent organic-inorganic hybrid films (mass ratio PVA/PEG/B2O3=10/7/1) are obtained by polymer-assisted sol-gel synthesis and solution-casting method at ambient temperature. An aqueous solution of boric acid (H3BO3) and ethanol solution of trimethyl borate ((СН3О)3В) with pH adjustment are used as sources of cross-linking borate units. Surface morphology and structure of the obtained hybrid films are studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). XRD indicated that amorphous structure with poor crystallinity is formed. SEM showed a homogeneous and microporous surface free of crystallites. The results of FTIR spectroscopy revealed that the borate unit types and chemical bonds in the hybrid network are functionally dependent on the type of boron-containing solution and pH. The most crosslinked hybrid structure including a large number of polyborate ions is obtained from an aqueous solution of H3BO3 at pH 10. Based on spectral data a probable crosslinking mechanism in the hybrid network consisting of B-O-C bonds of ester complexes and hydrogen bonds is proposed.


Nonlinear predictive control based on artificial neural network model for pilot reformer plant: Approach for ratio control
Original Research Article
Pages 286 – 293
B.Parvizi, A. Khanlarkhani, Y. Palizdar
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The reformer box is an important operation unit in many refineries such as petrochemical, oil refineries and DRI (direct reduction of iron) production plants for producing syngas from different hydrocarbons. As the heart of a DRI production plant in MIDREX technology, it is very crucial to control the syngas composition in desired condition, especially hydrogen to carbon monoxide ratio which should be kept in a limited range of 1.6-2 to achieve the most proper reducing gas for converting the iron pellets to sponge iron with best percentage of carbon. In operation, this process package is difficult to handle from control stand point due to its nonlinear behavior, multivariable interaction and existence of constraints on its different reaction conditions. Neural network techniques have been increasingly used for a wide variety of applications where statistical methods have been traditionally employed. In this work we proposed a multi input multi output (MIMO) feed foreward neural network based multivariable control strategy to simultaneously control the inlet gas composition and reaction temperature, to control the outflow gas composition in desired condition. Modeling and controlling were investigated by use of data collected from a methane reforming pilot plant using CO2 and steam, in process conditions near to those in a MIDREX reforming plant in sponge iron production. Different reaction temperatures from 700 to 1100 ˚C with different values of gases were randomly selected and used to generate around 5000 data sets of input- output data structure. Gas conversions and H2/CO ratio were considered as the set points and tracking results of each showed the effective performance of the neural network- model predictive control (NN-MPC) strategy in this application.


Co, Ni, Cu phthalocyanines with tetra substituted bisbenzimide
Original Research Article
Pages 294 – 297
M. Canlıca
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Cyclotetramerization of bulky substituted phthalonitrile derivative 3 to the Co(II)Pc, Ni(II)Pc and Cu(II)Pc derivatives [4,5,6] was accomplished in quinoline with DBU at reflux temperature. The complexes were characterized by UV-Vis, FT-IR, mass spectra and elemental analysis.


Application of direct simulation Monte Carlo for development of micro gas sensor
Original Research Article
Pages 298 – 305
M. B. Gerdroodbary, D. D. Ganji, M. Taeibi-Rahni, Sh. Vakilipour, R. Moradi
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Development of a new micro gas sensor is essential for the analysis of the outcome of gas separation devices. In this paper, direct simulation Monte Carlo (DSMC) modeling of low-pressure gas sensor was performed to investigate the effect of physical parameters on the performance and main characteristics of this type of actuator in various operating conditions. Extensive parametric studies were done and the effect of ambient pressure, temperature and gap of arms were comprehensively investigated. Our findings showed that gap size significantly influences the flow features and force generation inside the sensor.


Cloud point extraction combined with flame atomic absorption spectrometry for analysis of trace silver nanoparticles in environmental waters
Original Research Article
Pages 306– 311
H.Z. Wu, L.F. Meng
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A cloud-point extraction (CPE) method using non-ionic surfactant Tergitol TMN-6 (TMN-6) is developed for the extraction and pre-concentration of silver nanoparticles (AgNPs). Effective separation of ionic silver species and AgNPs is achieved by using sodium thiosulfate (Na2S2O3) as a masking agent. Addition of 1M (NH4)2SO4 enhanced the phase separation and thus increased the extraction efficiency of AgNPs. An enrichment factor of 57 was obtained with 1% (v/v) TMN-6, and the recoveries of AgNPs spiked into environmental samples were in the range of 96.7% to 108%. A low limit of detection (LOD) of 6.5 μg/L was achieved using flame atomic absorption spectrometry (FAAS) for quantification. The relative standard deviation (RSD) was 2.1% (n=9). This proposed method provides an efficient approach for the analysis and tracking of AgNPs in environmental water samples.


Selected papers presented at the 5th Asia-Pacific Conference on Engineering Technology (APCET 2017), May 27-30, 2017, Beijing, China.
Pages312 – 313
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Effects of sodium polyacrylate and potassium polymer on growth and physiological characteristics of different flue-cured tobaccos
Original Research Article
Pages 315 – 323
W.X. Huang, Z.Z. Wei, G.Y. Niu, Y.J Zhang, H.F. Shao
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To investigate water retention effects and physiological regulation mechanism of water-retaining agents on the growth and development of different flue-cured tobacco varieties, a pot experiment was conducted using ‘Yuyan 6’ and ‘Yuyan 10’ to study the effects of sodium polyacrylate and potassium polymer on the agronomic characteristics, the root activity, the activity of antioxidant enzymes, the content of malondialdehyde (MDA) and proline in the leaves of flue-cured tobaccos. The results were as follows. (1) The application of water-retaining agents increased the plant height, the stem diameter, the number of effective leaves, the maximum leaf area and the root activity of flue-cured tobaccos and the effects were more significant for Yuyan 10 of relatively poor drought resistance. (2) The activity of SOD, POD and CAT of flue-cured tobaccos treated with water-retaining agents was reduced to different extents. (3) The application of water-retaining agents lowered the MDA content of flue-cured tobaccos but the effects were more significant for Yuyan 10 of relatively poor drought resistance. (4) The application of water-retaining agents decreased the proline content of flue-cured tobaccos under drought conditions, but the decrease of proline content in Yuyan 6 was larger than that in Yuyan 10. Yuyan 6 was highly drought-tolerant, so water-retaining agents could better promote the adaptability of Yuyan 10 to drought stress. Furthermore, water-retaining agent potassium polymer showed a stronger regulatory capability for the growth and physiological metabolism of flue-cured tobaccos than water-retaining agent sodium polyacrylate.


Effects of deposition pressure on Cu2ZnSnS4 films prepared by one-step sputtering with quaternary target
Original Research Article
Pages 324 – 328
H.G. Yang , J.D. Zhang, M.C. Li , R.T. Hao , G.L Song
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Cu2ZnSnS4 (CZTS) films were deposited from single-phase Cu2ZnSnS4 quaternary compound target by RF sputtering without post sulfurization process. The as-prepared CZTS films were annealed with 400°C in Ar atmosphere to obtain the single-phase kesterite structure. The influence of sputtering pressure on surface morphology, crystal structure, optical absorption coefficient, band gap, and the influence of the chemical composition of CZTS films was investigated. The diffraction peaks of (112) are sharp and the characteristic peaks of the kesterite-type structure such as (220) and (312) are clearly observed in X-Ray Diffraction patterns. The composition and optical properties of the samples were determined with energy dispersive X-ray spectroscopy (EDS) and UV-VIS-NIR spectrophotometer. While at the sputtering pressure of 0.2 Pa, an attractive Cu-poor and Zn-rich, large grain size and single-phase CZTS film can be obtained. Research result show that the CZTS films exhibit a high absorption coefficient of the order of 104 cm-1, and an optical band gap of 1.49 eV.


A novel all-thin-film electrochromic device for modulating optical transmittance
Original Research Article
Pages 329 – 333
H.G. Yang, R.T. Hao, M.C. Li , G.L Song
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An all-thin-film glass/ITO/WO3/LiAlO2/NiOx/ITO device was successfully fabricated for electrochromic application, in which LiAlO2 was used as the ion conducting layer material. The thin films were prepared by magnetron sputtering with a substrate temperature about -120 ℃. The film structure was characterized by X-ray diffraction (XRD), and the film morphology was characterized by scanning electron microscopy (SEM). The electrochromic properties of the films and the device were measured with cyclic voltammetry and spectrophotometry. For the obtained electrochromic device, the average visible light transmittances of bleached and colored state can reach 73.4% and 32.8%, respectively, and the optical transmittance modulation can reach 40.6%. The results indicated that the LiAlO2 thin film was a suitable ion conductor for the electrochromic device, and the monolithic system glass/ITO/WO3/LiAlO2/NiOx/ITO has great potential to be applied in smart windows.


Thickness dependence of internal stress in electrodeposited nano-twinned copper
Original Research Article
Pages 334 – 338
S. Zhan, Y.L. Yang, W.Y. Peng, J.G. Chen, Z.B. Li, X.J. Hou, L. Feng, G.Q. Suo, Z.G. Chen, J. Zou, Y.D. Wang
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Electrodeposited pure copper with nano-scaled twins was proved to be a tradeoff for the contradiction of high mechanical strength and high electrical conductivity. In this work the internal stress of the nano-twinned copper was explored by means of X-ray diffraction analysis. The results show that the internal stress is associated with the deposition thickness. The macro-stress of the film is very small and constant. The type-II micro-stress (grain-orientation-dependent stress) is also small, while it becomes higher with the increase of deposition thickness.


To the paper:
Chemical profile of Artemisia annua from the region of Sliven, Bulgaria. A preliminary NMR studyn

Pages 339 – 339
.V. Kurteva, A. Trendafilova, S. Simova
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IIncorrect structure of the reference compound used for the semi-quantitative NMR analysis necessitates correction of the concentrations in the experimental part and estimated quantity of artemisinin in results and discussion. The correct structure of “Salophen” used is 4-acetamidophenyl 2-hydroxybenzoate, and figure 2 has to be replaced.