STUDIA CHEMIA - Issue no. 1 / 2020 - Table of contents
Professor Petru Ilea on his 65th Anniversary
Ionel Cătălin POPESCU, Liana Maria MUREȘAN, Graziella Liana TURDEAN
Professor Petru Ilea was born on the 23rd of April 1953. In 1977 he graduated from Technical University of Timisoara as a chemical engineer. He received his PhD degree in chemical engineering in 1994, under the supervision of the distinguished Professor Liviu Oniciu. As Teaching Assistant (1987), Assistant Professor (1990), Associate Professor (2000) and Professor (2005) at the Faculty of Chemistry and Chemical Engineering Cluj-Napoca, Petru Ilea introduced and developed the electrochemical engineering and electrochemical technology programs in the undergraduate and graduate curricula at our faculty. His courses were appreciated by both undergraduate and graduate students. He focused his research efforts in the domains of electrochemical engineering and technology. At the same time, the environmental applications of electrochemistry were among the most fruitful scientific preoccupations of Professor Petru Ilea. In addition to over 80 scientific papers, Professor Petru Ilea also coauthored 3 books and managed numerous grants and research projects. He counts more than 110 participations to scientific conferences with lectures, posters and oral communications. The research grants he coordinated, substantially contributed to the development of electrochemical engineering and technology at “Babeş-Bolyai” University. It is worth mentioning, that starting with 2006 Professor Petru Ilea is the head of the Physical-Chemical Analysis Center at the Institute of Interdisciplinary Research in Bio-Nano-Sciences of University “Babes-Bolyai” Cluj-Napoca. Professor Petru Ilea was one of the founders of the Doctoral School of Chemical Engineering at our faculty and he was its head starting with 2017. Professor Petru Ilea was a very active member of the academic community. He has served as Chancellor of Faculty of Chemistry and Chemical Engineering (2000-2009). During several years (2000-2016) he was an active member of the Faculty Council. Since 2007 he is an active member of CNADTCU/Engineering Sciences (Division of Chemical engineering, medical engineering, material and nanomaterials science). This issue of Studia Universitas Babeş-Bolyai, Seria Chemia wishes to honor Professor Petru Ilea and to recognize his achievements within the academic community. The intention of the editors was to bring together contributions from his co-workers, scientists that have close professional contact with him and those working intensively in the field of chemical engineering and technology. Now, at this anniversary moment, we – the colleagues of the Electrochemistry group, as well as all the colleagues and researchers of the Faculty of Chemistry and Chemical Engineering of the “Babeş-Bolyai” University, express Professor Petru Ilea their appreciation for his entire activity, along with the best wishes for a long life of successful future achievements! Prof. dr. Ionel Catalin POPESCU Prof. dr. Liana Maria MURESAN Prof. habil. dr. ing. Graziella Liana TURDEAN Cluj-Napoca, March 2020
Cyclic Voltammetry and Short-Time Scale Chronoamperometry at Layer-by-Layer Self-Assembled Au Modified Electrodes. Fructose Biosensor
Ionel Cătălin POPESCU
Cyclic voltammetry (CV) and short-time scale chronoamperometry measurements were performed aiming to investigate the layer-by-layer selfassembled multilayer structures built on Au electrodes. The attractive electrostatic interactions exerted between the successively deposited layers of charged polymers were exploited in order to immobilize a cationic Os redox polymer onto the surface of Au modified electrodes. CV responses observed at the resulted Au modified electrodes proved the efficiency of the proposed design. The chronoamperometric responses were fitted by using a three-phase exponential decay function. The fitting parameters allowed comparing the ability of charge transfer of the investigated modified electrodes. The most efficient structure was used as an amperometric transducer for electrical communication between fructose dehydrogenase and the Au electrode. In order to validate the new approach as a proof of concept for obtaining reagentless biosensors, a functional amperometric biosensor for D-fructose was successfully built.
Keywords: Self-assembled multilayer architecture, electrostatic interactions, Au modified electrodes, reagentless amperometric biosensors, Os redox polymer.
Inhibition Effect of Some Commercial Corrosion Inhibitors on Mild Steel in 7.0 m Phosphoric Acid
Julieta Daniela CHELARU, Mihaela CIOBRA, Liana Maria MUREŞAN
Corrosion tests were carried out in order to find the best inhibitor for the protection of steel pipelines used in H3PO4 and fertilizers industry. The corrosion inhibition efficiency of five commercial inhibitors was investigated on mild steel by using electrochemical methods (EIS and polarization curves) in a 7M H3PO4 solution (pH 0.5). The efficiency of best corrosion inhibitors was tested at different concentrations.
Keywords: mild steel, corrosion inhibitors, electrochemical impedance spectroscopy, polarization curves, inhibitor efficiency, phosphoric acid.
Paracetamol Detection at a Graphite Paste Modified Electrode Based on Platinum Nanoparticles Immobilised on Al-SBA-15 Composite Material
Thi Thanh Hien NGO, Ioana Carmen FORT, Thanh Huyen PHAM, Graziella Liana TURDEAN
A composite material was obtained by immobilizing platinum nanoparticles (Pt-NPs) within an ordered mesoporous structure Al-SBA15 (having improved acidity due to the presence of Al). This was used for preparing a graphite paste modified electrode (Pt/Al-SBA-15-GPE), which was applied for paracetamol (PA) detection. The obtained electrode was investigated by electrochemical methods (e.g. cyclic voltammetry, CV and electrochemical impedance spectroscopy, EIS), in order to estimate the electrochemical parameters, which were compared with those of GPE unmodified electrode. Square-wave voltammetry (SWV) was used to obtain the analytical parameters of Pt/Al-SBA-15-GPE for PA detection. The good analytical parameters recommend the composite mesoporous material (Pt/Al-SBA-15) to be used for preparing modified electrodes for PA detection in real samples.
Keywords: Pt nanoparticles, ordered mesoporous structure, graphite paste modified electrode, paracetamol
Synthesis of Novel N-Substituted Amphionic Melamines with the Tandem 4-(1-carboxy-n-alkoxy)phenyl / 4-(noctyloxy) phenyl Units as Potential Dendritic Building-Blocks
Stefania IONESCU-ZINCA, Pedro LAMEIRAS, Dan PORUMB, Emese GÁL, Mircea DARABANTU
Starting from etheric type derivatives of 4-aminophenol, namely (4-aminophenoxy)acetic acid or 4-(4-aminophenoxy)butyric acid and 4-(n-octyloxy)aniline, we report herein two routes of access to two novel Nsubstituted amphionic melamines with the tandem 4-(1-carboxy-n-alkoxy) phenyl/4-(n-octyloxy)phenyl units against the piperazin-1-yl group, as a basic site. The successful SN2-Ar aminations of cyanuric chloride performed with these amine-nucleophiles are discussed in terms of chemoselectivity, mainly in the third step of the synthesis, implying piperazine as such or its N-Boc-mono-protected form. The amphionic nature of the targeted melamines was fully confirmed both in solution (VT-NMR) and in the solid state (IR).
Keywords: (4-aminophenoxy)acetic acid, 4-(4-aminophenoxy)butyric acid, amphionic melamines, N-Boc-piperazine, 4-(n-octyloxy)aniline
Copper(II) Complexes with New n-Substituted Sulfonamides - Synthesis, Crystal Structure and Evaluation of the Nuclease Activity
Andreea BODOKI, Gloria ALZUET-PIÑA, Joaquín BORRÁS, Tamara TOPALĂ, Adriana HANGAN, Gheorghe BORODI, Luminița OPREAN
Binary Cu(II) complexes of two new N-substituted sulfonamides, N-(pyridin-2-yl-methyl)biphenyl-4-sulfonamide (HL1) and N-bis-(pyridin-2-ylmethyl) biphenyl-4-4’-sulfonamide (H2L2), have been synthesized and characterized by X-ray diffraction, spectroscopic and electrochemical techniques. The structure of complex [Cu(L1)2] consists of a discrete monomeric Cu(II) species stabilized by π-π stacking interactions involving the pyridyl and phenyl rings of the coordinated ligands. In contrast, in the case of complex [Cu(L2)]n, each symmetrical sulfonamide structure coordinates two Cu(II) ions, giving rise to a polymeric chain. Upon coordination, CuN4 chromophores with the N-pyrydil atoms in trans position are generated, and the coordination geometry of both complexes can be best described as highly distorted square-planar. The ability of complex [Cu(L1)2] to promote DNA cleavage with ascorbate activation was also evaluated; the complex has a moderate nuclease activity, being able to partially cleave supercoiled DNA to nicked circular and linear DNA. We herein also report the evaluation of the nuclease activity of complex Cu2(N-(pyridin-2-yl)biphenyl-4-sulfonamidate)4, previously characterized in terms of structure by our group.
Keywords: Cu(II) complexes, N-substituted sulfonamides, X-ray diffraction, nuclease activity
Characterization and Classification of Medicinal Plant Extracts According to Their Antioxidant Activity Using High-Performance Liquid Chromatography and Multivariate Analysis
Ileana M. SIMION, Augustin C. MOȚ, Radu D. GĂCEANU, Horia F. POP, Costel SÂRBU
Fuzzy divisive hierarchical clustering (FDHC) alongside with principal component analysis, hierarchical cluster analysis and linear discriminant analysis are efficiently employed for the characterization and clustering of some medicinal plants according to their antioxidant capacity. These methods are applied to the numerical data obtained from the chromatographic profiles monitored at 242, 260, 280, 320, 340 and 380 nm by high-performance liquid chromatography with a multistep isocratic and gradient elution system and diode array detection (HPLC-DAD). The samples were successfully classified according to the antioxidant activity determined using the DPPH assay. A correct classification rate of 100% was obtained when the samples were divided into two groups corresponding to high antioxidant activity and low antioxidant activity. Moreover, it is suggested to use the scores obtained applying principal component analysis and unprocessed data (the processed data by scaling and normalization did not improve the results), the analysis being faster with the same results. The proposed methodology could be considered as a promising tool with future applications in plant material investigations and other analytical fields.
Keywords: Fuzzy clustering, chemometrics, high-performance liquid chromatography, antioxidant capacity, medicinal plants
Effect of Some Antioxidant Food Additives on the Degradation of Cornelian Cherry Anthocyanins
Bianca MOLDOVAN, Luminiţa DAVID
Anthocyanin rich fruits present a great potential as source of natural food colorants. Their use in the food industry is limited by their low stability. The influence of storage media and addition of three widely used antioxidant food additives, such as citric acid, ascorbic acid and butylated hydroxyanisole, on the stability of Cornelian cherry anthocyanins, was investigated at room temperature. In aqueous solutions, the degradation of these valuable pigments occurred slower compared to alcoholic solution. Addition of ascorbic acid significantly enhanced anthocyanins degradation in ethanolic or aqueous solutions, while citric acid and BHA had a positive effect on the anthocyanins’ stability in ethanol. The Cornelian cherry anthocyanins’ degradation followed first-order reaction kinetics. The obtained kinetic parameters (reaction rate constants k and halflifes t1/2) clearly indicated that Cornelian cherry anthocyanins stored in ethanol in presence of citric acid present the highest stability, the degradation rate constant being 0.7410-3 h-1.
Keywords: Cornus mas L., antioxidant food additives, anthocyanins, degradation kinetics
Virgin Olive Oil Phenols-Spectroscopic Evaluation in Basic Medium: Analysis of Total Content of Hydroxytyrosol
Here a spectrophotometric technique in the visible region combined with an environmental friendly ultra-pure water based liquid-liquid extraction procedure has been described for the determination of total hydroxytyrosol in virgin olive oils regardless of whether it is free or combined. Determination of total hydroxytyrosol was carried out where the absorption peak of the colored compounds formed with autopolymerization of quinones that occured following the oxidation of hydroxytyrosol and its secoiridoid derivatives in a basic medium was measured as an analytical signal. The method was linear in a concentration range of 0.2-15.0 mg L-1 with a correlation coefficient of 0.9990. Detection and quantification limits were 0.05 and 0.18 mg L-1, respectively. Intra-day and inter-day precision studies indicated that the proposed method was repeatable. In addition, the liquidliquid extraction procedure was quite efficient with recovery values between 108 and 117%. Finally, the proposed method was successfully applied to the analysis of total hydroxytyrosol in a virgin olive oil and the results were compared with those obtained by a method existing in the literature for the determination of total hydroxytyrosol based on acid hydrolysis of secoiridoid aglycons followed by liquid chromatography-tandem mass spectrometry.
Keywords: hydroxytyrosol; virgin olive oil; phenolic compounds; visible spectroscopy; liquid-liquid extraction
Optimization, Kinetics and Thermodynamics of the Solid-Liquid Extraction Process of Flavonoids from Rosemary (Rosemarinus Officinalis) Leaves
Milan MITIĆ, Sonja JANKOVIĆ, Jelena MRMOŠANIN, Milan STOJKOVIĆ, Danijela KOSTIĆ, Ružica MICIĆ
Solid-liquid extraction of total flavonoids (TF) from rosemary (Rosemarinus officinalis) leaves was studied in the present work. The effects of type of solvent and its concentration, temperature and extraction time on amount of flavonoids as well as the effects of these parameters on the kinetics and thermodynamic parameters of extraction process were investigated. The effects of the process factors on the TF were assessed using the full factorial test plan 23. Extraction using 50% ethanol in a 50 oC during 100 min, was the most suitable conditions to produce a extract with high content of flavonoids (32.428 mg catechin equivalents / g rosemary leaves). The following twoparametric models were analyzed: non-stationary diffusion model trough the plant material, model of Ponomarev and parabolic diffusion model. All models gave a good fit to the experimental data (root mean square, RMS<2%, coefficient of determination, R2>93%). The ΔGo, ΔSo and ΔHo values of the flavonoids extraction process were -4.89 – (-7.02) kJ/mol, 23.59 – 25.91 KJ/mol and 0.95 – 9.90 kJ/mol, respectively, indicating spontaneous, irreversible, and endothermic process.
Keywords: rosemary, flavonoids, kinetic model
Tracking the Growing Rings in Biogenic Aragonite from Fish Otolith Using Confocal Raman Microspectroscopy and Imaging
Geza LAZAR, Calin FIRTA, Sanja MATIĆ-SKOKO, Melita PEHARDA, Dario VRDOLJAK, Hana UVANOVIĆ, Fran NEKVAPIL, Branko GLAMUZINA, Simona CINTA PINZARU
Fish otoliths pose increasing interest due to their potential of rendering information about environmental changes, underlined in their non-linear time-dependent biogenic crystal growth. Otoliths are acellular, metabolically inert and continuously grow in a complex process which still needs to be understood. In the present work confocal Raman microspectroscopy (CRM) and imaging is employed to investigate the growth pattern in otoliths from Sparus aurata of Mediterranean provenance. CRM signal acquired from otolith sagittal section is exploited to associate it with the periodic growth increments denoted as rings. Raman signal collected from the core to the margins with micrometer spatial resolution invariably revealed characteristic signal of aragonite. Relative intensity variability was observed particularly for the lattice modes, indicating changes in crystalline orientation relative to incident laser. Bands associated with organic fraction were absent in the 90-1840 cm-1 spectral range. Daily growth rings were further studied using the Raman mapping of main aragonite bands intensities at 1083, 704 and the lattice modes in the 100-350 cm-1 range. The spectral intensity pattern closely follows the daily growth pattern. Traces of toxic or heavy metals incorporated in biogenic carbonate mineral were spuriously detected in the mapped areas, according to the position and width of the Raman bands of witherite (BaCO3), strontianite (SrCO3), along with the main aragonite and trace of its calcite polymorph.
Keywords: Confocal Raman micro-spectroscopy, fish otoliths, Raman mapping, growth rings, aragonite
Structural, Morphological and Dissolution Properties of ZrO2-Based Biocomposites for Dental Applications
Liliana BIZO, Klara SABO, Réka BARÁBAS, Gabriel KATONA, Lucian BARBU-TUDORAN, Antonela BERAR
In the present work, zirconia-based biocomposites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP). The biocomposites were synthesized by the conventional ceramic processing route. The structure and morphology of the materials were investigated using X-ray powder diffraction (XRPD), scanning and transmission electronic microscopy (SEM and TEM). The stability of the tetragonal structure of ZrO2 was confirmed by XRPD analyses. Moreover, their bioactivity was studied by soaking the samples in artificial saliva (AS) to evaluate the effect of MgO and HAP on the biological performances of the prepared biocomposites. UV-VIS analyses carried out on artificial saliva after immersion of the prepared materials showed that MgO plays an important role in the post-immersion dissolution process.
Keywords: zirconia (ZrO2), magnesium oxide (MgO), hydroxyapatite (HAP), biocomposites.
Surface Characterization and Cytotoxicity Analysis of the Titanium Alloys for Dentistry
Paula Argentina JIMAN, Marioara MOLDOVAN, Codruta SAROSI, Alexandrina MUNTEAN, Andreea Simona POP, Viorica TARMURE, Catalin POPA, Aurel George MOHAN
Three methods of treating the Ti and Ti-6Al-4V alloy surface used as dental implants have been tried both to increase the corrosion resistance and to create diffusion barriers, which prevent the release of toxic ions in the body, at the separation surface, implant living tissue. The anticorrosive performances of the experimental oxide films, realized on the pure Ti and Ti-6Al-4V alloy were evaluated electrochemically by cyclic voltammetry after immersion of samples in Ringer’s solution at 37°C. The A2-Ti sample (Ti-6Al-4V alloy anodized with H3PO4, 1N, and citric acid, 20 g/l electrolyte solution) shows lower viability values, compared to the other samples, with a tendency to decrease after 48h of incubation. The cytotoxic effect is slightly higher in A1-Ti (Ti-6Al-4V alloy anodized with 0.6% H3PO4 electrolyte solution) compared to Ti over a period. This can be attributed to the presence of aluminium and vanadium. The results revealed that the specific processing of titanium and titanium alloy (Ti-6Al-4V) by obtaining an oxide layer influence the toxicity that is stabilize and decrease with time, which makes to be used in dental implantology.
Keywords: Ti-6Al-4V surface treatment, electrochemical processing, dental implant, cytotoxicity, SEM.
Principal Component Analysis and Thermomechanical Preference of White Au Alloys Without Ag
Mladen MIRIĆ, Biljana ARSIĆ, Miloš ƉORĐEVIĆ, Dragan ƉORĐEVIĆ, Dragoslav GUSKOVIĆ, Svetlana IVANOV
Addition of different amounts of Cu and Ag to Au alloys, as well as some new elements (Zn and Cd), gives alloys of the different colour spectrum (from red to yellow) and different technological and metallurgical characteristics. The trend today is the implementation of new alloys not containing Ag, and including new elements, such as Ga and In. Differences in two Au alloys exist: the first alloy contains Ni and Pd, and the second alloy is without them. The values of electrical conductivity and hardness are different, due to the reduction, which was shown using PCA (r=0.985 and the strong positive correlation between hardness and electrical conductivity). Performed tests confirm that those multiphase multi component gold alloys can find their application not only in jewellery making but also in the world of modern electrical engineering. The performed statistical analysis shows strong positive and negative correlations of properties of investigated Au alloys, and it provides significant savings in the design and efficiency of metallurgical processes.
Keywords: alloy, PCA, metallurgical process
Synthesis and Characterisation of Fe3O4-SnO2 nanocomposites with electrochemical properties
Sergiu MACAVEI, Maria ŞTEFAN, Florina POGACEAN, Ovidiu PANĂ, Cristian LEOSTEAN, Adriana POPA, Dana TOLOMAN, Lucian BARBUTUDORAN
Composite Fe3O4-SnO2 nanoparticles were synthesized by growing SnO2 nanoparticles on the surface of previously prepared Fe3O4 nanoparticles. First, Fe3O4 nanoparticles were prepared by chemical precipitation of precursors followed by the obtaining of SnO2 nanoparticles by chemical precipitation or sol-gel process. The composite nanoparticle samples were characterized by using X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM) and X-Ray photoelectron Spectroscopy (XPS) techniques. Also, electrochemical behaviour was recorded. The results revealed that by adjusting the composition of components one can control the properties of composite nanoparticles.
Keywords: SnO2; nanoparticles; photocatalytic properties, electrochemical properties
Morpho-Textural and Fluorescence Studies on SIO2 and SIO2@Ce3+
Elena-Mirela PICIORUȘ, Cătălin IANĂȘI, Roxana NICOLA, Paula SFÎRLOAGĂ, Paula SVERA, Ana-Maria PUTZ
Spherical silica xerogels were synthesized by Stöber route using tetra-ethyl-orthosilicate (TEOS) in order to obtain good properties for opto-electronic and catalytic applications. The reactants mole ratio was n TEOS: H2O: ETOH: NH3 (where n = 0.098 ÷ 0.26: 0.45: 0.789: 0.06). To study these properties, we know from literature, that nanoparticles under 100 nm show unique electrical, mechanical and optical properties. We have choosen the optimum sample, with the smaller surface area and particles size of 91 nm. To improve the optical properties, this sample was further doped with 0.1% Ce3+. The obtained xerogel was thermally treated at 300, 600 and 900 oC. The changes in properties were put in evidence by morpho-textural (N2 adsorption– desorption isotherms and SEM images) and optical measurements (FT-IR, Fluorescence and Raman spectra’s).
Keywords: sol-gel, Ce (III) carbonate hydrate, Stöber, spherical particles
Plantwide Control and Dynamics Behavior of an Integrated Plant Coupling Nitrobenzene Hydrogenation and Methyl-Cyclohexane Dehydrogenation
Ahtesham JAVAID, Costin S. BILDEA
Coupling of exothermic and endothermic processes is an application of process intensification where two or more processes can be combined in single unit for better utilization of material and energy. Nitrobenzene hydrogenation and dehydrogenation of Methyl cyclohexane in a single adiabatic reactor was investigated and found efficient, stable and economical in the previous study. The scope of this research is to implement plantwide control structure to analyze the dynamics behavior of an integrated system using Aspen Dynamics. Integrated plants where un-reacted reactants are recycled have high sensitivity towards disturbances. The complexity of the plant is reduced by fixing flow rates of reactants at reactor inlet using feedback control strategy. On introduction of individual and combined disturbances in flow rates of reactants ±10%, the system showed robust behavior and achieved stable operation. The system allows production rate changes keeping high purity of products.
Keywords: Aspen Dynamics; Plantwide Control; Process Intensification; Reaction Coupling.
Demetallization of Heavy Vacuum Residuum by Titanium-Vanadium Zeolite Adsorbents
Yerdos ONGARBAYEV, Shynar OTEULI, Yerbol TILEUBERDI, Galymzhan MALDYBAEV, Saule NURZHANOVA
Demetallization and desulfurization of vacuum residuum from the Pavlodar Petrochemical Plant (Kazakhstan) was carried out by adsorbents based on zeolite modified with titanium compounds and vanadium oxide. The process was carried out at a temperature of 320-360oC for 1 to 3 hours at atmospheric pressure. The results of determining the physico-chemical characteristics of the modified adsorbents showed that, after modification, their specific surface area increases, but the specific pore volume decreases. The maximum degree of demetallization is observed when using an adsorbent based on zeolite modified with titanium oxides and vanadium oxides. The change in the structure of vanadylporphyrins in vacuum residuum composition after the demetallization process is determined. After demetallization etioporphyrins have C27-C32 with a center of mass at C29, phylloporphyrins have C28-C34, after treatment at 360°C, the center of mass shifts towards an increase in the number of carbon atoms C31.
Keywords: demetallization, desulfurization, heavy vacuum residuum, adsorbent, zeolite, vanadium oxide, titanium, etioporphyrins, phylloporphyrins
Experimental Study of Structural-Mechanical Properties of Heavy Oil
Ryskol BAYAMIROVA, Aliya TOGASHEVA, Akshyryn ZHOLBASSAROVA, Zharas ISLAMBERDIYEV, Max BISSENGALIEV, Daden SUIEROV
Structural-mechanical properties of heavy oil from Kazakhstan deposits under the heat treatment were studied in this work. The most important and the least studied issues in the technology for the preparation and collection of oil products is the evaluation of the structural and mechanical properties of heavy oils and emulsions and ways to regulate formation them. A feature of the wells operation of fields with high viscosity oils is a sharp increase in water cut at the initial stage of development, which is associated with an excessively large difference in the rheological characteristics of reservoir oil and water. The formation of stable emulsions does not allow for the effective separation of oil from water and leads to a deterioration in product quality. In this regard, in modern conditions of intensification of hydrocarbon production, consideration of the options for the formation and destruction of complex emulsions is a prerequisite for the effective operation of oilfield treatment facilities. Therefore, the research relevance is of reducing the irretrievable losses of hydrocarbons in production systems and study the physical-chemical, structural-mechanical properties of heavy oils emulsions and to develop methods for their regulation, as well as improving oil treatment devices.
Keywords: heavy oil, asphaltene, tar, water-oil emulsions, structural-mechanical properties
Mathematical Approach for Pilot-Scale Experiment Setup on Biogas Production
Adrian Eugen CIOABLĂ, Mădălina IVANOVICI, Gabriela-Alina DUMITREL, Laurențiu-Valentin ORDODI, Delia-Gabriela CĂLINOIU, Gavrilă TRIFTORDAI, Vasile PODE
In this work, pilot scale experiments were carried to evaluate the biogas production through anaerobic co-digestion for two different mixtures of feedstock based on agricultural biomass and agricultural waste. The first mixture consisted of degraded row barley and wastewater from treatment plant and the second mixture contained wheat, corn grains and shell sunflower seeds with wastewater from treatment plant. The temperature, pH, pressure and the amount of the produced biogas were daily monitored for 26 days and the results of the two experimental charges were assessed and compared using statistical analysis: the box plot method and summary statistics. The latter feedstock mixture showed a better production of biogas for which the mean value of produced biogas amount is 18.43 m3, whereas the mean value of the biogas generated for the former feedstock mixture was 14.95 m3.
Keywords: biogas production, agricultural biomass, pilot scale, co-digestion, statistics
Qualitative Analysis of Filters for the Mechanical Nanofiltration of Household Drinking Water
Oana-Adriana CRIȘAN, Marius Sorin PUSTAN, Corina Julieta BÎRLEANU, Ancuța Elena TIUC, Ioana SUR, Horea-George CRIȘAN, Florina Maria ȘERDEAN, Lazăr FLĂMÎND, Tiberiu RUSU
The research carried out in this paper aimed to identify and compare the mechanical filtration capacity of the existing nanoparticles, correlated with the electro-chemical properties of the drinking water provided to the household users through the public network of Cluj-Napoca. The tested filters are available to the general public and the results of the research provide both the certainty of the importance of using drinking water filters, but also the prospect of purchasing an optimal relation quality - price filter based on the needs of the domestic users. The qualitative analysis of the tested filters was carried out by laboratory testing of a representative sample of drinking water filters that once reached the maximum lifetime, were cut and subjected to microscopic analysis using an Atomic force microscope (AFM). The microscopic analysis aimed to determine the filtration capacity by identifying the size and agglomeration density of the nanoparticles retained by mechanical filtration.
Keywords: mechanical nanofiltration, atomic force microscopy, nanoindentation, optical microscopy, water filters, drinking water
An Ecological Treatment Method for Ifosfamide Contaminated Waste Water Resulting from Oncological Therapy
Valentin ORDODI, Ana-Maria PANĂ, Alina DUMITREL, Daniel HĂDĂRUGĂ, Andra TĂMAȘ, Vasile PODE, Anamaria TODEA, Virgil PĂUNESCU, Șerban NEGRU
Ifosfamide is a potent alkylating agent used to treat many forms of human cancer. Exposure to this substance for the long term even in small quantities has serious negative effects on human health and the environment. This study presents an ecological method of electrochemical inactivation of ifosfamide in an automatic laboratory installation. The neutralization process consists of ifosfamide electrochemical and chemical oxidation via reactive chlorine species generated in situ at the anode of the electrochemical reactor with asymmetric current densities. The neutralization efficiency of ifosfamide using this method is approximately 99% if the duration of the electrodegradation process under the presented conditions is 30 minutes.
Keywords: electrochemical wastewater treatment, ifosfamide, electrooxidation, asymmetric current density reactor
Enzymatic Degradation of Azo Dyes Using Peroxidase Immobilized onto Commercial Carriers with Epoxy Groups
Paula BORZA, Ioana Cristina BENEA, Ioan BÎTCAN, Anamaria TODEA, Simona Gabriela MUNTEAN, Francisc PETER
The treatment of colored wastewater has been paid attention in the recent years because of the high amount of dyes, mostly carcinogenic, discharged into the water. Enzymatic degradation shows several advantages such as: shorter processing time, reduction in sludge volume and ease of controlling the process. In this work, seven different industrial dyes were tested as substrates for horseradish peroxidase. The native enzyme was covalently immobilized onto two types of epoxy-supports, different in spacer length. Among the tested dyes the highest substrate conversions were achieved for Amido Black 10 (AB10). The highest recovered activity was obtained when the epoxy-activated support with longer spacer arm was used. After ten reuse cycles for the degradation of AB10, the covalently bound peroxidase preserved about 80% of the initial activity.
Keywords: horseradish peroxidase, biocatalysis, ReliZyme™ support, covalent immobilization, dye degradation, environment
Preliminary Assessment of Particulate Concentration Near Coal Fired Power Plant
Bogdana VUJIĆ, Vasile PODE, Jelena MIĆIĆ, Francisc POPESCU, Una MARČETA, Adrian Eugen CIOABLA
This study shows the results of preliminary monitoring of particulate matter (PM10 and PM2.5) at four measurement points, during the three campaigns (spring, autumn, winter) The study was conducted for the first time in residential area near coal-fired power plant, Ugljevik, Bosnia and Herzegovina. The power plant flue gas cleaning equipment in the time of this research was out of the function. Authors investigated seasonal variations of PMs concentration levels, influence of terrain structure and meteorological condition on PMs distribution and identification of PMs origin sources. The results revealed that seasonal variation was more expressed in the case of PM2.5 concentration, while for PM10, occasionally episodic pollution (399μg/m3) was recorded. Also, it was noted that prevailing meteorological conditions and surrounding terrain structure could have limiting effect on PMs dispersion. In order to detect PMs origin, linear regression analysis was applied. Authors revealed that PM2.5 originating from power plant could be prescribed partly for M1 where the greatest correlation was calculated (R2=0,45). Although the measuring sites were set in proper position regarding dominant winds and terrain structure, it was identified that certain measurement sites were affected by the other local particulate matter sources, especially in case of PM10.
Keywords: particulate matter, PM2.5, PM10, air quality assessment, large combustion plants
Influence of Landfill Methane Emissions on Environment – Distribution Modelling and Assessment
Bogdana VUJIĆ, Nemanja STANISAVLJEVIC, Francisc POPESCU, Nikolina TOSIC, Una MARČETA, Marjana PARDANJAC, Vasile PODE
Landfilling practice in countries with waste management in transition is associated with non-controlled landfill gas and leachate emission. This practice requires sanitary landfill operations and remediation of unsanitary landfills as a prerequisite to join European Union. In order to get first insights on methane distributions for subsequent risk assessment model, this research, assess methane behavior patterns after emissions in the ambient air on environment from the controlled landfill site in Novi Sad, Republic of Serbia. Methane emission rate was assessed and crosschecked using landfill gas emissions model (LandGEM). The ADMS Mapper was used for the 3D simulation of the real environment of research field, including the complex structure of the landfill body and surrounding area. For simulation of methane dispersion into atmosphere, advanced Gaussian dispersion model ADMS Urban was applied. After processing and synthesis of the meteorological data, and defining the emission potential, simulations of the methane dispersion under different meteorological conditions (wind speed and direction, atmospheric temperature, humidity, pressure and cloud cover) were performed. As a result, methane distribution pattern was noted, several most unfavorable meteorological conditions and scenarios of methane distribution were assessed, and most vulnerable zones and locations influenced by the landfill methane emissions were identified.
Keywords: Methane emission, Air dispersion, Modelling, LandGem, ADMS urban, Serbia