STUDIA CHEMIA - Issue no.4 / 2017 - Table of contents

In Memoriam Prof. Emil Chifu (1925-1997)

Keywords:

The oxidation of catechin in the presence of atmospheric oxygen in a methanol/buffer model solution was studied by investigating generated products using LC/MS and spectrophotometry. It was proved that catechin was slowly converted to dimeric species with similar structures and properties. The catechin autoxidation was investigated spectrophotometrically at different pH ranging between 5 and 10. Using the initial linear dependence of the kinetic curves [Dimers] = f(t) the initial reaction rates were estimated for the autoxidation of catechin in methanol/buffered solutions. It was found that the dimer formation is favored at pH 8.

Keywords: catechin, autoxidation, dehydrocatechin.

This paper focuses on a comparative analysis between the carboxylate precursors obtained through the redox reaction between cobalt nitrate and 1,2-propanediol, and cobalt nitrate with 1,3-propanediol, respectively. The formation of the lactate and malonate precursors was followed with thermal analysis, FTIR spectrometry and acido-basic analysis (conductometric/ potentiometric titrimetry). The decomposition of the carboxylate precursors and the formation rate of cobalt oxides were observed by X-ray diffractometry and FTIR spectrometry, following advanced thermal treatments at 500°C, 800°C and 1000°C, with a pretreatment at 300°C. The differences between the two positional diol isomers are comparatively discussed.

Keywords: lactate, malonate, Co3O4, electrometric titrimetry, thermal treatment

The particulate matter (PM) from the atmosphere is able to penetrate in the respiratory system presenting several health risks such as acute respiratory items, allergic issues, and chronic risks such as silicosis and asthma. PM from atmosphere is classified by diameter as PM10 – particles with aerodynamic diameter up to 10 μm, PM2.5 – particles with aerodynamic diameter up to 2.5 μm, and PM1 - particles with aerodynamic diameter up to 1 μm. The first major PM source is the street dust (SD) which induces mineral fraction into the atmosphere such as: quartz, kaolinite, calcite, muscovite, and goethite. The second PM source is the pollen from several species like Tilia Cordata, Sambucus Nigra, Jasminus Communis, Rosaceae Family, Lilium Candidum, and Brassica Rapa, during later spring and early summer. Elements from both sources were found in PM samples collected from atmosphere: sedimentary particles, PM10 and PM2.5. In vivo experiments show that PM10 affects upper respiratory pathways such as nasal cavity and pharynges meanwhile PM2.5 was found in the expectoration matter from tracheal area. These studies reveal that 5 minutes of exposure at a concentration of 125 μg/m3 conducts to formation of severe deposits on respiratory mucosa.

Keywords: PM 10, PM 2.5, hazard

The experiments carried out in this paper tested the effectiveness of the polysulfone-dimethyldioctodecylammonium bromide (PSU-DMOA) and polysulfone-Tween 80 in dead-end facilities. The efficiency of these membranes has been proved by determining the permeate flow and the retention coefficient. Analyzing the experimental data, it was found that for the polysulfone-dimethyldioctodecylammonium bromide composite membrane the retention rate is higher than for the polysulfone-Tween 80 composite membrane, the t values being obtained for the highest pressure used in the system.

Keywords: composite membranes, ultrafiltration, surfactants, food dye

We have previously demonstrated that derivatization of hemoglobin with periodate-modified sugar derivatives incurs increases in the pro-oxidant reactivity and, also, that serum bovine serum albumin can resolve this problem entirely. Here, we described a new polymer based on hemoglobin and another oxygen-containing compound, alginate. The rate of autooxidation increases after derivatization, but serum albumin alleviates this problem. The peroxide reactivity and oxygen affinity were also tested but no significant differences were observed between derivatized and native hemoglobin.

Keywords: blood substitute, hemoglobin, alginate, oxidative stress

Nanostructured hydroxyapatite (HAP) and silicon substituted hydroxyapatites (HAP-Si), with 0.47 and 2.34 wt% Si, were prepared by wet precipitation method. Their structure was investigated by X rays diffraction (XRD), FTIR spectroscopy, energy dispersive X ray (EDX) spectroscopy and their images were obtained by TEM, SEM and AFM. Their behavior in water and SBF was investigated by inductively coupled plasma optical emission spectrometry (ICP-OES) for an immersion time from 1 to 90 days. While Ca and P release from HAP is very low, the presence of Si enhances greatly their release in water, along with a continuous and long lasting Si release. In simulated body fluid, SBF, Ca, P and Mg are removed from the solution, by the formation of a new HAP enriched in Mg, while silicon is released as in water. Thus, Si doped HAP might have advantageous applications as bone and tooth materials.

Keywords: hydroxyapatite, silicon doped HAP, elements release, simulated body fluid

Endodontic cement based on calcium silicate has been the focus of many studies. However, the quality of resulted endodontic cement needs improvement. This paper focuses on endodontic cement obtained from Portland cement enriched with two types of hydroxyapatite, simple and doped with 5% Zn. Hydroxyapatites were synthesized using a wet precipitation method and investigated by X-ray diffraction, FTIR, TEM and AFM. From a structural point of view, both hydroxyapatites were obtained in a single crystalline phase, containing particles in the nanometric range, as judged by XRD, TEM and AFM. FTIR analysis presents O-H and P-O bands specific to those in pure hydroxyapatite, confirming a hydroxyapatite lattice in both materials. Several experimental compositions of commercial Portland cement mixed with hydroxyapatite were prepared. The influence of stoichiometric and Zn doped hydroxyapatite on the resulted endodontic cement was observed in the setting time. The setting time for both cements decreased exponentially at both temperatures (22 ⁰C and 37 ⁰C). The normal consistency water remains constant for all experimented slurries.

Keywords: Endodontic cement, hydroxyapatite, Zn doped hydroxyapatite, Portland cement

HAP powder of a low crystallinity and rather large specific surface area was synthesized by an environmentally friendly, cost effective precipitation method, and characterized by XRD, FTIR, and BET isotherms. TEM and AFM are used to envisage the surface of HAP nano particles, showing a high porosity of this ceramic powder. It was used for the removal of metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) from mine wastewater. Metal contents in the initial and treated samples were quantified by inductively coupled plasma atomic emission spectrometry and high-resolution continuum source atomic absorption spectrometry. By the use of HAP, an efficient removal of all metals was ensured. The increase of Ca2+ ions content in the treated water suggests an ion exchange mechanism.

Keywords: hydroxyapatite, heavy metal removal, mine wastewater, sorption kinetics

The influence of aza-substitution on sumanene and C52 fullerene was investigated. Various substitution patterns, derived for the structures of pyrrole, indolizine and pyridine have been proposed and aromaticity indices like HOMA, NICS, delocalization indices PDI and FLU were considered, at B3LYP/6-311+G(d) level of theory. The results outlined an enhanced aromatic character for the sumanene derivatives where similar aza-substitution patterns as encountered in pyrrole and indolizine have been considered.

Keywords: sumanene, fullerene, aromaticity, aza-substitution

The electrochemical behavior of 10H-phenothiazine-1-carboxylic acid was investigated by square wave anodic stripping voltammetry (SWASV) at a glassy carbon electrode, which evidenced the first monoelectronic oxidation step at low potentials (around 0.25 V), slightly modulated by the nature of the solvent. The effect of three different solvents (acetonitrile, dimethyl sulfoxide and chloroform) on the strength of intramolecular hydrogen bonding associations was evidenced by DFT calculations. The computed electron density at the heterocyclic nitrogen atom appeared well correlated to the recorded oxidation potential. The possibility to use of 10H-phenothiazine-1-carboxylic acid as potential mediator for electrochemical detection of Malachite Green was explored, but the phenothiazine derivative appeared not suitable for the detection of the dye.

Keywords: 10H-phenothiazine-1-carboxylic acid, SWASV, intramolecular hydrogen bonds

Antibiotics are natural or semi-synthetic compounds used for many decades in human, veterinary and plant medicine to prevent and/or to treat bacterial infections and also to promote productivity in animal farming. Traces of antibiotics are found in waste, surface and ground waters, the main source of water pollution being considered waste waters from the industrial production, hospitals, livestock farms, households and incompletely metabolized drugs. The uncontrolled input of antibiotics in surface waters can lead to some unexpected health effects and to an increased resistance to these drugs. The aim of this work consists in the monitoring of six antibiotics (Ampicillin, Amoxicillin, Penicillin G, Ceftazidime, Tetracycline and Doxycycline) in river waters and sediment samples from the Romanian Tisza River Watershed. Solid-phase extraction (SPE) on Oasis HLB Waters cartridges was used for the isolation of antibiotics from water matrices and ultrasound-assisted extraction (USAE) followed by SPE for the sediment samples. Then, the antibiotics were analysed by high-performance liquid chromatography coupled with diode array detector or mass spectrometer (HPLC-DAD/MS). The developed SPE/USAEHPLC- DAD/MS procedures were applied to monitor these antibiotics in river waters during thirteen months and to analyse them in some sediment samples. The obtained results showed the presence of Tetracycline, Doxycycline and Ceftazidime in the investigated samples.

Keywords: antibiotics, high-performance liquid chromatography, mass spectrometry, solid-phase extraction, ultrasound-assisted extraction, river waters, sediments

The aim of the present work was to prepare and characterize a series of dental giomers and their corresponding dental adhesive and to evaluate the adhesion of the new materials at the restoration/tooth interface. The experimental giomers were prepared as monopastes by blending the resin matrices, a new pre-reacted glass, a radiopaque glass and fluorhydroxyapatite. The novelty of the work is represented by the using of a polyalkenoic acid based on acrylic acid, itaconic acid and N-acryloyl –Lleucine as the main component of the pre-reacted glass and of the primer in the adhesive system. In addition, the using of an original synthesized urethane tetra-methacrylate Bis-GMA analogue (Bis-GMAexp) as base monomer in the resin represents another element of novelty. The morphology of giomer samples was investigated by scanning electron microscopy. The sealing ability was tested by dye penetration method completed with atomic force microscopy investigation. The microleakage was evaluated using the score method. The results pointed out a remarkable dentin sealing for the new adhesive system and a strong adhesion at Bis-GMAexp-based giomer/ adhesive system/tooth interfaces in substantial agreement with very low value of microleakage.

Keywords: dental giomers, adhesive system, microleakage, SEM, AFM

Five representative potshards collected from the Tăşnad-Sere C 52 archaeological site were investigated in order to evaluate the occurring differences of the raw materials used and the technology applied. The structural and compositional differences shown by petrographic analysis (optical microscopy /OM/ and XRD) and FTIR spectroscopy data indicate that according to both the raw materials composition (clay sediments and temper) and the pottery technique the samples studied form two distinct groups.

Keywords: ancient ceramics, provenance, optical microscopy, PXRD, FTIR spectroscopy

The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, doped with magnesium, silicon, strontium and zinc, synthesized using aqueous precipitation method were investigated by thermal analyses (TG-DTA). Results show high thermal stability of pure and multidoped hydroxyapatite pastes, up to 1000 oC and even after ageing for 1 year, making these pastes promising nano materials for medical applications.

Keywords: hydroxyapatite, doped hydroxyapatites, paste, thermal analysis

The Cu(II), Co(II) and Ni(II) complexes with N-modified glycine derived from p-nitrophenylserinol were synthesized and characterized by their spectral and thermal properties. The thermal stability of the ligand and synthesized complexes was discussed in the 20-700oC temperature range. The results indicate that the organic compound acts as a bidentate ligand, its coordination involving the carboxylate oxygen and the nitrogen atom belonging to the amino group of the glycine fragment. All complexes correspond to the molar ratio M : L : H2O = 1 : 2 : 2. The shape of the ESR spectra at room temperature and the principal values of the g tensor suggest a pseudotetrahedral local symmetry around the metal ions.

Keywords: glycine, metal complexes, thermal behavior, spectroscopic studies

Single-crystal X-ray diffraction studies revealed a monomeric structure with O→Se intramolecular coordination in compounds [Me2C(OH)CH2][2-(Me2NCH2)C6H4]Se (1) and [2-(O=CH)C6H4]Se[S(S)P(OPri)2] (2). These interactions result in distorted T-shaped coordination geometries around selenium in both compounds and prevent a C,N-chelating behavior of the 2-(Me2NCH2)C6H4 group in 1 and a bidentate behaviour of the dithiophosphorus ligand in 2, respectively.

Keywords: organoselenium compounds; intramolecular coordination; solid state structure; dithiophosphato ligands.

Direct bonding of the bracket to the enamel is the elective procedure for the orthodontic treatment. Among various factors influencing the adhesive force at the enamel level, the etching technique seems to be the most important one. The present study aims at evaluating the influence of the storage media and the etching technique used, on the bond strength between different bracket types and dental structures. The results of this study showed that, regardless of the brackets and the immesion solution used, by working with the classic etch and rinse technique the adhesion force is higher than by using a self etching adhesive.

Keywords: SEM, etching technique, in vitro, adhesion

Mixed-ligand complexes of Cu(II) and Ni(II) with deprotonated theophylline (th) and propane-1,2-diamine (pda) were synthesized and characterized by elemental analysis, IR spectroscopy, and thermal analysis. Calculations and geometry optimization were made applying Mopac 2012 program at the level of semi-empirical method PM6.

Keywords: propane-1,2-diamine, theophylline, mixed-ligand complexes, PM6

The paper presents the design of decentralized control systems for the carbonation column of the ammonia-soda production process. The proposed control structures are tested on the basis of an experimentally identified multiple-input-multiple-output dynamic model, capable of describing the behavior of the main carbonation column variables. Two new control structures are investigated. The first one proposes a new pairing of the manipulated to the controlled variables, based on the Relative Gain Array Matrix. The second one implements ratio control aimed to ensure the desired relationship between the inlet ammoniacal-brine and CO2 flows. Behavior of the designed control structures are tested in the presence of setpoint changes and action of typical disturbances. Results are compared to the traditional decentralized control system configuration in order to reveal both the incentives and the limitations of the proposed control structures.

Keywords: carbonation column, decentralized control, flowrate ratio control

Syngas is a very important product, with a variety of uses; it may even become a primary source of fuel, and replace natural gas. This is because, syngas has the building blocks to create all the products and chemicals currently generated in the petrochemical industry. Fuels manufactured from synthesis gas offer special opportunities based both on environmental and energy performance. The aim of the present work is to design and compare different chemical production processes for fuels generation using syngas as raw-material. ChemCAD process simulator software was used as the main tool for process modelling and simulation. The investigation was focused on the conversion of syngas to methanol, dimethyl ether and hydrogen at a large scale. For comparison reasons, the same amount of syngas (e.g. 10000 kmol/h) was used in all three cases under investigation. After comparison, syngas to hydrogen process seems to be the best option from thermal energy point of view and in terms of environmental impact.

Keywords: syngas, process modelling and simulation, hydrogen, methanol, dimethyl ether (DME)

The objective of this study was to describe the hydrogen production from catalytic reforming of liquefied petroleum gas (LPG) with carbon capture and storage (CCS). Nowadays, hydrogen requires a lot of attention as a clean fuel as well as a chemical used in industrial applications (e.g. hydrogenation processes especially in oil refinery sector). The size of evaluated plant was 100000 Nm3/h hydrogen with a purity of 99.95% (vol.) to be in line with industrial hydrogen production capacities used in the oil refinery sector. A pre-combustion CO2 capture process based on Methyl- DiEthanol-Amine (MDEA) was also considered to reduce the greenhouse gas emissions (decarbonisation of fossil LPG used). The carbon capture rate was about 78%. The evaluation was made using process flow modeling (ChemCAD) and the simulation results were compared with experimental data reported in the literature. A similar hydrogen production process from LPG reforming without carbon capture was also considered to assess the energy penalty for CO2 capture. This work is an important study for evaluation of reducing carbon footprint in oil refinery sector.

Keywords: Liquefied petroleum gas (LPG); Hydrogen production; Carbon capture and storage (CCS)

Anthocyanins (ACNs) are water-soluble plant pigments belonging to the group of flavonoids, with antioxidant, anti-inflammatory and antibacterial activity. The antioxidant activities of extracts from berries and hibiscus were tested with the Briggs–Rauscher method. Adsorption of anthocyanins on biomaterials is a method for their stabilization. Hydroxyapatite (HAP) doped with inorganic silica has an increased specific surface, porosity and chemical reactivity. Anthocyanins from extracts of different berries were adsorbed on hydroxyapatite-based materials. The adsorption and desorption capacity of hydroxyapatite-based materials were measured and the adsorption capacity of different anthocyanin extracts were compared. It was concluded that the highest adsorption capacity and efficiency were obtained in the case of blueberry. Based on the results of the desorption experiments, it has been proven that HAP-Si-blueberry is more adequate to obtain a retard effect, despite the fact that the antioxidant activities of blueberry and blackcurrant are similar.

Keywords: anthocyanin, antioxidant activity, hydroxyapatite-based materials, berries extract, hibiscus extract

Nanostructured hydroxyapatite (HAP) and three multiple substituted HAPs, containing Mg, Zn, Sr and Si were synthesized by a wet precipitation method The presence of the HAP lattice as unique crystalline phase was established by XRD and by FTIR spectroscopy. The chemical composition was confirmed by SEM-EDX. The TEM, SEM and AFM imaging showed the morphology of these biomaterials. The elements release in water and in simulated body fluid (SBF) was monitored in time from 1 to 90 days, by using inductively coupled plasma optical emission spectrometry (ICP-OES). The results are important for the future use of these hydroxyapatite biomaterials, as bone substitutes or coatings on metallic implants, able to release essential physiological elements, both in vitro and in vivo, with great impact in orthopedics and dentistry.

Keywords: multisubstituted hydroxyapatites, magnesium, zinc, strontium, silicon, ions release, water, SBF

This paper presents the experimental results obtained by sulfur dioxide chemisorption into carbonate suspension with sulfites addition at different temperatures and concentration of the absorbent suspension. Presence of sulfites in the absorbent suspension has a positive influence on the global rate of the absorption process. The acceleration of SO2 chemisorption process in the absorbent suspension containing MeSO3 – MeCO3 is determined by the higher concentration of ions in the liquid phase resulted from higher solubility of MeSO3 comparative with MeCO3. The addition of MeSO3 at a concentration of 10% in the composition of the absorbent suspension determines a significant decrease of the time required for obtaining a high conversion.

Keywords: wet desulfurization, carbonate suspension, sulfites addition

This paper presents a report on kinetics of malachite green (MG) dye removal from model aqueous solutions using a biomaterial formed by corn cob activated carbon (CCAC). The sorbent was characterized using specific surface area and pore size distribution (Brunauer–Emmett–Teller, BET) analysis. The BET analysis confirmed the macro-porosity of the adsorbent. Effects of initial concentration of MG dye and CCAC quantity, particle size and stirring rate on adsorption capacities and efficiency were monitored through pseudo first- and second-order models, intra-particle and film diffusion models to present adsorption rate parameters. The removal efficiency of MG increased with the adsorbent quantity and particle size.

Keywords: corn cob biomass, activated carbon, malachite green, aqueous phase, characterization techniques, kinetics

The paper presents a comparative study of some physical properties, microstructure and antioxidant capacity of soluble coffee obtained at laboratory scale using spray-drying (SD) and freeze-drying (FD) as dehydration techniques. SEM was used for monitoring structures and size of the coffee powder. The results of SEM show the difference in the microstructure with the used drying technique. SD dried coffee has only spherical shape, narrow distribution, with the particle mean size of about 10 m and smooth surface. The FD dried coffee has spherical shape with the size of about 40 m and flaky structure, non-spherical shape, with the dimensions between 10 x 20 m and 30 x 90 m. EPR was used for the determination of coffee antioxidant capacity. SD coffee powder shows a higher antioxidant activity in comparison with FD dried coffee.

Keywords: soluble coffee, spray-drying, freeze-drying, physical properties, microstructure, antioxidant activity

Contamination of vineyard soils with heavy-metals has been a worldwide concern, determination of these elements it is important for the wine industry. The aim of this research was to determine the concentration of different heavy metals (Cd, Pb, U, Hg, As, Sr, Co, Cu, Ni and Cr) from vineyard soil on different depths in an area of vineyard cultivation from Dealu Bujorului Galati County. In order to highlight the combination of different sources, natural or anthropogenic of heavy metals the isotopic ratios for 206Pb/207Pb, 208Pb/206Pb, 206Pb/207Pb and 87Sr/86Sr from soil were established. The highest concentrations for heavy metals were recorded on the surface, with increasing depth of the soil these concentrations decrease. Regarding of Pb sources (lithogenic or anthropogenic), the average 206Pb/207Pb, 208Pb/206Pb and 206Pb/204Pb ratios in soil profile increase horizons followed the order: 1.13526 (0-10 cm 206Pb/207Pb) > 1.13427 (10-20 cm 206Pb/207Pb); 2.12626 (10-20 cm 208Pb/206Pb) > 2.12472 (10-20 cm 208Pb/206Pb) and 17.36201 (10-20 cm 206Pb/204Pb) > 17.36128 (0-10 cm 206Pb/204Pb). Statistically, in the case of 206Pb/207Pb and 208Pb/206Pb there are very significant differences between the analyzed variants while 206Pb/204Pb does not show any differences with in terms of distribution on the depth of the soil profile. Our results confirm that the 207Pb/206Pb, 208Pb/206Pb, 204Pb/206Pb and 87Sr/86Sr isotope ratio can be used to track the geographical origin of wine, discriminate between wine production regions, and be used to characterize wine terroirs for forensic purpose.

Keywords: heavy metals, soil profile, 207Pb/206Pb, 208Pb/206Pb, 204Pb/206Pb, 87Sr/86Sr isotope ratio

Mineralogical and chemical characterization of soils is important in for the use of soils as agricultural land. The soil from downstream Bârzava River was characterized and existing geological features of this soil were presented and correlate with the size surfaces. pH measurements of soils samples collected from three different locations and from two different depths were performed. The soil samples were also analysed in order to assess the major and trace elements content. It is known that the pH and heavy metal concentrations are vital factors for plant growth and the obtained results could be use in future for elaboration of some soil bioremediation techniques.

Keywords: soil geological features, acidity control, metal concentration

This study investigates the usability of the cathode ray tube (CRT) glass waste in a binder system. The raw materials – glass waste, river sand and cement were characterised. CRT waste was added in the amount of 30, 40 to 50 weight percent, as replacement for river sand. Glass chemical composition shows a high content in lead and alkaline oxides. Mortar prisms were prepared and kept under humid conditions. The mechanical properties were studied after 7, 28 and 90 days respectively. SEM with additional EDS was used in order to investigate the microstructure of the samples. All the samples containing glass waste achieved higher compressive strength than the control mortar. After 14, 28 and 42 days of maintaining the mortar in water no evidence of Pb was detected in the solutions.

Keywords: cement, mortar, CRT glass waste, compressive strength

The corrosion inhibition efficiency of three commercial inhibitors on low carbon steel was investigated by electrochemical methods (EIS and polarization curves). The efficiency of corrosion inhibitors was tested at different concentrations. Corrosion tests were carried out in a solution simulating a saline wastewater from petroleum industry (pH = 3) in order to find the best inhibitor for the protection of steel pipelines.

Keywords: steel, corrosion inhibitors, electrochemical impedance spectroscopy, polarization curves, inhibitor efficiency, synthetic wastewater from petroleum industry.

This paper work contains the study of non-stationary dissolution of individual urea granules used as fertilizers. The present study is based on The Generalized Dimensional Analysis and includes comments about the fundamental factors, the important factors, the secondary factors and about the unimportant factors which can control the phenomenon. It also contains experimental determinations on simple and filmed urea granules that lead to a general equation for the dissolving process.

Keywords: Generalized Dimensional Analysis, non-stationary dissolution, pure and filmed urea granules, mathematical equations for non steady-state dissolution.

New precursors for functionalized grass fibres were obtained through deposition of functionalized calix[4]arenes on G14 short glass fibers. The methods employed for the preparation as well as the characterization by thermal analysis, FT-IR spectroscopy, TEM and SEM microscopy of the newly obtained materials is presented.

Keywords: calixarenes, functionalized glass fibers, thermal analyses, electronic microscopy

In this paper are presented the experimental results obtained in assessing the degree of swelling of the leather by means of shrinkage temperature. The moisture content of the skin was determined in its various processing steps, correlated with the leather shrinkage value.

Keywords: drying process, skin type, shrinkage temperature

The aim of this paper was to determine the minerals and lactose from a Zonar lactoserum concentrate (L-ZS) obtained by lyophilization as compared to other two commercial powders: a bio whey concentrate (BWP) and a whey protein isolate (IWP), in order to investigate the influence of the mineral and lactose concentration on the protein denaturation temperature. The BCAA content from protein hydrolysates and surface structure of whey powder samples have been also investigated. Lactose content of samples whas: 47.4 g/100g for L-ZS, 46.4 g/100g for BWP, 0 g/100g for WPI. The highest concentrations of minerals Ca, K, Mg, Na and P has been found in BWP, followed by, L-ZS and IWP powders. The fact that L-ZS sample shows a peak temperature (Tp) with 15.82 °C higher than in the case of BWP sample, makes it more resistant to denaturation. The IWP powder has Tp of 87.25 °C, because contains the high quantity proteins that are more resistant to unfolding (denaturation) than the other two samples. Loss of calcium ions leads to partial protein unfolding. The lower mineral content increases the stability of whey protein. A high lactose content leads to the protein aggregation; the functional properties of powder is changes by protein crosslinking. Branched-chain amino acids content in studied samples is in accordance with whey proteins powders type.

Keywords: lactoserum Zonar, bio whey concentrate, whey, protein isolate, lactose, BCAA, minerals, DSC, SEM

Derivatives of bis-sulfone 1,3-bis{(p-tolyl)SO2}-5-tertbutylbenzene 1, containing P(III) and P(V) were obtained and characterized in solution by multinuclear NMR spectroscopy. For two of the compounds ([2,6-{(p-tolyl)SO2}24-t-Bu-C6H2]PCl2 2 and [2,6-{(p-tolyl)SO2}24-t-Bu- C6H2]P(O)(H)OEt) 4 the crystal and molecular structures in solid state were also determined by single crystal X-ray diffraction

Keywords: bis-sulfone, phosphorus derivatives, dichlorophosphine

The regularities of precipitation and dissolution of thallium (III) oxide were studied by using cyclic and linear voltammetry. It is established that at 1.5V potential, a peak corresponding to the process of oxidation of monovalent to trivalent thallium is observed, according to: Tl+ → Tl3+ + 2e-. Two peaks are observed in the cathode region, at 0.65V and -0.17V potential values. At E = -0.17V, the thallium oxide Tl2O3 dissolves, as at E = 0.65V, the intermediate products of the hydrolysis of trivalent thallium (Tl(OH)2+, Tl (OH)2+) are probably recovered. It was found that with increase of solution pH, the dissolution processes of thallium oxide intensified, while the optimum pH value was 11, also activation energy of the electrodeposition of thallium(III) oxide were calculated.

Keywords: thallium, thallium(III) oxide, electrolysis, voltammetry, precipitation, dissolution/solution

In this study, diethylene glycol (DEG), as a hydrogen bond donor (HBD), was mixed with three ammonium based salts, namely N,Ndiethylethanolammnium chloride, tetra-n-butylammonium bromide and choline chloride, as well as two phosphonium based salts, namely benzyltriphenylphosphonium chloride and methyltriphenylphosphonium bromide, to prepare five different deep eutectic solvents (DESs) series. The DESs freezing points and functional groups were investigated. In addition, the physical properties viscosity, density, conductivity and surface tension were determined as function of temperature in the particular temperature range of 293.15- 353.15 K. It is worth mentioning that all examined DESs were stable and in liquid phase at room temperature which emphasize their promising potential to be utilized as inexpensive environment-friendlier solvents. Owing to their low recorded freezing points and viscosities, DEG based DESs can be effortlessly processed without any further heating required in diverse industrial applications.

Keywords: deep eutectic solvents; ionic liquids; diethylene glycol; physical properties; chemical processes; industrial applications.

Advanced analytical and impact assessment methods are needed for the development of modern surfactants, so the composition, the effect and other properties of surfactants are examined by analytical tools which may be suitable for the quality testing of the raw materials, the intermediates and the final products. The HLB values of non-ionic surfactants and their mixtures were determined by three different methods: theoretical HLB based on the chemical structure and the given HLB of surfactants, the Greenwald method and an improved, titrimetric method. Our aim was to investigate if the new method to determine the water number and HLB value is suitable for this type of commercial surfactants and their mixtures. The particle size and the turbidity of micelles formed in surfactant solutions were also measured and evaluated.

Keywords: surfactant, surfactant mixtures, theoretical HLB value, experimental HLB value

This work reported a theoretical and experimental study on the thin layer drying kinetics of chicken meat samples under different air drying conditions. Experimental drying curves of chicken meat were performed under different drying air conditions (three air temperatures: 40, 50 and 60 °C, air velocities:1 ms−1, and at atmosphere humidity). The drying rate was found to increase significantly with increase in temperature. The duration of constant rate period was found to be insignificant considering the total duration of drying and the entire drying period was considered to follow falling rate period. The experimental moisture ratio data was fitted to eight thin layer drying models. The Midilli et al. model showed the best fit in all drying conditions. The effective moisture diffusivity has been found to be varying between 4.39 x 10-10 and 9.96 x 10-10 m2s-1 and activation energy was 27.85 kJ mol-1.

Keywords: Chicken meat, mathematical modeling, diffusion, activation energy

An alternative source of energy like biogas has become of interest to reduce the dependence on depleting fossil fuels for the source of energy. It is environmentally friendly and can be generated from various biomass wastes. It consists of CH4 (55%- 65%) and CO2 (35%- 45%) with a calorific value of 22 000- 25 000 kJ/m3 when raw and after CO2 is removed, the methane gas has a calorific value up to 39 000 kJ/ m3 and is referred to as biomethane. Ammonia is used as an absorbent in chemical scrubbing to remove CO2 from biogas. A continuous system consisting of 1L digester was used for biogas production which was bubbled through an absorbent in 500mL gas washing bottle at a constant temperature in a water. The obtained biomethane potential was found to be 0.387 m3 CH4/ kg VS which simply means that more methane gas can be obtained when using ammonia for absorption. An increase in the gas flow rate leads to an increase in the mass transfer coefficient resulting in an increase in the rate of absorption. The initial CO2 concentration affects the removal efficiency because more work needs to be done for biogas with a high initial concentration of CO2. NH3 has better absorption capacity because higher biogas purity was achieved at lower NH3 concentration. The removal efficiency for NH3 increased from 69%-79% on average with CH4 concentration reaching over 85% vol. this is equivalent to a calorific value ranging from 25- 33.5 MJ/Nm3 which is promising in terms of the gas ability to run in an automobile engine.

Keywords: absorption, concentration, efficiency, energy, fuel