Cekerevac M.I.,IHIS Techno experts Doo |
Nikolic-Bujanovic L.N.,IHIS Techno experts Doo |
Simicic M.V.,IHIS Techno experts Doo
Hemijska Industrija | Year: 2010
In part one of the two-part series, electrochemical generation of ferrate in strongly alkaline solution (10-15 M) of NaOH and KOH in wide range of electrode potentials, between hydrogen evolution and oxygen evolution reaction, was investigated and discussed. (Hem. ind. 63 (2009) 385-395). In this part, optimization of electrolysis parameters of ferate(VI) synthesis is elaborated. The most important process parameters which affect the efficiency of ferrate generation are: anode material, alkaline electrolyte concentration, regime of electrical potential control, current density and electrolyte temperature. An optimum current efficiency and yield of ferrate(VI) synthesis are obtained when electrical steel with 3 wt.% of silicon is applied as anode material. The lowest current efficiency is observed for anodes made of structural steel with high concentration of manganese, chromium and nickel. The influence of alloying elements on the process of electrochemical synthesis of ferrate(VI) is discussed in terms of their influence on formation and stability of anodic passive layer and oxygen evolution reaction. The current efficiency increases with the increase of the bulk electrolyte concentration from 10 M NaOH and KOH and shows its maximum value for the 14 M NaOH. The increase in temperature causes the increase in yield of ferrate(VI), which has a maximal value at about 50 °C, and after that, at higher temperatures, ferrate (VI) instability causes the yield to decrease. Considering the influence of electrical regime control it is observed that the maximum yield of ferrate(VI) can be achieved with constant anodic potential of about 0.65 V versus Hg|HgO and with pulsating potential, Emax = 0.8 V and Emin = 0.5 V versus Hg|HgO, and pulse duration ration of tmax:tmin = 2:1. Circulation of electrolyte shows relatively small, but positive, effect on the synthesis efficiency, particularly in cases when potassium hydroxide is present in the electrolyte.
Zaric D.B.,IHIS Techno experts D.o.o. |
Bulatovic M.L.,University of Belgrade |
Rakin M.B.,University of Belgrade |
Krunic T.Z.,University of Belgrade |
And 2 more authors.
RSC Advances | Year: 2016
The aim of this study was to investigate the survival of probiotics (Lactobacillus acidophilus NCFM, Lactobacillus rhamnosus HN001 and Bifidobacterium lactis HN019) in milk chocolate masses prepared at temperatures 35°C and 40°C. The influence of probiotics and preparation temperature on rheology, particle size distribution and sensory properties of the chocolates, was examined during 6 months of storage at 20 ± 2°C. An inoculation temperature of 40°C significantly improves the rheological and sensory properties of probiotic chocolate, as well as leading to the survival of L. acidophilus NCFM and L. rhamnosus HN001 strains. After 6 months of storage, the survival of these strains was above 90%, with a viable cell count of about 8.1log(CFU g-1). An inoculation temperature of 40°C provides higher scores of overall sensory quality (4.52-4.68), higher quality category (excellent), lower maximal viscosity (for 1.2 Pa s) of chocolates, than a temperature of 35°C. Compared to the chocolate without probiotics, those inoculated at 40°C achieved less increase in volume weighted mean diameter distribution (average 0.8%) than chocolates inoculated at 35°C. Based on the results reported in this paper, seeding of the probiotics in industrial conditions can be done in the mixing tank (at 40°C) before the phase of chocolate shaping. Addition of probiotics at this stage facilitates the manufacturing process, improves the overall quality of chocolate and preserves the probiotics as a key component of this type of product. © The Royal Society of Chemistry 2016.
Nikolic-Bujanovic L.,IHIS Techno experts d.o.o. |
Cekerevac M.,IHIS Techno experts d.o.o. |
Vojinovic-Miloradov M.,University of Novi Sad |
Jokic A.,University of Prishtina |
Simicic M.,IHIS Techno experts d.o.o.
Journal of Industrial and Engineering Chemistry | Year: 2012
The influence of anode composition and temperature on the anode electrochemical activity and subsequent ferrate(VI) production in 10. M NaOH solution has been studied. Results obtained from the pure iron, gray and white cast iron were compared to establish the most promising anode in terms of ferrate production efficiency. The cyclic voltammetry measurements associated with the potentiodynamic polarization results induce that the pure iron has the lowest electrochemical activity. Presence of silicon in outer layer was confirmed by X-ray diffraction of reaction products on WCI and GCI in the form of iron(II)iron(III) silicon oxide-hydroxide. © 2012 The Korean Society of Industrial and Engineering Chemistry.
Simicic M.V.,IHIS Techno experts d.o.o |
Govedarica D.D.,University of Novi Sad
Hemijska Industrija | Year: 2011
Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, Cassandra and Norsok M-506 of quite different origins in order to predict uniform corrosivity of hot aquifers in eight different pipelines. Because of the varying calculation criteria for the different models, these can give very different corrosion rate predictions for the same data input. This is especially true under conditions where the formation of protective films may occur, such as at elevated temperatures. The evaluation of models was conducted by comparison using weight-loss coupons and three corrosion inhibitors were obtained from commercial suppliers. The tests were performed during the 60-day period. Even though inhibitors' efficiencies of 98% had been achieved in laboratory testing, inhibitors' availabilities of 85% have been used due to logistics problems and other issues. The results, given in mmpy, i.e., mm/year, are very consistent with Norsok M-506 prediction. This is presumably because the model considers the effect of the formation of a passive iron carbonate film at temperatures above 80 °C and significant reduction in corrosion rate. Corrosion inhibitor A showed a better performance than inhibitors B and C in all cases but the target corrosion rates of less than 0.1 mmpy were achieved for all inhibitors. The chemical type of corrosion inhibitor A is based on quaternary amines mixed with methanol, isopropyl alcohol, xylene and ethylbenzene. Based on the obtained results the carbon steel lifetime of 30 years, provided proper inhibitors are present and 3mm corrosion allowance, can be achieved for hot aquifers service with presented water compositions.
Pajin B.,University of Novi Sad |
Dokic L.,University of Novi Sad |
Zaric D.,IHIS Techno Experts DOO |
Soronja-Simovic D.,University of Novi Sad |
And 2 more authors.
Journal of Food Engineering | Year: 2013
The aim of this paper is to define the optimal conditions for the pre-crystallization of chocolate produced in a ball mill, that contains 20% soya milk. Chocolate mass and soya milk are refined in a ball mill employing three refining times (30, 60 and 90 min) and pre-crystallization temperatures (26, 28 and 30 °C). Increasing the refining time leads to organized chocolate systems with soya milk. The nucleation time of the system refined for 90 min and pre-crystallized at 30 °C is three times longer compared to that pre-crystallized at 26 °C. By prolonging the refining time, the system becomes dominantly viscous due to the refining and homogenization (tanδ > 1). Taking into consideration all three parameters, i.e., viscosity, yield stress and the area of the thixotropic loop, a refining time of 90 min at the pre-crystallization temperature of 30 °C seems optimal. © 2012 Elsevier Ltd. All rights reserved.
Nikolic-Bujanovic L.N.,IHIS Techno experts d.o.o |
Simicic M.V.,IHIS Techno experts d.o.o |
Cekerevac M.I.,IHIS Techno experts d.o.o
Hemijska Industrija | Year: 2012
The electrochemical methodologies for synthesis of BaFeO4 and Ag2FeO4 are presented in this article. The first step was to prepare a solution of the K2FeO4 as starting reagent by anodic dissolution in the transpassive potential region of the electrical steel in 10M KOH. The current density applied was fixed at 20 mA/cm2 at 55 °C. Solid BaFeO4 and Ag2FeO4 were precipitated from K2FeO4 solution by the addition of Ba(OH)2. 8H2O and AgNO3 solutions, respectively. The yield of solid salt synthesized was calculated by the hromitne titration, while their phase composition was determined by XRD analysis. Significant decomposition for BaFeO4 stored in dry conditions was not observed. Solid phase synthesized Ag2FeO4 is less stable than BaFeO4 due to its high sensitivity to light and susceptibility in such conditions to degradation to Ag2O and AgO.
Vidojevic S.,IHIS Techno Experts D.o.o.
Advances in Space Research | Year: 2014
Two major effects of Langmuir wave electric field influence on spectral line shapes are appearance of depressions shifted from unperturbed line and an additional dynamical line broadening. More realistic and accurate models of Langmuir waves are needed to study these effects with more confidence. In this article we present distribution shapes of a high-quality data set of Langmuir waves electric field observed by the WIND satellite. Using well developed numerical techniques, the distributions of the empirical measurements are modeled by family of Pearson distributions. The results suggest that the existing theoretical models of energy conversion between an electron beam and surrounding plasma is more complex. If the processes of the Langmuir wave generation are better understood, the influence of Langmuir waves on spectral line shapes could be modeled better. © 2014 Published by Elsevier Ltd.
Possible applications of ferrate(Vi) in the treatment of industrial wastewater effluent in the laboratory [Mogućnost primene ferata(VI) u tretmanu efluenta industrijske otpadne vode u laboratorijskim uslovima]
Nikolic-Bujanovic L.N.,IHIS Techno experts d.o.o |
Cekerevac M.I.,IHIS Techno experts d.o.o |
Tomic M.M.,IHIS Techno experts d.o.o |
Zdravkovic M.Z.,IHIS Techno experts d.o.o
Hemijska Industrija | Year: 2015
This paper shows the effects of ferrate(VI) application in the treatment of industrial wastewater effluent in laboratory conditions. The used samples are mixture of wastewater effluent from various industrial plants whose composition was determined by analyzing samples before the ferrate(VI) treatment. Determining physical-chemical characteristics of the samples showed very high chemical oxygen demand (COD) and the concentrations of individual pollutants are higher than the allowed maximum. In the tested samples, the COD was from 18 (sample 1) to 580 times (sample 2) greater than allowed (allowed 45–150 mg/l), while the concentrations of certain metals were several times higher than allowed (Cu allowed 0,1 mg/l, Zn allowed 0,2 mg/l). Also, a high concentration of total phosphorus content (allowed 2 mg/l) and fluoride was found (allowed 20 mg/l), 2–3 times higher than permissible. The applied Na2FeO4 was synthesized by electrochemical method and applied in situ. Physical–chemical testing of samples, after treatment with different amounts (2, 5, 8, and 10 ml) of Na2FeO4 in concentration of 8 g/l showed that ferrate(VI) can be used as a multifunctional agent in the purification of industrial wastewater, where in the amount of contaminating matter is reduced below the maximum permitted level. It was demonstrated the high efficiency of ferrate(VI) as a strong oxidant in the removal of total P and suspended materials. Also pointed out was the high sorption power of the generated ferric(III)hydroxide, which with its developed surface absorbs 95,5% of the F– and removes it from the solution in the form of sludge. The shown high efficiency of ferrate(VI) in the total removal of P (70 to 99.5%) and F– (89 to 95.5%), depending on the presence of the total COD value or the presence of the total organic substances. At high values of the COD the major part of ferrate(VI) is consumed in the oxidation of organic material and the formation of Fe(OH)3, which accelerate the process of decomposition of ferrate(VI), which contributes to reduced efficiency of the removal of P and F–. © 2015, Association of Chemists and Chemical Engineers of Serbia. All rights reserved.
Nikolic-Bujanovic L.,IHIS Techno experts D.o.o |
Cekerevac M.,IHIS Techno experts D.o.o |
Tomic M.,IHIS Techno experts D.o.o |
Zdravkovic M.,IHIS Techno experts D.o.o
Water Science and Technology | Year: 2016
The possibility of removing pharmaceuticals from aqueous solutions was examined using ibuprofen (Ibu) oxidation as an example, using in situ electrochemically synthesized ferrate(VI), a strong oxidant and coagulant, with forming of non-harmful byproducts. A solution of ibuprofen of 206 mg/L in 0.1 M phosphate buffer solution was treated with different amounts of fresh, electrochemically synthesized ferrate(VI). The changes of ibuprofen concentration in samples were determined using a UV-Vis spectrophotometer. The extent of mineralization was estimated using the changes in chemical oxygen demand (COD) values and total organic carbon (TOC) values of test samples. The largest reduction of the concentration of Ibu (41.75%) was obtained by adding 69.2 mg/L ferrate(VI) as Fe (Ibu: Fe= 1: 0.34). An effective removal of ibuprofen from aqueous solutions was recorded up to 68% and it can be done by using ferrate(VI) in the ratio Ibu: Fe= 1:3 as Fe. The possibility of ibuprofen removal by ferrate(VI) was confirmed by COD and TOC results, which demonstrated reduction up to 65% and 63.6%, respectively. © 2016 IWA Publishing.
PubMed | IHIS Techno experts d.o.o
Type: Evaluation Studies | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2016
The possibility of removing pharmaceuticals from aqueous solutions was examined using ibuprofen (Ibu) oxidation as an example, using in situ electrochemically synthesized ferrate(VI), a strong oxidant and coagulant, with forming of non-harmful byproducts. A solution of ibuprofen of 206 mg/L in 0.1 M phosphate buffer solution was treated with different amounts of fresh, electrochemically synthesized ferrate(VI). The changes of ibuprofen concentration in samples were determined using a UV-Vis spectrophotometer. The extent of mineralization was estimated using the changes in chemical oxygen demand (COD) values and total organic carbon (TOC) values of test samples. The largest reduction of the concentration of Ibu (41.75%) was obtained by adding 69.2 mg/L ferrate(VI) as Fe (Ibu: Fe = 1: 0.34). An effective removal of ibuprofen from aqueous solutions was recorded up to 68% and it can be done by using ferrate(VI) in the ratio Ibu: Fe = 1:3 as Fe. The possibility of ibuprofen removal by ferrate(VI) was confirmed by COD and TOC results, which demonstrated reduction up to 65% and 63.6%, respectively.