Resistance of CEM III/B based materials to acid attack

Cementni materijali u poljoprivrednim i drugim industrijskim objektima izloženi su dejstvu kiselina. Zbog toga vek konstrukcija zavisi od trajnosti maltera ili betonskih elemenata u agresivnoj sredini. U radu je predstavljena otpornost na koroziju koja je uzrokovana sulfatnom, nitratnom, ureom, mlečnom i sirćetnom kiselinom. Skenirajuća elektronska mikroskopija (SEM) korišćena je da se ispita efekat agresivnih rastvora na mikrostrukturu i mehaničke osobine maltera. Hemijska otpornost prizmi od maltera i dve vrste betona testirana je prema metodi Koch-Steinegger. Kako je uslov za otpornost na agresivne rastvore taj da zatezna čvrstoća maltera nije manja od 70% u odnosu na referentne prizme negovane u vodi, može se zaključiti da su malter i beton, napravljeni sa CEM III/B, u ovom istraživanju otporni na sve kiseline kojima su tretirani. .Cement based materials in the agricultural and other industrial structures are exposed to acid attack. That is the reason why the service life of structure depends on the durability of mortar or concrete elements in aggressive environment. Resistance to corrosion caused by sulphate, nitrate, carbamide, lactic acid and acetic acid was presented. Optical and scanning electron microscopy (SEM) was used to examine the effect of aggressive solutions on the microstructure and mechanical properties of mortar. The chemical resistance of mortar prisms and two types of concrete were tested according to the Koch-Steinegger method. As the condition for resistance in aggressive solution is that flexural strength of mortar prisms is no less than 70 % compared to referent prisms cured in water it can be concluded that mortar and concrete made with CEM III/B in this investigation are resistant to all treated acids

Geochemical and Sedimentation History of Neogene Lacustrine Sediments from the Valjevo-Mionica Basin (Serbia)

Valjevo-Mionica Basin is one of the numerous lacustrine Neogene basins in Serbia. After Aleksinac Basin, according to the quality and amount of oil shale, it is one of the main deposits of this raw material in Serbia. The most important oil shale deposits in Valjevo- Mionica Basin are located in the central part of the basin (Bela stena series, Sušeočka and Radobićka Bela Stena). The kerogen content in oil shales ranged from 8 - 16 %. The average oil yield of 6.3 % is of economical value. Total of 62 samples of Neogene lacustrine sedimentary rocks to the depth of 400 m were investigated in this study. The first objective of the study was to reconstruct geological history (evolution) of the sediments i.e. to determine the palaeoconditions in depositional environment during its formation. For this purpose numerous geochemical methods and approaches were used. The second objective of the study was to determine the origin, type, maturity and liquid hydrocarbon potential of organic matter (OM). Aimed at detailed estimation of the oil shale OM potential, and prediction of the conditions necessary to become active oil generating source rock, pyrolytic experiments were performed on the bitumen-free sample. Bearing in mind that some metal ions (e.g. Al(III)-ion in clay minerals) (Jovančićević et al., 1993; Peters et al., 2005) have catalytic influence on most of the maturation processes, and that Pt(IV)- and Ru(III)- ions are often components of catalysts in many laboratory investigations and industrial procedures (Hu et al., 1994; Kawaguchi et al., 2005), the pyrolytic experiments of bitumen-free rock were performed also in the presence of simple inorganic compounds, H2[PtCl6] and RuCl3, to investigate if their presence changes the yield and hydrocarbon composition of liquid pyrolysates

Thermal recycling of high density polyethylene and polypropylene old/new challenge during COVID-19 pandemic

Plenary Lectur

Determination of the Iodine Value – Novel Environmental Friendly Insights

The iodine value (iodine number) is characteristic for the content of unsaturated fatty acids in fats, fixed oils, emulsifiers and solubilizers. The determination of the iodine value is of significance for pharmaceutics, food chemistry and cosmetics. Standard methods for the iodine value determination approved by the Association of Official Analytical Collaboration (AOAC) International, the American Oil Chemists’ Society (AOCS), the International Organization for Standardization (ISO) and the European Pharmacopoeia (Eur. Ph.) [1-3] use hazardous solvents for fat samples such as cyclohexane/ glacial acetic acid mixture or chloroform, whereas glacial acetic acid is unique solvent for iodine monochloride or iodine monobromide that serves as iodination agent. Certain earlier proposals for more environmental friendly and faster iodine value determination considered utilization of 1,3-dibromo-5,5-dimethylhydantoin and potassium iodide instead of iodine monobromide, however also in glacial acetic acid as a solvent [4,5]. Recently, combining data from American and ISO standards, the Metrohm (2019) [6] proposed utilization of glacial acetic acid as a solvent for the fat sample and addition of magnesium acetate as catalyst to significantly reduce the reaction time, from 1 h to 5 minutes. In the current study we report certain novelties, which may contribute to development of less hazardous and environmental friendly method for the iodine value determination. Our method considers utilization of ethyl acetate as a solvent for the sample instead of cyclohexane/glacial acetic acid mixture or chloroform, whereas iodine monochloride in glacial acetic acid has been replaced by water solution of iodine monochloride (stabilized by small amount of hydrochloric acid). In the presence of ethyl acetate, starch solution does not yield the characteristic blue colour with iodine. Nevertheless, the titration end point can be recognized clearly and precisely without indicator. The method was tested on the following samples: coconut oil, olive oil, sunflower oil and linseed oil, covering a wide range of the iodine value from ~8 to ~180. Comparison of the average iodine values for studied samples obtained by the proposed and standard AOAC method indicates standard deviation less than 0.60, whereas repeatability limit for the proposed method is bellow 1.7 that is in line with statistical results for the precision of the Wijs method reported in ISO 3961 (2018) standard [2]

Effect of nano-silica and aggregate type on properties of ultra high performance concrete

The aim of this investigation is to develop ultra high performance concrete (UHPC) for multipurpose - higher mechanical and ionizing radiation protection. The effect of nano-silica replacement (2 or 5%) on the properties of UHPC was compared with the referent concrete by testing compressive and flexural strength. As nano-silica influences cement hydration and modifies the pore structure, qualitative and quantitative analysis of pores was done using a device RapidAir 457. The second objective of this paper is to evaluate the influence of different aggregates on concrete properties. Two types of aggregate were used: quartz and barite. One of the most important characteristics of the concrete for protection against gamma and X radiation is its Total Attenuation Coefficient (µ/ρ)tot

Utilizing metabolites from curcuma longa for the development of ph-responsive test strips

Introduction: Metabolites from Curcuma longa show pH-dependent color-changing properties. During this study, test strips were developed using Curcuma longa metabolites, which enable the rapid estima- tion of acidity/alkalinity in natural and artificial samples. Methods: Commercially available Curcuma longa powder (5.00 g) was mixed with ethanol (45 mL) and subjected to 30 minutes of ultrasonic extraction. After 60 minutes of settling, the resulting suspension was filtered and supplemented with ethanol to reach a final volume of 50 mL. Circular pieces of filter paper were immersed in 15 mL of the colored filtrate in Petri dishes for 10 minutes. The impregnated pieces of filter paper were then dried at 65°C for 10 minutes and cut into desired rectangular shapes. Results: Analysis of the prepared test strips’ behavior was conducted across a pH range from 0 to 14, en- compassing various solutions (HCl, NaOH, and buffered solutions) whose pH values were measured by a pH meter. The test strips exhibited a yellow-orange color at pH values below 8.5, while a brown color was observed at pH values of 8.5 and above. Conclusion: The experimental data obtained in this investigation demonstrate significant agreement with the literature value for the first pKa of curcumin (pKa1=8.4), a compound displaying the distinctive orange color found in dry Curcuma longa powder, and possessing pH-dependent color-changing char- acteristics. Therefore, test strips prepared from an ethanolic extract of Curcuma longa powder constitute a promising tool for the routine assessment of acidity/alkalinity across various samples in molecular bi- ology, (bio)chemistry, pharmacy, medicine, and related fields.The poster presentation of the abstract, including a 3-minute oral presentation, was conducted by the corresponding author on the first day of the conference in Belgrade, on October 6th 202

Preliminary study of copper(II) ions removal from wastewater using solid residue obtained by co-pyrolysis of lignite and high density polyethylene mixture

In this study the solid residue obtained by the co-pyrolysis of low quality, mineral-rich lignite taken from the Kostolac Basin, Serbia (45.36% of ash; 33.42% of total organic carbon; net calorific value of 9.5 MJ/kg) and high density polyethylene, HDPE (mass ratio, 1:1) at 500 oC was tested as a sorbent for Cu2+ ions, considering that as a coaly-based material, simultaneously enriched in clays, it may have good adsorption properties. Sorption experiments of were performed using 0.5 g of solid co-pyrolysis lignite/HDPE product, as sorbent which was treated with 5 cm3 of model solutions containing ~ 200 times higher concentration of Cu2+ ions (242.60 mg/dm3), in relationship to its maximal allowed content in surface water of bad quality. Model solutions were prepared using corresponding nitrates dissolved in distilled water. Two model solutions were prepared. The first model solution contained individual Cu2+ ions, whereas the second one contained mixture of Cu2+, Pb2+, Co2+ and Cd2+ ions. Concentration of each ion in latter was also ~ 200 times higher than its maximal allowed content in surface water of bad quality. Treatment with distilled water was used as a blank. Concentrations of heavy metal ions in initial model solutions and supernatants obtained after sorption experiments were measured using inductively coupled plasma – optical emission spectrometry. The obtained results indicated very efficient sorption of Cu2+ ions from its individual model solution, attaining 99.96%. The efficiency of Cu2+ ions sorption was also high (99.95%) from model solution, which contained mixture of metal ions. It is important to mention that sorption of other metal ions from model solution mixture was also effective (99.99%, 80.70% and 71.04% for Pb2, Cd2+ and Co2+, respectively). The preliminary results showed promising sorption properties of solid residue obtained by the co-pyrolysis of lignite and HDPE against Cu2+, but also possibly for other heavy metals, particularly, Pb2+ ions.Abstracts and Field guides: [https://opac.geologie.ac.at/wwwopacx/wwwopac.ashx?command=getcontent&server=images&value=Pangeo_Austria_2022.pdf

Izbor komponentnih materijala za beton sa aspekta trajnosti

Betonske konstrukcije su često u eksploataciji izložene spoljašnjim uticajima. Preporuke koje definiše evropski stan-dard SRPS EN 206 za korišćenje betona u pojedinim klasa-ma izloženosti nisu dovoljne i iz tog razloga je usvojen i standard SRPS U.M1.206 koji predstavlja nacionalni doda-tak za njegovu primenu. Dejstvo mraza značajno utiče na trajnost betonske konstrukcije jer može da dovede do raza-ranja strukture betona. Zaštita se postiže dodavanjem hemij-skih dodataka koji uvlače vazduh u svež beton. U radu je prikazana mogućnost primene novog dodatka Sika Aer Solid. Ispitivana je otpornost betona na dejstvo mraza, mraza u prisustvu soli za odmrzavanje, prodiranje vode pod pritiskom i koeficijent migracije hlorida u laboratorijskim uslovima i uzorcima izvađenim iz betonskih prefabrikovanih elemenata. Betoni sa Sika Aer Solid su za istu klasu konzistencije u odnosu na aerirane betone imali bolja svojstva i u svežem i u očvrslom stanju

Synthesis of Iodine monochloride Using a Chlorine Solution in Glacial acetic acid with Simultaneous Disinfectant Generation

Iodine monochloride is an interhalogen compound that acts as an iodinating reagent for aromatic compounds, a halogenating agent for unsaturated compounds and for cleavage of carbon-metal bonds. The direct synthesis of solid iodine monochloride from elements is a very hazardous procedure in the laboratory due to the high toxicity of chlorine and iodine. In this paper, a safer method for obtaining a solution of iodine monochloride in glacial acetic acid, which is used as a reagent for determination of the iodine value of fats and oils, is presented. Laboratory preparation of iodine monochloride solution in glacial acetic acid is described in AOAC Official Method 993.20 - Iodine Value of Fats and Oils: chlorine gas passes through the iodine solution in acetic acid until a change in the colour of the solution is observed. If excess of chlorine is present in the resultant solution, it must be neutralised by adding of iodine solution in acetic acid. The main disadvantage of this method is the barely noticeable change in colour from brown to reddish brown and the lack of a procedure for the safe removal of chlorine excess after preparing the reagent. Considering the fact that chlorine gas is soluble in glacial acetic acid, we have overcome the mentioned deficiencies of AOAC Official Method 993.20 by introducing chlorine gas into the glacial acetic acid at 298K. The figure shows the process to obtain a chlorine solution in glacial acetic acid. The necessary volume of concentrated hydrochloric acid is added to the solid potassium permanganate in the reactor vessel (A) and the container is immediately closed. Chlorine gas is released, which flows through concentrated sulphuric acid (B) to remove moisture. After that, the chlorine is introduced into a vessel filled with glacial acetic acid (C). The excess chlorine is then dissolved in a 10% (w/v) sodium hydroxide solution (D) to produce a mixture of sodium hypochlorite and sodium hydroxide, which requires dilution with an appropriate volume of water to obtain an alkaline hypochlorite solution, which has strong disinfectant properties. The chlorine content in the glacial acetic acid solution is determined by iodometric titration; the same technique is used for determining the hypochlorite content after absorbing the excess chlorine in the sodium hydroxide solution. The final solution of iodine monochloride is prepared simply by adding a calculated volume of chlorine solution in glacial acetic acid to a specified volume of iodine in the same solvent. The results of our study demonstrate that the reaction of 0.12 mol potassium permanganate with 80 cm3 concentrated hydrochloric acid produce 200 cm3 of 0.85 mol/dm3 chlorine solution in glacial acetic acid and 250 cm3 of 0.34 mol/dm3 alkali sodium hypochlorite solution. This amount of chlorine solution in glacial acetic acid is sufficient to prepare approximately 3 dm3 of 0.1 mol/ dm3 iodine monochloride solution in the same solvent.This poster presentation was presented at the 22nd European Meeting on Environmental Chemistry 5-8 December 2022, Ljubljana, Slovenia [https://www.emec22.com