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Thirteen samples of esters based on dodecanedioic acid with different chemical structures were synthesized. Among these were di-2-octyl dodecanedioate, didecyl dodecanedioate, di-2-ethylhexanol dodecanedioate, di-2-ethylbutyl dodecanedioate, dioctyl dodecanedioate, dihexyl dodecanedioate, and dioleyl dodecanedioate. Diesters were synthesized through the esterification of dodecanedioic acid with selected long-chain and branched alcohols with acid catalyst of H2SO4. These esters were tested in terms of their suitability for application as lubricants. The results showed that the lubricity properties, based on their pour point, flash point, and oxidation stability of the esters were significantly affected by the linear and branched alcohols used. An excellent pour point property of di-2-ethylbutyl dodecanedioate and di-2-ethylhexanol dodecanedioate at −55 °C and −50 °C was observed compared to their respective same linear carbon number esters of dihexyl dodecanedioate at 10 °C and dioctyl dodecanedioate at 20 °C. These are due to the presence of the branched group in their molecule vicinity structure. However, the esters flash points were insignificantly affected by the presence of branched structure. The selected esters could be used for biolubricants or engine oil. This work is licensed under a Creative Commons Attribution 4.0 International License. Sintetizirano je trinaest uzoraka estera na bazi dodekandiojske kiseline različitih kemijskih struktura. Među njima su bili di-2-oktil dodekandioat, didecil dodekandioat, di-2-etilheksanol dodekandioat, di-2-etilbutil dodekandioat, dioktil dodekandioat, diheksil dodekandioat i dioleil dodekandioat. Diesteri su sintetizirani esterifikacijom dodekandiojske kiseline s odabranim dugolančanim i razgranatim alkoholima s kiselinskim katalizatorom H2SO4. Ti su esteri ispitani u smislu njihove prikladnosti za primjenu kao maziva. Rezultati su pokazali da su na svojstva mazivosti, temeljena na njihovoj točki tečenja, točki zapaljenja i oksidacijskoj stabilnosti estera, znatno utjecali upotrijebljeni linearni i razgranati alkoholi. Uočeno je izvrsno svojstvo točke tečenja di-2-etilbutil dodekandioata i di-2-etilheksanol dodekandioata pri −55 °C i −50 °C u usporedbi s njihovim istim ravnopravnim esterima ugljikova broja diheksil dodekandioata pri 10 °C i dioktil dodekandioata pri 20 °C, zbog prisutnosti razgranate skupine u strukturi njihove blizine molekule. Međutim, prisutnost razgranate strukture neznatno je utjecala na točke zapaljenja estera. Odabrani esteri mogli bi se rabiti za biomaziva ili motorno ulje. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Human hair is a biological sample that is, unlike blood, noninvasively collected and can be used in the assessment of element intake. Before analysis, hair samples need to be washed to eliminate external contamination, for which no standard procedure exists. The present study evaluated the efficiency of different processes for washing hair samples (by non-ionic detergent, acids, solvents, and their mixtures), including ultrasonication before ICP-MS element (As, Ca, Cd, Cu, Fe, Hg, Mg, Mn, Mo, Pb, Se, and Zn) analysis. All tested washing procedures using detergent or solvents were satisfactory, while nitric and hydrochloric acid solutions yielded to “released” and lost elements due to damaged hair (visible discolouration and hair impairment). The application of ultrasonication improved washing efficiency up to 10 %, depending on the tested element and washing procedure.

One of the main disadvantages of the use of synthetic or semi-synthetic polymeric materials is their degradation and aging. The purpose of this study was to use artificial neural networks (ANN) and multiple linear regressions (MLR) to predict the carbonyl, hydroxyl, and polyene indices (ICO, IOH, and IOP), and viscosity average molecular weight (MV) of poly(vinyl chloride), polystyrene, and poly(methyl methacrylate). These physicochemical properties are considered fundamental during the study of photostabilization of polymers. From the five repeating units of monomers, the structure of the polymer studied is shown. Quantitative structure-property relationship (QSPR) models obtained by using relevant descriptors showed good predictability. Internal validation {R2, RMSE, and Q2LOO}, external validation {R2, RMSE, Q2pred, rm2, Δrm2, k, and k’}, and applicability domain were used to validate these models. The comparison of the results shows that the ANN models are more efficient than those of the MLR models. Accordingly, the QSPR model developed in this study provides excellent predictions, and can be used to predict ICO, IOH, IOP, and MV of polymers, particularly for those that have not been tested. This work is licensed under a Creative Commons Attribution 4.0 International License. Jedan od glavnih nedostataka upotrebe sintetičkih ili polusintetičkih polimernih materijala je njihova razgradnja i starenje. Svrha ove studije je primjena umjetnih neuronskih mreža (ANN) i višestrukih linearnih regresija (MLR) za predviđanje karbonilnih, hidroksilnih i polienskih indeksa (ICO, IOH i IOP) i prosječne molekulske mase viskoznosti (MV) poli(vinil-klorida), polistirena i poli(metil metakrilata). Ta fizikalno-kemijska svojstva smatraju se važnim tijekom proučavanja fotostabilizacije polimera. Iz pet ponavljajućih jedinica monomera prikazana je struktura ispitivanog polimera. Kvantitativni modeli odnosa strukture-svojstava (QSPR) dobiveni primjenom relevantnih deskriptora pokazali su dobru predvidljivost. Za potvrdu tih modela provedene su: interna provjera {R2, RMSE i Q2LOO}, vanjska provjera {R2, RMSE, Q2pred, rm2, Δrm2, k i k’} i domena primjenjivosti. Usporedba rezultata pokazuje da su modeli ANN učinkovitiji od modela MLR. Prema tome, model QSPR razvijen u ovoj studiji pruža izvrsna predviđanja i može se primjenjivati za predviđanje ICO, IOH, IOP i MV polimera, posebno za one koji nisu testirani. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Many studies highlight the health benefits of mushrooms, which are consequently becoming more and more interesting for researchers. The content of amino acids (AA), total phenolic content (TPC), and antioxidative activity (AAc) were determined in wild as well as cultivated mushrooms. The AA included: L-tryptophan (Trp), L-arginine (Arg), L-cysteine (Cys), L-methionine (Met), L-alanine (Ala), L-phenylalanine (Phe), L-lysine (Lys), L-valine (Val), L-glycine (Gly), and L-leucine (Leu). The wild mushrooms: Lactarius piperatus, Amanita caesarea, Lactarius deliciosus, Lycoperdon pyriforme, Macrolepiota procera, and cultivated mushrooms: Agaricus bisporus, Boletus aestivalis, Cantharellus cibarius, Pleurotus ostreatus, and Agaricus bisporus var. avellaneus were investigated in this study. The AA was determined by HPTLC method and quantified with a Camag TLC scanner and WINCAT software by scanning the plates at 540 nm. The TPC was spectrophotometrically estimated as gallic acid equivalents/g of fresh weight according to Folin-Ciocalteu’s method. The radical scavenging activity (RSA) of mushroom extracts was determined by DPPH assay. The highest content of Ala, Gly, Phe, Lys, Val, and Leu was found in Pleurotus ostreatus. The total phenolic content (mg GAE/g) in investigated mushrooms ranged from 1.90 to 35.56, and the % RSA ranged from 43.88 to 90.17. This study promotes the consumption of food rich in bioactive compounds, mushrooms being among such food. Further research on mushrooms from Bosnia and Herzegovina and their benefits in the overall maintenance of human health and protection from age-related diseases is necessary.

In the current study, an artificial neural network (ANN) and multiple linear regressions (MLR) have been used to develop predictive models for the estimation of molecular diffusion coefficients of 1252 polar and non-polar binary gases at multiple pressures over a wide range of temperatures and substances. The quality and reliability of each method were estimated in terms of the correlation coefficient (R), mean squared errors (MSE), root mean squared error (RMSE), and in terms of external validation coefficients (Q2ext). The comparison between the artificial neural network (ANN) and the multiple linear regressions (MLR) revealed that the neural network models showed a good predicting ability with lower errors (the roots of the mean squared errors in the total database were 0.1400 for ANN1 and 0.1300 for ANN2), and (root mean squared errors in the total databases were 0.5172 for MLR1 and 0.5000 for MLR2). This work is licensed under a Creative Commons Attribution 4.0 International License. U ovoj studiji primijenjene su umjetna neuronska mreža (ANN) i model višestruke linearne regresije (MLR) za razvoj prediktivnih modela za procjenu koeficijenata molekularne difuzije 1252 polarnih i nepolarnih binarnih plinova pri višestrukim tlakovima u širokom rasponu temperatura i tvari. Kvaliteta i pouzdanost svake metode procijenjeni su pomoću korelacijskog koeficijenta (R), srednjih kvadratnih pogrešaka (MSE), korijena srednje kvadratne pogreške (RMSE) te koeficijenata vanjske validacije (Q2ext). Usporedba između umjetne neuronske mreže (ANN) i višestrukih linearnih regresija (MLR) otkrila je da modeli neuronske mreže pokazuju dobru sposobnost predviđanja s nižim pogreškama (korijeni srednjih kvadratnih pogrešaka u ukupnoj bazi podataka bili su 0,1400 za ANN1 i 0 (1300 za ANN2 a pogreške korijena srednje vrijednosti u ukupnim bazama podataka bile su 0,5172 za MLR1 i 0,5000 za MLR2). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Epoksidirana palmina oleinska kiselina često se smatra vrlo vrijednom oleokemijskom tvari zbog širokog raspona industrijskih primjena, uključujući kozmetiku, osobnu njegu i farmaceutske proizvode. U ovoj studiji, oleinska kiselina potekla iz palmina ulja s jodnim brojem 98,99 g/100 g, koja sadrži 75 % oleinske kiseline, 12 % linoleinske kiseline, 6,5 % palmitinske kiseline i 6,5 % stearinske kiseline, epoksidizirana je in situ proizvedenom performičnom kiselinom s vodikovim peroksidom kao donorom kisika i mravljom kiselinom kao aktivnim nosačem kisika u prisutnosti katalitičke količine anorganske kiseline. Konstanta brzine za epoksidaciju oleinske kiseline bila je 1,133 ∙ 10–3 mol–1 s–1, a energija aktivacije 91,12 kJ mol–1 pri temperaturi 75 °C. Termodinamički parametri kao što su entalpija, entropija i slobodna energija aktivacije iznosili su 88,2 kJ mol–1, −67,90 J mol–1 K–1, odnosno 88,36 kJ mol–1. Relativni podatci konverzije pokazali su da je moguće razviti epokside iz lokalnih, prirodnih i obnovljivih izvora kao što je palmino ulje. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna. Epoxidized palm oleic acid is often regarded as a highly valuable oleochemical due to its wide range of industrial applications, including cosmetics, personal care, and pharmaceutical products. In this study, oleic acid derived from palm oil with iodine value of 98.99 g/100 g, containing 75 % of oleic acid, 12 % of linoleic acid, 6.5 % of palmitic acid, and 6.5 % of stearic acid was epoxidised by in situ generated performic acid with hydrogen peroxide as oxygen donor and formic acid as active oxygen carrier in the presence of catalytic amount of inorganic acid. The rate constant for epoxidation of oleic acid was found to be 1.133 ∙ 10–3 mol–1 s–1 and activation energy was 91.12 kJ mol–1 at temperature of 75 °C. In addition, thermodynamic parameters such as enthalpy, entropy, and free energy of activation were 88.2 kJ mol–1, −67.90 J mol–1 K–1, and 88.36 kJ mol–1, respectively. Relative conversion data showed that it was possible to develop epoxides from locally available, natural, renewable resources such as palm oil. This work is licensed under a Creative Commons Attribution 4.0 International License.

Prethodne IUPAC-ove preporuke imenovanja (nomenklature) jednonitnih polimera na osnovi podrijetla (NOP) odnosile su se uglavnom na kopolimere, nelinearne polimere, združene polimere i generičke polimere. Pravila navedena u ovim preporukama omogućuju jasnije i preciznije imenovanje polimera na osnovi podrijetla, kako homopolimera tako i kopolimera. Prikazani sveobuhvatni sustav imenovanja polimera na osnovi podrijetla prihvatljiva je alternativa sustavu imenovanja polimera na osnovi strukture. Zbog raširene i česte uporabe dodatno su opisane i preporuke za uporabu uvriježenih imena polimera.

Biodiesel is the first alternative fuel which physico-chemical properties are regulated by appropriate standards: American ASTM D 6751 and European standard EN 14214. The process of biodiesel production consists of four main phases: 1) preparation of feedstock, 2) transesterification, 3) phase separation, and 4) processing of the reaction product - purification of crude biodiesel to meet the specification provided by EN 14214. The purification process of crude biodiesel is usually carried out by two notable techniques: wet and dry washing. The most commonly used is wet process. A major drawback in the use of water in purification process is the generation of large amount of wastewater that greatly increases the biodiesel production costs followed by drying of the product, which requires additional amount of energy and time. The greatest lack of dry washing using different ion-exchange resins is the inability to remove glycerol and methanol from crude biodiesel to the limits prescribed by EN 14214 as well as the disposal problem of spent ion-exchange resins. Because of aforementioned, the use of membrane technology in the process of biodiesel purification has appeared as an alternative for the existing purification techniques. The membrane filtration is environmentally friendly and, in comparison with other two methods for biodiesel purification, requires less energy. Ultra- and/or nano- membrane filtration of biodiesel has so far provided the very good results. By membrane filtration, glycerol, methanol and water content in biodiesel can be decreased to the amounts prescribed by the standards. In frame of this work the short overview of the possibility to use the ultra- and/or nano- filtration in purification process of biodiesel will be presented.

Nastavak postupaka proračuna gravitacijskih separatora. Dani su postupci proračuna za vodoravne trofazne gravitacijske separatore.

Različiti postupci dimenzioniranja mogu se naći u literaturi. Više ih je za standardne tipove separatora. Za specifične izvedbe nema ih mnogo, obično su to postupci u kojima ima mnogo iskustvenih podataka i koje primjenjuju projektne organizacije, koje ih ne objavljuju. Ovdje su dani postupci za osam osnovnih tipova separatora: dva za dvofazne separatore i šest za trofazne. Postupci su dani s primjerima radi lakšeg razumijevanja postupka.