Efekat višestrukih stresora na multitrofički biodiverzitet barskih ekosistema

This study deals with the effects of multiple anthropogenic activities (i.e. stressors) on the richness and abundance of phytoplankton, macrophytes, zooplankton, benthic and epiphytic macroinvertebrates, and fishes, and their trophic groups. Multiple anthropogenic stressors were integrated in one measure by calculating anthropogenic stress index. The aim was to compare the responses of different pond communities to anthropogenic impact, disentangle the potential mechanisms responsible for variations in pond biodiversity (direct, water-chemistry mediated, and cascading effects), and to quantify pond net-community response to anthropogenic impact. In addition, the importance of pond natural variability on the variations of biodiversity of pond hydrobiocenoses was analysed. All communities were sampled in September 2016, from the 18 study sites distributed across the six permanent ponds that differ in origin, connectedness, the intensity of a river impact, and the level of pond coverage in surrounding area. The effects of anthropogenic stressors varied across the distinct pond communities, from negative effects on the richness and abundance of macrophytes and on the richness of epiphytic macroinvertebrates, via neutral effects on benthic macroinvertebrates, to positive effects on fish abundance through predominance of the invasive species. The natural pond variability affected the pond communities and water chemistry in the majority of cases and it is expected to alter the effects of anthropogenic stressors on pond communities. The underlying mechanisms of anthropogenic stressors clearly differed among different trophic levels. Direct effects were mainly detected witihin primary producers, while the consumers were mainly affected indirectly: the increase of nutrient concentrations in water affected abundance and richness of invertebrate trophic groups, while cascading effects were the most influential drivers of multitrophic diversity in the fish community. Despite the variable responses of different communities and their trophic groups, the total netcommunity effect of the anthropogenic stressors was negative

Comparison of Box-Behnken, Face Central Composite and Full Factorial Designs in Optimization of Hempseed Oil Extraction by n-Hexane: a Case Study

Statistical multivariate methods like Box-Behnken, face central composite and full factorial designs (BBD, FCCD and FFD, respectively) in combination with the response surface methodology (RSM) were compared when applied in modeling and optimization of the hempseed oil (HSO) extraction by n-hexane. The effects of solvent-to-seed ratio, operation temperature and extraction time on HSO yield were investigated at the solvent-to-seed ratio of 3:1, 6.5:1 or 10:1 mL/g, the extraction temperature of 20, 45 or 70 °C and the extraction time of 5, 10 or 15 min. All three methods were efficient in the statistical modeling and optimization of the influential process variables and led to almost the same optimal process conditions and predicted HSO yield. Having better statistical performances and being economically advantageous over the FFD with repetition, the BBD or FCCD combined with the RSM is recommended for the optimization of liquid-solid extraction processes

Korišćenje otpadnih koštica šljive kao izvora ulja i katalizatora za proizvodnju biodizela

Possibilities of using waste plum stones in biodiesel production were investigated. The plum kernels were used as a source to obtain oil by the Soxhlet extraction method, while the whole plum stones, the plum stone shells that remained after the crashing, and the plum kernel cake that remained after the oil extraction, were burned off to obtain ashes. The collected ashes were characterized by elemental composition, porosity, and base strength and tested for catalytic activity in transesterification of esterified plum kernel oil. Dominant elements were potassium, calcium, and magnesium at different contents in the three obtained ashes. The most active catalyst was the plum stone shell ash, so the effect of temperature (40, 50, and 60°C) on the reaction rate was investigated. The reaction rate constant increased with the reaction temperature with the activation energy value of 58.8 kJ mol-1. In addition, the plum stone shell ash can be reused as a catalyst after recalcination.U ovom radu istraživana je mogućnost korišćenja otpadnih koštica šljive u proizvodnji biodizela. Jezgra šljive su iskorišćena kao sirovina za dobijanje ulja primenom Soxhlet-ove metode ekstrakcije. Cele koštice, ljuske koštica šljive i pogača dobijena nakon ekstrakcije ulja iz jezgra šljive spaljeni su da bi se dobio pepeo, koji je korišćen kao katalizator. Dobijene tri vrste sakupljenog pepela su najpre okarakterisane u pogledu hemijskog sastava, poroznosti i baznosti, a zatim je testirana katalitička aktivnost u transesterifikaciji esterifikovanog ulja koštica šljive. Dominantni elementi u pepelu, kao što su kalijum, kalcijum i magnezijum, imali su različit sadržaj u sve tri vrste pepela. Najveću katalitičku aktivnost pokazao je pepeo koštica šljive, zbog čega je dalje istraživan uticaj temperature (40, 50 i 60 °C) na brzinu reakcije katalizovane ovim pepelom. Konstanta brzine reakcije povećavala se sa porastom temperature reakcije, a vrednost energije aktivacije je 58,8 kJ mol-1 . Pored toga, pepeo koštica šljive može se ponovo koristiti kao katalizator nakon rekalcinacije

Optimization of the heterogeneously catalysed methanolysis of plum kernel oil in the presence of menthol-based deep eutectic solvent

Waste plum kernels from the fruit processing industry might be a valuable oil source for biodiesel production which use can reduce the biodiesel production cost. The application of green cosolvents, like deep eutectic solvents (DESs), in the alcoholysis reaction can improve the oil conversion rate. This study reports on the optimization the plum kernel oil methanolysis over 35CaO/ZP (35% CaO supported on a fly ash-based zeolite) in the presence of triethanolamine:menthol (TEOA:M, 2:1 mol/mol) DES as cosolvent. The reactions were carried out in a 250 mL batch magnetic stirred reactor (900 rpm) with a reflux condenser under atmosferic pressure and at 60 °C. The effect of the catalyst amount (2-10% based on the oil mass), TEOA:M DES amount (1-9% based on the oil mass) and methanol:oil molar ratio (6:1-12:1 mol/mol) on the fatty acid methyl esters (FAMEs) content was analyzed according to a Box-Behnken design. The obtained experimental data of the FAME content were modeled by a second-order polynomial equation and the response surface methodology was used for determining the optimal reaction conditions for achieving the highest FAME content. According to the analysis of variance (ANOVA), the catalyst amount had the most significant influence on the FAME content, followed by the TEOA:M DES amount and the methanol:oil molar ratio. By analyzing the second-order polynomial equation, it can be concluded that the catalyst amount and TEOA:M DES amount have a positive effect on the FAME content. The maximum FAME content (99.67%) was achieved under the following optimal reaction conditions: catalyst amount of 8% (based on the oil mass), TEOA:M DES amount of 4.8% (based on the oil mass), and methanol:oil molar ratio of 6.1:1

Kinetic modeling of the biodiesel production from sunflower oil over corn cob ash

The investigation of reaction kinetics is crucial for practical implications in process equipment design and scaling up. In this study, a kinetic analysis of the methanolysis of a blend of radish and castor oil catalyzed by calcium oxide was carried out. The objectives were to propose a comprehensive model for describing the kinetics of this methanolysis reaction and determine its activation energy. The methanolysis was conducted in a batch reactor under atmospheric pressure with the following reaction conditions: a radish-to-castor oil blend mass ratio of 1:1, a methanol-to-oil molar ratio of 12:1, a catalyst amount of 5% of the oil blend weight, and reaction temperatures of 30 C, 45 C, and 60 C. The model involving the changing reaction mechanism and the triacylglycerol (TAG) mass transfer limitation was first simplified to a pseudo-first order model regarding TAGs and fatty acid methyl esters, which was then used to calculate the apparent reaction rate constant. A good agreement between the calculated and experimental values of the TAG conversion degree was proved by a low mean relative percentage deviation of ±6.1% (based on 66 data), thus validating the applied simple kinetic model. A positive effect of the reaction temperature on the apparent reaction rate constant was observed. Using the Arrhenius equation, the activation energy of methanolysis was determined to be 46.12 kJ/mol. The obtained value of activation energy is much lower than values of activation energy determined for the calcium oxide-catalyzed methanolysis of single oil feedstocks, such as soybean, canola, Jatropha, and waste frying oils. The lower activation energy suggests the potential for enhanced efficiency and feasibility of utilizing this blend as a feedstock for biodiesel production compared to the individual oily feedstocks previously studied

Optimizacija proizvodnje biodizela kukuruznog ulja metanolizom katalizovanom pepelom kurdeljke

The use of low-cost or priceless feedstocks such as byproducts in biodiesel production results in a reduced overall process costs. The present paper reports the use of corn germs and corn cobs as byproducts from corn-based starch production in the biodiesel production by the methanolysis of the oil extracted from corn germs, catalyzed by the ash produced by combustion of corn cobs. The major aim was to optimize the methanol-to-oil molar ratio, catalyst loading, and reaction time in a batch stirred reactor with respect to the content of methyl ester fatty acids (FAME). The statistical modeling and optimization were carried out using a second-order polynomial (quadratic) model developed by the response surface methodology combined with a 33 factorial design with 3 central points. The FAME content was determined by a high-pressure liquid chromatography method. The analysis of variance showed that only the catalyst amount, the reaction time, the catalyst amount interaction with reaction time and all three quadratic terms were the significant model terms with the confidence level of 95 %. The optimum reaction conditions (the catalyst amounts of 19.8 %, the methanol-to-oil molar ratio of 9.4 mol/mol and the reaction time of 31 min) provided the FAME content of 98.1 %, which was in an excellent agreement with the predicted FAME content (98.4 %). Thus, both corn germs and corn cobs may be suitable feedstocks for biodiesel production.Upotreba jeftinih ili bezvrednih sirovina, kao što su sporedni proizvodi, u proizvodnji biodizela ima za rezultat smanjene ukupne troškove procesa. U ovom radu su prikazani rezultati upotrebe kukuruznih klica i okrunjenog kukuruznog klipa (kurdeljke, krudeljke) kao sporednih proizvoda iz proizvodnje kukuruznog skroba u proizvodnji biodizela metanolizom ulja izdvojenog iz kukuruznih klica, katalizovane pepelom dobijenim sagorevanjem kurdeljke. Glavni cilj je bila optimizacija molskog odnosa metanol-ulje, količine katalizatora i reakcionog vremena u šaržnom reaktoru sa mešanjem u odnosu na sadržaj metilestra masnih kiselina (MEMK). Statističko modelovanje i optimizacija izvršeni su korišćenjem kvadratnog modela, razvijenog metodologijom odzivne površine, u kombinaciji sa 33 faktorijelnim planom sa 3 centralne tačke. Sadržaj MEMK-a je određen metodom tečne hromatografije pod visokim pritiskom. Analiza varijanse je pokazala da su samo uticaji količine katalizatora, reakcionog vremena, interakcije količine katalizatora sa reakcionim vremenom i sva tri kvadratna člana statistički značajni sa nivoom pouzdanosti od 95 %. Pod optimalnim reakcionim uslovima (količina katalizatora 19,8 %, molski odnos metanol/ulje 9,4 mol/mol i reakciono vreme 31 min) dobijen je sadržaj MEMK-a od 98,1 %, koji se slaže sa predviđenim sadržajem MEMK-a (98,4 %). Prema tome, i kukuruzne klice i kurdeljka mogu biti pogodne sirovine za proizvodnju biodizela

A triethanolamine:choline chloride deep eutectic solvent as a cosolvent in the ethanolysis of Brassica nigra L. seed oil

Black mustard (Brassica nigra L.) seeds oil (BMSO), characterized by a high content of erucic acid (C22:1), belongs to inedible oils. Since BMSO has a high percentage of monounsaturated and branched fatty acids, it is a suitable raw material for biodiesel production. Also, green cosolvents, like deep eutectic solvents (DESs), can improve the biodiesel production process. This study reports the influence of the triethanolamine:choline chloride DES (2:1 mol/mol) on the BMSO ethanolysis over calcined CaO as a catalyst, under the following reaction conditions: temperature of 50, 60, and 70 ºC, ethanol-to-oil molar ratio of 12:1, as well as TEOA:ChCl DES and calcined CaO content of 20% and 10%, respectively. At 70 ºC, the ChCl:TEOA DES provided a high content of fatty acid ethyl esters (FAEE) (98.46±0.7%) after 1.5 min, compared to the control reaction (without the presence of DES), where the maximum FAEE content (98.05±0.6%) was achieved within 4 h. BMSO ethanolysis was described by the kinetic model of the pseudo-first order and the model of variable reaction order concerning TAG and the autocatalytic behavior of the ethanolysis reaction. Both kinetic models, with great accuracy, fitted the experimental data. As a result, physicochemical properties of the obtained biodiesel were within the limit values prescribed by the quality standard EN 14214. Also, the reusability of calcined CaO was proven even in four cycles with the FAEE content of over 90%

Pepeo pšenične slame kao katalizator u proizvodnji biodizela

Wheat straw ash (WSA) was investigated as a new catalyst in biodiesel production from sunflower oil. The catalyst was characterized by temperature-programmed decomposition, X-ray powder diffraction, Hg porosimetry, N2 physisorption, and scanning electron microscopy - energy dispersive X-ray spectroscopy methods. The methanolysis reaction was tested in the temperature range of 55–65 oC, the catalyst loading range 10–20 % of the oil weight, and the methanol-to-oil molar ratio range 18 : 1–24 : 1. The reaction conditions of the sunflower oil methanolysis over WSA were optimized by using the response surface methodology in combination with the historical experimental design. The optimum process conditions ensuring the highest fatty acid methyl esters (FAME) content of 98.6 % were the reaction temperature of 60.3 oC, the catalyst loading of 11.6 % (based on the oil weight), the methanol-to-oil molar ratio of 18.3 :1, and the reaction time of 124 min. The values of the statistical criteria, such as coefficients of determination (R2 = 0.811, R2pred = 0.789, R2adj = 0.761) and the mean relative percent deviation (MRPD) value of 10.6 % (66 data) implied the acceptability and precision of the developed model. The FAME content after 4 h of reaction under the optimal conditions decreased to 37, 12, and 3 %, after the first, second, and third reuse, respectively.Pepeo pšenične slame (PPS) je korišćen kao katalizator u proizvodnji biodizela iz sunco-kretovog ulja. Karakterizacija katalizatora je izvršena primenom metoda tempera-turski programiranom razgradnjom (temperature-programmed decomposition, TPDe), rentgenskom difrakcijom (X-ray diffraction, XRD), Hg porozimetrijom, N2 fizi-sorpcijom i skenirajućom elektronskom mikrosopijom sa energo-disperzivnom spek-trometrijom (scanning electron microscopy and energy dispersive X-ray spectroscopy, SEM-EDS). Reakcija metanolize istraživana je pri sledećim reakcionim uslovima: tem-peraturni opseg 55-65 °C; količina katalizatora 10-20 % (računato na masu ulja) i opseg molskog odnosa methanol : ulje 18 : 1 – 24 : 1. Optimizacija reakcionih uslova izvršena je metodologijom površine odziva u kombinaciji sa istorijskim eksperimentalnim planom. Maksimalni prinos metil estara masnih kiselina (MEMK) od 98,6 % postignut je pri sledećim optimalnim reakcionim uslovima: temperatura 60,3 oC, količina katalizatora 11,6 % (računato na masu ulja), molski odnos methanol : ulje 18,3 : 1 i vreme trajanja reakcije 124 min. Vrednosti koeficijenata determinacije (R2 = 0,811, R2pred = 0,789, R2adj = 0,761) i srednjeg relativnog odstupanja (10,6 %, 66 podataka) ukazali su na prihvatljivost i pouzdanost razvijenog modela. Sadržaj MEMK nakon 4 h reakcije pri optimalnim uslovima smanjen je na 37, 12 i 3 % nakon prve, druge i treće upotrebe katalizatora, redom

White Mustard (Sinapis alba L.) Oil in Biodiesel Production: A Review

White mustard (Sinapis alba L.) seed oil is used for cooking, food preservation, body and hair revitalization, biodiesel production, and as a diesel fuel additive and alternative biofuel. This review focuses on biodiesel production from white mustard seed oil as a feedstock. The review starts by outlining the botany and cultivation of white mustard plants, seed harvest, drying and storage, and seed oil composition and properties. This is followed by white mustard seed pretreatments (shelling, preheating, and grinding) and processing techniques for oil recovery (pressing, solvent extraction, and steam distillation) from whole seeds, ground seed or kernels, and press cake. Novel technologies, such as aqueous, enzyme-assisted aqueous, supercritical CO2, and ultrasound-assisted solvent extraction, are also discussed. The main part of the review considers biodiesel production from white mustard seed oil, including fuel properties and performance. The economic, environmental, social, and human health risk/toxicological impacts of white mustard-based biodiesel production and use are also discussed

Triethanolamine as an efficient cosolvent for biodiesel production by cao-catalyzed sunflower oil ethanolysis: An optimization study

Triethanolamine was applied as an efficient „green“ cosolvent for biodiesel production by CaO-catalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4 °C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75 °C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3798