In this research, the possibility of using Ca(OH)2 in the form of commercial hydrated lime as a catalyst for the methanolysis of refined rapeseed oil was evaluated. Characterization of unused catalyst was performed by SEM-EDS, laser diffraction, XRF, BET, XRD and TG/DTG methods, and vegetable oil was analyzed for physicochemical characteristics. Within methanolysis, the effects of catalyst loading, reaction temperature and reaction time on methyl ester yield, density and viscosity of biodiesel, as well as the possibility of catalyst reuse were investigated. The obtained results showed that hydrated lime is an efficient catalyst for transesterification of vegetable oil, whereby the use of 3 wt% of catalyst relative to oil weight, at temperature 60℃ and mixing rate 1000 rpm after 120 min of transesterification reaction achieved a yield of methyl esters 98.76%. With three reuses of hydrated lime, without intermediate washing and regeneration procedures, the yield of rapeseed oil methyl ester remained above 90%.

Biodizel je naziv za gorivo dobiveno iz obnovljivih izvora koje se može upotrebljavati u nemodificiranim dizelskim motorima umjesto uobičajenog fosilnog dizelskog goriva. Biodizel je ustvari komercijalni naziv za smjesu metilnog estera, koja se danas može naći na tržištu tekućih goriva, prije svega u EU-u, gdje se i prodaje krajnjim korisnicima. Globalna proizvodnja biodizela u 2014. godini premašila je 30 milijardi litara od čega oko 39 % otpada na EU.1 Kao osnovna sirovina za dobivanje biodizela mogu poslužiti svi izvori biomase bogati triacilglicerolima. U prvom redu tu spadaju jestiva biljna ulja, zatim nejestiva, otpadna i upotrijebljena ulja, kao i životinjske masti. Metanoliza biljnih ulja može biti podijeljena na osnovu prisutnosti i vrste katalizatora ili topljivosti katalizatora u reakcijskoj smjesi. Ovisno o tome odvija li se reakcija metanolize s ili bez prisutnosti katalizatora, metanoliza može biti katalizirana i nekatalizirana. Kemijski katalizatori metanolize razlikuju se kako po svojoj prirodi tako i na osnovi njihove topljivosti u reakcijskoj smjesi. Ovisno o tome je li katalizator u reakcijskoj smjesi topljiv ili nije, kemijski katalizirana metanoliza može biti podijeljena na homogeno, heterogeno i homogeno-heterogeno kataliziranu metanolizu. Osnovna karakteristika homogeno katalizirane metanolize je otopljen katalizator u reakcijskoj smjesi. Homogeni katalizatori metanolize mogu biti lužine i kiseline. Najčešće istraživan i u komercijalnim procesima najčešće primjenjivan način dobivanja biodizela je metanoliza katalizirana lužinama. Proces transesterifikacije s lužnatim katalizatorom uobičajen je način proizvodnje biodizela iz rafiniranih biljnih ulja. Kao lužnati katalizatori najčešće se upotrebljavaju kalijev hidroksid (KOH), natrijev hidroksid (NaOH) i natrijev metoksid (NaOCH3). Unatoč brojnim prednostima homogeno katalizirane metanolize, glavni nedostatak joj je nemogućnost ponovne uporabe katalizatora. Pored toga, katalizator zaostaje u esterskoj frakciji, odakle ga je potrebno ukloniti, što se najčešće provodi višestrukim ispiranjem s vodom, a otpadna voda čini značajan problem za okoliš.2,3 Uporabom katalizatora koji se ne otapaju u reakcijskoj smjesi, pojednostavljuje se način izdvajanja i rafiniranja proizvoda, smanjuju okolišni problemi i omogućava ponovna uporaba katalizatora. Uporabom heterogenih katalizatora dobiva se kvalitetniji i čišći biodizel kao i glicerol, a zbog jednostavnijeg postupka i mogućnosti višestruke uporabe katalizatora danas se homogena kataliza sve više nastoji zamijeniti heterogenom.3,4,5 U posljednje vrijeme heterogeno katalizirana metanoliza vrlo se intenzivno istražuje. U različitim laboratorijskim istraživanjima heterogeno katalizirane metanolize upotrebljavan je velik broj različitih spojeva u funkciji katalizatora.6 Pri tome je mnogo pozornosti posvećeno istraživanju vrste, načina pripreme i količine heterogenog katalizatora, kao i uvjetima pri kojima se izvodi reakcija metanolize. Katalitička aktivnost heterogenih katalizatora ovisi o mnogo čimbenika, prije svega o njihovoj prirodi, veličini i specifičnoj površini čestica te primijenjenim uvjetima u kojima se reakcija izvodi.7 Između objavljenih rezultata ovih istraživanja postoje razlike oko optimalnih uvjeta procesa, pa čak i oko postojanja katalitičke aktivnosti nekih spojeva. Najveći broj istraživanja heterogeno katalizirane metanolize odnosi se na primjenu zemnoalkalijskih metala, točnije njihovih oksida kao katalizatora reakcije.3 Katalitička aktivnost oksida zemnoalkalijskih metala raste s povećanjem njihove bazičnosti i to redoslijedom;

Although it is primarily grown as food, corn also represents a very good raw material for the production of biogas due to the favourable starch and fibre ratio that is the basis of its structure. In addition, an important fact is that there are large arable or potentially arable areas in our country that are triturated with different pollutants, so that the production of plant crops for dietary purposes on these surfaces is not possible. The aim of this paper was to determine the biometric potential of various varieties of corn grain in laboratory conditions through a series of experimental measurements. The obtained results are based on the assessment of the possibility of applying energy plantations of corn grown on contaminated arable or recultivated surfaces in the production of biogas.

Soda ash plant in Lukavac (Bosnia and Herzegovina) generates significant quantities of different types of waste that are heavily burdening the environment. Fly ash and slag from the energy plant along with the waste filter brine from the soda plant represent the most important waste streams both in terms of quantity and level of environmental impact. Consequently, ongoing research is being carried out to find new ways of using these materials. The basic characteristics of flying ash, which may have an impact on its potential application, are: chemical composition, granulometric composition, specific gravity, specific surface, pozzolanic properties and radioactivity. In this research, the possibility of using solid waste, primarily fly ash from the energy plant, as well as the precipitate from the sediment pond I of „White Sea“ sediment basin in the production of geopolymer, has been investigated. The obtained results show that, by adjusting the ratio of these materials, geopolymers of satisfactory characteristics can be obtained, and that the initial composition of the mixture, determined by combining the proportion of individual raw materials, is extremely important for the preparation of geopolymers of appropriate physicochemical characteristics, using fly ash, precipitate from the “White Sea”, and water glass with NaOH and water, which are of particular importance.

Due to the increased use of fossil fuels and industrial production, the concentration of carbon dioxide in the atmosphere increases, causing greenhouse effect and, consequently, climate change. Stationary CO2 sources like coal power plants produce the bulk of the world’s CO2 emissions. Electricity and heat plants and other fuel transformation activities account for 40% of total global CO2 emissions. Therefore, great interest in the possibilities of CCS systems to reduce CO2 emission is evident, either through removal or reduction measures. The experimental part of this paper deals with the determination of the potential of alternative media for use in CCS technologies, describing the lab-scale investigation. The role of alternative media in that context has been assigned to recurrent water from fly ash and slag disposal pond Jezero II of Power Plant Tuzla. When choosing an alternative medium for CCS applications, the following features were considered: that the medium currently has a negative impact on the environment; that the medium is available in sufficient quantities; that the medium has a low price and that its final disposal causes costs. Hence, the ability of the selected media (recurrent water) for CO2 capture has been confirmed and its capacity in that context roughly determined.

Contact lenses suffer from two limitations: low oxygen permeability and deposition of protein and lipids. In order to prevent bioadhesion, surface must be completely inert to all biological reactions. To achieve this, surface properties must be tailored. Also, to improve comfort, surface must be highly wettable and lubricous. In this paper the surface of silicone contact lenses was modified by plasma induced copolymerization of acrylic acid. A wettable surface was generated and in addition carboxyl groups that were created on the surface provided an ideal reactive platform for subsequent grafting of polyethylene glycol. Each surface modification step was analysed by XPS and contact angle measurements. Lysozyme adsorption on modified silicone contact lenses was analysed by surface-MALDI-ToF-MS and XPS. After incubation with lysozyme, surface-MALDI-TOF-MS and XPS analysis showed a reduction of adsorbed lysozyme on hydrogel modified contact lenses. Surface modification of silicone with PEG is a method for reduction of protein adsorption on contact lenses.

Uvod:Pivo može sadržavati minerale u bioloski raspoloživoj formi. Sadržaj minerala u pivu može da varira. Alkohol u odnosu na vodu cesto omogucuje bolju topivost nekih spojeva sa specificnim funkcionalnim hemijskim grupama. Cilj rada:Cilj rada je bio ispitati da li postoje znacajne razlike u kolicini minerala kod alkoholnog i bezalkoholnog piva. Materijali i metode: Analizirani su uzorci bezalkoholnog i alkoholnog svijetlog piva. Dvije grupe uzoraka su bile ispitivane: alkoholno svijetlo pivo (A1 i A2), a dvije bezalkoholno (B1 i B2). Uzorci B1 grupe su bili proizvedeni bioloskim a uzorci (B2) fizickim postupkom. Za analizu sadržaja minerala u svim ispitivanim uzorcima koristena je Atomska apsorpciona spektrofotometrija. Rezultati i rasprava: Sadržaj minerala u uzorcima bezalkoholnog (B1) bio veci nego u uzorcima alkoholnog svijetlog piva (A1). Uzorci B1 i A1 su od istog proizvođaca. U ovom slucaju povoljniji mineraloski sastav pokazuje bezalkoholno pivo. Sadržaj minerala u uzorcima alkoholnog pivu (A2) bio je veci nego u uzorcima bezalkoholnog svijetlog piva (B2). Uzorci B2 i A2 su od razlicitih proizvođaca. Zakljucci:Sadržaj minerala u alkoholnom i bezalkoholnom svijetlom pivu zavise od tehnoloskog postupka proizvodnje ali i od udjela minerala u osnovnim sirovinama. Vecina minerala u pivu poticu iz osnovnih sirovina: vode, slada, hmelja i ne sladovanih žitarica.

The aim of this paper was to investigate the possibility of obtaining oil from spent coffee grounds, which are left behind after the coffee is prepared, as the potential feedstock for biodiesel production. The effect of process parameters, such as are the type of solvent, the ratio of spent coffee grounds/solvent and the extraction time on oil yielded from coffee grounds was examined. The oil was obtained by maceration and extraction in the Soxhlet apparatus. The obtain results show that the spent coffee grounds could be used as an alternative raw material for biodiesel production, because it contains a significant amount of oil that can be extracted. The oil yield depends on the extraction (maceration) process parameters. The maximum oil yield obtained by the Soxhlet extraction with the n-hexane for the period of 5 h was 11.85% (the weight percentage of oil on dry mater), whereas with petroleum ether the oil yield was slightly lower and amounted to 10.44%. The yield of the oil extracted by maceration increases with the decrease of spent coffee grounds/solvent ratio from 1/3 to 1/7 g/cm3, and other parameters being constant. The oil yield increases with the duration of the maceration. Greater oil yield, ranging from 3 to 8.5%, can be obtained with n-hexane compared to the extraction with petroleum ether. Furthermore, n-hexane is less volatile and flammable, compared to petroleum ether, so it is more convenient to use.