16 research outputs found
Superkritična ekstrakcija kao metoda za uklanjanje pesticida iz zemljišta
The aim of this paper is to study the applicability of supercritical extraction with carbon dioxide to the decontamination of soils containing pesticides (in this case with atrazine). The analyzed results indicate that this method can be successfully used for the realization of prominent purpose.Cilj ovog rada je ukazivanje na mogućnost primene superkritične ekstrakcije sa ugljendioksidom na dekontaminaciju zemljišta zagađenih pesticidima (u ovom slučaju atrazinom). Analizirani rezultati ukazuju da se ova metoda veoma uspešno može koristiti za ostvarivanje istaknutog cilja
Proces rafinisanja biomase sa superkritičnom vodom
Biobased industries, based on renewable sources and energy are still in development to supporting a decentralized production that can be alternative to the well – supported centralized petrochemical production plants. In recent time conversion of different organic supstances, including wastes, sludge, biomass to biofuels and biobased chemicals has attracted a lot of researcher attention. Supercritical water is emerging as a solvent and reaction medium capable of providing selective processes while significantly reducing the reaction time, leading to the possibility of developing compactequipment for the use in biomass decentralized production plants. Hydrothermal processes that use sub or supercritical water as processing media are consider as promising technologies for the conversion of organic substances into biofuls and biobased chemicals. In this paper a short review of the hydrothermal processes and potentials of their use for the conversion of organic wastes and biomass into fuels and chemicals is given.Bioindustrija zasnovana na obnovljivim sirovinama i energiji je u stalnom razvoju i doprinosi decentralizaciji proizvodnje. Ona predstavlja alternativu dosadašnjim centralizovanim petrohemijskim postrojenjima. U novije vreme konverzija različitih organskih supstanci uključujući otpad, mulj i biomasu u biogoriva i biohemikalije privlači sve veću pažnju istraživača. Superkritična voda se sve više u procesima koristi kao rastvarač i reakcioni medijum čime se omogućava selektivnost procesa i značajno skraćuje vremena trajanja reakcije. Skraćenjem vremena reakcije omogućava se lakši izbor procesne opreme u decentralizovanim postojenjima za preradu biomase. Hidrotermalni procesi koji koriste subkritičnu i superkritičnu vodu kao procesni medijum se sve više posmatraju kao obećavajuća tehnologija za konverziju organskih supstanci u biogoriva i biohemikalije. U ovom radu daje se kratak pregled hidrotermalnih procesa i mogućnosti njihovog korišćenja za konverziju organskog otpada i biomase u gorivo i hemikalije
Bioetanol kao alternativno gorivo
Great demographic expansion of the population as well as steady increase in
industrial production led to a substantial decline in natural resources, of energy, and
thus contributed to the dramatic environmental pollution. Benzin obtained from crude
oil by burning gives hazardous products such as carbon monoxide, sulfur dioxide,
oxides of nitrogen and lead compounds. Addition of ethanol to gasoline reduces the
pollution of the atmosphere and increases the octane number of gasoline. The greatest
significance of the application of ethanol in terms of reducing atmospheric pollution is
the reduction in emissions of carbon monoxide, which belongs to gases that
significantly contribute to the greenhouse effect.Velika demografska ekspanzija stanovništva kao i stalni porast industrijske
proizvodnje doveli su do osetnog smanjenja prirodnih resursa energije, a time doprineli
i dramatičnom zagađenju životne okoline. Benzin dobijen iz nafte, sagorevanjem daje
štetne produkte kao što su ugljenmonoksid, sumpordioksid, oksidi azota i olovna
jedinjenja. Dodatkom etanola benzinu smanjuje se zagađenje atmosfere i povećava se
oktanski broj benzina. Najveći značaj primene etanola sa aspekta smanjenja zagađenja
atmosfere je smanjenje emisije ugljenmonoksida koji pripada gasovima koji značajno
doprinose efektu staklene bašte
Smanjenje potrošnje energije korišćenjem metode visokog pritiska
Using high pressure as a processing tool surpasses legal limitations for solvent
residues and restrictions on use of conventional solvents in chemical processes.
Additionally, new, high valuable products with special properties can be produced. The
presentation will give a limited overview of applications of sub-and supercritical fluids
and will present energy savings compared to conventional production methods. The
main advantages of these tools are low environmental impact, low energy consumption
and sustainability. For these processes recent advances and trends of developments will
be presented.Korišćenjem visokog pritiska prilikom izvođenja nekog procesa prevazilaze
se zakonske barijere u pogledu količine zaostalih organskih rastvarača i određena
ograničenja u vezi njihove primene. Ovom metodom mogu se dobiti novi visokovredni
proizvodi sa posebnim karakteristikama. Dat je pregled subkritičnih i superkritičnih
fluida i prikazana je ušteda energije u poređenju sa primenom konvencionalnih metoda.
Glavne prednosti ovog postupka su mali uticaj na okruženje, niska potrošnja energije i
ekonomska održivost. Prikazi postignutih poboljšanja kao i pravci daljeg razvoja ove
metode, takođe su dati u radu
Influence pressure and size particle to extraction by CO2
Supercritical fluid extraction (SFE) is an efficient extraction technique for the separation of various organic compounds from herbs, or more generally, from plant materials. These proporties of SFE make the products more advantageous in the field of foods, pharmaceuticals, and cosmetics. The aim of this study was to investigate the effect of pressure and particle size on the extraction yield and the quality of the extracts
Proučavanje mogućnosti mikrotalasne polimerizacije monomera na osnovu obnovljivih sirovina
Polylactide belongs to the biodegradable and biocompatible polymers, and degrade
to harmless component, lactic acid, which allows their use in various areas. The
development of new methods for the synthesis of polylactide can further extend the
application of this polymer and makes its use more economical. The use of microwaves
in the synthesis of the polymer can reduce the polymerization time of only 10 to 30
minutes and save a large amount of energy. In this paper, polylactide is synthesized in a
microwave reactor, using a frequency of 2,45 GHz and a power of 150 W. FITR
analysis confirmed the structure of the resulting polylactide and the thermal properties
were studied using differential scanning calorimetry.Polilaktid spada u grupu biorazgradivih i biokompatibilnih polimera i može se
razložiti na neškodljivu komponentu, mlečnu kiselinu, što omogućava njegovu primenu u
najrazličitijim oblastima. Razvoj novih metoda sinteze polilaktida može proširiti područje
primene ovog polimera i učiniti njegovu upotrebu ekonomičnijom. Upotreba mikrotalasa
u sintezi polimera može skratiti vreme polimerizacije na svega 10 do 30 minuta štedeći
veliku količinu energiju. U ovom radu polilaktid je sintetisan u mikrotalasnom reaktoru,
koristeći frekvenciju od 2.45 GHz i snagu od 150 W. FTIC analiza je potvrdila strukturu
dobijenog polilaktida, a toplotna svojstva su proučavana metodom diferencijalne
skenirajuće kalorimetrije.Vrednost temperatura prelaska u staklasto stanje i temperatura
kristalizacije dobijenog polimera zavise od molskog odnosa monomera (L-laktida) i
katalizatora (kalaj-oktoata)
Metode uklanjanja fenola iz otpadne vode
Phenol is a major pollutant in the wastewater because of its presence in the effluent of major processing and refining plants. It has severe effect on human being, both short term and long term. Various methods are used for removal of the phenol from wastewater such as adsorption, photodecomposition, volatilization and other various biological and non-biological methods. In the present study attempt is done to present the survey of the research on the phenol removal by various methods. The methods such as polymerization, electrocoagulation, extraction, photodecomposition, advanced oxidation and ion exchange were used effectively by various investigators. These methods are reported to be efficient for the phenol removal. Suitable method for phenol removal can be selected based on availability of the material, extent of separation required and properties of phenolic effluent.Fenol je jedan od glavnih polutanata u otpadnoj industrijskoj vodi. Utiče na zdravlje ljidi i taj uticaj se ispoljava kako posle kraćeg tako i posle dužeg prisustva. Za uklanjanje fenola iz otpadne vode koriste se metode kao što su adsorpcija, fotorazgradnja, isparavanje (volatilizacija) kao i biološke i nebiološke metode. U ovom radu daje se prikaz istraživanja o uklanjanju fenola različitim metodama kao što su polimerizacija, elektrokoagulacija, fotorazgradnja, unapređena oksidacija i jonska izmena. Izbor metode za uklanjanje fenola može biti učinjen na osnovu raspoloživog materijala, zahtevanog intenziteta prečišćavanja i osobina fenolnog efluenta
Ricinusovo ulje kao obnovljiva sirovina za dobijanje poliuretanskih materijala
Traditionally, polyurethanes (PU) are manufactured by reacting isocyanates with petroleum-based polyols (polyether or polyester). Because oil resources are diminishing and are becoming expensive to produce, engineers and scientist have discovered new technologies to fabricate plastics from renewable resources. The goal of this work was to determine mechanical properties of polyurethanes synthesized from castor oil and different isocyantes: isophorone diisocyanate IPDI, 1,6-diisocyanatohexane (HDI) and aliphatic polycyclotrimer (HDIt). The samples were prepared by a one-step reactive process with stoichiometric balance of reactive groups. The catalysed synthesis was performed at normal pressure. It was estimated that a mechanical properties of prepared samples were strongly influenced by the isocyanate type.Tradicionalno se poliuretani (PU) dobijaju reagovanjem izocijanata sa poliolima (polietarski i poliestarski) koji se uobičajeno dobijaju iz nafte. Pošto se ti resursi smanjuju i postaju sve skuplji inženjeri i naučnici su razvili nove tehnologije za proizvodnju plastike iz obnovljivih sirovina. Cilj ovog rada je bio da se odrede mehanička svojstva poluretanskih materijala dobijenih jednostepenim reaktivnim procesom od ricinusovog ulja i različitih izocijanata: izoforon diizocijanata (IPDI), 1,6-diisocianatoheksana (HDI) i alifatičnog poliizocijanata ciklotrimera (HDIt) sa stehiometrijskim balansom reaktivnih grupa. Katalitička sinteza se odvijala na normalnom pritisku. Ustanovljeno je da su mehanička svojstva dobijenih materijala bila uslovljena tipom izocijanata
Strukturiranje ekološki prihvatljivih elastomernih kompozitnih materijala
For the waste rubber recycling, it is obligative to know the chemical composition of the waste products, if it is to be used in the new composite elastomeric material formulation. The composite elastomeric materials obtained from the waste rubber powder have a very diverse application (farm floors, sports stadiums, tyres production, in construction as a vibration protection material). The aim of this work was to prepare elastomeric composites based on recycled elastomer powder (REP). A few types of elastomeric materials were synthesized based on natural rubber, polybutadiene rubber, styrene-butadiene rubber, (NR/BR/SBR, 40/40/20 phr), carbon black and recycled elastomer powder were synthesized. It was assessed that composites NR/BR/SBR/REP have shorter optimum curing time tc90 than samples without REP. By increasing the REP content the tc90 value and tensile strength are decreasing, but the abrasion resistance is increasing.Kod recikliranja otpadne gume neophodno je poznavati hemijski sastav otpadnog proizvoda, ukoliko će se on koristiti u recepturama za nove hibridne elastomerne materijale. Kompozitni elastomerni materijali dobijeni od praha otpadne gume imaju veoma raznovrsnu primenu (podovi na farmama, sportski stadioni, dobijanje pneumatika, u građevinarstvu kao materijali za zaštitu od vibracija itd). Cilj ovog rada je bio da se dobiju elastomerni kompoziti na osnovu reciklirane gume. Sintetisano je nekoliko tipova elastomernih materijala na osnovu prirodnog kaučuka, stiren-butadienskog kaučuka i polibutadienskog kaučuka (NR/BR/SBR, 40/40/20 phr), čestica čađi i recikliranog gumenog praha. Ustanovljeno je da kompoziti NR/BR/SBR/REP imaju kraće optimalno vreme umrežavanja u poređenju sa uzorcima NR/BR/SBR bez REP. Porastom količine REP smanjuje se vreme optimalnog umrežavanja i prekidna črstoća, a povećava se otpornost na abraziju