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Determination of phenol in wastewater
No full textOpstanak svijeta i živih bića ovisi o vodi pa nedostatak vodenih resursa dovodi do ozbiljnih problema. Više od 50 % svjetske populacije se suočava s nestašicom vode. Neki od uzroka tome su konstantan rast stanovništva, onečišćenje površinskih i podzemnih voda, neodgovarajuća raspodjela vodenih resursa te povremene suše. Onečišćena voda jednako utječe i na životinjski i biljni svijet. Smrt mnogih vodenih životinja posljedica je ulaska onečišćene vode u more. Budući da naš svijet nije odvojen od svijeta vodenih bića, ptica i biljaka, opasnost od ovih uzastopnih onečišćenja sve je veća i veća. U današnje vrijeme porast emisija industrijskih otpadnih voda predstavlja sve veći problem. Među opasnijim onečišćivalima ističu se fenolni spojevi čije je određivanje ključno za procjenu kvalitete vode i za sigurnost okoliša. Oni predstavljaju značajan rizik za ekosustav i ljudsko zdravlje zbog svojih toksičnih i kancerogenih svojstava. Ovaj rad ima za cilj istaknuti analitičke metode određivanja fenola u otpadnim vodama. Od analitičkih metoda, ističu se spektrofotometrijska metoda, tekućinska kromatografija visoke učinkovitosti (engl. High-Perfomance Liquid Chromatography, HPLC) i masena spektrometrija (engl. Mass Spectrometry, MS). Odabir odgovarajuće metode ovisi o sastavu i količini vode koja se obrađuje, željenoj učinkovitosti postupka, ekološkoj prihvatljivosti te operativnim troškovima.The survival of the world and of living beings depends on water. Therefore, the deficiency of water resources can cause serious problems. More than 50 % of the world's population faces some form of water deficiency. Some of the causes are the constant population growth, the pollution of both surface and ground waters, the inadequate distribution of water resources and the occasional droughts. Moreover, polluted water equally affects the animal and the plant kingdoms and the death of many water animals is a direct consequence of polluted water entering the sea. Given the fact that our world is not separated from the worlds of animals, birds and plants, the danger of these various types of pollution becomes greater every day. Today, the increasing emission of industrial wastewater represents a growing issue. Phenolic compunds can be traced among the most dangerous pollutans and their identification is crucial for the water's quality assessment and for the environment's safeguard. They represent a high risk for the ecosystem and for the human health due to their toxic and carcinogenic properties. This thesis gives an overview of analytical methods for the detection of phenols in wastewater. Among the analytical methods, spectrophotometric method, High Performance Liquid Chromatography and Mass Spectrometry need to be pointed out. The choice of an appropriate method depends on the composition and quantity of water, the desired efficiency of the process, environmental acceptability and operational costs
Determination of amorphous phase content in manganites
No full textKristale karakterizira uređena kristalna struktura, dok amorfne tvari nemaju uređenu strukturu. Razlika između amorfnih i kristalnih tvari je u stupnju prostorne uređenosti, ali i u brojim fizikalnim svojstvima. Amorfna faza utječe na fizikalna svojstva mnogih materijala poput funkcionalne keramike (perovskiti), farmaceutika, građevinskih materijala itd. Kod perovskita, prisutnost amorfne faze utječe na katalitička svojstva. Cilj ovog rada bio je razviti pouzdanu tehniku za kvantificiranje amorfne faze u uzorcima lantanovog (LaMnO3), kalcijevog (CaMnO3) i barijevog (BaMnO3) manganita. Korišteni uzorci manganita pripremljeni su limunskim i koprecipitacijskim postupkom u prethodnim istraživanjima, a u svrhu određivanja udjela amorfne faze u njih je umiješano 10 % Al2O3 (korunda) kao standarda. Snimljeni su difraktogrami pripremljenih uzoraka te je proveden postupak Rietveldove metode utočnjavanja u besplatnom softverskom paketu FullProf. Isti postupak je zatim primijenjen za određivanje porasta udjela amorfne faze u La0,8Sr0,2MnO3 uzorku pripremljenom koprecipitacijskim postupkom i podvrgnutom naknadnom usitnjavanju u planetarnom mlinu. Na temelju dobivenih rezultata utvrđeno je da ovakva tehnika za kvantificiranje udjela amorfne faze pouzdana i jednostavna.Crystals are characterized by an ordered crystalline structure, while amorphous substances do not have an ordered structure. The difference between amorphous and crystalline substances is in the degree of spatial arrangement, but also in numerous physical properties. The amorphous phase affects the physical properties of many materials such as functional ceramics (perovskites), pharmaceuticals, construction materials, etc. In perovskites, the presence of the amorphous phase affects catalytic properties. The aim of this work was to develop a reliable technique for quantifying the amorphous phase content in samples of lanthanum (LaMnO3), calcium (CaMnO3) and barium (BaMnO3) manganites. The used manganites samples were prepared in previous studies, and to determine the amorphous phase content 10 % of Al2O3 (corundum) as standard was mixed with manganites. The diffractograms of prepared samples were recorded and Rietveld refinement was done using the open-source FullProf software. The same procedure was then applied for the determination of amorphous phase content increase in La0.8Sr0.2MnO3 sample prepared by coprecipitation and then ground by ball milling. Based on the obtained results, this technique for quantifying the amorphous phase was found to be reliable and simple
The influence of citric acid on the properties of TPS/PLA blends
No full textU težnji za smanjenjem akumulacije sintetske plastike u okolišu, sve se više istražuju i razvijaju novi materijali koji će, nakon što završe u okolišu, biti potpuno razgradljivi. Stoga su u ovom radu pripremljene biorazgradive mješavine termoplastičnog škroba (TPS) i polilaktida (PLA). TPS/PLA polimerne mješavine različitog sastava pojedine komponente, bez i s dodatkom limunske kiseline (LK) pripremljene su umješavanjem u Brabender miješalici.
TPS je priređen plastifikacijom krumpirovog škroba s udjelom od 40 mas. % glicerola u jednopužnom ekstruderu. Udio limunske kiseline bio je 5 i 10 mas. %. Istražen je utjecaj limunske kiseline na toplinska, mehanička, barijerna svojstva kao i uvid u morfološku strukturu TPS/PLA polimernih mješavina. Struktura polimera i mješavina, te esterifikacija limunskom kiselinom potvrđena je kombiniranom tehnikom infracrvene spektroskopije s Fourierovim transformacijama i prigušene totalne refleksije, FTIR-ATR spektroskopijom.
Uvid u morfološku strukturu istražen je primjenom elektronske pretražne mikorskopije (SEM), toplinska svojstva i stupanj kristalnosti TPS/PLA mješavina primjenom diferencijalne pretražne kalorimetrije (DSC) i toplinska stabilnost termogravimetrijskom analizom (TGA) te kao pokazatelj barijernih svojstava ispitana je apsorpcija vode. Mehanička svojstva mješavina određena su rasteznim ispitivanjem. Na SEM mikrografijama TPS/PLA mješavina vidljiva je slaba adhezija između TPS i PLA, dok dodatkom limunske kiseline dolazi do poboljšanja adhezije što utječe na bolju homogenosti, odnosno međusobnu mješljivost TPS/PLA mješavina. DSC analizom potvrđeno je djelovanje limunske kiseline kao mogućeg kompatibilizatora. Također, veći udio TPS-a u TPS/PLA mješavinama utječe na povećanje stupnja kristalnosti PLA. Dodatkom limunske kiseline od 5 mas. % u TPS/PLA mješavine, vidljivo je poboljšanje mehaničkih svojstava, te smanjenje vrijednosti apsorpcije vode.
Na osnovu svih provedenih ispitivanja, TPS/PLA 50/50 polimerna mješavina s 5 mas.% limunske kiseline izdvojila se kao dobar kandidat za daljnja istraživanja kao obećavajući materijal.In an effort to reduce the accumulation of synthetic plastics in the environment, new materials are increasingly being researched and developed that, once they end up in the environment, will be completely degradable. Therefore, biodegradable mixtures of thermoplastic starch (TPS) and polylactide (PLA) were prepared in this work. TPS/PLA polymer mixtures with different compositions of individual components, without and with the addition of citric acid (LK) were prepared by mixing in a Brabender mixer. TPS was prepared by plasticizing potato starch with a proportion of 40 wt. % of glycerol in a single-screw extruder. The proportion of citric acid was 5 and 10 wt. %. The influence of citric acid on thermal, mechanical, and barrier properties was investigated, as well as an insight into the morphological structure of TPS/PLA polymer mixtures. The structure of polymers and mixtures, as well as esterification with citric acid, was confirmed by the combined technique of infrared spectroscopy with Fourier transforms and attenuated total reflection, FTIR-ATR spectroscopy. Insight into the morphological structure was investigated using scanning electron microscopy (SEM), thermal properties and degree of crystallinity of the TPS/PLA mixture using differential scanning calorimetry (DSC) and thermal stability using thermogravimetric analysis (TGA), and water absorption was tested as an indicator of barrier properties. The mechanical properties of the mixtures were determined by tensile testing. On the SEM micrographs of the TPS/PLA mixture, weak adhesion between TPS and PLA is visible, while the addition of citric acid improves the adhesion, which affects the better homogeneity, that is, the mutual miscibility of the TPS/PLA mixture. DSC analysis confirmed the action of citric acid as well as a possible compatibilizer. Also, the greater part of TPS in TPS/PLA blends affects the increase in the degree of crystallinity of PLA. With the addition of citric acid of 5 wt. % in the TPS/PLA blends, an improvement in mechanical properties and a decrease in the water absorption value are visible. Based on all the conducted tests, the TPS/PLA 50/50 polymer blend with
5 wt.% citric acid stood out as a good candidate for further research as a promising material
Effect of water matrix on removal of pesticides by UF/NF/RO membranes
No full textUklanjanje pesticida iz vode postalo je jedno od prioritetnih istraživanja u posljednjih nekoliko godina zbog sve većeg utjecaja pesticida na okoliš i zdravlje. U ovom radu ispitivano je uklanjanje tri pesticida (klotianidin, acetamiprid i tiakloprid) membranskim separacijskim procesima. Ovi pesticidi pripadaju skupini neonikotinoida i poznati su po svojoj dugotrajnoj prisutnosti u biljkama. Klotianidin i tiakloprid vrlo su otrovni stoga je Europska unija zabranila njihovu upotrebu. Tlačni membranski separacijski procesi ultrafiltracije, nanofiltracije (NF) i reverzne osmoze (RO) korišteni su za uklanjanje navedenih pesticida u demineraliziranoj i vodovodnoj vodi te u modelnoj otopini pri konstantnom tlaku od 10 bar. Razlikuju se u veličini pora što rezultira različitim zadržavanjem pesticida na membrani. Ultrafiltracijske membrane nisu uklonile pesticide iz svih matica vode, dok su NF i RO membrane imale visoke faktore zadržavanja > 80 %, odnosno > 90 %. Rezultati su pokazali da je mehanizam isključenja veličinom dominantan mehanizam. Pesticidi su hidrofilni te nije došlo do interakcija između između korištenih membrana i pesticida što je potvrđeno infracrvenom spektroskopijom s Fourier-ovom transformacijom.The removal of pesticides from water has become one of the research priorities in recent years due to the increasing impact of pesticides on the environment and health. In this work, the removal of three pesticides (clothianidin, acetamiprid, and thiacloprid) was studied using pressure membrane separation processes. These pesticides belong to the neonicotinoid group and are known for their long-term presence in plants. Clothianidin and thiacloprid are very toxic, which is why the European Union has banned their use. The pressure membrane separation processes ultrafiltration, nanofiltration (NF) and reverse osmosis (RO) were used to remove the above pesticides in demineralized and tap water and in a model solution at a constant pressure of 10 bar. They differ in their pore size, resulting in different retention of pesticides on the membrane. Ultrafiltration membranes did not remove pesticides from water matrices, while NF and RO membranes had high retention factors > 80% and > 90%, respectively. The results showed that the size exclusion mechanism is the dominant mechanism. The pesticides are hydrophilic, and there were no interactions between the membranes used and the pesticides, which was confirmed by Fourier transform infrared spectroscopy
Remediation of groundwater contaminated with heavy metals
No full textU ovom radu istražuju se problemi vezani uz onečišćenje podzemnih voda teškim metalima. Teški metali su toksični, biološki nerazgradivi i postojani, što predstavlja ozbiljan rizik za vodene ekosustave i ljudsko zdravlje. U svrhu uklanjanja teških metala iz voda razvijene su je brojne fizikalno kemijske metode temeljene na različitim principima. U ovom radu dan je pregled remedijacijskih tehnika za uklanjanje teških metala, koje uključuju kemijsku precipitaciju, koagulaciju, flotaciju, adsorpciju, ionsku izmjenu, membranske postupke te elektrokemijske, biološke i fotokatalitičke metode. Odabir odgovarajuće metode ovisi o nekoliko čimbenika kao što su sastav i količinu vode koja se obrađuje, željena učinkovitost postupka, kapitalni i operativni troškovi te ekološka prihvatljivost.This paper researches the problems related to the contamination of groundwater with heavy metals. Heavy metals are toxic, non-biodegradable and persistent, which poses a serious risk to aquatic ecosystems and human health. In order to remove heavy metals from water, numerous physical and chemical methods based on different principles have been developed. This paper provides an overview of remediation techniques for the removal of heavy metals, which include chemical precipitation, coagulation, flotation, adsorption, ion exchange, membrane processes and electrochemical, biological and photocatalytic methods. The selection of the appropriate method depends on several factors such as the composition and quantity of water to be treated, the desired efficiency of the process, capital and operating costs and environmental acceptability
Measuring techniques and monitoring of the malting, fermentation and beer aging processes
No full textU ovome radu izložena je kratka pozadina, objašnjenje tehnika mjerenja parametara, opis proizvodnje sladovine i njenog fermentiranja, te konačno odležavanja. Svaki od tih segmenata uključuje interdisciplinarne pristupe kako bi sam proces postao definiraniji i dao nam veću kontrolu nad svim navedenim faktorima izrade. Poznavanje sirovina je od ultimativne važnosti, kako bi nadolazeći tehnološki procesi bili što lakše i efikasnije izvedeni. Pri izradi sladovine, razumijevanje biokemijskih procesa iza slađenja i njenog ukomljavanja je druga najbitnija stavka, gdje proizvod dobije svoju glavnu odliku kvalitete. Bez sladovine koja zadovoljava kriterije dobrog omjera fermentabilnog i nefermentabilnog udjela šećera, te udjela proteina, nema ni krajnje kvalitete produkta. U procesu fermentiranja ključno je paziti na parametre koje odgovaraju optimalnim uvjetima rada kvasca, kako bi maksimalno smanjili razvijanja nepoželjnih nusprodukata izazvanih stresom stanice. Takve reakcije uglavnom uključuju dovoljan prinos nutrijenata, pogodnu temperaturu i pH+ smjese, adekvatnu aeriranost sladovine, te dobar genotip i fenotip vrste kvasca stabilnog metabolizma koji neće biti sklon mutacijama. Odležavanje je proces koji danas uključuje nešto drugačiju definiciju od one povijesne. Nekad je odležavanje bilo isključivo temeljeno na gravitacijskom sedimentiranju iz sladovine flokuliranih stanica, tvrdih smola i ostataka proteina iz stabiliziranog koloida, te njenom odstajanju nad sedimentom, čime bi se kemijski sastav promjenio reakcijama razlaganja tanina i oslobađanjem estera iz mase kvasca. Danas se služimo centrifugalnim sedimentacijama i mikro-filtracijama kako bi nastali produkt što brže zadovoljio kriterije proizvoda.This paper presents a brief background, explanation of parameter measurement techniques, description of malt production and fermentation, and finally aging. Each of these segments includes interdisciplinary approaches in order to make the process itself more defined and to give us greater control over all the mentioned manufacturing factors. Knowledge of raw materials is of ultimate importance, so that the upcoming technological processes are carried out as easily and efficiently as possible. When making wort, understanding the biochemical processes behind malting and its maturation is the second most important item, where the product gets its main quality feature. Without malt that meets the criteria of a good ratio of fermentable and non-fermentable sugar content, and protein content, there is no ultimate product quality. In the fermentation process, it is crucial to pay attention to the parameters that correspond to the optimal working conditions of the yeast, in order to maximally reduce the development of undesirable by-products caused by cell stress. Such reactions mainly include a sufficient yield of nutrients, a suitable temperature and pH+ of the mixture, adequate aeration of the malt, and a good genotype and phenotype of a type of yeast with a stable metabolism that will not be prone to mutations. Aging is a process that today includes a slightly different definition than the historical one. In the past, aging was exclusively based on gravitational sedimentation from the wort of flocculated cells, hard resins and protein residues from the stabilized colloid, and its settling over the sediment, which would change the chemical composition through tannin decomposition reactions and the release of esters from the yeast mass. Today, we use centrifugal sedimentation and micro-filtration in order for the resulting product to meet the product criteria as quickly as possible
Synthesis, spectroscopic characterization and computational modeling of new di-heterostilbenes
No full textSintetizirani su novi tienobenzo-triazoli: 7-metil-1-(tiofen-2-ilmetil)-1H-tieno[3',2':3,4]benzo[1,2-d][1,2,3]triazol; 1-(4-fluorbenzil)-7-metil-1H-tieno[3',2':3,4]-benzo[1,2-d][1,2,3]triazol; 1-(4-metoksibenzil)-7-metil-1H-tieno[3',2':3,4]benzo[1,2-d]-
[1,2,3]triazol i 1-(furan-2-ilmetil)-7-metil-1H-tieno[3',2':3,4]benzo[1,2-d][1,2,3]triazol. Oni i njihovi prekursori, triazolostilbeni su spektroskopski proučavani, a njihove strukture dokazane su 1H i 13C NMR spektrima. Čisti izomeri jednog od triazolostilbena podvrgnuti su osvjetljavanju pri 313 nm u vremenskim intervalima, tijekom kojih se prate promjene UV spektara. Jednom od spojeva računalno je određena struktura i granične orbitale.New thienobenzo-triazoles were synthesized: 7-methyl-1-(thiophen-2-ylmethyl)-1H-
thieno[3',2':3,4]benzo[1,2-d][1,2,3]triazole; 1-(4-fluorobenzyl)-7-methyl-1H-thieno[3',2':3,4]-
benzo[1,2-d][1,2,3]triazole; 1-(4-methoxybenzyl)-7-methyl-1H-thieno[3',2':3,4]benzo[1,2- d][1,2,3]triazole and 1-(furan-2-ylmethyl)-7-methyl-1H-thieno[3',2':3,4]benzo[1,2- d][1,2,3]triazole. They and their precursors, triazolostilbenes were studied spectroscopically and their structures were proved by 1H and 13C NMR spectra. Pure isomers of one triazolostilbene are subjected to illumination at 313 nm in time intervals, during which changes in UV spectra are monitored. For one of the compounds, the structure and frontier orbitals were calculated by computational study
Biological processes for biohydrogen production
No full textBiovodik (bioH2) je vodik proizveden održivim i ekološki prihvatljivim biološkim procesima koji uključuju mikroorganizme poput bakterija i algi. Jedan od najpoznatijih bioloških procesa za proizvodnju bioH2 je fermentacija. Tijekom fermentacije bakterije razgrađuju organsku tvar (šećer ili celuloza) u anaerobnim uvjetima proizvodeći pri tome bioH2 kao metabolički nusprodukt. Sama proizvodnja bioH2 privukla je pažnju kao potencijalni obnovljivi izvor energije jer se bioH2 može proizvesti iz organskih materijala poput poljoprivrednog otpada, otpadnih voda ili biomase. Obzirom na način proizvodnje, bioH2 se smatra čistim i održivim izvorom energije što ga čini konkurentnim tradicionalnim izvorima energije. BioH2, uz to što se može koristiti kao gorivo, je i vrijedna sirovina u proizvodnje električne energije, pročišćavanju vode te proizvodnji amonijaka i gnojiva, sinteze metanola i polimera, rafiniranju nafte (hidrokreking i hidroobrada), proizvodnji farmaceutika itd. U okviru ovog završnog rada napravljen je literaturni pregled bioloških procesa proizvodnje bioH2 kao obnovljivog i alternativnog izvora energije.Biohydrogen (BioH2) is hydrogen produced by sustainable and environmentally friendly biological processes involving microorganisms such as bacteria and algae. One of the best-known biological processes for BioH2 production is fermentation. During fermentation, bacteria break down organic material (such as sugar or cellulose) under anaerobic conditions, producing BioH2 as a metabolic byproduct. The production of BioH2 has attracted attention as a potential renewable energy source because it can be produced from organic material such as agricultural waste, wastewater, or biomass. Because of the production method, BioH2 is considered a clean and sustainable energy source that can compete with conventional energy sources. In addition to its use as a fuel, BioH2 is
a valuable resource for electric power generation, water treatment, ammonia and fertilizers production, methanol and polymer synthesis, petroleum refining (hydrocracking and hydrotreating), pharmaceutical production, and more. This final thesis includes a literature review of biological processes for the BioH2 production as a renewable and alternative energy source
Hydrolytic degradation of poly(lactic acid)
No full textsve atraktivniji u području tkivnog inženjerstva radi izvrsnih svojstava. PLA je polimer koji se dobiva iz obnovljivih izvora, poput kukuruza ili šećerne trske, što ga čini ekološki prihvatljivim u usporedbi s konvencionalnim polimerima dobivenima iz fosilnih goriva. PLA se sve češće koristi u medicinskim područjima, gdje služi kao materijal za razvoj nosača, implantata i drugih materijala koji potiču regeneraciju tkiva. Svojstva PLA moguće je jednostavno prilagoditi. Dodavanjem različitih komponenata u PLA matricu mogu se prilagoditi mehanička svojstva, brzina razgradnje te interakcija s tkivom. Najčešći izazovi u korištenju PLA kompozita jesu kontrolirana razgradnja te biološki odgovor stanica domaćina. Cilj ovog rada bio je pratiti hidrolitičku razgradnju kompozita poli(mliječne kiseline), hidroksiapatita (HAp) te kitozana u mediju koji simulira fiziološki sastav u vremenskom periodu od dva, četiri, šest odnosno osam tjedana. Istražen je utjecaj hidrolitičke razgradnje na strukturu i svojstva pripremljenih kompozita. Karakterizacija uzoraka prije i nakon razgradnje provedena je infracrvenom spektroskopijom s Fourierovim transformacijama (engl. Fourier Transform Infrared Spectroscopy, FTIR), mehaničkim testom na tlačnu čvrstoću te je isto tako snimljena morfologija uzoraka pretražnim elektronskim mikroskopom (engl. Scanning electron microscopy, SEM). Dobiveni rezultati ukazuju na zadržavanje svojstava pripremljenih kompozita tijekom cijelog perioda razgradnje. Radi navedenog, može se zaključiti kako su pripremljeni kompoziti pogodni za dugotrajno liječenje koštanih defekata.Poly(lactic acid) or PLA is a biodegradable and bioactive polymer that is becoming increasingly attractive in the field of tissue engineering due to its excellent properties. PLA is a polymer derived from renewable sources such as corn or sugarcane, making it environmentally friendly compared to conventional polymers obtained from fossil fuels. PLA is increasingly used in medical fields, where it serves as a material for the development of scaffolds, implants, and other materials that promote tissue regeneration. The properties of PLA can be easily tailored. By adding different components to the PLA matrix, mechanical properties, degradation rate, and tissue interaction can be adjusted. The most common challenges in using PLA composites are controlled degradation and the biological response of host cells. The aim of this study was to monitor the hydrolytic degradation of the composite of poly(lactic acid), hydroxyapatite (HAp), and chitosan in a medium simulating physiological composition over a period of two, four, six, and eight weeks. The influence of hydrolytic degradation on the structure and properties of the prepared composites was investigated. Characterization of samples before and after degradation was conducted using Fourier Transform Infrared Spectroscopy (FTIR), compressive strength mechanical testing, and scanning electron microscopy (SEM). The results obtained indicate the retention of the properties of the prepared composites throughout the entire degradation period. Therefore, it can be concluded that the prepared composites are suitable for the longterm treatment of bone defects
Development and application of a soft sensor at a propylene production plant
No full textU ovome radu prikazan je razvoj modela softverskih senzora za kontinuirano praćenje sadržaja propilena u rafinerijskom postrojenju propan/propilen splitter. Dobiveni podaci ulaznih varijabli usklađeni su vremenski sa izlaznom varijablom te su obrađeni različitim metodama predobrade. U programskom jeziku Python izrađeni su modeli softverskih senzora primjenom neuronskih mreža s višeslojnim perceptonom (engl. Multi-layer percepton, MLP) i neuronskih mreža s dugotrajnim kratkoročnim pamćenjem (engl. long short-term memory, LSTM). Pri razvoju MLP modela analizirani su hiperparametri modela kao što su: broj neurona u skrivenom sloju i utjecaj vrste prijenosne funkcije (sigmoid, tanh, ReLU i ELU) na kvalitetu razvijenih neuronskih mreža. Pri razvoju LSTM modela se dodatno ispitivao i broj vremenskih koraka u prošlost te broj LSTM jedinica. Oba modela dala su visoke i slične vrijednosti koeficijenata korelacije te niske pogreške između modeliranog sadržaja propilena i realnih podataka sa postrojenja te se mogu primijeniti u rafinerijskom informacijskom sustavu. Analiza trenda i histograma pogreške razvijenih modela dodatno ukazuje na zadovoljavajuću kvalitetu razvijenih modela. Primjenom softverskih senzora smanjuje se potreba za korištenjem skupe mjerne analitičke opreme i opreme koja se često kvari, te je u konačnici moguće potpuno zamijeniti postojeće analizatore u procesu. Primjenom softverskih senzora na postrojenju unaprijedit će se automatsko vođenje procesa što će utjecati na stabilnije odvijanje procesa i veću kvalitetu konačnog proizvoda.This paper presents the development of soft sensor models for continuous monitoring of propylene content in rafinery propane/propylene splitter. The goal of this paper is to develop soft sensor models based on given experimental data about refinery process of propane and propylene separation, validate and compare developed models. The development of models began with the preprocessing of the collected measurement data. Soft sensor models were created in the Python programming language using the methods of multilayer percepton networks and long short-term memory networks. During development of multilayer percepton networks model it was tested how hyperparameters such as number of neurons in hidden layers and activation function (sigmoid, tanh, ReLU i ELU) affect on quality of the developed neural networks. During the development of LSTM models, additional testing of the number of time steps into the past and the number of LSTM units on model quality were examined. A statistical analysis of the results was carried out, which shows that both types of models give high correlation values of model data with real propylene content data, so both types of models can be applied in the refinery information system. Error trend analysis and error histogram of the developed models additionally indicate the satisfactory quality of the developed models. By applying the developed soft sensors it is possible to decrease the need for high cost measurement equipment and equipment that breaks down frequently, and ultimately completely replace the existing analyzers in the process and improve the automatic management of the process. Application of software sensors will improve automatic process control, which will result in more stable process management at the plant and higher quality of the final product