Heterogeneous catalytic transesterification of waste vegetable oil using modified natural zeolite

Objectives: In the search of an economical process for biodiesel synthesis, waste cooking oil was analyzed as a potential feedstock. The influence of different concentrations and granulations of the zeolite catalyst on the yield and quality of the final product was also investigated. Methods: The pretreatment of waste oil was carried out using the simple processes of filtration and drying with CaCl2, after which its physicochemical properties were determined. Transesterification of waste oil with methanol was carried out using zeolite clinoptilolite as the catalyst. Its preparation included modification with sodium hydroxide, drying at 105°C and calcination at 300°C. As for the waste oil, the density, acid and peroxide number, moisture content, kinematic viscosity and flash point of the obtained biodiesels were determined by standardized methods. After the synthesis, the Fourier transformation infrared (FT-IR) spectra of the obtained biodiesel and waste cooking oil were recorded and compared. Results: The process of transesterification with methanol was found to be suitable due to the high conversion of waste oil esters under relatively mild reaction conditions. Moreover, modified natural clinoptilolite proved to be a suitable catalyst for the process of biodiesel production. At each catalyst concentration and granulation, the biodiesel yield was satisfactory and its quality parameters met the prescribed standards. Conclusion: The basic characteristics of the biodiesel obtained from waste cooking oil enable its potential application. Moreover, the properties of clinoptilolite, such as concentration and particle size, can be adjusted for each transesterification process to attain high quality product. The performed experiment presents an example of the efficient linking of biofuel production and waste oil disposal processes

Suspension grade poly(vinyl chloride) and hazards of its production

Poli(vinil-klorid) (PVC) najstariji je i više od 70 godina jedan od najvažnijih polimera, na kojeg otpada oko 20 % ukupne svjetske proizvodnje polimera. Usprkos svim tehničkim i gospodarskim problemima vezanim za proizvodnju PVC-a, prigovorima zaštitara okoliša i prirode o rizičnosti proizvodnje i uporabe PVC-a te općenito opasnosti klorne kemije za okoliš, procjenjuje se kako će godišnja potrošnja PVC-a u svijetu do 2010. rasti po stopi od 4,5 %.1 PVC se proizvodi polimerizacijom vinil-klorida (VC) slobodno-radikalskim procesima u suspenziji, emulziji ili u masi. Na svjetskoj razini, 80 % PVC-a proizvodi se suspenzijskom polimerizacijom, 12 % emulzijskom, a 8 % polimerizacijom u masi. U suspenzijskom postupku monomer, ukapljeni vinil-klorid, mehanički se dispergira u vodi i polimerizira s pomoću u monomeru topljiva inicijatora, uz dodatak zaštitnog koloida. Proces je diskontinuiran, a provodi se u zatvorenom sustavu. S ekološkoga gledišta, suvremena suspenzijska polimerizacija opterećena je relativno malim brojem problema, od kojih je najveći kancerogenost monomera, vinil-klorida, objavljena 1973. Ubrzo, alarmiranjem svjetske javnosti te angažiranjem tehnologa, liječnika i znanstvenika pronađena su rješenja kojima je uklonjena opasnost od emisije monomera tijekom tehnološkog procesa, izloženost radnika kancerogenom VC-u te opasnost od visoke koncentracije ostatnog monomera u polimerizatu. Definirane su maksimalne dopuštene koncentracije VC-a. Suvremeni postupak proizvodnje, uz otplinjavanje i rekuperaciju neizreagiranog vinil-klorida, demonomerizaciju polimerne suspenzije i obradu otpadnih voda te dobru kontrolu proizvodnog procesa, omogućuje siguran rad postrojenja i uporabu PVC-a u prehrambenoj i farmaceutskoj industriji te za medicinske potrebe.Poly(vinyl chloride) (PVC) has, for more than 70 years been one of the most important polymers, with a worldwide capacity of about 20 % of the total plastic production. Despite all technical and economic problems on the production of PVC and public debates about the ecology and environmental hazards of PVC production and use, and chlorine chemistry, in general, PVC production worldwide grows at the rate of more than 9 % per year.1 PVC is obtained by free-radical polymerizations of vinyl chloride (VC) in suspension, emulsion or in bulk. Worldwide, 80 % of total PVC production is obtained by suspension polymerization, 20 % by emulsion polymerization and 8 % by bulk polymerization. In suspension polymerization the monomer, liquid VC, is mechanically dispersed in water and polymerized by monomer-soluble initiator in the presence of protective colloid. The process is carried out in a batch reactor, in a closed system. From the environmental viewpoint, modern suspension polymerization is strained with a relatively small number of problems. Among them, the most important is monomer cancerogenity, as published in 1973. Very soon, the technologists, physicians and scientists were engaged and new technological solutions were found, which eliminated monomer emission during the technological process, exposure of workers to VC, as well as the danger of high residual monomer concentration in the polymer. The maximum allowed concentrations of VC were also defined. Modern technology, using degassing and recovery of excess vinyl chloride, demonomerization of polymer suspension, waste water treatment and good process control, enable safe plant operation and use of PVC in food and pharmaceutical industry and medicine

Modification of properties of poly(L-lactide)

Modifikacija svojstava biorazgradljivog poli(L-laktida) (PLLA)provedena je dodatkom biorazgradljivih mljevenih koštica masline(MKM) i biorazgradljivih citratnih omekšavala, tributil-citrata (TBC) i tributil-acetil-citrata (TBAC). Mješavine i kompoziti pripremljeni su različitim postupcima preradbe te su analizirana njihova svojstva. Rezultati diferencijalne pretražne kalorimetrije (DSC) pokazuju da postupak preradbe materijala uvelike utječe na toplinska svojstva istraživanih uzoraka i da nema razlike u djelovanju odabranih omekšavala, pa je istraživački rad nastavljen s tributil-acetil-citratom. Dodatak punila MKM neznatno utječe na toplinska svojstva PLLA, dok najveći utjecaj ima na kristalizaciju PLLA. Omekšavalo snižava vrijednosti temperatura toplinskih prijelaza i povećava kristalnost PLLA. Neizotermna termogravimetrijska analiza (TGA) pokazala je da dodatak punila MKM pogoršava, a dodatak omekšavala TBAC poboljšava toplinsku postojanost PLLA. Istraživanje morfologije uzoraka pretražnim elektronskim mikroskopom (SEM) potvrdilo je slabe interakcije PLLA i punila MKM, na koje dodatak TBAC nema utjecaja. Spektri pripremljenih uzoraka dobiveni Fourierovom pretvornom infracrvenom spektrometrijom (FT-IR) pokazuju da samo kod omekšanih kompozita nastaju vodikove veze između komponenata. Punilo MKM smanjuje rastezljivost i čvrstoću PLLA, dok TBAC povećava rastezljivost i znatno smanjuje čvrstoću PLLA. Starenje uzoraka utječe na toplinska svojstva istraživanih mješavina i kompozita, u prvom redu na proces kristalizacije i taljenja kristala PLLA. Biorazgradnja u tlu pripravljenih PLLA uzoraka znatno se ma mnogo manji utjecaj. Migracija omekšavala pod utjecajem topline povećava se s vremenom izlaganja zadanoj temperaturi. Punilo MKM pospješuje migraciju TBAC-a iz istraživanih kompozita. Migracija omekšavala pod utjecajem simulanata hrane povećava se s vremenom izloženosti simulantima hrane i uzrokuje promjene toplinskih svojstava istraživanih uzoraka.Properties of poly(L-lactide) (PLLA) were modifi ed using olive stone flour (OSF) and citrate plasticizers such as tributyl citrate (TBC) and acetyltributyl citrate (TBAC). The properties of blends and composites prepared by applying different processing procedures were investigated. The results of differential scanning calorimetry (DSC) indicate that thermal properties of the samples were greatly affected by processing procedure, without any difference among the chosen plasticizers. Thus, the research has been continued with acetyltributyl citrate. OSF slightly affects thermal properties of PLLA; the greatest infl uence is on the crystallization of PLLA. Plasticizer lowers the value of thermal transition temperatures, but increases the crystallinity of PLLA. Non-isothermal thermogravimetric analysis (TGA) showed that addition of OSF deteriorates the thermal stability of PLLA while TBAC improves it. Scanning electron microscope (SEM) images confirmed weak interactions between PLLA and OSF and no infl uence of TBAC on it. According to Fourier transform infrared spectroscopy (FT-IR) spectrums in plasticized composites only hydrogen bonds were formed. OSF reduces the fl exibility and the strength of PLLA while TBAC increases the fl exibility and signifi cantly reduces the strength of PLLA. Thermal properties of the investigated blends and composites, especially the process of crystallization and melting of PLLA crystals have been affected by ageing. Biodegradation of prepared PLLA samples in the soil was increased substantially by addition of OSF and TBAC, but TBAC has a lower infl uence. The migration of plasticizer at elevated temperatures increases with time exposure to given temperatures. In such conditions OSF facilitates migration of TBAC from the investigated composites. Migration of plasticizer from samples immersed in food-simulating solvents increases with time exposure to food-simulating solvents. Therefore, thermal properties of the investigated samples have been changed

The Influence of Food Simulants on Poly(3-hydroxybutyrate)/Montmorillonite Composites

Cilj ovog rada bio je pripremiti poli(3-hidroksibutirat)/montmorilonit (PHB/MMT) kompozite na laboratorijskoj preši uz zagrijavanje te odrediti utjecaj različitih modelnih otopina na kompozite i migraciju punila. Analiza modelnih otopina nakon ispitivanja migracije provedena je pomoću UV/Vis spektroskopije. Zbog utvrđene hidrolize PHB-a pod utjecajem modelnih otopina nemoguće je odrediti migraciju MMT-a iz kompozita PHB/MMT. Diferencijalna pretražna kalorimetrija (DSC) potvrdila je razgradnju PHB-a. Provedenim istraživanjem ukazalo se na potencijal uporabe UV/Vis spektroskopije kod ispitivanja utjecaja modelnih otopina na polimerne kompozite. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.The aim of this work was to prepare poly(3-hydroxybutyrate)/montmorillonite (PHB/MMT) composites on the laboratory press with heating, and to determine the influence of different food simulants on the composites and the filler migration. Analysis of the food simulants after migration testing was conducted with UV/Vis spectroscopy. Due to the established hydrolysis of PHB under the influence of the food simulants, it was impossible to determine the migration of MMT from PHB/MMT composites. Differential scanning calorimetry (DSC) confirmed the degradation of PHB. This research showed the potential of UV/Vis spectroscopy in dealing with the influence of food simulants on polymer composites. This work is licensed under a Creative Commons Attribution 4.0 International License

Kinetic Analysis of Isothermal Degradation of Poly(ethylene oxide) Modified by Phenyl Hepta Isobutyl Polyhedral Oligomeric Silsesquioxanes

Čvrsti polimerni elektroliti na bazi poli(etilen-oksida) (PEO) i litijevih soli imaju slabu ionsku provodnost pri temperaturi uporabe, a osnovni razlog je visok stupanj kristalnosti PEO-a. Udio kristalne faze u PEO-u može se smanjiti dodatkom nanočestica, u koje spadaju i poliedarski oligomerni silseskvioksani (POSS). U ovom radu upotrijebljeni su metil-, fluoro- i kloro-fenil hepta izobutil poliedarski oligomerni silseskvioksani. Istraživan je njihov utjecaj na kinetiku izotermne razgradnje PEO-a. Aktivacijska energija, predeksponencijalni faktor i kinetički model izračunati su pomoću programa Netzsch Thermokinetics Professional. Utvrđeno je da se proces izotermne toplinske razgradnje odvija kroz jedan stupanj koji je najbolje opisan autokatalitičkim modelima. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Poly(ethylene oxide) (PEO) and lithium salts based solid polymer electrolytes exhibit low ionic conductivity at the service temperatures, the main reason being the high crystallinity of PEO. Degree of crystallinity is often lowered by addition of nanoparticles, among them being a very interesting group known as polyhedral oligomeric silsesquioxanes (POSSs). In this work, the influence of POSS nanoparticles (methyl-, fluoro-, and chloro-phenil heptaisobutyl POSS) on kinetics of isothermal PEO degradation was investigated. Activation energy, pre-exponential factor, and kinetic model were determined using Netzsch Thermokinetics Professional program. It was found that the process of isothermal degradation occurs through one step, best described by autocatalytic models. According to Fig. 2 and Table 2, all investigated samples at 360, 370, and 380 °C after 60 min reach constant mass plateau with residual mass (mf) 3–7 %. In this temperature range, degradation of both PEO and POSSs occur. Before starting the kinetic analysis, the time necessary to gain isothermal conditions was subtracted. Activation energy (E) and pre-exponential factor (A) calculated using linear regression (LR), as well as the kinetic model of thermal degradation f(α) are summarised in Table 4. Activation energies of PEO/POSS 1, PEO/POSS 3 i PEO/POSS 5 samples are similar to those of PEO. The highest and lowest value of activation energy for PEO/POSS 4 and PEO/POSS 2 samples, respectively, is the result of their inherent thermal stability. Dependence of activation energy on conversion is of the same shape for all samples, implying the same mechanism of thermal degradation. DTG curves exhibit one degradation step only. Results of F-test (Table 3) indicate that extended Prout-Tompkins model as well as other autocatalytic models are statistically the best for description of the isothermal degradation of PEO and PEO/POSS composites. Also, the sigmoidal shape of degradation curves (Fig. 3) is characteristic for autocatalytic processes. Finally, calculated models are in very good agreement with experimental data (Fig. 6). This work is licensed under a Creative Commons Attribution 4.0 International License

The Influence of Sodium Alginate on the Properties of Poly(ethylene oxide) as the Matrix for the Preparation of Solid Polymer Electrolyte

Istraživan je utjecaj natrijeva alginata (NaAlg) na strukturu i svojstva filmova poli(etilen-oksida) (PEO) izlivenih iz vodenih otopina primjenom infracrvene spektroskopije s Fourierovom transformacijom (FT-IR), diferencijalne pretražne kalorimetrije (DSC), neizotermne termogravimetrije (TG) i elektrokemijske impedancijske spektroskopije (EIS). Cilj istraživanja je pronalaženje optimalne mješavine za pripravu filma čvrstog polimernog elektrolita (SPE) za litij-ionske baterije (LIB). U filmovima mješavina PEO/NaAlg stvaraju se vodikove veze između PEO-a i NaAlg-a te nastaju mješljive mješavine s manjim udjelom kristalne faze u odnosu na film čistog PEO-a. Filmovi mješavina toplinski su nestabilniji od filma čistog PEO-a i pokazuju dielektrična svojstva. Zbog najmanjeg udjela kristalne faze PEO-a mješavina 80PEO/20NaAlg može biti polimerna matrica koja bi dodatkom litijeve soli tvorila pogodan SPE. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Investigation of the influence of sodium alginate (NaAlg) on the structure and properties of poly(ethylene oxide) (PEO) films cast from aqueous solutions was performed by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), non-isothermal thermogravimetry (TG), and electrochemical impedance spectroscopy (EIS). The research aimed to find the optimal blend for the preparation of a solid polymer electrolyte (SPE) film for lithium-ion batteries (LIB). In PEO/NaAlg blend films, hydrogen bonds are formed between PEO and NaAlg, the blends are miscible, and have a lower content of crystalline phase compared to pure PEO film. The films of the blends are more thermally unstable than the film of pure PEO, and show dielectric properties, but the blend 80PEO/20NaAlg is suitable for the preparation of SPE by addition of lithium salt due to the lowest content of PEO crystalline phase. This work is licensed under a Creative Commons Attribution 4.0 International License