591 research outputs found
Sort by
Synthesis of the new sensor material for determination of anionic surfactant
No full textAnionski tenzidi su visoko pjeneće površinski aktivne tvari. Disocijacijom u vodenoj otopini daju organske anione i smanjuju napetost površine. Lako se raspršuju te se koriste u praškastim i tekućim detergentima. Anionski tenzidi se mogu odrediti titracijskim, spektrofotometrijskim, kromatografskim metodama i metodama injektiranja u protok. Titracijske metode se zasnivaju na stvaranju ionskih asocijata (ionskih parova) anionskih tenzida s kationskim titransima. Ionski parovi su čestice suprotno nabijenih iona povezanih Coulombovim privlačnim silama u koncentriranim otopinama elektrolita. Ionsko-selektivne elektrode su elektrokemijski senzori koji omogućuju potenciometrijsko određivanje analita. Otapanjem i uparavanjem otopina dimetildioktadecilamonijeva klorida (DMDODAC) i natrijeva tetrafenilborata (NaTPB), dobiven je talog ionskog para dimetildioktadecilamonijeva tetrafenilborata (DMDODA-TPB). Nastali ionski par je zatim ekstrahiran, pročišćen i izoliran. Novo sintetizirani materijal DMDODA-TPB testiran je kao senzorski materijal pri potenciometrijskoj titraciji anionskog tenzida. Standardna otopina cetilpiridinijeva klorida (CPC) koncentracije 4 x 10-3 moldm-3 korištena je kao titrans, a kao analit otopina natrijevog dodecilsulfata (NaDDS) koncentracije 4 x 10-3 moldm-3.Anionic surfactants are high-foaming active compounds. When dissociate in aqueous solutions, they form organic anions and reduce surface tension. They are well dispersed in water, and used in powder detergents and liquid detergents. Anionic surfactants can be analyzed by using titration methods, spectrophotometric methods, chromatographic methods and by flow injection analysis. Titration methods are based on the forming of ion associates (ion pairs) between anionic surfactants and cationic titrants. Ion-pairs are formed from oppositely charged ions associated by Coulomb interactions in concentrated electrolyte solutions. Ion-selective electrodes are electrochemical sensors that are designed for the potentiometric determination of analytes. The precipitate of ion pair dimethyldioctadecylammonium tetraphenylborate (DMDODA-TPB) was formed by dissolving and evaporating of dimethyldioctadecylammonium chloride (DMDODAC) and sodium tetraphenylborate (NaTPB) solutions. The ion pair was then extracted, purified and isolated. The new synthesized material DMDODA-TPB has been tested as a sensor material in potentiometric titration of anionic surfactants. Standard solution of cetylpyridinium chloride (CPC) at concentration of 4 x 10-3 moldm-3 was used as a titrant and a solution of sodium dodecylsulfate (NaDDS) at concentration of 4 x 10-3 moldm-3 was used as the analyte
Potentiometric Characterisation of Amylose and Dodecyl-trimethyl Ammonium Bromide Interaction
No full textPovršinski aktivne tvari ili tenzidi su bifunkcionalni organski spojevi koji se sastoje od hidrofilne i hidrofobne dugolančane ugljikovodične skupine. Tenzidi imaju važnu ulogu u mnogim praktičnim primjenama gdje se koriste kao detergenti za pranje i čiščenje u kućanstvu i industriji, u tekstilnoj industriji kao omekšivači tkanina, u prehrambenoj, naftnoj industriji, industriji agrokemikalija, industriji papira, farmaceutskoj i kozmetičarskoj industriji i mnogim drugima. Amiloza je ravnolančasti i nerazgranati polimer koji se sastoji od glukoznih jedinica povezanih α-1,4 glikozidnim vezama koje čine spiralno uvijeni lanac u obliku heliksa. Potenciometrijskom titracijom otopina amiloze (0; 0.1; 0.5; 1; 2 i 4%) sa dodecil-trimetil amonijevim bromidom( 4 x 10‾3 mol/dm3) pratilo se stvaranje inkluzijskog kompleksa promjenom kritične micelarne koncentracije. Kompleks amiloze sa DTAB nastaje tako da masni ugljikovodični lanac kationskog tenzida DTAB ulazi u heliks amiloze, a hidrofilni dio molekule usmjeren je izvan površine amiloze odnosno heliksa. Tijekom eksperimenta korištene su srebro/srebrov klorid (Ag/AgCl) kao referentna elektroda i tenzidno-osjetljiva elektroda sa plastificiranom PVC membranom.Surface active agents or surfactants are bifunctional organic compounds that consist of hydrophilic and hydrophobic long-chain hydrocarbon groups. Surfactants play an important role in many practical applications where they are used as detergents for washing and cleaning in the household and industry, the textile industry as fabric softeners, food industry, oil industry, agrochemicals industry, paper industry, the pharmaceutical industry and cosmetic industry and many others. Amylose is a straight-chain and unbranched polymer consisting of glucose units linked by α-1,4 glycosidic bonds, which chain consists of spirally wound in a helical fashion. Potentiometric titration of amylose (0; 0.1; 0.5; 1; 2 and 4%) with dodecyl-trimethyl ammonium bromide (4 x 10‾3 mol/dm3) was used to track formation of inclusion complex by changing critical micellar concentration. The complex of amylose with DTAB occurs so that fatty hydrocarbon chain cationic surfactant DTAB has enters the helix of amylose and the hirophillic part of molecule is directed towards the outside of helix. During the experiment silver / silver chloride (Ag / AgCl) werw used as the reference electrode and the surfactant-sensitive electrodes with plasticized PVC membrane
Colored Solutions Concentration Determination Using Smartphone
No full textOtapanjem soli prijelaznih metala u vodi dobivaju se obojane otopine. Obojanost se javlja zbog apsorbiranja dijela vidljivog spektra. Fotoni valnih duljina koji prođu neapsorbirani kroz otopinu uzrokuju obojanost. Određivanje nepoznate koncentracije obojanih otopina vrši se spektrofotometrijski; pripremom serije otopina poznatih koncentracija, mjerenjem apsorbancija tih otopina i konstrukcijom kalibracijskog pravca ovisnosti apsorbancije o koncentraciji. Svaki pametni telefon koji ima kameru može se koristiti kao fotoaparat. Kamere na pametnim telefonima mogu se razlikovati po broju megapiksela, kvaliteti senzora, kvaliteti leće, stabilizaciji slike itd. Dostupnost pametnih telefona tijekom posljednjih godina se iznimno povećala. Osim njihove primarne funkcije, kao sredstvo za komunikaciju, imaju i velik potencijal na različitim područjima tehnologije, marketinga, znanosti, itd. Cilj rada bio je utvrditi može li se pametni telefon koristiti za određivanje nepoznate koncentracije obojanih otopina. Određivane su koncentracije otopina CuSO4 i KMnO4 u rasponu koncentracija od 2∙10-3 M do 1 M za CuSO4, te od 2∙10-5 M do 10-2 M za KMnO4. Dobiveni rezultati pokazuju da je metoda pogodna za određivanje nepoznate koncentracije KMnO4 u rasponu koncentracija od 2∙10-5M do 1.5∙10-3 M koristeći intenzitete zelene za računanje apsorbancije. Za određivanje nepoznate koncentracije CuSO4 moguće je koristiti intenzitete crvene u rasponu koncentracija od 2∙10-3 M do 1 M. Za otopinu KMnO4 bolji je kalibracijski pravac bez korištenja širokokutne leće sa intenzitetima plave i zelene. Korištenje širokokutne leće rezultira boljim kalibracijski pravcima za obje otopine (intenziteti crvene). Metoda je brza, dostupna i jeftina te se može koristiti kao preliminarna metoda za neka jednostavna određivanja koncentracije obojanih otopina.Colored solutions are obtained by dissolving transition metal salts in water. Coloration occurs due to partial absorption of visible light spectrum. Fotons that pass unabsorbed cause the coloration. Concentration determination of colored solutions is performed by spectrophotometry. Preparing solutions of known concentration and measuring absorbance leads to the construction of calibration curve. Unknown concentration of solution can be found by measuring apsorbance and using absorbance in linear equatation. Any smartphone that has a camera can be used for taking pictures. Cameras can differ by megapixel count, sensor quality, lens quality, image stabilization. Availability of smartphones has increased over the last few years. In addition to their primary function as a means of communication smartphones have great potential in various areas of technology, marketing, science etc. The aim of this experiment was to determine whether smartphones can be used for concentration determination of colored solutions. Solutions that were used for determination of concentration are KMnO4 with concentration range from 2∙10-5 M to 10-2 M and CuSO4 from 2∙10-3 M to 1M . The results show that the method is suitable for determining concentration of KMnO4 in concentration range from 2∙10-5 M to 1.5∙10-3 M using the intensity of green to calculate absorbance. Intensities of red were used to determine unknown concentration of CuSO4 in concentration range from 2∙10-3 M to 1M. By using the wide-angle lens calibration curve tends to be better for both solutions if the intensity of red is used for calculation of absorbance. The calibration curve obtained for KMnO4 is better without using wide-angle lens if the intensity of green or blue is used for calculation of absorbance. The method is fast, cheap and can be preliminary method for basic determination of colored solutions unknown concentration
Aromatic Heterocycles
No full textAromatski spojevi su velika skupina cikličkih organskih spojeva izrazite kemijske stabilnosti. Takvi spojevi, iako nezasićeni, ne podliježu lako reakcijama adicije, već su za njih karakteristične reakcije supstitucije. Oni mogu biti benzenoidni (benzen, naftalen, antracen), heterociklički (pirol, piridin, tiofen) te nebenzenoidni (ferocen, azulen). Heterociklički aromatski spojevi su organski ciklički spojevi koji u prstenu osim ugljikova atoma imaju i atome drugih elemenata (dušik, kisik, sumpor). Oni su važni u biološkom svijetu. Ugljikohidrati su heterociklički spojevi, to su i klorofil i hem koji daju zelenu boju lišća te crvenu boju krvi. Heterociklički aromatski prsteni često su reaktivna mjesta u mnogim enzimima i koenzimima. Vežu se na duge lance nukleinskih kiselina. Heterociklički aromatski spojevi se nalaze posvuda i njihova funkcija je često vrlo bitna.Aromatic compounds are a group of cycles organic compounds outstanding chemical stability. These compounds, although unsaturated, not respond to addition reactions, but they are characterized by the subtitution reaction. Their classification : benzenoid (benzene, naphthalene, anthracene) ,heterocycles (pyrolle, pyridine, thiophene) and nonbenzenoide (ferrocene, azulene). Aromatic heterocycles are organic cycles compounds with atoms of other elements (nitrogen, oxygen, sulfur) in ring with the carbon atom. They are important in the biological world. Carbohydrates are aromatic heterocycles, the chlorophyll and heme are to. Chlorophyll gives green color of leaves, heme gives red color of blood. Aromatic heterocycles make reactive spot of many enzymes and coenzymes. They are attached to the long chains of nucleic acids. Aromatic heterocycles are everywhere and their function is very important
Elektrokemijska impedancijska spektroskopija
No full textElektrokemijska impedancijska spektroskopija (EIS) je pouzdana i nedestruktivna metoda pogodna za mjerenja u elektrokemijskim sustavima. EIS je vrlo moćna tehnika koja se koristi u sve većem broju različitih područja , zbog vrlo jednostavne primjene, koja se sastoji od: mjerenja impedancijskog spektra, modeliranja, matematičkog prilagođavanja i ekstrakcije parametara. Unaprijeđenjem računalnih programa za analizu podataka impedancije u ovisnosti o frekvenciji, te potenciostata, metoda je potpuno automatizirana i danas ima vrlo široko područje primjene vezano uz različite elektrodne procese. Neke primjene EIS metode su utvrđivanje brzine reakcija, određivanje kapaciteta, vodljivosti, te debljine sloja i prisutnosti pora i raspuklina na ispitivanom uzorku. S obzirom da EIS može poslužiti za karakterizaciju svojstava površina i mase svih materijala (vodiča, izolatora, poluvodiča i ionskih medija), metoda je pogodna kod ispitivanja materijala u većini industrija.Electrochemical impedance spectroscopy (EIS) is a reliable and nondestructive method suitable for measurements in electrochemical systems. EIS is a very powerful technique which is used in a growing number of different areas, because of a very simple application which consists of: measuring the impedance spectrum, modeling, mathematical adjustment and parameter extraction. Since the advancement of analysis software and potentiostat, the method is fully automated and today has a wide range of applications related to the different electrode processes. Some applications of EIS method include determining the reaction rate, determination of capacity, conductivity, thickness and presence of pores and cracks in the sample examined. Given that the EIS can be used to characterize the surface properties and mass of all types of materials (conductors, insulators, semiconductors and ionic medium), the method is suitable for testing materials in most industries
Analysis of atmospheric pollutants data measured in Slavonski Brod during summer period of year 2013.
No full textAtmosferski polutanti značajno utječu na zdravlje živih bića i biljnih vrsta. Veliki problem predstavlja visoka koncentracija polutanata u gradskim sredinama. U ovom radu prikazani su rezultati mjerenja volumnih koncentracija ozona, benzena, sumporovodika, dušikovih oksida i lebdećih čestica na području Slavonskog Broda u ljetnom periodu 2013. godine, kao i svojstva svakog od polutanata. Mjerna postaja nalazi se na povišenju i u blizini rafinerije koja se smatra glavnim proizvođačem polutanata.Atmospheric pollutants have a big impact on live beings and plants. The biggest problem is the high pollutant concentration in the urban areas. This analysis presents the results of measuring the volume concentrations of ozone, benzene, hydrogen sulfide, nitrogen oxides and particulate matter, in the area of Slavonski Brod, during the summer period of 2013. Also, the properties of each pollutant are explained. Measuring station is located on an elevation, near the refinery, which is considered the main source of the pollutants
Use of HPLC for surfactant separation and quantification
No full textKromatografija je fizikalna metoda koja se koristi za razdvajanje smjesa. Sastojci koji se razdvajaju, raspodjeljuju se između dviju faza (stacionarne i mobilne faze). Kod tekućinske kromatografije visoke razlučivosti (HPLC) se za mobilnu fazu koristi tekućina, a stacionarnu fazu čine punila vrlo finih zrnaca. Tenzidi ili površinske aktivne tvari su biofunkcionalni organski spojevi koji se sastoje od hidrofilne i hidrofobne skupine. Dijele se na anionske, kationske, neionske i amfolitske tenzide. Kationski tenzidi imaju bakteriocidna, antimikrobna, antikorozijska svojstva te se koriste u industrijskim, kozmetičkim i farmaceutskim proizvodima. Tyrosur je lokalni antibiotik. Dolazi u obliku gela i praška. Koristi se kod liječenja manjih površinskih ozljeda na koži. Cetilpiridinijev klorid (CPC) je kationski kvaterni amonijev spoj. Koristi se u nekim vodicama za ispiranje usta, pastama za zube, pastilama i gelovima. To je antiseptik koji ubija bakterije i druge mikroorganizme. U realnom uzorku (Tyrosur gel) određena je koncentracija kationskog tenzida CPC pomoću HPLC-a. Prethodno je napravljena kalibracija CPC u tri točke koristeći sljedeće koncentracije: 1×10-5, 5×10-5, te 8,5×10-5 kako bi se vidjelo na kojem vremenu izlazi pik CPCa. Kalibracijska krivulja CPC-a napravljena je na osnovi podataka o visini pikova pojedinih koncentracija. Tijekom analize koristio se UV-detektor (SPD-10 AV) i kolona Acclaim surfactant (5µm, 250×4,6 mm). Na temelju analize i dobivenih podataka, izračunat je udio CPC-a u realnom uzorku.Chromatography is a physical method which is used to separate the mixture. Ingredients which are separated are distributed between two phases (the stationary and mobile phases). At high performance liquid chromatography (HPLC) device for the mobile phase is used liquid and the stationary phase consists of fillers of very fine grains. Surfactants or surface active agents are bifunctional organic compounds that consist of hydrophilic and hydrophobic groups. They are divided into anionic, cationic, nonionic and ampholytic surfactants. Cationic surfactants have a bactericidal, anti-microbial, anti-corrosion properties and are used in industrial, cosmetic and pharmaceutical products. Tyrosur is a local antibiotic. It comes in the form of gel and powder. It is used in the treatment of minor superficial skin injuries. Cetylpyridinium chloride (CPC) is a cationic quaternary ammonium compound. It is used in some mouthwashes, toothpastes, lozenges and gels. It is an antiseptic that kills bacteria and other microorganisms. HPLC was used for cationic surfactant, CPC, determination in real sample (Tyrosur gel). We previously made calibration of CPC in three points using the following concentrations: 1 × 10-5 , 5 × 10-5 and 8.5 × 10-5 to see where was the peak of CPC. The calibration curve for CPC was made on the basis of data for peak heights for every CPC concentration level. During analysis we used the UV detector (SPD - 10 AV) and Acclaim Surfactant column (5μm , 250 × 4.6 mm). We calculated the proportion of CPC in real sample based on the analysis and the resulting data
Colloid systems
No full textU ovom radu opisani su koloidni sustavi, koji se sastoje od disperzne faze i disperznog sredstva. Navedene sustave karakteriziraju molekulsko-kinetička, optička i električna svojstva. Stupanj disperzije predstavlja odnos zbroja površina čestica disperzne faze prema zbroju njihovog volumena. Metode kojima se dobivaju koloidni sustavi dijele se na disperzijske i kondenzacijske, a primjeri koloidnih sustava ovise o agregatnom stanju disperznog sredstva i disperzne faze. Koloidna čestica predstavlja skup velikog broja molekula ili atoma date komponente, odnosno predstavlja molekulski ili atomski agregat koji čini jezgru koloidne čestice. Zbog malih dimenzija koloidnih čestica (10-9 m do 10-6 m), koloidi se odlikuju velikom graničnom površinom između dispergirane faze i disperznoga sredstva, što bitno utječe na karakteristična svojstva koloida.In this thesis colloidal systems were described which consist of dispersed phase and dispersion medium. Thementioned systems are characterized bymolecular - kinetic, optical and electric properties. The degree of dispersion is represented as theratio of summed areas and volumes of those particles. There are two methods of producing colloidal systems: dispersion and condensation, where the examples of colloidal systems depend on the state of matter of dispersion medium and dispersed phase. Colloidal particle represents aggregate of a large number of molecules or atoms which build up given components, or in other words, it represents molecular or atomic aggregate which is a core of colloidal particle, respectively.Colloids are characterized by large surface area between dispersed phase and dispersion medium, because of the their small dimensions (from 10-9 m to 10-6 m). This fact has an impact on the properties of colloids
Termogravimetrijska analiza uzoraka titanijevog dioksida i cinkovog oksida
No full textTitanijev dioksid pojavljuje se u prirodi u tri polimorfne modifikacije: rutil, anatas i brukit. Cinkov oksid najznačajniji je spoj cinka. Otrovan je za niţe organizme (plijesni i gljivice), ima baktericidna svojstva. Oba spoja upotrebljavaju se u proizvodnji pigmenata za boje, krema za sunčanje, pastama za zube, u farmaceutskim i mnogim drugim proizvodima. Nanomaterijali su jednokomponentni ili višekomponentni materijali čija je barem jedna dimenzija komponente izmeĎu 0,1 i 100 nanometara. Termogravimetrijska analiza je metoda termalne analize koja se temelji na mjerenju promjene mase uzorka kao funkcije temperature ili kao funkcije vremena (pri konstantnoj temperaturi). Metodom simultane TGA/DSC analize ispitana su četiri uzorka titanijeva dioksida i jedan cinkovog oksida, te su rezultati prokomentirani.Titanium dioxide (titania) is naturally occurring in nature in three polymorphic modifications: rutile, anatase and brookite. Zinc oxide is the most important zinc compound. It is poisonous for lower organisms (fungus and yeast), and it has antibacterial properties. Both compounds are used in production of various paints, sun block creams, toothbrush paste, in pharmaceutical and many other products. Nanomaterials are single or multi component materials in which at least one of the components has dimensions between 0.1 and 100 nanometers. Thermogravimetry analysis is a method of thermal analysis based on measuring change in mass of sample as a function of temperature or as a function of time (at constant temperature). Using the simultaneous TGA/DSC method, four different titania samples, and one zinc oxide sample were investigated and commented
Study of the Oxidation Properties of a Copper Schiff Base Complex by Difeferential Pulse Voltametry
No full textU ovom radu opisana je uporaba diferencijalne pulsne voltametrije u svrhu ispitivanja oksidacijskih svojstava kompleksa bakra sa Schiffovom bazom (1E)-1-N-{[4-(4-{[(E)-N- (2-aminofenil) karboksiimidoil] fenoksi} butoksi) fenil] metiliden} benzen-1,2-diaminom, S36. Snimanjem diferencijalnih pulsnih voltamograma pratila se oksidacija ovoga kompleksa. Dobiveni diferencijalni pulsni voltamogrami snimljeni na elektrodi od staklastog ugljika pokazali su da se bakar u kompleksu oksidira iz Cu+ u Cu2+ . Također se pratio utjecaj promjene koncentracije otopine kompleksa na struju i potencijal oksidacijskog strujnog vrha. Dobiveni voltamogrami pokazuju da struja i potencijal oksidacijskog strujnog vrha rastu s porastom koncentracije.In this work, an application of differential pulse voltammetry on testing of oxidation properties of the copper complex with Schiff base (1E)-1-N-{[4-(4-{[(E)-N-(2- aminophenyl) carboxyimidoyl] phenoxy} butoxy) phenyl] methilidene} benzene -1,2- diamine, S36 is described. By recording defferential pulse voltammograms, oxidation of this complex was followed. Gained results of the differential pulse voltammograms, recorded on glassy carbon electrode, showed that cooper in the complex oxidated from Cu+ to Cu2+. The influence of concentration change of solution of the complex on oxidation peak current and potential, was also monitored. Obtained voltammograms showed that oxidation peak current and potential increased with an increase of concentration