Zaštita Materijala 3. 2021

Ion exchange of sodium with hydrochloric acid in ZSM-5 zeolite

Abstract

ZSM-5 zeolites are highly silicate materials that have significant application in catalytic processes in petrochemistry, especially due to their high selectivity. Most reactions in the petrochemical industry are acid-catalyzed. The acidic properties of zeolite depend on the number of acid centers, i.e. the presence of hydrogen ions, and therefore, in this paper the possibility of reducing the sodium content in the pores of high silicate zeolite ZSM-5 with the modulus (SiO₂ / Al₂O₃ = 1000) will be investigated, by applying ion exchange with hydrochloric acid. Chemical analysis of samples before and after ion exchange, and application of instrumental methods of X-Ray diffraction, FT-IR spectroscopy, and SEM analysis monitored  the influence of the quantity of hydrogen ions on the chemical composition and the structure of ZSM-5 zeolite at different acid concentrations and at different exchange times.

It has been shown that the application of ion exchange with hydrochloric acid can reduce the sodium content in zeolite. Even with the application of 5% HCl for 6 hours, the content of sodium in the zeolite is reduced by over 98%. A similar effect is achieved by applying more concentrated hydrochloric acid solutions for a shorter ion exchange time. By prolonging the ion exchange time, there are no significant changes in terms of the final ion exchange. On the other hand, the application of HCl solutions of higher concentrations leads to a slight decrease in the aluminum content in the zeolite, which may partially affect the structural stability of the zeolite. The results obtained by FT-IR and SEM analysis and X-Ray diffraction confirm the possibility of ion exchange with hydrochloric acid, without significant changes in the crystal structure of the zeolite.

Keywords: zeolite, sodium ion exchange, characterization of H-ZSM-5, XRD, FT-IR, SEM.

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Jonska izmjena natrijuma sa hlorovodoničnom kiselinom na zeolitu ZSM-5

Izvod

ZSM-5 zeoliti su visokosilikatni materijali koji imaju značajnu primjenu kod katalitičkih procesa u petrohemiji, naročito zbog visoke selektivnosti. Većina reakcija u petrohemijskoj industriji je katalizovana kiselinama. Kiselinska svojstva zeolita su zavisna od količine kiselih centara, odnosno prisustva vodoničnih jona, te će stoga, u ovom radu biti ispitana mogućnost smanjenja sadržaja natrijuma u porama visokosilikatnog zeolita ZSM-5 sa modulom (SiO₂/Al₂O₃ = 1000) primjenom procesa jonske izmjene sa hlorovodoničnom kiselinom. Hemijskom analizom uzoraka prije i poslije jonske izmjene, te primjenom instrumentalnih  metoda X-Ray difrakcije, FT-IR spektroskopije i SEM analize praćen je uticaj  količine vodoničnih jona na  hemijski sastav i promjenu strukture ZSM-5 zeolita pri različitim koncentracijama kiseline, te različitim vremenima jonske izmjene.

Pokazano je da je primjenom jonske izmjene sa hlorovodoničnom kiselinom moguće smanjiti sadržaj natrijuma u zeolitu. Već pri primjeni 5% HCl u trajanju od 6 sati postiže se redukcija sadržaja natrijuma u zeolitu od preko 98%. Sličan efekat se postiže pri primjeni koncentrovanijih rastvora  hlorovodonične kiseline za kraće vrijeme jonske izmjene. Produženjem vremena jonske izmjene, ne dolazi do znatnijih promjena u pogledu konačne jonske izmjene. S druge strane, primjena rastvora HCl većih koncentracija dovodi do blagog pada sadržaja aluminijuma u zeolitu, što može djelimično uticati na strukturnu stabilnost zeolita. Rezultati dobijeni FT-IR i SEM analizom, te X-Ray difrakcijom potvrđuju mogućnost jonske izmjene sa hlorovodoničnom kiselinom, bez značajnijih promjena kristalne strukture zeolita.

Ključne riječi: zeolit, jonska izmjena natrijuma, karakterizacija H-ZSM-5,  XRD, FT-IR, SEM.

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Vitrification as a method of soil remediation

Abstract

Various types of contaminated soil and hazardous waste that have a negative impact on the environment and human health can be treated with the vitrification process. This process is based on thermal treatment of contaminated soil or waste at high temperatures, with the addition of additives, whereby the soil/waste melts and a stable glass is formed. The resulting glass and glass-ceramic products have good mechanical resistance, chemically are resistant and immobilize contaminants, thus preventing their further negative impact on the environment. This paper presents a literature review of the vitrification process of different types of contaminated soil and hazardous waste.

Keywords: vitrification, contaminated soil, waste, environment protection.

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Vitrifikacija kao metoda remedijacije zemljišta

Primenom tehnike vitrifikacije mogu se tretirati različite vrste kontaminiranog tla i opasnog otpada koji imaju negativan uticaj na životnu sredinu i zdravlje ljudi. Neki od otpada koji se mogu tretirati postupkom vitrifikacije su: radioaktivni otpad, jalovina, šljaka, mulj, komunalni (organski) otpad, prašina iz elektrolučnih peći, leteći pepeo itd. Postupak vitrifikacije zasnovan je na termičkoj obradi kontaminiranih zemljišta ili otpada na temperaturi od 1400-2000°C, uz dodatak agenasa za vitrifikaciju, pri čemu se zemljište/otpad topi i formira stabilna amorfna masa. Proces vitrifikacije prenosi toksične elemente u amforni proizvod koji ima dobru mehaničku otpornost, hemijski je otporan i imobiliše zagađivače, sprečavajući na taj način njihov dalji negativni uticaj na životnu sredinu. U zavisnosti od lokacije procesa, vitrifikacija može biti in situ ili ex situ.

Ključne reči: vitrifikacija, kontaminirano zemljište, otpad, zaštita životne sredine.

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Decreasing of water absorptiveness of paper by coating nanofibrillated cellulose films

Abstract

Nanofibrillated films based on TEMPO-oxidized cotton linters were applied to reduce the hydrophilic properties of paper. For this purpose, aqueous dispersions of nanofibrillated cellulose of different composition: 1 and 3% of nanofibrillated cellulose, up to 13% of CaCO₃ and/or Al(OH)₃, up to 20% of propane-1,2-diol (glycol), and up to 21% of TEMPO-oxidized cotton linters were coated on the model paper, without additional adhesive. The pristine model paper and papers coated with nanofibrillated cellulose-based composite films were characterized in terms of water absorptiveness by COBB method and water drop contact angle measurements. The surface appearance was characterized by scanning electron microscopy (SEM) and surface chemistry by infrared spectroscopy with Fourier transform and attenuated total reflection (ATR-FTIR). Additionally, optical properties, i.e. measurement of reflection curves and CIE degrees of whiteness, were determined according to appropriate standards. For all papers coated with nanofibrillated cellulose-based films, depending on the composition of the dispersions, a decrease in sorption properties was achieved, without changes in optical properties and surface morphology of the paper compared to the pristine paper.

Keywords: Nanofibrillated cellulose films, TEMPO-oxidized cellulose, paper, water absorptiveness, contact angle, optical properties, surface morphology.

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Smanjenje sposobnosti upijanja vode papira oslojenih filmovima na bazi nanofibrilisane celuloze

Izvod

Nanofibrilisani filmovi na bazi TEMPO-oksidisanog pamučnog lintersa upotrebljeni su za smanjenje hidrofilnih svojstava papira. U tu svrhu su vodene disperzije nanofibrilisane celuloze različitog sastava: 1 i 3% nanofibrilisane celuloze, do 13% CaCO₃ i/ili Al(OH)₃, do 20% propan-1,2-diol (glikol) i do 21% TEMPO-oksidisanih vlakana pamuka, nanošene na model papire, bez dodatka adheziva. Polazni i modifikovani model papiri sa oslojenim filmovima na bazi nanofibrilisane celuloze karakterisani su sa aspekta sposobnosti upijanja vode po COBB metodi i određen je ugao kvašenja. Izgled i hemijski sastav površine papira karakterisani su skenirajućom elektronskom mikroskopijom (SEM) i infracrvenom spektroskopijom sa Furijeovom transformacijom (ATR-FTIR). Pored toga, primenom odgovarajućih standarda određena su optička svojstva polaznog i modifikovanih papira (CIE lab koordinate, refleksija, CIE stepen beline). Zavisno od sastava disperzija, svi model papiri pokazali su određeno smanjenje sposobnosti upijanja vode, bez promena optičkih svojstava i morfologije površine papira u odnosu na nemodifikovani papir.

Klučne reči: Nanofibrilisani celulozni filmovi, TEMPO-oksidisana celuloza, papir, sposobnost upijanja vode, ugao kvašenja, optička svojstva, morfologija površine.

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Inhibition of corrosion of SS 18/8 alloy is sea water by Thiourea-Zn²⁺ system

Abstract

The  corrosion resistance of SS 18/8 in natural sea water, in presence of an inhibitor named Thiourea-Zn²⁺ has been evaluated. Weight loss method, polarization study and AC impedance spectra have been employed to evaluate the corrosion resistance of SS 18/8 alloy in natural sea water, in presence of an inhibitor named Thiourea-Zn²⁺ system.  Weight loss method reveals that Thiourea-Zn²⁺ system offers a maximum corrosion inhibition efficiency of 95% in controlling corrosion of SS 18/8 alloy in natural sea water. Synergism parameters are found to be greater than 1, confirming the synergistic effect existing between Thiourea-Zn²⁺. Adsorption of inhibitor molecules on the metal surface obey Langmuir adsorption isotherm.  Polarisation study reveals that the inhibitors named Thiourea-Zn²⁺ system functions as mixed type of inhibitor.  AC impedance spectra confirm the formation of a protective film on the metal surface. This formulation of Thiourea-Zn²⁺ may be used in cooling water systems where SS 18/8 alloy pipelines are used to carry sea water which is used as coolant. Also, Thiourea-Zn²⁺ coating can be given on SS 18/8 alloy to protect it from corrosion by sea water when SS 18/8 alloy is used as hull plates in ship industry.

Keywords: sea water corrosion, SS 18/8 alloy pipelines, SS 18/8 alloy hull plates, Thiourea-Zn²⁺ system, Langmuir adsorption isotherm

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Inhibicija korozije legure SS 18/8 u morskoj vodi sistemom Thiourea-Zn²⁺

Izvod

Procenjena je otpornost korozije SS 18/8 u prirodnoj morskoj vodi, u prisustvu inhibitora  Thiourea-Zn²⁺. Za procenu otpornosti na koroziju legure SS 18/8 u prirodnoj morskoj vodi, u prisustvu inhibitora Thiourea-Zn²⁺ korišćeni su metod gubitka težine, studija polarizacije i spektri AC impedanse. Metoda gubitka težine otkriva da Thiourea-Zn²⁺ sistem nudi maksimalnu efikasnost inhibicije korozije od 95% u kontroli korozije legure SS 18/8 u prirodnoj morskoj vodi. Utvrđeno je da su parametri sinergizma veći od 1, što potvrđuje sinergijski efekat koji postoji između Thiourea-Zn²⁺. Adsorpcija molekula inhibitora na površini metala podleže Langmuirovoj adsorpcionoj izotermi. Studija polarizacije otkriva da inhibitori Thiourea-Zn²⁺ sistem funkcionišu kao mešani tip inhibitora. Spektri AC impedanse potvrđuju stvaranje zaštitnog filma na metalnoj površini. Ova formulacija Thiourea-Zn²⁺ može se koristiti u sistemima za hlađenje vodom gde se legirani cevovodi SS 18/8 koriste za transport morske vode, koja se koristi kao rashladna tečnost. Takođe, premaz Thiourea-Zn²⁺ može se naneti na leguru SS 18/8 da bi se zaštitio od korozije morskom vodom kada se legura SS 18/8 koristi kao ploče trupa u brodskoj industriji.

Ključne reči: korozija morske vode, legirani cevovodi SS 18/8, legurne ploče trupa SS 18/8, sistem Thiourea-Zn²⁺, izoterma Langmuirove adsorpcije.

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Candesartan: a pharmaceutical product as effective corrosion inhibitor for Aluminum in Acidic Solution

Abstract

The corrosion performance of aluminum in 1 M hydrochloric acid solution in the existence and absence of Candesartan drug was examined utilizing, potentiodynamic polarization (PDP) and AC impedance (EIS) tests. It was found that the inhibition efficacy (%IE) of Candesartan drug was influenced by its doses and temperature and reached to 92.9% at 40×10^-6 M, 30^oC. The adsorption isotherm agreed with Langmuir model. From Tafel data the investigated Candesartan drug acts as mixed kind inhibitor. The influence of temperature on the rate of dissolution and the thermodynamic parameters in the existence and absence of Candesartan drug were also, studied and explained. All tests gave similar results.

Keywords: Corrosion inhibition, aluminum, HCl, Candesartan drug, adsorption, impedance, polarization.

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Candesartan: farmaceutski proizvod kao efikasni inhibitor korozije za aluminijum u kiselom rastvoru

Izvod

Ispitivane su performanse korozije aluminijuma u ​​1M rastvoru hlorovodonične kiseline u prisustvu i odsustvu leka Candesartan primenom postupaka potenciodinamičke polarizacije (PDP) i AC impedanse (EIS). Utvrđeno je da su na efikasnost inhibicije (% IE) leka Candesartan uticale njegove doze i temperatura i dostigla je 92,9% pri 40×10^-6 M na 30⁰C. Izoterma adsorpcije se slaže sa Langmuirovim modelom. Prema podacima Tafela, ispitivani lek Candesartan deluje kao inhibitor mešovite vrste. Takođe, proučavan je i objašnjen uticaj temperature na brzinu rastvaranja i termodinamičke parametre u prisustvu i odsustvu leka Candesartan. Svi testovi su dali slične rezultate.

Ključne reči: inhibicija korozije, aluminijum, HCl, lek Candesartan, adsorpcija, impedansa, polarizacija.

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Electrochemical behavior of various implantation biomaterials in the presence of various simulated body fluids–an overview

Abstract

In Modern medicine, metals and alloys are being used as implants. The Corrosion behaviour of various biomaterials under artificial body fluids are being studied. Artificial biomaterials are being implanted inside the human body to replace bone, teeth, etc. Even organs are being medically substituted with different types of metals such as mild steel, carbon steel, Ni-Cr alloy, Fe-Cr alloy, 22 carat Gold,24 carat Gold Tin, etc. due to their biocompatibility. This is achieved by connecting these metals directly with body tissues. The metals tend to corrode when it gets in contact with human body fluids. The body fluids thereby come in direct contact with tissues and the tissues are in contact with the metal thus causing the metal to corrode. And hence the corrosion resistance studies such as polarisation, AC impedance, cyclic voltammetric studies, etc, are being conducted in a medium like artificial blood plasma, artificial urine, artificial salvia, artificial sweat, Hank solution, Ringer solution, etc. The different body fluids are examined in the presence of different implantation metals by electrochemical methods and protective films are formed which are analyzed by various surface analysis techniques such as AFM, FTIR-UV, SEM, etc. The research findings will thereby be very helpful to the medical field.

Keywords: Corrosion, Hank solution, Alloy, Artificial body fluids.

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Elektrohemijsko ponašanje različitih metala za implantaciju u prisustvu različitih simuliranih telesnih tečnosti – pregled

Izvod

U savremenoj medicini metali i legure se koriste kao implantati. Proučava se ponašanje korozije različitih biomaterijala u veštačkim telesnim tečnostima. U ljudsko telo se ugrađuju veštački biomaterijali koji zamenjuju kosti, zube itd. Čak se i organi medicinski zamjenjuju različitim vrstama metala, poput mekog čelika, ugljeničnog čelika, legure Ni-Cr, legure Fe-Cr, 22-karatnog zlata, 24-karatnog zlatnog kalaja itd., zbog njihove biokompatibilnosti. To se postiže povezivanjem ovih metala direktno sa tkivima tela. Metali imaju tendenciju korozije kada dođu u kontakt sa tečnostima ljudskog tela. Telesne tečnosti na taj način dolaze u direktan kontakt sa tkivima, a tkiva su u kontaktu sa metalom i na taj način izazivaju koroziju metala. Stoga se studije otpornosti na koroziju, poput polarizacije, impedanse naizmenične struje, cikličnih voltametrijskih studija itd., sprovode u medijumu poput veštačke krvne plazme, veštačkog urina, veštačke salvije, veštačkog znoja, Henkovog rastvora, Ringerovog rastvora itd. Tečnosti se ispituju u prisustvu različitih implantacionih metala elektrohemijskim metodama i formiraju se zaštitni filmovi koji se analiziraju različitim tehnikama površinske analize kao što su AFM, FTIR-UV, SEM itd. Nalazi istraživanja će time biti od velike pomoći medicinskom polju.

Ključne reči: Korozija, Henkov rastvor, legura, veštačke telesne tečnosti.

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Influence of digene tablet juice orally taken in on the corrosion resistance of orthodontic wire made of SS 18/8 in presence of artificial saliva

Abstract

Dentists make use of orthodontic wires such as SS 18/8, SS 316, Ni-Cr etc., to regulate the growth of teeth. In the saliva environment these wires undergo corrosion. Aside from this, they undergo corrosion by the food items , juices and Tablets orally in taken. Corrosion resistance of SS 18/8 alloy in artificial saliva (AS) , in the absence and presence of Digene Tablet juice, has been investigated by polarization and AC impendance techniques. It is inferred that corrosion resistance of SS 18/8 alloy in artificial saliva decreases in presence of Digene Tablet. This is exposed by decrease in Linear Polarization Resistance (LPR) value, Charge transfer resistance (R_t) value, in impedance value, and increase in corrosion current and double layer capacitance value(C_dl). In presence of Digene Tablet, the LPR value decreases from  3488228   to  1629535 Ohmcm². The corrosion current value increases from  1.447 x10^-8 to 2.637×10^-8A/cm² . The Charge transfer resistance (R_t) value decreases from 37796  to 10481Ohmcm². The double layer capacitance value increases from 1.349×10^-10 F/cm²  to  4.866×10^-10F/cm². The impedance value decreases from 4.857 to 4.428. Hence it implies that people with orthodontic wire made of SS 18/8 alloy should avoid taking Digene Tablet juice orally.

Keywords: orthodontic wires, SS18/8, corrosion resistance, Digene Tablet juice, artificial saliva.

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Uticaj oralno uzetog soka tableta digene na otpornost na koroziju ortodontske žice od SS 18/8 u prisustvu veštačke pljuvačke

Izvod

Stomatolozi koriste ortodontske žice kao što su SS 18/8, SS 316, Ni-Cr itd. za regulaciju rasta zuba. U okruženju pljuvačke ove žice podležu koroziji. Osim toga, podvrgavaju se koroziji usled uzimanja hrane, sokova i tableta. Otpornost na koroziju legure SS 18/8 u veštačkoj pljuvački (AS), u odsustvu i prisustvu soka Digene tablete, ispitana je tehnikama polarizacije i impedanse naizmenične struje. Zaključuje se da se otpornost legure SS 18/8 na koroziju u veštačkoj pljuvački smanjuje u prisustvu Digene tablete. Ovo je izloženo smanjenjem vrednosti otpora linearne polarizacije (LPR), vrednosti otpora prenošenja naboja (Rt), vrednosti impedanse i povećanjem korozione struje i vrednosti dvoslojne kapacitivnosti (Cdl). U prisustvu tablete Digene, vrednost LPR se smanjuje sa 3488228 na 1629535 Ohmcm². Vrednost struje korozije se povećava sa 1,447 k10^-8 na 2,637k10^-8 A/cm². Vrednost otpora prenosu naboja (Rt) opada sa 37796 na 10481 Ohmcm². Vrednost kapaciteta dvostrukog sloja povećava se sa 1.349k10^-10 F/cm² na 4.866k10^-10F/cm². Vrednost impedanse se smanjuje sa 4,857 na 4,428. Stoga implicira da bi ljudi sa ortodontskom žicom od legure SS 18/8 trebali izbegavati oralno uzimanje soka Digene tablete.

Ključne reči: ortodontske žice, SS18/8, otpornost na koroziju, sok tablete Digene, veštačka pljuvačka.

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Application of perlite and waste of paper production for manufacturing of cement clinker

Abstract

The possibility of making cement clinker with the integrated use of natural raw materials of volcanic origin and waste from paper production (scope) has been studied. The analysis of the dependence of the composition of the raw mixture based on the system chalk – perlite – scope on the specified characteristics of cement using the specially developed computer program “Clinker” has been carried out. The composition of the initial mixture for the manufacturing of cement clinker was determined with a quantitative ratio of perlite : scope = 1 : 3.5 has been investigated. The features of the formation of the phase composition and properties of the binder during the firing of the raw mixture in the range of maximum temperatures 1200 – 1400 ⁰C are shown.

Keywords: cement, clinker, perlite, scope, mixture raw material, composition, firing, phases crystalline, properties.

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Primena perlita i otpada od proizvodnje papira za proizvodnju cementnog clinkera

Izvod

Proučavana je mogućnost proizvodnje cementnog klinkera uz integrisanu upotrebu prirodnih sirovina vulkanskog porekla i otpada iz proizvodnje papira (obim). Sprovedena je analiza zavisnosti sastava sirovinske smeše na osnovu sistemske krede – perlit – opsega od navedenih karakteristika cementa pomoću posebno razvijenog računarskog programa „Klinker“. Sastav početne smeše za proizvodnju cementnog klinkera određen je kvantitativnim odnosom perlita: opseg = 1: 3,5 je ispitan. Prikazane su karakteristike formiranja faznog sastava i svojstva veziva tokom pečenja sirove smeše u opsegu maksimalnih temperatura 1200 – 1400 ⁰C.

Ključne reči: cement, klinker, perlit, opseg, mešavina sirovina, sastav, pečenje, faze kristalne, svojstva.

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