Zaštita Materijala 4. 2023

Corrosion protection of mild steel using nanomaterials coating

Abstract

Effectiveness of nanoparticle coatings in preventing corrosion of mild steel metal samples were experimentally determined. TiO₂ and ZrO₂ nanoparticles coatings were done by brush coating. Different samples were prepared by varying the parameters such as thickness of coatings, concentration of nanoparticles and temperature of heat treatment. Corrosion rate of both uncoated mild steel and coated using TiO₂, ZrO₂ samples was determined in the corrosive environments of 1M HCl and 3.5 wt% NaCl. From the experiments it was found that the coated mild steel samples prepared at temperature 80oC are more effective than samples prepared at 200 ^oC. It is observed that TiO₂ coatings prepared with ratio 2:0.3, 0.182 mm coating thickness and heat treated at 80^oC, and ZrO₂ coatings with thickness of 0.185 mm, prepared from nanoparticle paste of 1:0.3 ratios, heat treated at 80 ^oC, have shown better protection for mild steel in 1M HCl and 3.5% NaCl solutions compared with other TiO₂ and ZrO₂ coatings.

Keywords: corrosion protection, nano composites; corrosion resistance, mild steel

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Zaštita od korozije mekog čelika korišćenjem premaza od nanomaterijala

Izvod

Eksperimentalno je utvrđena efikasnost premaza nanočestica u sprečavanju korozije uzoraka metala od mekog čelika. Oblaganje nanočestica TiO₂ i ZrO₂ urađeno je premazivanjem četkom. Različiti uzorci su pripremljeni variranjem parametara kao što su debljina premaza, koncentracija nanočestica i temperatura termičke obrade. Stopa korozije i neobloženog mekog čelika i obloženog uzorcima TiO₂, ZrO₂ određena je u korozivnom okruženju 1M HCl i 3,5 tež% NaCl. Iz eksperimenata je ustanovljeno da su obloženi uzorci mekog čelika pripremljeni na temperaturi 80oC efikasniji od uzoraka pripremljenih na 200^oC. Uočeno je da su se bolje pokazali TiO₂ premazi pripremljeni u odnosu 2:0,3, debljine prevlake 0,182 mm i termički obrađeni na 80^oC i ZrO₂ prevlake debljine 0,185 mm, pripremljene od paste nanočestica u odnosu 1:0,3, termički obrađene na 80^oC. zaštita mekog čelika u 1MHC i 3,5% rastvorima NaCl u poređenju sa drugim TiO₂ i ZrO₂ premazima.

Ključne reči: zaštita od korozije, nano kompoziti; otpornost na koroziju, meki čelik

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Recent findings on corrosion of ferritic stainless steel weldments: A review

Abstract

This study covers the review of the degradation of ferritic stainless-steel weldments between 2015 and 2022. The industrial and automotive sectors make extensive use of ferritic stainless steel (FSS) due to its superior oxidation and corrosion resistance, low price, high thermal conductivity, and low thermal expansion. However, it has been reported that ferritic stainless steel is harder to weld than austenitic stainless steel and that doing so would probably result in a weaker welded joint owing to the coarsening of grains high welding temperatures. According to past research, the amount of heat applied during the welding procedure affected how soon the FSS (409 M) weldment degraded after being exposed to NaCl (3.5%) medium. The coarsening of the grains was considered to be the cause of this. When the shielding gas’ CO₂ content increased, the intergranular corrosion of the FSS weld metal was found to increase. Welds made with the ER430LNb filler metal had significantly lower intergranular corrosion of FSS (AISI 441) than those made with the ER430Ti filler metal. It was discovered that boiling Cu-CuSO₄ – 50% H₂SO₄ solution increased the corrosion rate for the FSS (AISI 430) weldment more than boiling 40% HNO₃ Solution. Weldments made of FSS (AISI 430) were found to be negatively affected by the Cu-CuSO₄ – 50% H₂SO₄ environment in terms of intergranular corrosion attack.

Keywords: Corrosion, weldment, ferritic stainless steel, welding, FSS

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Novi nalazi o koroziji feritnih varova od nerdjajuceg celika – pregled

Izvod

Ova studija pokriva pregled degradacije feritnih zavarenih spojeva od nerđajućeg čelika između 2015. i 2022. Industrijski i automobilski sektor u velikoj meri koriste feritni nerđajući čelik (FSS) zbog njegove superiorne otpornosti na oksidaciju i koroziju, niske cene, visoke toplotne provodljivosti, i nisko toplotno širenje. Međutim, prijavljeno je da je feritni nerđajući čelik teže zavariti od austenitnog nerđajućeg čelika i da bi to verovatno rezultiralo slabijim zavarenim spojem jer visoke temperature zavarivanja ogrubljuju zrno. Prema prošlim istraživanjima, količina toplote primenjene tokom postupka zavarivanja uticala je na to koliko brzo se FSS (409 M) zavar degradirao nakon izlaganja medijumu NaCl (3,5%). Smatralo se da je uzrok tome ugrušavanje zrna. Kada se povećao sadržaj CO₂ u zaštitnom gasu, otkriveno je da se povećava intergranularna korozija metala šava FSS. Zavari napravljeni dodatnim metalom ER430LNb imali su značajno manju intergranularnu koroziju FSS (AISI 441) od onih napravljenih sa dodatnim metalom ER430Ti. Otkriveno je da ključanje rastvora Cu-CuSO₄ – 50% H₂SO₄ povećava stopu korozije za FSS (AISI 430) zavar više od ključanja 40% rastvora HNO₃. Utvrđeno je da na zavare napravljene od FSS (AISI 430) negativno utiče okruženje Cu-CuSO₄ – 50% H₂SO₄ u smislu napada intergranularne korozije.

Ključne reči: Korozija, zavarivanje, feritni nerđajući čelik, zavarivanje, FSS

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Effect of polka raspberry (Rubus idaeus L.) extract on corrosion inhibition of bronze

Abstract

Plant extracts contain a large number of organic compounds, and one of the large groups of compounds present are phenolic compounds. Researchers have shown that a certain number of these compounds can be used as effective metal corrosion inhibitors. Plant extracts of raspberries (leaves, flowers, and fruit) were obtained by ultrasonic extraction using 96% ethanol as a solvent. The UV/Vis spectrophotometric method was used to determine the content of total phenols in plant extracts. Phenolic acids and flavonoids in plant extracts were separated and quantified using the HPLC method. Tafel extrapolation was used for electrochemical characteristics. The corrosion characteristics and behavior of bronze in 3% NaCl solution, with and without the presence of plant extracts were investigated. The content of total phenols in leaves was found to be 107.14±3.63 mg/g in flowers 148.99±9.02 mg/g and in fruits was 8.75±0.61 mg/g. Leaf extract in a concentration of 0.04828 g/L according to the Tafel extrapolation method provides the best protection for bronze in a 3% NaCl solution. The same concentration in the case of flower and fruit extracts proved to be the most favorable.

Keywords: raspberry extract, ultrasound, corrosion inhibition, bronze

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Uticaj ekstrakta polka maline (Rubus idaeus L.) na inhibiciju korozije bronze

Izvod

Biljni ekstrakti sadrže veliki broj organskih spojeva, a jedni od mnogih su fenolni spojevi. Ispitivanja su pokazala da se određeni broj ovih spojeve može primijeniti kao efikasni inhibitori korozije metala. Biljni ekstrakti maline (list, cvijet i plod) dobijeni su metodom ultrazvučne ekstrakcije uz primjenu 96% etanola kao rastvarača. UV/Vis spektrofotometrijskom metodom je određen sadržaj ukupnih fenola u biljnim ekstraktima. HPLC-metodom su razdvojene i kvantificirane fenolne kiseline i flavonoidi u biljnim ekstraktima. Za elektrohemijske karakteristike korištena je Tafelova ekstrapolacija. Ispitivane su korozione karakteristike i ponašanje bronze u 3% rastvoru NaCl i u prisustvu biljnih ekstrakata.  Sadržaj ukupnih fenola kod lista je 107.14±3.63, cvijeta 148.99±9.02 i ploda 8.75±0.61 mgGAE/g ekstrakta. Metodom Tafelove ekstrapolacije je utvrđeno da koncentracija ekstrakta lista, cvijeta i ploda  od 0.04828 g/L pruža najbolju zaštitu bronzi u 3% NaCl.

Ključne riječi: ekstrakt maline, ultrazvuk, inhibicija korozije, bronza

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Utilization of plastic and glass waste mixed with sand as an alternative brick materials

Abstract

Nowadays, the research for innovative approaches to and practices for plastic waste in a circular economy has acquired a big attention. Plastic waste causes a serious environmental pollution concern. Meantime, the cement industry is one of the biggest sources of carbon monoxide and carbon dioxide emissions, which is considered as another environmental challenge to change of climate. All those and others side effects of plastic waste, make the plastic sand glass bricks an attractive alternative material to construction. In this paper, the plastic and glass waste were used at different percentage for replacing cement as a binder to produce non-traditional concretes. The literature review reveals that there is a deficiency of studies that manage the plastic sand glass as a construction material from economic perspective. Plastic sand glass bricks prepared could be a workable solution for combating issues related to solid waste. The results showed that the compressive strength decreased with increasing ratios of plastic to sand. On another hand, it is increased with increasing of sand ratio. Plastic brick prepared poses a density less than the conventional bricks, and acceptable hardness. Low water absorption also reflected that the plastic brick could be used in the construction. TGA and DSC analysis showed that the plastic brick prepared has a good thermal stability and the decomposition is in the limited and acceptable range. Optimization of the two effective variables (plastic/sand and galas ratios) has been made and correlating the results obtained using Box–Wilson statistical method to create a model for describing the predictable properties of a new product.

Keywords: material waste, brick industry, compressive strength, hardness

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Korišćenje plastičnog i staklenog otpada pomešanog sa peskom kao alternativni materijali od cigle

Izvod

U današnje vreme, istraživanje inovativnih pristupa i praksa za plastični otpad u cirkularnoj ekonomiji dobija veliku pažnju. Plastični otpad izaziva ozbiljnu zabrinutost zbog zagađenja životne sredine. U međuvremenu, industrija cementa je jedan od najvećih izvora emisije ugljen-monoksida i ugljen-dioksida, što se smatra još jednim ekološkim izazovom promene klime. Sve te i druge nuspojave plastičnog otpada čine plastične peščane staklene cigle atraktivnim alternativnim materijalom za izgradnju. U ovom radu plastični i stakleni otpad korišćeni su u različitim procentima za zamenu cementa kao veziva za proizvodnju netradicionalnih betona. Pregled literature otkriva da postoji nedostatak studija koje upravljaju plastičnim peščanim staklom kao građevinskim materijalom iz ekonomske perspektive. Pripremljene plastične staklene opeke od peska mogu biti izvodljivo rešenje za borbu protiv problema u vezi sa čvrstim otpadom. Rezultati su pokazali da se čvrstoća na pritisak smanjuje sa povećanjem odnosa plastike i peska. S druge strane, povećava se sa povećanjem odnosa peska. Pripremljena plastična cigla ima gustinu manju od konvencionalne cigle i prihvatljivu tvrdoću. Niska apsorpcija vode je, takođe, pokazala da se plastična cigla može koristiti u konstrukciji. TGA i DSC analize su pokazale da pripremljena plastična cigla ima dobru termičku stabilnost i da je razlaganje u ograničenom i prihvatljivom opsegu. Urađena je optimizacija dve efektivne varijable (odnos plastika/pesak i galas) i korelacija rezultata dobijenih primenom Bok-Vilson statističke metode za kreiranje modela za opisivanje predvidljivih osobina novog proizvoda.

Ključne reči: materijalni otpad; Industrija opeke; jačina pritiska; tvrdoća

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A preliminary study on assessment of air quality in Tirana, Albania

Abstract

The concentrations of particulate matter and Fe in airborne particulate matter and transplanted moss were investigated to evaluate the air quality of Tirana city. It was carried out in the summer of 2021 and the winter of 2020–2021. Particulate matter of various sizes (PM2.5 and PM10) was collected on Teflon-coated glass fibre filters. Fe was determined in PMs and moss transplants, the last were exposed for two months at the same monitoring site as PMs. The measurements were carried out in areas with heavy traffic during the summer under relatively high air temperatures, up to 23° C, which can affect the high concentrations of solid particles in the air and therefore high Fe levels. Statistical analysis was used to discuss the results of particulate matter and iron in solid particles and moss. A higher concentration of Fe was found in total suspended particles (TSP) and a lower concentration in smaller particles. The concentration data were compared with the recommended values in the European Directives. The concentrations of all parameters under investigation were higher than the permitted ones for rural and residential areas and lower than the recommended values for industrial areas. Correlation analysis revealed high and significant correlations (R > 0.8, p < 0.05) between Fe concentrations in moss transplants and particulate matter, showing a high effect of particulate matter on airborne Fe. It may increase human exposure through inhalation and lead to harmful health problems. This requires stronger measures to improve air quality in the city.

Keywords: air quality, PM, moss bags, cross roads, residential area, Tirana

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Preliminarna studija o proceni kvaliteta vazduha u Tirani, Albanija

Izvod

Koncentracije čestica i Fe u česticama u vazduhu i presađenoj mahovini su istražene da bi se procenio kvalitet vazduha grada Tirane. Izveden je u leto 2021. i u zimu 2020–2021. Čestice različitih veličina (PM2,5 i PM10) su sakupljene na filterima od staklenih vlakana obloženih teflonom. Fe je određen u PM i transplantacijama mahovine, poslednji su bili izloženi dva meseca na istom mestu praćenja kao i PM. Merenja su vršena u područjima sa gustim saobraćajem tokom leta pod relativno visokim temperaturama vazduha, do 23°C, što može uticati na visoke koncentracije čvrstih čestica u vazduhu, a samim tim i na visok nivo Fe. Statistička analiza je korišćena za razmatranje rezultata čestica i gvožđa u čvrstim česticama i mahovini. Veća koncentracija Fe je nađena u ukupnim suspendovanim česticama (TSP), a niža koncentracija u manjim česticama. Podaci o koncentracijama su upoređeni sa vrednostima preporučenim u evropskim direktivama. Koncentracije svih ispitivanih parametara bile su veće od dozvoljenih za ruralna i stambena područja i niže od preporučenih vrednosti za industrijska područja. Korelaciona analiza je pokazala visoke i značajne korelacije (R > 0,8, p < 0,05) između koncentracija Fe u transplantaciji mahovine i čestice, pokazujući visok efekat čestica na Fe u vazduhu. Može povećati izloženost ljudi udisanjem i dovesti do štetnih zdravstvenih problema. Za to su potrebne jače mere za poboljšanje kvaliteta vazduha u gradu.

Ključne reči: kvalitet vazduha, PM, kese od mahovine, raskrsnice puteva, stambeno naselje, Tirana

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Predictive model for the corrosion inhibition of mild steel in 1.5 M HCl by the leaf-juice of Carica papaya

Abstract

This current study employed the predictive models driven by the artificial neural network (ANN) and multiple regression (MR) to forecast the corrosion inhibition of mild steel in 1.5 M HCl by the leaves of the Carica papaya plant. Corrosion studies were carried out using the weight loss method at room temperature. The corrosion rate of the mild steel coupon, obtained from the study environment was predicted taking into cognizance the influence of the independent variables viz: the time of exposure, the concentration of HCl (1.5 M), and the concentration of the papaya leaf juice. The fresh papaya leaves were obtained within the surrounding of the Federal University of Technology, Owerri, Imo State, Nigeria. A grinding machine powered by an internal combustion engine was used for grinding the fresh leaves, and a white cloth was utilized to squeeze out the juice. Filtration of the produced juice was done twice with a clean white cloth. Different bowls containing mild steel coupons (5.0 x 5.0 x 0.1 cm) and HCl (1.5 M) solutions were treated with Carica papaya leaf extracts at concentrations of 5 ml, 10 ml, 15 ml, and 20 ml. Results indicated that the highest inhibition efficiency of 95.91% was observed after 120 hours when 20 ml of papaya leaf extract was added. Conversely, the highest corrosion rate of 114.19 mpy was recorded after 24 hours of exposure to HCl (1.5 M) with 5 ml of papaya leaf extract. Generally, the addition of papaya leaf extract in different concentrations added to 1.5 M HCl resulted in a decrease in the rate of mild steel corrosion over time. It was noted that the prediction of the experimental corrosion rate by the artificial neural network offered a lesser error in comparison with that obtained by multiple regression according to the error margin obtained after the prediction of the experimental corrosion rate.

Keywords: Inhibitive model, papaya leaf juice, corrosion, mild steel, artificial neural network, multiple regression

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Modeliranje inhibitornog ponašanja ekstrakta lista papaje na koroziju mekog čelika u 1,5 M HCl

Izvod

Ova studija razvila je model za inhibiciju korozije mekog čelika u 1,5M HCl od strane listova biljke papaje Carica. Studije korozije su sprovedene metodom gubitka težine na sobnoj temperaturi. Brzina korozije uzorka od mekog čelika, dobijenog iz okruženja za proučavanje, je predviđena uzimajući u obzir uticaj nezavisnih varijabli, a to su: vreme izlaganja, koncentracija HCl (1,5M) i koncentracija soka lista papaje. Predviđanje je postignuto korišćenjem višestruke regresije (MR) i veštačkih neuronskih mreža (ANN). Pre toga, sveži listovi papaje su nabavljeni u okruženju Federalnog tehnološkog univerziteta, Overri, država Imo, Nigerija. Za mlevenje svežeg lišća korišćena je mašina za mlevenje sa motorom sa unutrašnjim sagorevanjem, a za ceđenje soka korišćena je bela krpa. Filtriranje proizvedenog soka je obavljeno dva puta čistom belom krpom. Različite posude koje su sadržavale uzorke od mekog čelika (5,0 k 5,0 k 0,1 cm) i rastvore HCl (1,5 M) tretirane su ekstraktima listova Carica papaje u koncentracijama od 5 ml, 10 ml, 15 ml i 20 ml. Rezultati su pokazali da je najveća efikasnost inhibicije od 95,91% primećena nakon 120 sati kada je dodato 20 ml ekstrakta lista papaje. Nasuprot tome, najveća brzina korozije od 114,19 mpi je zabeležena nakon 24 sata izlaganja HCl (1,5M) sa 5 ml ekstrakta lista papaje. Generalno, dodavanje ekstrakta listova papaje u različitim koncentracijama koje se dodaju u 1,5M HCl rezultiralo je smanjenjem brzine blage korozije čelika tokom vremena. Primećeno je da predviđanje eksperimentalne brzine korozije veštačkom neuronskom mrežom nudi manju grešku u poređenju sa onom dobijenom višestrukom regresijom prema margini greške dobijenoj nakon predviđanja eksperimentalne brzine korozije.

Ključne reči: Inhibitivni model, sok od lista papaje, korozija, meki čelik, veštačka neuronska mreža, višestruka regresija

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Metallurgical investigations on 17th century Maratha Shivrai copper coins

Abstract

The technical and numismatic complexities of Maratha Shivrai copper coins have been well documented. However, more information still needs to be on the chemical, mineralogical, microstructure composition, and metallurgical process employed for coin minting. Five Shivari coins (17-18 century CE) were studied under ED-XRF, XRD, and cross-sectional analysis by SEM-EDX. Scientific investigations reveal that the Maratha practiced excellent cupellation techniques to remove most ore impurities. The ED-XRF data on the surface and interior indicate that the coin comprises pure copper, and copper content varies between 97.73% to 100%. The coin surfaces are free from ore impurities like sulphur, Lead, tin, phosphorus, etc., and the black stains observed are due to copper mineralization detected through XRD analysis. There is a slight iron concentration gradient on the coin surfaces (4.48%) vis-à-vis the inner core (0.14%). Cross-sectional analysis revealed many cracks and cavities in the coin interior due to copper mineralization threatening its stability if not taken care of. The archaeo-metallurgical studies of the coin interior reveal that significant impurities like Lead, sulphur, tin, iron, etc., are present in traces due to excellent polling, and Shivrai is a single-phase copper coin.

Keywords:  Shivrai copper coins, Maratha dynasty, Cupellation, Metallography, Corrosion

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Metalurška istraživanja bakarnog novca iz 17. veka Maratha Shivrai

Izvod

Tehnička i numizmatička složenost bakarnih kovanica Maratha Šivrai je dobro dokumentovana. Međutim, još uvek je potrebno više informacija o hemijskom, mineraloškom, mikrostrukturnom sastavu i metalurškom procesu koji se koristi za kovanje novčića. Pet Šivari kovanica (17-18 vek n.e.) proučavano je pod ED-KSRF, KSRD i analizom poprečnog preseka pomoću SEM-EDKS. Naučna istraživanja otkrivaju da su Maratha praktikovali odlične tehnike kupelacije kako bi uklonili većinu nečistoća rude. Podaci ED-KSRF na površini i unutrašnjosti ukazuju da novčić sadrži čisti bakar, a sadržaj bakra varira između 97,73% do 100%. Površine novčića su slobodne od rudnih nečistoća kao što su sumpor, olovo, kalaj, fosfor, itd., a uočene crne mrlje su posledica mineralizacije bakra otkrivene KSRD analizom. Postoji blagi gradijent koncentracije gvožđa na površini novčića (4,48%) u odnosu na unutrašnje jezgro (0,14%). Analiza poprečnog preseka otkrila je mnogo pukotina i šupljina u unutrašnjosti novčića zbog mineralizacije bakra koja ugrožava njegovu stabilnost ako se ne vodi računa o tome. Arheo-metalurška istraživanja unutrašnjosti novčića otkrivaju da su značajne nečistoće poput olova, sumpora, kalaja, gvožđa itd. prisutne u tragovima zbog odličnog ispitivanja, a Šivrai je jednofazni bakarni novčić.

Ključne reči: Šivrai bakarni novčići, dinastija Maratha, kupelacija, metalografija, korozija

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Taguchi design of experiments based optimization and experimental investigation of mechanical performance of hybrid epoxy nanocomposites

Abstract

The rising demand of safety in the aerospace and automobile industry is continuously motivating researchers to develop high strength, lightweight hybrid polymer composites, usually consisting a combination of carbon nanotubes (CNTs) and ceramic nanoparticles in the epoxy matrix. However, the development of such composites are usually hindered by some existing challenges, such as optimization of the concentration of CNTs, nanoparticles and their distribution in viscous epoxy matrices. In order to make the most of the impressive mechanical characteristics of CNTs and SiO₂ nanoparticles, ultrasonic dual mixing (UDM) technique was employed to develop MWCNT/SiO₂ based hybrid epoxy nanocomposites (HENCs). A well-known approach, such as the Taguchi design of experiment, was used to optimize the concentration of MWCNT, SiO₂ nanoparticles in epoxy and curing cycle of epoxy with respect to the tensile strength of the resulting HENCs. Additionally, the tensile strength, Young’s Modulus, Strain to failure, and hardness were measured for HENCs. The results revealed that the optimal concentration of 1% MWCNT and 10% SiO₂ leads to the maximum increase in tensile strength and other mechanical properties of the HENCs. 

Keywords: hybrid nanocomposite, ultrasonic dual mixing, optimization, micromechanics, epoxy, Mechanical properties

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Taguchi dizajn optimizacije zasnovane na eksperimentima i eksperimentalno ispitivanje mehaničkih performansi hibridnih epoksidnih nanokompozita

Izvod

Rastuća potražnja za bezbednošću u vazduhoplovnoj i automobilskoj industriji kontinuirano motiviše istraživače da razviju lagane hibridne polimerne kompozite visoke čvrstoće, koji se obično sastoje od kombinacije ugljeničnih nanocevi (CNT) i keramičkih nanočestica u epoksidnoj matrici. Međutim, razvoj ovakvih kompozita obično ometaju neki postojeći izazovi, kao što su optimizacija koncentracije CNT-a, nanočestica i njihova distribucija u viskoznim epoksidnim matricama. Da bi se maksimalno iskoristile impresivne mehaničke karakteristike CNT-a i nanočestica SiO₂, korišćena je tehnika ultrazvučnog dvostrukog mešanja (UDM) za razvoj hibridnih epoksidnih nanokompozita (HENC) zasnovanih na MVCNT/SiO₂. Dobro poznati pristup, kao što je Taguchi dizajn eksperimenta, korišćen je za optimizaciju koncentracije MVCNT, SiO₂ nanočestica u epoksidu i ciklusa očvršćavanja epoksida u odnosu na zateznu čvrstoću nastalih HENC. Dodatno, zatezna čvrstoća, Jangov modul, deformacija do loma i tvrdoća su mereni za HENC. Rezultati su otkrili da optimalna koncentracija od 1% MVCNT i 10% SiO₂ dovodi do maksimalnog povećanja zatezne čvrstoće i drugih mehaničkih svojstava HENC-a.

Ključne reči: hibridni nanokompozit, ultrazvučno dvostruko mešanje, optimizacija, mikromehanika, epoksid, mehanička svojstva

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Synthesis and solvatochromism of some hydroxy substituted phenyl azo pyridone dyes

Abstract

Aryl azo dyes are widely used due to their excellent physicochemical properties (primarily high value of the molar extinction coefficient and great resistance to light and wet processing) and the fact that can be obtained in a simple method of diazotization and coupling. In this paper, three new dyes of 5-(hydroxy substituted phenylazo)-3-cyano-6-hydroxy-4-methyl-2-pyridone were synthesized by a diazo coupling reaction. The obtained dyes were characterized by melting point, IR, NMR, and UV-Vis spectroscopy. Given the fact that the structure of the molecule and interactions obtained with the surrounding medium can affect its activity, the possibility of azo hydrazo tautomerism has been studied, as the influence of the position of the substituent present (orto-, meta- and para position). In addition, the effect of the solvent used was determined by applying a solvatochromic model using the LSER method (linear solvation energy relationship). Obtaining information about the inter- and intramolecular relationships that newly synthesized compounds can achieve may be of great importance for all further investigations and their potential application as biologically active compounds.

Keywords: Aryl azo dyes, carbonitrile, synthesis, azo-hydrazone tautomerism,  solvatochromism, intermolecular interaction

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Sinteza i solvatohromizam nekih hidroksi supstituisanih fenilazo piridonskih boja

Izvod

Aril azo boje imaju široku primenu zbog svojih odličnih fizičko-hemijskih svojstava (prvenstveno visoke vrednosti molarnog ekstinkcionog koeficijenta i velike otpornosti na svetlost i vlagu) i činjenice da se mogu dobiti jednostavnom metodom diazotizacije i kuplovanja. U ovom radu susintetisane tri boje 5-(hidroksi supstituisane fenilazo)-3-cijano-6-hidroksi-4-metil-2-piridona reakcijom diazo kuplovanja. Dobijene boje su okarakterisane tačkom topljenja, IR, NMR i UV-Vis spektroskopijom. S obzirom na to da struktura molekula i ostvarene interakcije sa okolnim medijumom mogu uticati na aktivnost ispitivanih jedinjenja, proučavan je solvatohromizam i mogućnost azo-hidrazon tautomerije, kao i uticaj položaja prisutnog supstituenta (orto-, meta- i para pozicija ) u strukturi ispitivanih jedinjenja. Pored toga, kvantitatifikovan je efekat korišćenih rastvarača primenom dva solvatohromna modela koristeći LSER metodu (linear solvation energy relationship). Dobijanje informacija o inter- i intra-molekulskim interakcijama koje sintetizovana jedinjenja mogu da ostvare su od velike važnosti za sva dalja istraživanja i njihovu potencijalnu primenu kao biološki aktivnih jedinjenja.

Ključne reči: Aril azo boje, karbonitil, sinteza, azo-hidrazon tautomerija, solvatohromizam, inetrmolekulske interakcije

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Anti-corrosion properties of expired ropinirole (ERN System) drug as inhibitor for mild steel in 1M HCl

Abstract

Ropinirole is utilized to forestall sickness and spewing brought about by disease chemotherapy and radiation treatment. It works by hindering serotonin, a characteristic substance in the body that causes queasiness and retching. After lapse, they can be utilized as consumption added substances or inhibitors. The consumption obstruction activity of terminated Ropinirole drug (ERN) on the erosion of mild steel in 1M HCl medium has been assessed by the weight reduction strategy. The weight reduction estimations showed that erosion restraint effectiveness expanded with expanding the convergence of the inhibitor, with greatest security productivity at 0.001 M. The temperature influences the pace of erosion; at high temperatures, the consumption restraint effectiveness diminishes, and erosion is noticed. The robotic parts of consumption obstruction have been concentrated by the potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The potentiodynamic polarization strategy uncovers that the inhibitor framework capabilities as a cathodic kind of inhibitor, controlling cathodic responses. An inhibitor can decrease corrosion current due to inhibited reaction rate and increase Linear polarization resistance due to the formation of a barrier on the electrode surface. time., since, within the sight of an inhibitor framework, the charge moves opposition esteem increments and the twofold layer capacitance esteem diminishes. The surface morphology of repressed gentle steel was dissected by filtering electron microscopy (SEM). The natural constituents on the gentle steel surface have been portrayed by energy dispersive X-beam spectroscopy (EDAX). The harshness of the gentle steel surface in cleaned MS, clear MS, and inhibitor frameworks has been described by nuclear power microscopy (AFM). The outcomes have obviously shown that ERN has a repressing limit with regards to decreasing the erosion of gentle steel submerged in hydrochloric corrosive medium.

Keywords: Acidic solutions, Ropinirole, Mild steel, EIS, Isotherm, SEM-EDAX and AFM.

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Antikorozivna svojstva leka Ropinirol (ERN sistem) sa isteklim rokom trajanja kao inhibitora za meki čelik u 1M HCl

Izvod

Ropinirol se koristi za prevenciju bolesti i za hemoterapiju i lečenje zračenjem. Deluje tako što ometa serotonin, karakterističnu supstancu u telu koja izaziva mučninu i povraćanje. Nakon isteka, mogu se koristiti kao inhibitori korozije. Aktivnost opstrukcije potrošnje prekinutog leka Ropinirol (ERN) na eroziju mekog čelika u 1M HCl medijumu je procenjena strategijom smanjenja težine. Procene smanjenja težine su pokazale da se efikasnost ograničavanja erozije povećava sa povećanjem konvergencije inhibitora, sa najvećom bezbednosnom produktivnošću na 0,001 M. Temperatura utiče na tempo erozije; na visokim temperaturama smanjuje se efikasnost ograničavanja potrošnje i primećuje se erozija. Robotski delovi opstrukcije potrošnje koncentrisani su metodom potenciodinamičke polarizacije i spektroskopijom elektrohemijske impedanse (EIS). Potenciodinamička strategija polarizacije otkriva da je okvir inhibitora sposoban kao katodna vrsta inhibitora, koji kontroliše katodne odgovore. Inhibitor može smanjiti struju korozije zbog inhibirane brzine reakcije i povećati otpor linearne polarizacije zbog formiranja barijere na površini elektrode. Površinska morfologija potisnutog mekog čelika je skenirana pomoću filterske elektronske mikroskopije (SEM). Prirodni sastojci na čeličnoj površini prikazani su spektroskopijom X-zraka sa disperzijom energije (EDAKS). Oštrina čelične površine u očišćenom MS, bistrom MS i inhibitorskim okvirima opisana je pomoću AFM. Rezultati su očigledno pokazali da ERN ima represivnu granicu u pogledu smanjenja erozije mekog čelika potopljenog u hlorovodoničnu korozivnu sredinu.

Ključne reči: kiseli rastvori, ropinirol, blagi čelik, EIS, izoterma, SEM-EDAX i AFM.

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Synthesis of copper sulphide thin film on Indium Tin Oxide glass plate by SILAR method and its characterization

Abstract

Thin film of copper sulphide has been deposited on Indium Tin Oxide (ITO) glass plate. This film has been characterized by UV-Visible reflectance spectroscopy, FTIR spectroscopy, EDAX, and SEM. The film has been subjected to polarization study by immersing in sea water. The above studies on the thin film has been compared with copper sulphide prepared by chemical method; that is by mixing a solution of copper sulphate and sodium sulphide solution. For comparison study methods such as UV-Visible reflectance  and FTIR have been employed. The UV-Visible reflectance spectrum reveals that the band gap of the copper sulphide film is 1.823eV. This indicates that the film functions as semi conductor. The UV- Visible absorption study of the film indicates that the λ_max appears at 310 nm. The FTIR study of the copper sulphide film confirms the presence of CuS. The polarization study reveals that the linear polarization resistance (LPR) value decreases, when compared to ITO plate immersed in sea water.This indicates that the current flowing through the thin film increases.Such a finding can be used in solar cells. This is supported by the fact that the current flowing through the thin film, when it is immersed in sea water increases, when compared to the current flowing through the empty glass plate (without black coating) is immersed in sea water. This is further supported by the fact that for black thin film, the band gap decreases after coating.
The EDAX study confirms the presence of elements Cu and S.The SEM study reveals the presence of thin film of copper sulphide on the ITO glass plate. The particle size of the copper sulphide is in the range of 101.1nm, 107.8nm and 114.5nm. Thus it is encouraging to note that copper sulphide nano particles have been prepared by SILAR method.

Keywords: synthesis of thin film, copper sulphide, SILAR method, characterization, FTIR, EDAX.

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Sinteza tankog filma bakar sulfida na staklenoj ploči od indijum-kalaj oksida metodom SILAR i njena karakterizacija

Izvod

Tanak film bakar-sulfida nanesen je na staklenu ploču indijum-kalaj oksida (ITO). Ovaj film je okarakterisan UV-vidljivom refleksivnom spektroskopijom, FTIR spektroskopijom, EDAKS i SEM. Film je podvrgnut proučavanju polarizacije uranjanjem u morsku vodu. Gore navedene studije o tankom filmu su upoređene sa bakar-sulfidom pripremljenim hemijskom metodom; odnosno mešanjem rastvora bakar-sulfata i rastvora natrijum-sulfida. Za poređenje korišćene su metode istraživanja kao što su UV-vidljiva refleksija i FTIR. Spektar UV-vidljive refleksije otkriva da je deo u okviru bakar-sulfidnog filma 1,823eV. Ovo ukazuje da film funkcioniše kao poluprovodnik. Studija UV-vidljive apsorpcije filma pokazuje da se λ max pojavljuje na 310 nm. FTIR studija filma bakar-sulfida potvrđuje prisustvo CuS. Studija polarizacije otkriva da se vrednost linearnog polarizacionog otpora (LPR) smanjuje u poređenju sa ITO pločom uronjenom u morsku vodu. Ovo ukazuje da se struja koja teče kroz tanki film povećava. Takav nalaz se može koristiti u solarnim ćelijama. Tome u prilog govori i činjenica da se struja koja teče kroz tanki film, kada je uronjen u morsku vodu, povećava, u poređenju sa strujom koja teče kroz praznu staklenu ploču (bez crnog premaza) uronjena u morsku vodu. Ovo je dodatno potkrepljeno činjenicom da se za crni tanki film, deo u pojasu smanjuje nakon nanošenja premaza. EDAKS studija potvrđuje prisustvo elemenata Cu i S. SEM studija otkriva prisustvo tankog filma bakar-sulfida na ITO staklenoj ploči. Veličina čestica bakarnog sulfida je u opsegu od 101,1 nm, 107,8 nm i 114,5 nm. Stoga je ohrabrujuće primetiti da su nanočestice bakar sulfida pripremljene SILAR metodom.

Ključne reči: Sinteza tankog filma, bakar sulfid, SILAR metoda, karakterizacija, FTIR, EDAKS.

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Performance analyses of hydroxyethyl cellulose (HEC) polymer as gelling agent in gravel-pack carrier fluid formulation for sand control of hydrocarbon production wells

Abstract

This study considers the performance of 40ppt and 60ppt hydroxyethyl cellulose (HEC) polymer used as a gelling agent in the formulation of carrier fluids for gravel pack transport in sand control operations in oil and gas wells. The gravel pack carrier fluid was prepared by adding adequate amounts of sodium persulfate (SP) used as gel breaker, Fe-2 used as an iron control agent, KCL brine as mixed fluid, K-35 used as pH buffer, BE-6, and BE-35 used as biocides, HEC used as a gelling agent, and distilled water. The effects of temperature, gel loading, and breaker fluid concentration on the rheology, gel break time, and sand settling of the formulated HEC carrier fluid were considered. The results showed that shear stress, plastic viscosity and yield point and consistency factor decreased with an increase in bottomhole temperature for both 40ppt and 60ppt HEC gels. Furthermore, flow behaviour index was observed to be within the range of 0.45±0.1 40ppt and 0.5±0.04 for 60ppt HEC of gel loading, respectively and showing shear-thinning characteristics. Good gravel settling was observed for the HEC gels when in contact with gravel, addition of breaker fluid greatly improved the sand/gravel suspension for 40ppt and 60ppt gel loadings. Gel break time of the HEC gel increased with increasing gel loading, and at higher breaker fluid concentrations, HEC gel degradation becomes more critical as temperature increases. The results highlight the adequate performance of HEC polymer as gravel pack fluid in sand control operation.

Keywords: Carrier fluid, HEC, Sand control, Breaker fluid, Gravel pack

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Analiza performansi polimera hidroksietil celuloze (HEC) kao sredstva za želiranje u tečnoj formulaciji nosača šljunka za kontrolu peska u bunarima za proizvodnju ugljovodonika

Izvod

Ova studija razmatra performanse polimera 40ppt i 60ppt hidroksietil celuloze (HEC) koji se koristi kao sredstvo za želiranje u formulaciji nosećih tečnosti za transport šljunčanog omotača u operacijama kontrole peska u naftnim i gasnim bušotinama. Tečnost za nosač šljunka je pripremljena dodavanjem adekvatnih količina natrijum persulfata (SP) koji se koristi kao razbijanje gela, Fe-2 koji se koristi kilo sredstvo za kontrolu gvožđa, KCL slani rastvor kao mešana tečnost, K-35 koji se koristi kao pH pufer, BE-6, i BE-35 koji se koristi kao biocid, HEC koji se koristi kao sredstvo za želiranje i destilovana voda. Razmatrani su efekti temperature, opterećenja gela i koncentracije tečnosti za razbijanje na reologiju, vreme lomljenja gela i taloženje peska formulisanog HEC nosećeg fluida. Rezultati su pokazali da se napon smicanja, plastični viskozitet i tačka tečenja i faktor konzistencije smanjuju sa povećanjem temperature na dnu rupe i za 40ppt i za 60ppt HEC gelove. Štaviše, uočeno je da je indeks ponašanja protoka u opsegu od 0,45±0,1 40ppt i 0,5±0,04 za 60ppt HEC opterećenja gela, respektivno i pokazuje karakteristike smicanja-razređivanja. Dobro taloženje šljunka je primećeno za HEC gelove kada su u kontaktu sa šljun­kom, dodavanje tečnosti za razbijanje uveliko je poboljšalo suspenziju peska/šljunka za 40ppt i 60ppt gel opterećenja. Vreme loma gela HEC gela se povećava sa povećanjem punjenja gela, a pri višim koncentracijama tečnosti za razbijanje, razgradnja HEC gela postaje kritičnija kako temperatura raste. Rezultati ističu adekvatne performanse HEC polimera kao tečnosti za šljunak u kontroli peska.

Ključne reči: Noseća tečnost, HEC, kontrola peska, tečnost za razbijanje, šljunak

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Simple model and integral method for simulating the growth of the borided layer FeB/Fe₂B on the AISI H13 steel

Abstract

The prediction of boride layer growth kinetics requires the development of a mathematical model. In the present study, two diffusion models (a simple model and an integral method-based model) were proposed to investigate the boriding kinetics of pack-borided AISI H13 steel. These two diffusion models did not consider the effect of boride incubation times of the total boride layer (FeB + Fe₂B). The diffusion coefficients of boron in the FeB and Fe₂B layers were estimated using the proposed integral method-based model. Additionally, the growth rate constants were determined and the layer thickness was calculated after finding the needed parameters. The results obtained were compared to the experimental ones taken from the work of Nait Abdellah et al.[4] and a good agreement has been noticed. Finally, the mass gain has been calculated for both phases, showing that of FeB increased more compared to that of Fe₂B over time.

Keywords: Diffusion model, simulation, boronizing, FeB, Fe₂B, integral method, layer thickness

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Jednostavan model i integralna metoda za simulaciju rasta boridnog sloja FeB/Fe2B na čeliku AISI H13

Izvod

Predviđanje kinetike rasta boridnog sloja zahteva razvoj matematičkog modela. U ovoj studiji predložena su dva modela difuzije (jednostavan model i model zasnovan na integralnoj metodi) za istraživanje kinetike borenja AISI H13 čelika sa bočnim pakovanjem. Ova dva modela difuzije nisu uzela u obzir efekat vremena inkubacije borida ukupnog sloja borida (FeB + Fe₂B). Koeficijenti difuzije bora u slojevima FeB i Fe₂B procenjeni su primenom predloženog modela zasnovanog na integralnoj metodi. Pored toga, određene su konstante brzine rasta i izračunata je debljina sloja nakon pronalaženja potrebnih parametara. Dobijeni rezultati su upoređeni sa eksperimentalnim rezultatima preuzetim iz rada Naita Abdelaha et al. [4] i uočen je dobar dogovor. Konačno, povećanje mase je izračunato za obe faze, pokazujući da se FeB povećava više u poređenju sa Fe₂B tokom vremena.

Ključne reči: model difuzije, simulacija, boronizacija, FeB, Fe₂B, integralna metoda, debljina sloja

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Novel modification of activated charcoal sheet with N-methylpolypyrrole and silver nanoparticles for removal of hexavalent chromium in water treatment processes

Abstract

The novel NPPY-AgNP’s@AC CPN were synthesized and used for batch mode reductive adsorption of hexavalent Chromium (Cr⁺⁶) ions in water treatment processes. The Activated Charcoal (AC) sheet was firstly encapsulated with silver nanoparticles (AgNP’s) by in-situ reduction method and capped with N-methylpolypyrrole (NPPY) to obtain NPPY-AgNP’s@AC conducting polymer nanocomposites (CPN). The obtained CPN were characterized by HR-FESEM, XRD, FTIR, and EDS. The nanocomposite materials showed excellent Cr⁺⁶ ions adsorption efficiency (Ad%) of 97.8% with adsorption capacity (qe) of 340 mg/g. The impact of various parameters like pH, adsorbent dose, initial Cr⁺⁶ ions concentration, temperature, and contact time on Ad% and qe were evaluated. The recycling experiments of NPPY-AgNP’s@AC CPN revealed their enhanced reuse performance and could be utilised for five consecutive cycles without suffering much reductions in their initial efficacy. The novel PPY-AgNP’s@AC CPN seems to be highly efficient materials for Cr⁺⁶ ions removal from polluted water.

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Nova modifikacija lista aktivnog uglja sa N-metilpolipirolom i nanočesticama srebra za uklanjanje heksavalentnog hroma u procesima tretmana vode

Izvod

Novi NPPI-AgNP’s@AC CPN su sintetizovani i korišćeni za serijsku reduktivnu adsorpciju heksavalentnih jona hroma (Cr⁺⁶) u procesima prečišćavanja vode. List sa aktivnim ugljem (AC) je prvo kapsuliran sa nanočesticama srebra (AgNP) metodom redukcije na licu mesta i zatvoren sa N-metilpolipirolom (NPPI) da bi se dobili NPPI-AgNP @AC provodljivi polimerni nanokompoziti (CPN). Dobijeni CPN su okarakterisani pomoću HR-FESEM, XRD, FTIR i EDS. Nanokompozitni materijali su pokazali odličnu efikasnost adsorpcije jona Cr⁺⁶ (Ad%) od 97,8% sa kapacitetom adsorpcije (qe) od 340 mg/g. Ocenjen je uticaj različitih parametara kao što su pH, doza adsorbenta, početna koncentracija Cr+6 jona, temperatura i vreme kontakta na Ad% i qe. Eksperimenti recikliranja NPPI-AgNP’s@AC CPN-a su otkrili njihove poboljšane performanse ponovne upotrebe i mogli su da se koriste u pet uzastopnih ciklusa bez mnogo smanjenja njihove početne efikasnosti. Čini se da je novi PPI-AgNP’s@AC CPN visoko efikasan materijal za uklanjanje Cr⁺⁶ jona iz zagađene vode.

Ključne reči: Joni teških metala, aktivni ugalj, nanočestice srebra, N-metilpolipirol, heksavalentni hromr

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Optical and structural properties of Nd₂O₃-SiO₂ nanocomposite as synthesized from sol-gel technique

Abstract

Nd₂O₃-SiO₂ nanocomposite was prepared in the current work utilising the sol-gel technique. After being heated in air, the amorphous phase of silicates transformed to crystalline phase via intermediate phase as oxide. Due to its comparatively small operating temperature and ability to form nanostructures with precise size, sol-gel approach is a compelling alternative. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), which verified the structural characteristics of neodymium silicate (Nd₂O₃-SiO₂) nanocomposites, were used to characterise the synthesised materials. The effect of duration and annealing temperature on the phase advancement of the silicates has been considered thoroughly. It was discovered that the sample was sintered for 3 hours at various temperatures, thus obtaining neodymium silicates. In addition, Optical characterization of Nd₂O₃ –SiO₂ was performed using Photoluminescence Spectroscopy (PL).

Keywords: Nanocomposites, neodymium silicate, sol-gel, annealing

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Optičke i strukturne osobine Nd₂O₃-SiO₂ nanokompozita sintetizovanog iz Sol-Gel tehnike

Izvod

Nanokompozit  Nd₂O₃-SiO₂ je pripremljen u radu primenom sol-gel tehnike. Nakon zagrevanja na vazduhu, amorfna faza silikata se transformiše u kristalnu fazu preko međufaze kao oksid. Zbog svoje relativno male radne temperature i sposobnosti formiranja nanostruktura sa preciznom veličinom, sol-gel pristup je ubedljiva alternativa. Rendgenska difrakcija praha (XRD), skenirajuća elektronska mikroskopija (SEM) i infracrvena spektroskopija Furijeove transformacije (FTIR), kojima su verifikovane strukturne karakteristike neodimijum silikata (Nd₂O₃-SiO₂) nanokompozita, korišćeni su za karakterizaciju sintetizovanih materijala.
Uticaj trajanja i temperature žarenja na napredovanje faze silikata je detaljno razmotren. Otkriveno je da  kada se uzorak sinteruje 3 sata na različitim temperaturama, dobija se neodimijum silikati. Pored toga, izvršena je optička karakterizacija Nd₂O₃ –SiO₂ korišćenjem fotoluminiscencione spektroskopije (PL).

Ključne reči: nanokompoziti, neodimijum silikat, sol-gel, žarenje

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Magnifying the GCD behaviour of FePO₄ composite with low temperature plasma exposed Bamboo charcoal enforced in energy storage devices

Abstract

Materials based on phosphate have been suggested as suitable electrode components for energy storage devices and also indicated that the phosphate framework can help to keep active sites stable. The physical and chemical properties of Fe-based phosphates make them promising cathode compounds for energy storage systems. In this work, the additive carbonous material as a bamboo charcoal (BCC) which was prepared and activated using the pyrolysis process. The irradiation of DC glow discharge plasma improved the surface attributes such as wettability, adhesion, and conductivity. Here, the hydrothermal technique was used to synthesize FePO₄ nano particles. The dielectric behaviour was analysed at room temperature for pure FePO₄ and composite of FePO₄/Plasma treated BCC. The GCD behaviour of pure FePO₄ and composite of FePO₄/Plasma treated BCC was analysed with aqueous electrolyte of 2M KOH at different current densities. In perspective, the dielectric constant and specific capacitance of the FePO₄/plasma treated BCC material seems to be very strong.

Key words: Bamboo charcoal (BCC), FePO₄ nano particles, DC glow discharge plasma, Surface modification, GCD, dielectric properties etc.

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Uvećavanje GCD ponašanja kompozita FePO₄ sa bambusovim ugljem izloženim plazmi niske temperature, primenjenim u uređajima za skladištenje energije

Izvod

Materijali zasnovani na fosfatu su predloženi kao prikladne komponente elektrode za uređaje za skladištenje energije i takođe su ukazali da fosfatni okvir može pomoći da se aktivna mesta održe stabilnima. Fizička i hemijska svojstva fosfata na bazi Fe čine ih obećavajućim katodnim jedinjenjima za sisteme za skladištenje energije. U ovom radu je aditivni ugljeni materijal kao bambusov ugalj koji je pripremljen i aktiviran postupkom pirolize (BCC). Zračenje plazme DC sjajnog pražnjenja poboljšalo je atribute površine kao što su kvašenje, adhezija i provodljivost. Ovde je korišćena hidrotermalna tehnika za sintezu nanočestica FePO₄. Dielektrično ponašanje je analizirano na sobnoj temperaturi za čisti FePO₄ i kompozit BCC tretiran sa FePO₄/plazmom. GCD ponašanje čistog FePO₄ i kompozita BCC tretiranog FePO₄/plazmom je analizirano sa vode­nim elektrolitom od 2M KOH pri različitim gustinama struje. U perspektivi, čini se da su dielektrična konstanta i specifična kapacitivnost BCC materijala tretiranog FePO₄/plazmom veoma jaki.

Ključne reči: Bambusov ugalj (BCC), FePO₄ nano čestice, DC usijana plazma, modifikacija površine, GCD, dielektrična svojstva itd.

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