Zaštita Materijala 4. 2025

Presentation of methods of obtaining, properties and possibilities of application of new anticorrosive agents – nanostructured materials based on lho

Abstract

In recent years, layered double hydroxide (LDH) has developed strongly in the field of corrosion protection of materials due to its special properties, which include exceptional anion exchange capability with increased anion capacitance as well as barrier resistance and a recorded structural memory effect. This article reviews recent work on the properties of LDH in the form of powders and films. The possibilities and advantages of using this compound to protect materials from corrosion are analyzed in detail.

Keywords: nanomaterials; anticorrosive agents; anion exchange; LDH powder and  ultrathin  film

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Prezentacija metoda dobijanja, svojstava i mogućnosti primene novih antikorozivnih sredstava – nanostrukturiranih materijala na bazi lho

Izvod

Poslednjih godina, slojeviti dvostruki hidroksid (LDH) se snažno razvio u oblasti zaštite materijala od korozije zbog svojih posebnih svojstava, koja uključuju izuzetnu sposobnost anjonske izmene sa povećanim anjonskim kapacitetom, kao i otpornošću na barijeru i zabeleženim efektom strukturne memorije. Ovaj članak daje pregled nedavnih radova o svojstvima LDH u obliku prahova i filmova. Detaljno su analizirane mogućnosti i prednosti korišćenja ovog jedinjenja za zaštitu materijala od korozije.

Ključne reči: Nanomaterijali, antikorozivna sredstva, anjonska izmena, LDH prah, ultratanki film

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Scope of nanomaterial as potential soil stabiliser in pavement engineering

Abstract

Present study explores the application of nanosilica in improving the strength of soil subgradeto reduce the pavement thickness. Changes in the plasticity characteristics of soil stabilised with nanosilica was evaluated through Atterberg limit tests. Unconfined compressive strength(UCS) tests were performed on specimen cured for 0, 7, 14 and 28 days to find the optimal percentage of nanosilica for achieving maximum strength. California bearing ratio (CBR) test indicated a substantial reduction in pavement thickness with addition of nanosilica to the soil. Results from Field emission scanning electron microscopy analysisconfirmed the formation of Calcium-Silicate-Hydrate gel responsible for strength improvement of the soil. Thus, inclusion of nanosilica can facilitate the reduction in the quantity of materials requiredfor laying pavement.

Keywords:Clay soil, nanosilica, unconfined compressive strength, California Bearing Ratio

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Obimnanomaterijala kao potencijalnogstabilizatoratla u putarstvu

Izvod

Ova studija istražuje primenu nanosilicijumdioksida u poboljšanju čvrstoće podloge kako bi se smanjila debljina kolovoza. Promene u karakteristikama plastičnosti tla stabilizovanog nanosilikom procenjene su Aterbergovim graničnim testovima. Ispitivanja čvrstoće neograničenog pritiska (UCS) su izvedenanauzorkukoji je očvršćavao 0, 7, 14 i 28 dana da bi se pronašao optimalni procenat nanosilicijumdioksida za postizanje maksimalne čvrstoće. Test kalifornijskogodnosanosivosti (CBR) pokazao je značajno smanjenje debljine kolovoza uz dodavanje nanosilicijum­dioksida u tlo. Rezultati analize polja emisione skenirajuće elektronske mikroskopije potvrdili su formiranje kalcijum-silikat-hidratnog gela odgovornog za poboljšanje čvrstoće tla. Dakle, uklju­čivanje nanosilijuma može olakšati smanjenje količine materijala potrebnih za postavljanje kolovoza.

Ključnereči: Glinenozemljište, nanosilicijum, neograničena tla čnačvrstoća, kalifornijski odnosnosivosti

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Poly (vinylidene fluoride) polymer electrolyte-based Supercapacitors

Abstract

PVDF, or polyvinylidenefluoride, is a popular polymer in the fluoropolymer family because of its superior mechanical strength, thermal stability, and piezoelectric qualities. It is chemically resistant to various substances, including diverse acids, bases, organic solvents, oil, and fat, and it is also easily processed.Electrochemical devices with superior energy storage effectiveness are necessary because of the increasing electricity consumption in the modern world. Because of its great power density, extended lifespan, remarkable charge/discharge cycle stability, and inexpensive cost, supercapacitors are regarded as amazing energy-storing devices. Supercapacitors’ electrochemical performance is entirely dependent on the selection of their basic components and their manufacturing process.Materials made from carbon with improved thermophysical characteristics and deformation strength are currently of great interest.These materials have various uses in numerous sectors because of their distinctive physical and chemical features.The abundance of research on the “structure-property,” manufacturing, application, and ecology of composite polymers based on polyvinylidene fluoride (PVDF) can be attributed to the many opportunities for their use in science and technology.It is feasible to achieve a high degree of multi-disciplinarity and integration of polymer science by using innovative technologies to build an expanded conceptual picture regarding polymeric materials. This leads to the formation of fundamental problems in polymer science, the solution affecting a significant improvement to the natural scientific picture of the modern world.PVDF is arguably the most sought-after polymer nowadays due to its ability to self-polarize in the presence of an electric field. Researchers and experts involved in the development of energy harvesting and storage devices such as self-charging supercapacitors are drawn to the piezoelectric, ferroelectric, and pyroelectric capabilities of PVDF.The advanced qualities of PVDF and its possible uses in a variety of polymer forms are explained.

Keywords: Polyvinylidenefluoride, charge carriers, supercapacitor, structural properties

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Superkondenzatorinabazipoli (vinilidenfluorida) polimernogelektrolita

Izvod

PVDF, ili polivinilidenfluorid, je popularan polimer u porodici fluoropolimera zbog svoje superiorne mehaničke čvrstoće, termičke stabilnosti i piezoelektričnih svojstava. Hemijski je otporan na razne supstance, uključujući razne kiseline, baze, organske rastvarače, ulje i masti, a takođe se lako obrađuje. Elektrohemijski uređaji sa superiornom efikasnošću skladištenja energije su neophodni zbog sve veće potrošnje električne energije u savremenom svetu. Zbog velike gustine snage, produženog veka trajanja, izuzetne stabilnosti ciklusa punjenja/pražnjenja i pristupačne cene, superkondenzatori se smatraju neverovatnim uređajima za skladištenje energije. Elektrohemijske performanse superkondenzatora u potpunosti zavise od izbora njihovih osnovnih komponenti i njihovog procesa proizvodnje. Materijali napravljeni od ugljenika sa poboljšanim termofizičkim karakteristikama i čvrstoćom na deformaciju trenutno su od velikog interesa. Ovi materijali imaju različite primene u brojnim sektorima zbog svojih karakterističnih fizičkih i hemijskih karakteristika. Obilje istraživanja o „strukturi-svojstvu“, proizvodnji, primeni i ekologiji kompozitnih polimera na bazi poliviniliden fluorida (PVDF) može se pripisati mnogim mogućnostima za njihovu upotrebu u nauci i tehnologiji. Moguće je postići visok stepen multidisciplinarnosti i integracije polimerne nauke korišćenjem inovativnih tehnologija za izgradnju proširene konceptualne slike o polimernim materijalima. Ovo dovodi do formiranja fundamentalnih problema u polimernoj nauci, a rešenje utiče na značajno poboljšanje prirodno-naučne slike savremenog sveta. PVDF je verovatno najtraženiji polimer danas zbog svoje sposobnosti samopolarizacije u prisustvu električnog polja. Istraživači i stručnjaci koji se bave razvojem uređaja za prikupljanje i skladištenje energije, kao što su samopuneći superkondenzatori, privučeni su piezoelektričnim, feroelektričnim i piroelektričnim mogućnostima PVDF-a. Objašnjena su napredna svojstva PVDF-a i njegova moguća upotreba u različitim polimernim oblicima.

Ključne reči: poliviniliden fluorid, nosioci naelektrisanja, superkondenzator, strukturna svojstva

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Clay and clay minerals: A brief review from fundamentals to applications

Abstract

Clay and clay minerals are naturally occurring materials and available abundantly on the earth. They are inexpensive, and have a range of structures and properties with mechanical and heat stability. They are layered magnesium or aluminium silicates composed of tetrahedrally coordinated silicate sheets and octahedrally coordinated magnesium or aluminium hydroxide sheets. Because of natural abundance and environment friendly nature, clay and clay minerals have been used in different industrial sectors. In this review article, classification of clay minerals, structures, properties and their applications in different sectors have been discussed. Some of the important sectors, where clay and clay minerals are being used extensivelyare Agriculture and farming, Fertilizers and soil conditioners, Pesticides and Herbicides, Animal feeds, Food industry, Detergent industry, Cosmetic and pharmaceutical industry, Biomedical industry, Textile and paint industry, Oil and gas Exploration, Construction Industry, Environmental Protection, Carbon dioxide capture, Photocatalysis, etc. We tried to update the current knowledge with recent developments and progress in clay and clay minerals in this review.

Keyword: Clay, Clay minerals, structure,property, applications, agriculture industry, pharmaceutical industry.

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Glina i minerali gline: kratak pregled od osnova do primene

Izvod

Glina i glineni minerali su prirodni materijali i dostupni su u izobilju na zemlji. Oni su jeftini i imaju niz struktura i svojstava sa mehaničkom i toplotnom stabilnošću. Oni su slojeviti magnezijum ili aluminijum silikati koji se sastoje od tetraedarsko koordinisanih silikatnih listova i oktaedaralno koordinisanih listova magnezijuma ili aluminijum hidroksida. Zbog prirodnog bogatstva i ekološke prirode, glina i glineni minerali se koriste u različitim industrijskim sektorima.U ovom preglednom članku razmatrana je klasifikacija minerala gline, strukture, svojstva i njihova primena u različitim sektorima. Neki od važnih sektora u kojima se glina i minerali gline intenzivno koriste su poljoprivreda i poljoprivreda, đubriva i regeneratori zemljišta, pesticidi i herbicidi, stočna hrana, prehrambena industrija, industrija deterdženata, kozmetička i farmaceutska industrija, biomedicinska industrija, industrija tekstila i boja, industrija nafte i gasa, zaštita nafte i gasa. hvatanje dioksida, fotokataliza, itd. U ovom pregledu smo pokušali da ažuriramo sadašnja saznanja sa nedavnim razvojem i napretkom u glini i mineralima gline.

Ključna reči: Glina, minerali gline, struktura, svojstva, primene, poljoprivredna industrija, farmaceutska industrija.

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Ballistic evaluation of body armour for defence application

Abstract

Bullet-resistant jackets (BRJs) and Bullet-resistant helmets (BRHs) serve as crucial protective gear for military and law enforcement personnel, offering critical defence against ballistic threats. Various inspection and testing protocols are employed to ensure the reliability and efficacy of materials used in the construction of BRJs and bullet-resistant helmets. The study begins with an overview of the various materials commonly utilized in the manufacturing of BRJs and helmets, including aramid fibers, ceramics, and composite materials. Visual inspections aid in identifying surface irregularities and defects, while NDT techniques such as ultrasonic testing and radiography help reveal internal flaws that might compromise the integrity of the protective gear. Furthermore, the study delves into the testing procedures essential for evaluating the ballistic resistance of these materials along withaddressing the importance of compliance with industry standards and certification requirements emphasizing the significance of rigorous inspection and testing protocols in maintaining the quality and reliability of materials used in the production of BRJs and bullet-resistant helmets. Implementing robust examination techniques and adhering to standardized testing procedures are imperative to ensure the safety and protection of individuals relying on this specialized equipment in high-risk environments.

Keywords:protective gear, aramid fibers, ballistic threats

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Balistička procena pancira za primenu u odbrani

Izvod

Otporni prsluci (BRJ) i kacige otporne na metke (BRH) služe kao ključna zaštitna oprema za vojno i policijsko osoblje, nudeći kritičnu odbranu od balističkih pretnji. Različiti protokoli inspekcije i ispitivanja se koriste kako bi se osigurala pouzdanost i efikasnost materijala koji se koriste u izradi BRJ i kaciga otpornih na metke. Studija počinje pregledom različitih materijala koji se obično koriste u proizvodnji BRJ i kaciga, uključujući aramidna vlakna, keramiku i kompozitne materijale. Vizuelni pregledi pomažu u identifikaciji površinskih nepravilnosti i defekata, dok tehnike NDT-a, kao što su ultrazvučno ispitivanje i radiografija, pomažu u otkrivanju unutrašnjih nedostataka koji bi mogli ugroziti integritet zaštitne opreme. Štaviše, studija se bavi postupcima ispitivanja neophodnim za procenu balističke otpornosti ovih materijala, zajedno sa obraćanjem važnosti usklađenosti sa industrijskim standardima i zahtevima za sertifikaciju, naglašavajući značaj rigoroznih protokola inspekcije i ispitivanja u održavanju kvaliteta i pouzdanosti materijala koji se koriste u proizvodnji BRJ i kaciga otpornih na metke. Primena robusnih tehnika ispitivanja i poštovanje standardizovanih procedura testiranja su imperativ kako bi se osigurala bezbednost i zaštita pojedinaca koji se oslanjaju na ovu specijalizovanu opremu u okruženjima visokog rizika.

Ključne reči: Zaštitna oprema, aramidna vlakna, balističke pretnje

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Predictive modeling of boriding kinetics on armco iron using linear regression approach

Abstract

Tools inevitably degrade over time, with lifetimesvarying based on material and usage. To mitigate this, thermochemical treatments such as boriding are employed. This process forms a boride layer with favorable tribological and mechanical properties. Generally, depending on the processing conditions, the layer may result in either a mono-phased Fe₂B or a bi-phased FeB/Fe₂B. This study examines a mono-phased Fe₂B layer formed by powder pack boriding of Armco Iron. The objective is to predict the thickness of this layer using a linear approach with minimal variables, and to compare the predictions with a more complex approach requiring additional parameters. Results show that both models yield similar predictive capabilities within the available interval, validating the linear model. However, the linear approach shows divergence when applied beyond the investigated interval, indicating limitations in its generalizability.

Keywords: Boride, boriding, layer, linear, regression, thickness

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Prediktivno modeliranje boronizacije kinetike u armco uzorcima gvožđa korištenjem pristupa linearne regresije

Izvod

Alati neizbježno degradiraju tokom vremena, s vijekom trajanja koji varira u zavisnosti od materijala i načina upotrebe. Kako bi se to ublažilo, koriste se termokemijski tretmani poput boronizacije. Ovim procesom formira se boridni sloj s povoljnim tribološkim i mehaničkim svojstvima. U zavisnosti od uslova obrade, sloj može biti mono-fazni Fe₂B ili bi-fazni FeB/Fe₂B. Ova studija ispituje mono-fazni Fe₂B sloj formiran boronizacijom Armco željeza metodom pakovanja u prah. Cilj je bio predvidjeti debljinu ovog sloja korištenjem linearnog pristupa s minimalnim brojem varijabli i uporediti te predikcije sa složenijim modelom koji zahtijeva dodatne parametre. Rezultati pokazuju da oba modela daju slične predikcije unutar dostupnog intervala, čime se potvrđuje tačnost linearnog modela. Međutim, linearni pristup pokazuje odstupanja kada se primijeni izvan istraživanog intervala, što ukazuje na ograničenja njegove generalizacije.

Ključne riječi: Borid, boronizacija, sloj, linearno, regresija, debljina

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Response surface methodology and artificial neural networks optimisation of CO₂ methanation simulation using Ni/MgAl₂O₄ catalyst in a multi-tubular fixed-bed reactor

Abstract

This study investigated the simulation and optimization of synthetic methane production over Ni/MgAl₂O₄in a multi-tubular fixed-bed reactor. The study comprises process simulation conducted using Aspen HYSYS software, modelling and optimization using response surface methodology (RSM) and artificial neural network (ANN) modelling performed using Design Experts and MATLAB software, respectively. In the process simulation for the CO₂methanation, sensitivity analyses were performed to determine the effects of temperature, pressure, H₂/CO₂ ratio, and CO fraction in the feedstock on CO₂conversion,CH₄ yield, and CH₄ selectivity. RSM and ANN models were built using datapoints provided by the process simulation results to model the relationship between input variables and output responses and perform optimisation for RSM model and ANN model coupled with genetic algorithm (GA). The process simulation results profoundly highlightedtheimpact of temperature in enhancing CO₂ conversion and CH₄ yield. Higher temperatures favoured the endothermic reversed water-gas shift (RWGS) reaction, leading to increased CO₂ conversion and CH₄ yield. CO₂ conversion, CH₄ selectivity and yield were found to be minimally affected by pressure. CO fraction in the feed was found to exert a delicate influence on the CO₂ conversion and CH₄ yield. Excessive CO fractions hindered the methanation process, reducing both CO₂ conversion and CH₄ yield. Additionally, the H₂/CO₂ ratio proved critical as higher ratios facilitated higher CO₂ conversion, CH₄ selectivity, and yield, emphasizing the significance of optimal hydrogen to CO₂ ratio for efficient methanation which was proposed to be at values higher than the stoichiometric value of 4:1. Furthermore, the ANN-GA model outperformed RSM in terms of prediction accuracy and optimization. The ANN model demonstrated superior capabilities in capturing the complex relationships between the input variables and output responses demonstrated by the performance metrics including R² values, MSE, RMSE etc. The optimisation results of the ANN-GA model provided more precise and efficient predictions when compared with RSM, offering a deeper understanding of the intricate interactions within the methanation process.

Keywords: Artificial Neural Networks, CO₂ Methanation, HYSYS Modelling, Response Surface Methodology, Reverse Water Gas Shift, Langmuir-Hinshelwood-Hougen-Watson Rate Expression

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Metodologija površine odziva i optimizacija veštačkih neuronskih mreža za simulaciju metanacije CO₂ korišćenjem Ni/MgAl₂O₄ katalizatora u višecevnom reaktoru sa fiksnim slojem

Izvod

Ova studija je istraživala simulaciju i optimizaciju proizvodnje sintetičkog metana preko Ni/MgAl2O4 u višecevnom reaktoru sa fiksnim slojem. Studija obuhvata simulaciju procesa sprovedenu korišćenjem softvera Aspen HYSYS, modeliranje i optimizaciju korišćenjem metodologije površine odziva (RSM) i modeliranje veštačkih neuronskih mreža (ANN) korišćenjem softvera Design Experts i MATLAB, respektivno. U simulaciji procesa za metanaciju CO2, izvršene su analize osetljivosti kako bi se utvrdili efekti temperature, pritiska, odnosa H2/CO2 i frakcije CO u sirovini na konverziju CO2, prinos CH4 i selektivnost CH4. RSM i ANN modeli su izgrađeni korišćenjem podataka dobijenih rezultatima simulacije procesa za modeliranje odnosa između ulaznih promenljivih i izlaznih odgovora i izvršenje optimizacije za RSM model i ANN model zajedno sa genetskim algoritmom (GA). Rezultati simulacije procesa su duboko istakli uticaj temperature na povećanje konverzije CO2 i prinosa CH4. Više temperature su favorizovale endotermnu obrnutu reakciju pretvaranja vode u gas (RWGS), što je dovelo do povećane konverzije CO2 i prinosa CH4. Utvrđeno je da su konverzija CO2, selektivnost CH4 i prinos minimalno pogođeni pritiskom. Utvrđeno je da frakcija CO u dovodu ima delikatan uticaj na konverziju CO2 i prinos CH4. Prekomerna frakcija CO je ometala proces metanacije, smanjujući i konverziju CO2 i prinos CH4. Pored toga, odnos H2/CO2 se pokazao kritičnim jer su viši odnosi olakšavali veću konverziju CO2, selektivnost CH4 i prinos, naglašavajući značaj optimalnog odnosa vodonika i CO2 za efikasnu metanaciju, za koji je predloženo da bude na vrednostima višim od stehiometrijske vrednosti od 4:1. Štaviše, ANN-GA model je nadmašio RSM u pogledu tačnosti predviđanja i optimizacije. Model veštačkih neurona (ANN) pokazao je superiorne mogućnosti u obuhvatanju složenih odnosa između ulaznih promenljivih i izlaznih odgovora, što su demonstrirale metrike performansi, uključujući R2 vrednosti, MSE, RMSE itd. Rezultati optimizacije ANN-GA modela pružili su preciznija i efikasnija predviđanja u poređenju sa RSM, nudeći dublje razumevanje složenih interakcija unutar procesa metanacije.

Ključne reči: Veštačke neuronske mreže, metanacija CO2, HYSYS modeliranje, metodologija površine odziva, obrnuto prebacivanje vodenog gasa, Izražavanje brzine Langmuir-Hinshelwood-Hougen-Watson

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Process simulation and optimisation of hydrogen production from natural gas via steam methane reforming: Aspen hysys simulation investigation

Abstract

The growing demand for hydrogen in the energy sector necessitates enhanced methods for its production. Presently, natural gas remains the primary feedstock for commercial hydrogen production. While green hydrogen production from renewable sources is gaining attention, it still faces economic challenges compared to fossil-derived hydrogen. This study focused on simulating hydrogen production from natural gas using the steam methane reforming (SMR) process. The simulation employed Abbas et al (2017) kinetics over 18 wt. % NiO/a-Al₂O₃catalyst within Aspen HYSYS V11 software and utilized the Peng Robinson fluid property package. Sensitivity analyses were conducted, emphasizing parameters such as temperature, pressure, molar flow rate of steam, and reactor volume. The goal was to optimize various process outcomes, including methane conversion, hydrogen selectivity and yield, methane selectivity, CO selectivity and yield, CO₂ selectivity and yield, H₂/CO ratio, and hydrogen production. The results indicated that methane conversion and selectivities for hydrogen, carbon monoxide, and carbon dioxide increased with rising temperatures and decreased with higher pressures. Conversely, CO conversion and methane selectivity decreased with increased temperature but rose with higher pressure. These outcomes aligned with Le Chatelier’s principle for both endothermic and exothermic reactions. The analysis of steam molar flow revealed increased methane conversion due to the higher reaction temperature provided by steam and a higher steam-to-carbon ratio. The simulation demonstrated the economic viability of hydrogen production through the steam methane reforming process. Additionally, it highlighted the significant contribution of steam sales to the overall economic feasibility of the process. Overall, the study underscores the technical feasibility of hydrogen production from natural gas using the steam methane reforming process.

Keywords: Steam methane reforming, Response surface methodology, CH₄ conversion, Hydrogen selectivity, Process simulation

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Simulacija procesa i optimizacija proizvodnje vodonika iz prirodnog gasa putem reforminga parnog metana: istraživanje simulacije aspen hysys

Izvod

Rastuća potražnja za vodonikom u energetskom sektoru zahteva poboljšane metode za njegovu proizvodnju. Trenutno, prirodni gas ostaje primarna sirovina za komercijalnu proizvodnju vodonika. Iako proizvodnja zelenog vodonika iz obnovljivih izvora dobija na pažnji, ona se i dalje suočava sa ekonomskim izazovima u poređenju sa vodonikom dobijenim iz fosilnih goriva. Ova studija se fokusirala na simulaciju proizvodnje vodonika iz prirodnog gasa korišćenjem procesa reforminga parnog metana (SMR). Simulacija je koristila kinetiku Abbas et al (2017) preko 18 tež.% NiO/a-Al₂O₃ katalizatora u okviru Aspen HYSYS V11 softvera i koristila je Peng Robinson paket za fluidne osobine. Sprovedene su analize osetljivosti, sa naglaskom na parametre kao što su temperatura, pritisak, molarna brzina protoka pare i zapremina reaktora. Cilj je bio optimizacija različitih ishoda procesa, uključujući konverziju metana, selektivnost i prinos vodonika, selektivnost i prinos CO, selektivnost i prinos CO₂, odnos H₂/CO i proizvodnju vodonika. Rezultati su pokazali da se konverzija metana i selektivnost za vodonik, ugljen-monoksid i ugljen-dioksid povećavaju sa porastom temperature, a opadaju sa višim pritiskom. Nasuprot tome, konverzija CO i selektivnost metana se smanjuju sa povećanjem temperature, ali se povećavaju sa višim pritiskom. Ovi rezultati su u skladu sa Le Šateljeovim principom i za endotermne i za egzotermne reakcije. Analiza molarnog protoka pare otkrila je povećanu konverziju metana zbog više temperature reakcije koju obezbeđuje para i većeg odnosa pare i ugljenika. Simulacija je pokazala ekonomsku isplativost proizvodnje vodonika kroz proces reforminga parnog metana. Pored toga, istakla je značajan doprinos prodaje pare ukupnoj ekonomskoj isplativosti procesa. Generalno, studija naglašava tehničku izvodljivost proizvodnje vodonika iz prirodnog gasa korišćenjem procesa reforminga parnog metana.

Ključne reči: Reforming parnog metana, metodologija površine odziva, konverzija CH₄, selektivnost vodonika, simulacija procesa

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Influence of lime sludge addition on the mechanical and microstructural performance of pond ash based geopolymer concrete

Abstract

This study investigates the addition of varying lime sludge (LS) proportions, and curing durations (3, 7, and 28 days) on the properties of geopolymer concrete (GC). All GC mixes were prepared with an 8 M sodium hydroxide solution and a fixed liquid-to-binder ratio of 0.4. The mechanical properties of the LS-based GC mixes were assessed and than control mix comprised entirely of pond ash (100% PA). Additionally, scanning electron microscopy (SEM) analysis was performed to investigate the microstructural differences between the control mix (100% PA, LSGC0) and the optimized mix with 50% PA and 50% LS (LSGC5). The results revealed that the LSGC5 mix achieved notable improvements in compressive, split tensile, and flexural strengths compared to the LSGC0 mix. SEM analysis highlighted the formation of a denser and more cohesive microstructure in the LSGC5 mix, attributed to the enhanced generation of calcium-alumino-silicate-hydrate (C–A–S–H) gels, which were less prevalent in the 100% PA mix. These findings demonstrate the efficacy of lime sludge as a sustainable replacement material, significantly enhancing the mechanical and microstructural properties of GC while reducing dependency on traditional cementitious components.

Keywords:Geopolymer concrete; pond ash; lime sludge; mechanical properties; microstructural properties.

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Uticaj dodavanja krečnog mulja na mehanička i mikrostrukturna svojstva geopolimer betona na baz pepela

Izvod

Ova studija istražuje dodavanje različitih proporcija krečnog mulja (LS) i trajanja očvršćavanja (3, 7 i 28 dana) na svojstva geopolimer betona (GC). Sve GC mešavine su pripremljene sa 8 M rastvorom natrijum hidroksida i fiksnim odnosom tečnosti prema vezivu od 0,4. Procenjene su mehaničke osobine mešavina GC na bazi LS, a zatim kontrolna mešavina koja se u potpunosti sastojala od pepela iz ribnjaka (100% PA). Pored toga, izvršena je analiza skenirajuće elektronske mikroskopije (SEM) da bi se istražile mikrostrukturne razlike između kontrolne mešavine (100% PA, LSGC0) i optimizovane mešavine sa 50% PA i 50% LS (LSGC5). Rezultati su otkrili da je mešavina LSGC5 postigla značajna poboljšanja u čvrstoći na pritisak, rascepu zatezanja i savijanja u poređenju sa mešavinom LSGC0. SEM analiza je istakla formiranje gušće i kohezivnije mikrostrukture u mešavini LSGC5, što se pripisuje povećanom stvaranju gelova kalcijum-alumino-silikat-hidrata (C–A–S–H), koji su bili manje zastupljeni u mešavini 100% PA. Ovi nalazi demonstriraju efikasnost krečnog mulja kao održivog zamenskog materijala, značajno poboljšavajući mehanička i mikrostrukturna svojstva GC-a uz smanjenje zavisnosti od tradicionalnih cementnih komponenti.

Ključne reči: Geopolimer beton; ribnjak pepeo; krečni mulj; mehanička svojstva; mikrostrukturna svojstva.

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Biochar made fromcoffee ground for adsorption of crystal violet dye

Abstract

Biochar was prepared by anaerobic heating coffee ground at 800 ^oC for 3 hours. The prepared sample was used to adsorb crystal violet dye in an aqueous environment. The result showed that the biochar sample had good adsorption capacity for crystal violet dye, with the maximum adsorption capacity of 128.87 (mg/g). Thus, low-cost biochar prepared from coffee grounds has great potential to be used as an adsorbent material to remove crystal violet dye in an aqueous environment.

Keywords:Biochar, crystal violet, coffee ground, isothermmodels, adsorption kinetics, wastewater treatment.

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Biougalj napravljen od mlevene kafe za adsorpciju kristalno ljubičaste boje

Izvod

Biougalj je pripremljen anaerobnim zagrevanjem mlevene kafe na 800 ^oC tokom 3 sata. Pripremljeni uzorak je korišćen za adsorbovanje kristalno ljubičaste boje u vodenom okruženju. Rezultat je pokazao da uzorak biouglja ima dobar kapacitet adsorpcije kristalno ljubičaste boje, sa maksimalnim kapacitetom adsorpcije od 128,87 (mg/g). Stoga, jeftin biougljen pripremljen od taloga kafe ima veliki potencijal da se koristi kao adsorbujući materijal za uklanjanje kristalno ljubičaste boje u vodenom okruženju.

Ključne reči: biougalj, kristalno ljubičasta boja, mlevena kafa, izotermni modeli, kinetika adsorpcije, tretman otpadnih voda

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Assessment of the properties of recycled oil palm leaflets and groundnut shells based composite panels

Abstract

This study was designed to examine the feasibility of recycling groundnut shells and oil palm leaflets into materials suitable for structural applications. Groundnut shell particles (GSP) and oil palm leaflet particles (OLP) were prepared and mixed at varying proportions (0, 25, 50, 75, and 100 %) on dry weight basis to produce composite panels. The ratio by weight of the binder (topbond) to composite mix was 1:1. Three samples were producedper formulation, dried completely, and then subjected to various tests to determine their suitability for structural applications. The results showed that increase in the content of the OLP from 0 % to 100 % yielded average water absorption (61.85 – 86.83) %, thickness swelling (3.33 – 6.17) %, void fraction (4.51 – 9.22)  %, bulk density (598.9 –  502.8) kgm^-3, thermal conductivity (0.2129 – 0.2004) Wm^-1K^-1, specific heat capacity (1475 – 1886) Jkg^-1K^-1, thermal diffusivity (2.410 – 2.113) 10^-7m²s^-1, heat penetration time (4.426 – 5.048) mins, flexural strength (1.454 – 1.312) N/mm², and modulus of elasticity (218.8 – 196.5) N/mm². Screwability and nailability were 100 % without alteration. It was revealed that the GSP-OLP panels developed in this study could be used as promising alternatives to plywood, asbestos, plaster of Paris which are known conventional ceilings applied for thermal insulation in building design. They could as well be applied internally as wall partition materials. Relying on the oil palm leaflets and groundnut shellsfor such undertaking could enhance low-cost building construction and at the same time mitigate the adverse effects associated with their disposal.

Keywords:Bulk density, ceiling, flexural strength, thermal insulation, waste materials

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Procena svojstva kompozitnih ploča na bazi recikliranog palminog ulja i ljuske kikirikija

Izvod

Ova studija je osmišljena da ispita izvodljivost recikliranja ljuske kikirikija i otpadaka uljane palme u materijale pogodne za konstrukcijske primene. Čestice ljuske kikirikija (GSP) i čestice listova uljane palme (OLP) su pripremljene i pomešane u različitim proporcijama (0, 25, 50, 75 i 100 %) na osnovu suve težine da bi se dobile kompozitne ploče. Odnos mase veziva (topbond) prema kompozitnoj mešavini bio je 1:1. Proizvedena su tri uzorka po formulaciji, potpuno osušena, a zatim podvrgnuta različitim testovima da bi se utvrdila njihova pogodnost za strukturalne primene. Rezultati su pokazali da povećanje sadržaja OLP-a od 0 % do 100 % daje prosečnu apsorpciju vode (61,85 – 86,83) %, debljinu bubrenja (3,33 – 6,17) %, udeo šupljina (4,51 – 9,22) %, toplotnu provodljivost 9 – 590 – 838. (0,2129-0,2004) Vm^-1K^-1, specifični toplotni kapacitet (1475–1886) Jkg¹K^-1, toplotna difuzivnost (2,410 – 2,113) 10-7 m²s-¹, vreme prodiranja toplote (4,426 – 5,045 min – 5,045 savijanja) N/mm², i modul elastičnosti (218,8 – 196,5) N/mm². Mogućnost uvrtanja i zakucavanja su 100% bez izmena. Otkriveno je da se GSP-OLP paneli razvijeni u ovoj studiji mogu koristiti kao obećavajuća alternativa šperploči, azbestu, gipsu iz Pariza koji su poznati konvencionalni plafoni koji se primenjuju za toplotnu izolaciju u projektovanju zgrada. Mogu se primeniti i unutra kao materijali za zidne pregrade. Oslanjanje na letke od uljane palme i ljuske kikirikija za takav poduhvat moglo bi poboljšati jeftinu izgradnju zgrada i istovremeno ublažiti štetne efekte povezane sa njihovim odlaganjem.

Ključne reči: Zapreminska gustina, plafon, čvrstoća na savijanje, toplotna izolacija, otpadni materijali

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High-performance eco-friendly concrete with improved strength, chloride ion penetration, and corrosion resistance by the high volume of Ground Granulate Blast Furnace Slag (GGBS)

Abstract

The present research aims to manufacture concrete that meets compressive strength parameters, has the lowest environmental impact, and resists chloride ion penetration and corrosion. This study used varied volumes of cement replacement with slag (GGBS) (30, 40, and 50)% by mass of cement for two concrete classes, C30 and C40. Fresh tests (slump, initial and final setting time), hardening (compressive, splitting, and flexural strength), and durability (porosity, water absorption, density, penetration depth, chloride ion migration coefficient, electrical resistivity, corrosion rate, mass loss, crack width due to corrosion, and microstructure analysis) were performed.

The environmental impact of concrete components in each mix was also assessed. The impressed current technique increased rebar corrosion in concrete specimens immersed in 5% sodium chloride. Replacing cement with GGBS by 30–50% increased the setting time and enhanced all hardening qualities. Mechanical qualities improved most at 40% GGBS, with C30 mixes’ compressive, tensile, and flexural strengths up 29.3%, 38.7%, and 15.8% at 90 days. Compare 21.3%, 19.2%, and 16.2% at 90 days for C40 combinations to the reference mixture. Strength reduced marginally at 50% GGBS but remained greater than the reference blend. However, a 50% GGBS replacement rate best-improved durability, microstructure, and environmental efficiency. The C30-50% GGBS mixture is ideal because it met the design requirements of C30 and C40, had the best improvement in porosity and water absorption, the slightest chloride penetration, and the best performance against corrosive environments of the six mixtures except C40-50% GGBS. Additionally, it is the least environmentally harmful combination.

Keywords: GGBS; Chloride ion penetration; Corrosion resistance; microstructure of concrete; environmental impact; Durability

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Visokokvalitetni ekološki beton sa poboljšanom čvrstoćom, penetracijom hloridnih jona i otpornošću na koroziju zahvaljujući velikoj količini mlevene granulirane zgure visoke peći (ggbs)

Izvod

Ovo istraživanje ima za cilj proizvodnju betona koji  zadovoljava parametre čvrstoc_́e na pritisak,  ima  najmanji uticaj na životnu sredinu i otporan je na prodiranje hloridnih jona i koroziju. U ovom istraživanju  korišc_́ene su različite zapremine zamene cementa šljakom (GGBS) (30, 40 i 50)% mase cementa za dve klase betona, C30 i C40. Svježi testovi (slijeganje, početno i konačno vrijeme vezivanja), očvršc_́avanje (čvrstoc_́a na pritisak, cijepanje i savijanje) i izdržljivost (poroznost, upijanje vode, gustina, dubina prodiranja, koeficijent migracije hloridnih jona, električna otpornost, brzina korozije, gubitak mase, širina prsline usled korozije i analiza mikrostrukture).

Takođe je procenjen uticaj komponenti betona na životnu sredinu u svakoj mešavini. Tehnika  impresionirane struje povec_́ala je koroziju armature u uzorcima betona potopljenim u 5% natrijum hlorida. Zamena cementa GGBS-om za 30–50% povec_́ala je vreme vezivanja i poboljšala  sve  kvalitete  očvršc_́avanja. Mehanički kvaliteti su senajviše poboljšali pri 40% GGBS, sa C30 mešavinama na pritisak, zatezanje i savijanje za 29,3%, 38,7% i 15,8% na 90 dana. Uporedite

21,3%, 19,2% i 16,2% na 90 dana za kombinacije C40 sa referentnom smešom. Snaga je neznatno smanjena na 50% GGBS, ali je ostala vec_́a od referentne mešavine. Međutim, stopa zamene od 50% GGBS najbolje je poboljšala izdržljivost, mikrostrukturu i ekološku efikasnost.  Smeša C30-50% GGBS je idealna jer je ispunjavala zahteve dizajna C30 i C40, imala je najbolje poboljšanje u poroznosti i apsorpciji vode, najmanju penetraciju hlorida i najbolje performanse protiv korozivnih sredina od šest smeša osim C40-50 % GGBS. Pored toga, to je najmanje štetna kombinacija po životnu sredinu.

Ključne reči:  GGBS,prodor hloridnih jona, otpornost na koroziju, mikrostruktura betona, uticaj na životnu sredinu, trajnost

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Microplastics from disposable paper cups: A growing concern in everyday life

Abstract

Microplastics (MPs) released from disposables are receiving widespread attention due to direct human exposure during use. The present study investigates the quantification and size classification of MPs released from disposable plastic-coated paper cups commonly used for serving hot beverages. In order to evaluate MPs that can possibly seep into hot beverages in 15 minutes, the study examines five different types of paper cups (A–E) with varying film thicknesses (20–80 microns) and capacities (70–220 ml). Fluorescence microscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and liquid particle counter (LPC) were employed to characterize MPs. The findings indicate high-density polyethylene (HDPE) MPs, primarily 2-5 μm with negligible percentage of particles larger than 15 μm. A 100 ml disposable cup may release up to 0.7 million MPs, affected by liquid pH and temperature. The results from the recyclability analysis shows up D as more resistant to moisture and biodegradability due to thicker paper boards than the HDPE film lining. Routine users may ingest 657-876 million MPs annually which could potentially affect human health and the environment. The results of the study are expected to provide insight into the health impacts and will contribute to the knowledge pool of microplastic removal technologies.

Keywords: Spectroscopy; HDPE; LPC; size variation; health effects; human ingestion.

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Mikroplastika iz papirnih čaša za jednokratnu upotrebu: sve veća zabrinutost u svakodnevnom životu

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Mikroplastika (MP) koja se oslobađa iz jednokratnih proizvoda dobija široku pažnju zbog direktnog izlaganja ljudi tokom upotrebe. Ova studija istražuje kvantifikaciju i klasifikaciju veličine MP-a koji se oslobađaju iz papirnih čaša obloženih plastikom za jednokratnu upotrebu koje se obično koriste za posluživanje toplih napitaka. Da bi se procenili MP koji mogu da prodru u tople napitke za 15 minuta, studija ispituje pet različitih tipova papirnih čaša (A–E) sa različitim debljinama filma (20–80 mikrona) i kapacitetima (70–220 ml). Fluorescentna mikroskopija, infracrvena spektroskopija Furijeove transformacije (FTIR), skenirajuća elektronska mikroskopija (SEM) i brojač tečnih čestica (LPC) korišćeni su za karakterizaciju MP. Nalazi ukazuju na polietilen visoke gustine (HDPE) MPs, prvenstveno 2-5 mm sa zanemarljivim procentom čestica većih od 15 mm. Čaša za jednokratnu upotrebu od 100 ml može osloboditi do 0,7 miliona MPs, pod uticajem pH tečnosti i temperature. Rezultati analize mogućnosti recikliranja pokazuju da je čaša D otpornija na vlagu i biorazgradljivost zbog debljih papirnih ploča od HDPE folije. Rutinski korisnici mogu uneti 657-876 miliona MP godišnje što bi potencijalno moglo da utiče na zdravlje ljudi i životnu sredinu. Očekuje se da će rezultati studije pružiti uvid u uticaje na zdravlje i doprineti prikupljanju znanja o tehnologijama za uklanjanje mikroplastike.

Ključne reči: spektroskopija; HDPE; LPC; varijacija veličine; efekti na zdravlje; ljudsko gutanje.

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The influence of thetartarate on the deposition-dissolution of zinc for the application in aqueous battery

Abstract

Zinc-ion batteries (ZIBs) have recently gained significant attention as a sustainable energy storage solution due to their cost-effectiveness and safety. Despite offering high theoretical capacity and low redox potential, ZIBs face challenges such as dendrite growth and low zinc utilization rates, which hinder their performance. The objective of this study was to optimize the electrolyte composition to enhance the performance of a zinc electrode electrochemically deposited on a copper substrate within the zinc(II)–NH₄Cl system. The influence of Zn²⁺ and NH₄⁺ ion concentrations, current density, and the addition of sodium tartrate on the morphology and behavior of the anode material during charge and discharge cycles was examined. Results demonstrated that the addition of sodium tartrate significantly improves the electrochemical performance of the anode material and reduces corrosion in the electrolyte. The findings from this study suggest that electrolyte engineering could potentially provide a solution for better performance and extended longevity of ZIBs.

Keywords: Zinc-ion batteries, sodium tartrate, additive, anode, corrosion.

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Uticaj tartarata na taloženje-rastvaranje cinka za primenu u baterijama na bazi vodenih rastvora

Izvod

Cink-jonske baterije (ZIB) su nedavno dobile značajnu pažnju kao održivo rešenje za skladištenje energije zbog svoje isplativosti i sigurnosti. Uprkos tome što nude visok teoretski kapacitet i nizak redoks potencijal, ZIB se suočavaju sa izazovima kao što su rast dendrita i niske stope iskorišćenja cinka, što ometa njihov učinak. Cilj ove studije je bio da se optimizuje sastav elektrolita kako bi se poboljšale performanse cink elektrode elektrohemijski deponovane na bakarnoj podlozi u sistemu cink(II)–NH4Cl. Ispitivan je uticaj koncentracija jona Zn2+ i NH4+, gustine struje i dodatka natrijum-tartarata na morfologiju i ponašanje anodnog materijala tokom ciklusa punjenja i pražnjenja. Rezultati su pokazali da dodatak natrijum tartarata značajno poboljšava elektrohemijske performanse anodnog materijala i smanjuje koroziju u elektrolitu. Nalazi ove studije sugerišu da bi inženjering elektrolita potencijalno mogao da pruži rešenje za bolje performanse i produženi vek ZIB-a.

Ključne reči: Cink-jonske baterije, natrijum tartarat, aditiv, anoda, korozija.

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Enhancing the capability through recycling: Doubling the world’s largest muon telescope with almost-buried iron tubes

Abstract

The GRAPES-3 experiment, housing the world’s largest muon telescope at 2200 m above sea level in Ooty, is designed to study cosmic-ray effects on Earth. To double the telescope’s capability, we have refurbished nearly the same number of proportional counters using iron pipes that are over half a century old. Before their utilization, these pipes were almost-buried 2300 meters underground at the Kolar Gold Field experiment following its decommissioning. The present work outlines various methods employed for repurposing these pipes, using several non-destructive characterization techniques, including X-ray Diffraction (XRD), Infrared Spectroscopy (IR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) techniques, to identify iron-bearing phases and conversion products. The results obtained from these instrumental techniques have been presented. This extension of the experiment serves as an exemplary demonstration of reducing, reusing, and recycling the iron tubes that would otherwise be discarded on a large scale.

Keywords:Material characterization; Sustainability; Proportional counter; Recycling; Muon

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Poboljšanje kapaciteta reciklažom: udvostručavanje najvećeg muonskog teleskopa na svetu skoro zakopanim gvozdenim cevima

Izvod

Eksperiment GRAPES-3, u kojem se nalazi najveći muonski teleskop na svetu na 2200 metara nadmorske visine u Utiju, osmišljen je za proučavanje efekata kosmičkih zraka na Zemlju. Da bismo udvostručili kapacitet teleskopa, obnovili smo skoro isti broj proporcionalnih brojača koristeći gvozdene cevi stare preko pola veka. Pre upotrebe, ove cevi su bile gotovo zakopane 2300 metara pod zemljom u eksperimentu Kolar Gold Field nakon njegovog prestanka rada. Ovaj rad opisuje različite metode koje se koriste za ponovnu namenu ovih cevi, koristeći nekoliko nedestruktivnih tehnika karakterizacije, uključujući rendgensku difrakciju (XRD), infracrvenu spektroskopiju (IR), skenirajuću elektronsku mikroskopiju (SEM) i tehnike energetski disperzivnog rendgenskog snimanja (EDX), kako bi se identifikovale faze koje sadrže gvožđe i proizvodi konverzije. Rezultati dobijeni ovim instrumentalnim tehnikama su predstavljeni. Ovo proširenje eksperimenta služi kao primerna demonstracija smanjenja, ponovne upotrebe i reciklaže gvozdenih cevi koje bi inače bile odbačene u velikim razmerama.

Ključne reči: Karakterizacija materijala; Održivost; Proporcionalni brojač; Reciklaža; Muon

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Issues of waste disposal in cement technology

Abstract

The possibility of cement production with increasing volumes of disposal of multi-tonnage waste from other industries has been studied. With the use of the “Clinker” computer program, new compositions of raw material mixtures based on the system of chalk – rice husk – TPP waste ash with a content of 42-51 wt.% of the specified waste were determined. The features of physicochemical transformations and the formation of the phase composition of cement clinker during the firing of a mixture based on man-made raw materials with a maximum temperature of
1400 °C and the properties of a mineral binding material are shown.

Keywords: cement, rice husk, fly ash, raw material mixture, composition, firing, crystalline phases, properties.

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Pitanja odlaganja otpada u tehnologiji cementa

Izvod

Proučavana je mogućnost proizvodnje cementa sa povećanjem obima odlaganja više tonažnog otpada iz drugih industrija. Korišćenjemr ačunarskog programa „Klinker“ utvrđeni su novi sastavi sirovinskih mešavina na bazi sistema kreda – pirinčana ljuska – otpadni pepeo TE sasadržajem 42-51 tež.% navedenog otpada. Osobine fizičko-hemijskih transformacija I formiranja faznog sastava cementnog klinkera pri pečenju smeše na bazi veštačkih sirovina sa maksimalnom temperaturom od 1400 °C prikazana su svojstva mineralnogv ezivnog materijala.

Ključne reči: cement, pirinčana ljuska, leteći pepeo, mešavina sirovina, sastav, pečenje, kristalne faze, svojstva.

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Studying the sodium effect on the Mo layer by varying the growth pressure on CIGS solar absorption Layer

Abstract

Efficiency degradation in flexible Cu(In,Ga)Se (CIGS) solar cells on stainless-steel (STS) substrates occurs due to iron impurity diffusion into the absorber layer. As the primary component of stainless-steel, iron can penetrate the back contact and enter the CIGS absorber, where Fe impurities are known to diminish solar cell performance. In this study, we developed a Sodium doped Molybdenum (Mo-Na) layer as a diffusion barrier on STS substrate using various growth pressures. We examined the Mo-Na diffusion barrier layer using Scanning Electron Microscopy (SEM), X-rdiffractometer (XRD), and Uv-Vis Spectrophotometer. XRD analysis revealed that films grown on STS substrates exhibited a pure chalcopyrite phase with a preferred (112) orientation. We deposited Mo back contact and CIGS layer through co-sputtering and selenization processes, respectively, to investigate Na diffusion through the barrier into the CIGS absorption layer. Secondary ion mass spectroscopy (SIMS) was employed to measure Na and Fe concentrations diffused in the CIGS layer. The SIMS depth profile and optical measurement results clearly showed that Na diffusion into the CIGS absorber layer could be regulated by adjusting the working pressure of the Mo-Na layer. Furthermore, we anticipate significant improvement in CIGS solar cell performance with the Mo-Na diffusion barrier layer, as Na concentration in the CIGS absorption layer affects the efficiency of CIGS solar cells.

Keywords: Flexible Cu(In,Ga)Se₂ (CIGS), Stainless steel, Sputtering, Diffusion barrier, Fe diffusion.

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Proučavanje efekta natrijuma na sloj mo variranjem pritiska rastana cigs solarnomapsorpcionom sloju

Izvod

Smanjenje efikasnosti u fleksibilnim Cu(In,Ga)Se (CIGS) solarnim ćelijama na podlogama od nerđajućeg čelika (STS) nastaje usled difuzije nečistoća gvožđa u sloj apsorbera. Kao primarna komponenta nerđajućeg čelika, gvožđe može da prodre u zadnji kontakt i uđe u CIGS apsorber, gde je poznato da nečistoće Fe smanjuju performanse solarnih ćelija. U ovoj studiji razvili smo sloj molibdena dopiranog natrijumom (Mo-Na) kao difuzionu barijeru na STS supstratu koristeći različite pritiske rasta. Ispitivali smo sloj Mo-Na difuzione barijere korišćenjem skenirajuće elektronske mikroskopije (SEM), Ks-rdifraktometra (KSRD) i Uv-Vis spektrofotometra. KSRD analiza je otkrila da filmovi uzgojeni na STS supstratima pokazuju čistu halkopiritnu fazu sa preferiranom (112) orijentacijom. Naneli smo Mo povratni kontakt i CIGS sloj kroz procese ko-prskanja i selenizacije, respektivno, da bismo istražili difuziju Na kroz barijeru u CIGS apsorpcioni sloj. Sekundarna jonska masena spektroskopija (SIMS) je korišćena za merenje koncentracija Na i Fe difuznih u CIGS sloju. SIMS profil dubine i rezultati optičkog merenja jasno su pokazali da se difuzija Na u sloj apsorbera CIGS može regulisati podešavanjem radnog pritiska Mo-Na sloja. Štaviše, očekujemo značajno poboljšanje performansi CIGS solarnih ćelija sa slojem barijere za difuziju Mo-Na, pošto koncentracija Na u CIGS apsorpcionom sloju utiče na efikasnost CIGS solarnih ćelija.

Ključne reči: Fleksibilni Cu(In,Ga)Se2 (CIGS), nerđajući čelik, raspršivanje, difuziona barijera, Fe difuzija.

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A review of sustainable construction and waste management: Brick manufacturing using agro-industrial wastes

Abstract

The construction industry is a large consumer of natural resources and a significant contributor to environmental deterioration. Sustainable construction practices, particularly in brick manufacture, have become important for mitigating these consequences. The use of agro-industrial waste as an alternative raw material in brick manufacture is an innovative approach to waste management and resource conservation. This research investigates the viability of using agro-industrial wastes such as rice husk ash, fly ash, bagasse, and other byproducts to make bricks. It assesses their environmental, economic, and technological advantages while confronting problems such as material variability, processing methods, and regulatory adherence. This thorough research seeks to establish a framework for using agro-industrial waste into conventional construction methods to attain sustainability objectives.

Keywords: Natural resources, sustainable construction, agro-industrial waste, waste management

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Pregled održive gradnje i upravljanja otpadom: proizvodnja cigle korišćenjem agroindustrijskog otpada

Izvod

Građevinska industrija je veliki potrošač prirodnih resursa i značajan doprinos pogoršanju životne sredine. Održive građevinske prakse, posebno u proizvodnji cigle, postale su važne za ublažavanje ovih posledica. Upotreba agroindustrijskog otpada kao alternativne sirovine u proizvodnji cigle je inovativan pristup upravljanju otpadom i očuvanju resursa. Ovo istraživanje istražuje održivost korišćenja agroindustrijskog otpada kao što su pepeo od pirinčane ljuske, leteći pepeo, bagasa i drugi nusproizvodi za proizvodnju cigle. Procenjuje njihove ekološke, ekonomske i tehnološke prednosti, dok se suočava sa problemima kao što su varijabilnost materijala, metode obrade i poštovanje propisa. Ovo temeljno istraživanje ima za cilj da uspostavi okvir za korišćenje agroindustrijskog otpada u konvencionalnim metodama gradnje kako bi se postigli ciljevi održivosti.

Ključne reči: Prirodni resursi, održiva gradnja, agroindustrijski otpad, upravljanje otpadom

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Effect of thin-layer conditions on stress-corrosion cracking of x70 steel in near neutral pH soilution at cathodic polarisation

Abstract

The priority task of modern underground main pipelines is to ensure the reliability of its operation, which largely depends on understanding the processes that occur on the surface of the pipes in the ground under conditions of cathodic protection. The purpose of this work is to study the features of stress-corrosion cracking (SCC) of X70 steel under conditions of thin-layer corrosion in near neutral pH environment. Potentiometry, voltammetry, massometry, electrolytic hydrogenation slow strain rate tests, scanning electronic microscopy were used. Differences in SCC mechanism of X70 steel at potentials of -0.950 V and -1.050 V in the investigated environments were experimentally determined. At -0.950 V, SCC of X70 steel in NS4 proceeds by anodic dissolution mechanism, and in the model soil environment – by mixed mechanism; at -1.050 V, SCC in the NS4 solution occurs by a mixed mechanism, and in a soil environment based on NS4 – by a hydrogen embrittlement mechanism. Obtained regularities are due to more significant embrittlement of the near-surface layer of the specimens in the model soil environment in thin layers under cathodic polarization, which leads to a change in SCC mechanism from plastic-brittle to completely brittle.

Keywords: pipe steel, slow strain rate tests, potentiometry, voltammetry, stress-corrosion cracking, thin-layer corrosion, hydrogenation

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Uticaj tankoslojnih uslova na naprezno-korozijsko pucanje čelika x70  blizu neutralnog pH pri katodnoj polarizaciji

Izvod

Prioritetni zadatak savremenih podzemnih magistralnih cevovoda je da obezbedi pouzdanost njegovog rada, što u velikoj meri zavisi od razumevanja procesa koji se dešavaju na površini cevi u zemlji u uslovima katodne zaštite. Svrha ovog rada je da se prouče karakteristike pucanja od naponske korozije (SCC) čelika X70 u uslovima tankoslojne korozije u okruženju blizu neutralnog pH. Korišćeni su potenciometrija, voltametrija, masometrija, elektrolitička hidrogenacija spore brzine deformacije, skenirajuća elektronska mikroskopija. Eksperimentalno su utvrđene razlike u SCC mehanizmu čelika X70 na potencijalima od -0,950 V i -1,050 V u ispitivanim sredinama. Na -0,950 V, SCC čelika X70 u NS4 se odvija mehanizmom anodnog rastvaranja, a u okruženju modelnog tla – mešovitim mehanizmom; na -1,050 V, SCC u rastvoru NS4 nastaje mešovitim mehanizmom, a u zemljištu zasnovanom na NS4 – mehanizmom vodoničnog krtenja. Dobijene pravilnosti su posledica značajnijeg krtenja pri površinskog sloja uzoraka u okruženju modelnog tla u tankim slojevima pod katodnom polarizacijom, što dovodi do promene mehanizma SCC od plastično krhkog do potpuno krhkog.

Ključne reči: čelik za cevi, ispitivanja sporog deformisanja, potenciometrija, voltametrija, naponsko-koroziono pucanje, tankoslojna korozija, hidrogenacija

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Investigations on self compacting concrete using fly ash and light expanded clay aggregates

Abstract

Compaction and curing both are equally important to achieve the desired strength and durability of concrete. In order to make concrete with better surface finish, improved strength and durability, it is essential to impart self compacting ability to concrete. Curing at early age is to reduce the plastic shrinkage, to ensure adequate surface strength and surface zone durability. This study examines self-compacting concrete (SCC) that contains saturated light expanded clay aggregate (LECA) and fly ash aggregate (FAA). The effects of LECA and FAA on SCC were examined with flow properties, microstructure, compressive strength, acid resistance (HCl), sulphate resistance (MgSO₄), and salt resistance (Nacl). The replacement of fine aggregate in the mixtures ranged from 0% to 25% with 5% interval by volume basis. Water filled LECA and FAA were also combined to produce SCC mixes. The findings demonstrate that substituting saturated lightweight aggregates for fine aggregate in SCC satisfied the filling ability, passing ability and segregation resistance. The compressive strength of SCC with 15% LECA & FAA, under internal curing is higher by 1.84% & 13.35% higher than that of the control concrete (CM_wc) at age of 28 days. F₁₅ mix exhibited less weight loss and lesser strength loss in acid & sulphate. Also less weight gain and lesser strength loss in salt resistance. SCC made with LECA & FAA blends to promote internal curing offers technical and cost benefits in the construction industry.

Keywords: Self compacting concrete, light expanded clay aggregate, fly ash aggregate, internal curing

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Istraživanja samozbijajuceg betona korišćenjem letećeg pepela i laganih ekspandovanih glinenih agregata

Izvod

Ova studija ispituje samozbijajući beton (SCC) koji sadrži zasićeni agregat letećeg pepela (FAA) i laki agregat ekspandirane gline (LECA). Zamena finog agregata u smešama se kretala od 0% do 25% na osnovu zapremine. LECA i FAA su takođe kombinovani da bi se proizvele SCC mešavine. Efekti LECA i FAA na SCC ispitivani su sa svojstvima tečenja, mikrostrukturom, čvrstoćom na pritisak, otpornošću na kiselinu (HCl), otpornošću na sulfat (MgSO4) i otpornošću na soli (Nacl). Nalazi pokazuju da zamena zasićenih lakih agregata finim agregatom u SCC mešavinama radi promovisanja unutrašnjeg očvršćavanja nudi tehničke i troškovne prednosti.

Ključne reči: samozbijajući beton, laki ekspandirani agregat, elektrofilterski agregat, unutrašnje očvršćavanje

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The choice of container material for storing pomegranate juice: Should one opt for SS 304 alloy or SS 316L alloy?

Abstract

The objective of this research is to examine the feasibility of storing pomegranate juice in containers constructed from SS 304 alloy, commonly referred to as Ever Silver, or SS 316 L alloy. The corrosion resistance of both SS 304 and SS 316L alloy was evaluated across different environments, including a water system, a pomegranate juice system, and a pomegranate juice system with added sugar (5000 g), utilizing AC impedance spectroscopy for measurement. Key corrosion parameters, including charge transfer resistance, impedance, phase angle, and double layer capacitance, were calculated. The findings indicate that SS 316 L alloy exhibits superior corrosion resistance compared to SS 304 alloy across all three systems. Consequently, it is recommended that pomegranate juice and pomegranate juice with sugar be stored in containers made of SS 316 L alloy, which is also applicable to the water system.

Keywords: corrosion resistance, pomegranate juice, SS 304, SS 316 L alloy, electrochemical study, AC impedance spectra

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Izbor materijala posude za skladištenje soka od nara: da li se treba odlučiti za leguru SS 304 ili leguru SS 316L?

Izvod

Cilj ovog istraživanja je da se ispita izvodljivost skladištenja soka od nara u posudama napravljenim od legure SS 304, koja se obično naziva Ever Silver, ili legura SS 316 L. Otpornost na koroziju legure SS 304 i SS 316L je procenjena u različitim okruženjima, uključujući sistem vode, sistem soka od nara i sistem soka od nara sa dodatkom šećera (5000 g), korišćenjem spektroskopije naizmenične impedanse za merenje. Izračunati su ključni parametri korozije, uključujući otpor prenosa naelektrisanja, impedansu, fazni ugao i dvoslojni kapacitet. Nalazi pokazuju da legura SS 316L pokazuje superiornu otpornost na koroziju u poređenju sa legurom SS 304 u sva tri sistema. Zbog toga se preporučuje da se sok od nara i sok od nara sa šećerom čuvaju u posudama napravljenim od legure SS 316L, koja je primenljiva i na vodovodni sistem.

Ključne reči: otpornost na koroziju, sok od nara, SS 304, legura SS 316L, elektrohemijska studija, AC impedansni spektri

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Investigation of structural, optical, and emission properties of SnO₂ nanoparticles by thermal decomposition method

Abstract

SnO₂ nanoparticles were synthesized usingthe thermal decomposition technique by varying the temperature from 300^°C to 600^°C. The synthesized nanoparticles (9 nm) were of rutile (tetragonal) phase with orientation along [110], [101], [200], [211], [220], [310], [112], [301], [202]crystal planes. The peak intensity of the crystal planes becomes prominent with an increase in decomposition temperature while the impurity phases diminish. The nanoparticle’s crystallite size and microstrain were calculated using the William Hall equation with the union deformation model. SnO₂ nanoparticles synthesized at 600^°Cshow a positive strain of 0.3571×10^-3indicates lattice expansion. At thermal decomposition of 500⁰C, the sample has maximum transparency with a band gap at ~ 4.19 eV and broad emission in the blue region of the EM Spectra with high intensity (5 x10⁵ counts), rendering it suitable for blue light LEDs.

Keywords: Thermal decomposition method,SnO₂Nanoparticles, Tin(II) chloride dihydrate

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Straživanje strukturnih, optičkih i emisionih svojstava SnO₂ nanočestica metodom termičke razgradnje

Izvod

SnO₂ nanočestice su sintetizovane tehnikom termičke razgradnje variranjem temperature od 300°C do 600°C. Sintetizovane nanočestice (9 nm) bile su rutilne (tetragonalne) faze sa orijentacijom duž kristalnih ravni [110], [101], [200], [211], [220], [310], [112], [301], [202]. Intenzitet pikova kristalnih ravni postaje izraženiji sa povećanjem temperature razgradnje, dok se faze nečistoća smanjuju. Veličina kristalita i mikronaprezanje nanočestica izračunati su korišćenjem jednačine Vilijama Hola sa modelom unijske deformacije. SnO2 nanočestice sintetizovane na 600°C pokazuju pozitivno naprezanje od 0,3571×10-3, što ukazuje na širenje rešetke. Pri termičkom razlaganju na 5000°C, uzorak ima maksimalnu transparentnost sa energetskim procepom od ~4,19 eV i širokom emisijom u plavom području EM spektra sa visokim intenzitetom (5 x 105 brojeva), što ga čini pogodnim za plave LED diode.

Ključne reči:  Metoda termičke razgradnje, nanočestice SnO₂, kalaj (II) hloriddihidrat

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