Experimental analysis of exposed concrete slabs through image analysis

The paper presents a comparative analysis of eight concrete slabs prepared under laboratory conditions. The slabs were cast using formwork of varying quality, cured for 1 and 7 days, and compacted for 7s and 10 s. The comparison of properties, specifically the pore surface area of different diameters, was conducted using image analysis software. The results show that curing conditions had no significant effect on the surface characteristics of exposed concrete, while both the type of formwork and compaction duration demonstrated a more significant influence

Simulation of the iron transport ladle preheating process

Because of very important compounds such as tin sulfide, tin is critical metal for green economy. SnS applications are mostly used in optoelectronic devices (photovoltaics), lithium- and sodium-ion batteries, and sensors among others with a significant potential for a variety of future uses. Thermochemical analysis of synthesis of SnS and SnS2 was used for an analysis of possibility for formation of the aimed product. This study explores pyrometallurgical method for synthesis of SnS using pure elements of tin and Sulphur through one strong exothermic reaction in laboratory conditions. The goal is to offer new synthesis method in one closed reactor at temperatures between 220° and 440°C. The mass loss during synthesis was followed in the static conditions. We concluded that this synthesis of SnS can be controlled via an exothermic reaction in very short time. The better results can be reached using the synthesis process in dynamic conditions via an intensive mixing through the synthesis reactio

New approaches and applications of natural zeolites for boron adsorption from aqueous solutions

Excessive mineral extraction and boric acid production can lead to elevated boron concentrations in wastewater. While boron is an essential micronutrient for humans, excessive exposure and intake can result in adverse health effects. Existing treatment processes for boron contaminated wastewater have various limitations related to effectiveness, production of additional solid waste and high operational costs. This study investigates the use of natural zeolite as a cost-effective, sustainable and environmentally friendly adsorbent for boron removal. Natural zeolites are alumosilicate porous minerals widely used in wastewater treatment applications. To enhance its adsorption properties, natural zeolite was modified using a nickel sulphate solution. In this work, four adsorbents were analyzed: raw natural zeolite, nickel-modified natural zeolite, zeolite/hydroxyapatite and nickel-modified zeolite/hydroxyapatite composite. The zeolite/hydroxyapatite composite was synthesized under hydrothermal conditions at 160 °C for 4 hours at autogenous pressure. Characterization of the adsorbents was performed using X-ray powder diffraction (XRPD), scanning electron microscopy and thermogravimetric analysis. XRPD analysis confirmed clinoptilolite as the dominant mineral phase in the zeolitic tuff and showed that hydrothermal treatment did not affect its crystallinity. The adsorption properties were tested using a synthetic boron solution at pH 9, where boron exists in both B(OH)3 and B(OH)4– forms. The results showed that the presence of nickel primarily on the surface of the adsorbent leads to an increase in boron adsorption, which is a consequence of its ability to form complexes with B(OH)4–. This research confirmed that adsorbents based on metal-saturated natural zeolite are promising adsorbents of boron compounds from wastewater

The effect of fluxing agent cations in fly ash-based glass on chemical stability

Recycling plays a key role in making the economy more efficient in terms of raw material usage. Coal fly ash (CFA), a by-product of coal combustion in thermal power plants, shares a chemical composition similar to some silicate glasses, making it a viable raw material for glass production. The paper presents the results of Na+ and Ca2+ ion incorporation into coal fly ash-based glass and its impact on chemical stability. The chemical resistance of the glasses was tested in distilled water, 0.01 mol/dm3 HCl, and 0.01 mol/dm3 NaOH. The concentrations of the elements in the solution indicate that the ion exchange process is the dominant dissolution mechanism for both glasses. Na-fly ash glass shows slightly lower stability in all solvents than Ca-fly ash glass. FTIR spectra show no change in the structure of the glasses after contact with solvents. The chemical stability of both glasses is satisfactory with a mass change of less than 1 %

The edaphic factor and orchids: Gymnadenia conopsea from contrasting geologies in the Central Balkans

Edaphic stress is one of the main factors affecting plant fitness, but it is still poorly understood, even in rare plants such as orchids. Gymnadenia conopsea is a terrestrial orchid that grows on different geological substrates, making it a model species for the study of adaptive responses to edaphic factors, including metals in soil. The samples of plant tissues of G. conopsea growing on carbonate, ultramafic and siliceous substrates in Serbia and the associated rhizosphere soil were collected and analysed for elemental concentrations. Two different strategies for the distribution of macro- and trace elements were found, corresponding to the trend generally observed in orchids. Trace elements (As, B, Cr, Co, Fe, Mn, and Ni) remain mainly in the underground organs and only a small proportion is transferred to the shoots. It was the opposite for the macroelements (Ca, Mg, K and P) with the highest accumulation occurred in the leaves and inflorescences. The tolerance of G. conopsea to the different geological substrates results from the moderate metal concentrations in the soils analysed and the exclusion strategy of the species, which is the most common response to metal induced stress in orchids

Primena ISO 59020: okvir za ocenu cirkularnosti u sektoru upravljanja otpadom

Prelazak na cirkularnu ekonomiju sve više se prepoznaje kao ključan za održivo upravljanje resursima. Međutim, trenutne direktive EU u ovoj oblasti ostaju uglavnom fokusirane na stope recikliranja, zanemarujući sistemske neefikasnosti i važnost prevencije i ponovne upotrebe. Ovaj rad kritički proučava potencijal adaptacije postojećeg okvira cirkularne ekonomije na zahteve standarda ISO 59020 za merenje i procenu cirkularnih performansi, i daje okvir praćenja cirkularnosti pri upravljanju otpadom. ISO 59020 uvodi obavezu merenja cirkularne ekonomije kroz jasno definisane granice zasnovane na životnom ciklusu proizvoda. Standard zahteva transparentno praćenje i kvantitativno izveštavanje tokova resursa, uključujući procenat ponovno korišćenih i recikliranih materijala. Sve metrike se izračunavaju korišćenjem standardizovanih formula, omogućavajući objektivnu i uporedivu ocenu cirkularnih performansi. Posebnu vrednost okvir pruža kroz mogućnost proširenja analize opcionim metrikama za energetske i vodene cikluse. Udeo obnovljivih izvora energije i stepen ponovne upotrebe vode pružaju sveobuhvatniji uvid u ukupne performanse sistema i povezuju cilju cirkularne ekonomije sa klimatskom politikom i efikasnim upravljanjem resursima. Komparativnom analizom rad pokazuje da ISO 59020 ima značajne razlike u oceni cirkularne ekonomije u odnosu na konvencionalne metrike EU, pre svega zahvaljujući uključivanju indirektnih indikatora za prevenciju i ponovnu upotrebu. Zaključuje se da bi se uključivanjem principa standarda ISO 59020 u direktive EU eliminisale osetljive tačke u merenju performansi cirkularne ekonomije, podstakle sistemske intervencije i olakšalo odvajanje apsolutne potrošnje resursa od ekonomskog rasta. Ovaj pristup omogućio bi stavljanje u fokus redizajn proizvoda, produženje veka trajanja robe i stvaranje inovativnih poslovnih modela zasnovanih na uslugama umesto na vlasništvu

Specifičnosti baterija za automobile i njihov uticaj na životnu sredinu

Za razumevanje zaštite životne sredine je ključan multidisciplinarni pristup ovoj problematici, kao i rešavanje kompleksnih ekoloških problema. Ovaj pristup uključuje saradnju različitih disciplina kao što su biologija, ekologija, sociologija, ekonomija, politika i mnoge druge. Ključni elementi multidisciplinarnog pristupa su integracija znanja iz različitih disciplina kako bi se stvorila celovita slika ekoloških izazova. Saradnja između različitih strana, uključujući vladu, industriju, naučne institucije i civilno društvo je ključno za zdrav pristup životnoj zajednici i njenom očuvanju i poboljšanju. Razmatranje životne sredine kao kompleksnog sistema gde svaki deo utiče na celinu je od izuzetnog značaja, dok primena principa održivosti pomaže kako bi se osiguralo da se potrebe današnjih generacija zadovolje bez ugrožavanja mogućnosti budućih generacija. Ovaj pristup omogućava bolje razumevanje i rešavanje problema poput klimatskih promena, degradacije zemljišta, izumiranja vrsta i zagađivanja vode. Automobilska industrija doprinosi zagadjenju životne sredine na nekoliko načina i zbog toga je bitno razmotriti koji su to izvori energije koji bi se primenili kao pogonska snaga automobila najefikasniji i pritom najmanje opterećuju i ovako veoma zagađenu životnu sredinu. U ovom radu su analizirani elementarni pokazatelji različitih izvora energije, odnosno baterija koje služe kao pogon automobila, i to fosilna goriva, litijumske baterije, natrujumske baterije i vodonik kao pogonsko gorivo za automobile. U cilju postavljanja komparacija uticaja različitih izvora energije za motorna vozila, može se postaviti zaključak da motori na fosilni pogon imaju visoka energetska gustina, široka dostupnost, ali produkuju emisiju štetnih gasova kao što su ugljen-dioksid (CO2), azotni oksidi (NOx), sumpor-dioksid (SO2) i isparljiva organska jedinjenja (VOC), što doprinosi zagađenju vazduha, efekatu staklene bašte i zdravstvenim problemima. Litijumske baterije imaju visoku energetsku gustinu, dug vek trajanja, široka primena u elektronici i električnim vozilima, ali je ekstrakcija litijuma veoma ekološki štetna, uključujući zagađenje vode i zemljišta. Sama proizvodnja litijumskih baterija zahteva velike količine vode i energije. Natrijumske baterije su znatno jeftinije, dostupnije, manje štetne za životnu sredinu. Natrijum je mnogo rasprostranjeniji od litijuma, što smanjuje ekološki otisak ekstrakcije. Ipak, ove bateije imaju nižu energetsku gustinu u poređenju sa litijumskim baterijama, što ih čini težim i glomaznijim. Vodonikove baterije proizvode samo vodu kao nusproizvod, što ih čini ekološki najprihvatljivijim. Mogu se koristiti za skladištenje energije iz obnovljivih izvora. Nedostaci primene vodinika kao goriva su, za sada, visoki troškovi proizvodnje i skladištenja vodonika, kao i potreba za infrastrukturom za distribuciju. Svaka tehnologija ima svoje prednosti i nedostatke, ali natrijumske baterije trenutno izgledaju kao najodrživija alternativa litijumskim baterijama zbog nižeg ekološkog otiska i veće dostupnosti resursa

Influence of mechanochemical activation on the sorption characteristics of sodium carbonate

Carbon dioxide is a secondary product of many industrial systems, which significantly affects the increase in its content in the air. This carbon dioxide directly affects environmental pollution. Absorption of the obtained CO2 in industrial plants is very important in the process of environmental protection. It has been observed that sodium carbonate has the ability to absorb carbon dioxide, and that mechanochemical activation significantly enhances this property. In this work, sodium carbonate is a mechanical activation and its sorption properties are monitored by X- ray diffraction and BET methods

Innovative oxidative system for leaching of Fe2+ from sphalerite concentrate

Sphalerite is a sulfide zinc mineral, which also contains supporting metals such as iron, copper and lead. In this work, we dealt with the extraction of iron from sphalerite in a new oxidation system. Manganese dioxide was used as the primary oxidant, and KI was used as a secondary oxidizing agent with the aim of creating an I2/I- oxidation cycle in a sulfuric acid medium. The thoughtful characterization (XRD, SEM, EDS) of the initial sample, as well as the precipitate formed after leaching was done. During the leaching tests, process parameters were varied

Assessment of Nontoxic Surfactant-Modifed Kaolinite for Potential Application as an Adsorbent for Mycotoxins

In this study, natural kaolin was modified with hexadecyltrimethylammonium bromide (HDTMA-Br) at two levels corresponding to 50% and 90% of its cation exchange capacity. The resulting materials, designated as HKR-50 and HKR-90, were used as adsorbents for the mycotoxins ochratoxin A (OCHRA) and zearalenone (ZEN). The characterization of the HKRs with several methods (X-ray diffraction, DRIFT spectroscopy, thermal analysis (DTA/TG), SEM, zeta potential measurements, and the determination of the point of zero charge and textural properties) confirmed the presence of surfactant ions on the organokaolinites’ surfaces. The adsorption of ZEN and OCHRA by HKRs followed nonlinear adsorption isotherms, suggesting a complex adsorption mechanism. The adsorption capacities of ZEN and OCHRA were similar for HKR-50 and HKR-90 at pH 3, with higher adsorption observed for ZEN (~13.0 mg/g for HKR-50 and HKR-90 for ZEN and ~8.0 mg/g for HKR-50 and HKR-90 for OCHRA). At pH 7, the adsorption of ZEN and OCHRA was lower than at pH 3, especially for OCHRA, but slightly increased with increased amounts of surfactant on the kaolinite surface (8.5 mg/g for HKR-50 and 10.8 mg/g for HKR-90 for ZEN and 2.6 mg/g for HKR-50 and 4.1 mg/g for HKR-90 for OCHRA). Special attention was paid to the safety assessment of the natural kaolin and HKR-90, and toxicological tests confirmed the safety of both materials, as no adverse effects were observed in rats