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Synthesis and characterization of polyphosphate glasses with addition of strontium and lanthanum
No full textPredmet rada ove doktorske disertacije bio je dobijanje i karakterizacija polifosfatnih stakala sa dodatkom stroncijuma i lantana.
U ispitivanjima su korišćene metode: atomska apsorpciona spektroskopija (AAS), spektrofotometrija (SF), rendgenska difrakcija (XRD), metoda piknometra (određivanje gustine), infracrvena spektroskopija (FTIR), diferencijalna skenirajuća kalorimetrija (DSC), skenirajuća elektronska mikroskopija (SEM) i termomikroskopija (HSM).
Prva faza istraživanja obuhvatala je sintezu i karakterizaciju četiri fosfatna stakla. Dva stakla su dobijena uvođenjem SrO u sistem, a dva uvođenjem La2O3. Karakterizacija stakala obuhvatala je ispitivanje fizičkih i strukturnih karakteristika stakala, kristalizacionih karakteristika i sinterabilnosti. Za određivanje strukturnih karakteristika stakala- korišćena je metoda infracrvene spektroskopske analize. Kristalizacione karakteristike stakala ispitivane su pri izotermskim i neizotermskim uslovima. Vrednosti energija aktivacije kristalizacije, Ea, rastu sa povećanjem količine stroncijuma i lantana u staklima. Ponašanje prahova stakala pri sinterovanju je ispitivano pomoću termomikroskopa. Dodatkom stroncijum- i lantan-oksida povećava se stabilnost stakla, a relativno visoke vrednosti parametara stabilnosti ukazuju na veću otpornost stakla procesu kristalizacije. Vrednosti energija aktivacije viskoznog toka, ΔGη, rastu sa povećanjem količine stroncijuma i lantana u staklima.
Druga faza istraživanja obuhvatila je sinterovanje prahova fosfatnih stakala i ispitivanje uticaja temperature sinterovanja na strukturne karakteristike, fazni sastav, poroznost i tvrdoću. Temperature sinterovanja prahova stakala određene su primenom termomikroskopske i DSC analize. Kristalne faze su identifikovane XRD analizom termički obrađenih uzoraka. Utvrđeno je prisustvo bioaktivnih faza β-CaP2O6, α-Ca3(PO4)2 i β-Ca3(PO4)2. Svi uzorci sinterovani na Tp imaju veću poroznost od uzoraka sinterovanih na Tms, što ukazuje da je ova poroznost uslovljena kristalizacijom. Tvrdoća sinterovanih uzoraka određena je metodom po Vikersu i pokazano je da sa porastom poroznosti tvrdoća uzoraka opada.
Treća faza istraživanja obuhvatala je analizu hemijske postojanosti uzoraka u rastvoru simulirane telesne tečnosti. Masa uzoraka je merena na analitičkoj vagi pre i posle eksperimenta, pH vrednost rastvora određivana je pH metrom, a koncentracije elemenata u rastvoru određivane su metodama AAS i SF. Sa porastom sadržaja SrO rastvorljivost stakla u SBF-u se povećava, dok se kod stakala sa lantanom rastvorljivost smanjuje sa povećanjem sadržaja La2O3. Uzorci stakala sa stroncijumom sinterovani na Tms i Tp pokazuju slabu rastvorljivost u SBF-u, čak i za najduže eksperimentalno vreme. Najveću rastvorljivost pokazuje uzorak sa nižim sadržajem lantana, sinterovan na Tms.
Rezultati ovog istraživanja omogućavaju određivanje uticaja toplotne obrade na mikrostrukturu staklo-keramike dobijene kontrolisanom kristalizacijom fosfatnih stakala i uticaj uslova sinterovanja na mikrostrukturu staklo-keramike dobijene sinter-kristalizacijom.The subject of this doctoral dissertation was the preparation and characterization of polyphosphate glasses with the addition of strontium and lanthanum.
The following methods were used in the tests: atomic absorption spectroscopy (AAS), spectrophotometry (SF), X-ray diffraction (XRD), pycnometer method (density determination), infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and thermomicroscopy (HSM).
The first phase of the research included the synthesis and characterization of four phosphate glasses. Two glasses were obtained by introducing SrO into the system, and two by introducing La2O3. The characterization of the glasses included examination of the physical and structural characteristics of the glasses, crystallization characteristics and sinterability. The method of infrared spectroscopic analysis was used to determine the structural characteristics of glasses. The crystallization characteristics of the glasses were examined under isothermal and non-isothermal conditions. The values of crystallization activation energies, Ea, increase with increasing amounts of strontium and lanthanum in the glasses. The behavior of glass powders during sintering was investigated using a thermomicroscope. The addition of strontium and lanthanum oxide increases the stability of the glass, and the relatively high values of the stability parameters indicate a greater resistance of the glass to the crystallization process. The values of the viscous flow activation energies, ΔGη, increase with increasing amounts of strontium and lanthanum in the glasses.
The second phase of the research included sintering of phosphate glass powders and examination of the influence of sintering temperature on structural characteristics, phase composition, porosity and hardness. The sintering temperatures of glass powders were determined using thermomicroscopic and DSC analysis. The crystalline phases were identified by XRD analysis of heat-treated samples. The presence of bioactive phases β-CaP2O6, α-Ca3(PO4)2 and β-Ca3(PO4)2 was determined. All samples sintered at Tp have higher porosity than samples sintered at Tms, which indicates that this porosity is due to crystallization. The hardness of the sintered samples was determined by the Vickers method and it was shown that the hardness of the samples decreases with the increase in porosity.
The third phase of the research included the analysis of the chemical stability of the samples in a simulated body fluid solution. The samples were measured on an analytical balance before and after the experiment, the pH value of the solution was determined with a pH meter, and the concentrations of elements in the solution were determined by the AAS and SF methods. As the SrO content increases, the solubility of the glass in SBF increases, while the solubility of the lanthanum glasses decreases with the increase in the La2O3 content. Samples of strontium glasses sintered at Tms and Tp show poor solubility in SBF, even for the longest experimental time. The highest solubility is shown by the sample with lower lanthanum content, sintered at Tms.
The results of this research allow determining the influence of heat treatment on the microstructure of glass-ceramics obtained by controlled crystallization of phosphate glasses and the influence of sintering conditions on the microstructure of glass-ceramics obtained by sinter-crystallization
Application of biochar derived from organic waste for the removal of heavy metals from wastewater
No full textSolving the problem of heavy metals removal from natural environment and from waste waters
in particular, biosorbents are increasingly used instead of conventional adsorbents as cheaper
than active carbon, and still highly efficient. The presence of heavy metals raises great concern
due to their toxicity, bioaccumulative properties and threats to human lives and environment. In
recent years, various low-cost adsorbents have been explored, such as microbe biomass (bacteria,
fungi, algae), forestry residues and agricultural waste (hay, maize), industrial waste (remnants of
food and beverage, byproducts of fermentation, active sludge, etc.), as well as plant remnants,
grass, sawdust, and other cellulosic materials. In this work the emphasis is put on investigating
the application of biochar resulted in the pyrolysis of biowaste- cherry pits and kombucha fungi-
in the removal of lead, as one of the heavy metals, from wastewaters possibly coming out of
mines, industrial processing of lead, the production of pigments, leaded petrol and other sources.
For this experiment the tests of adsorption capacity and efficacy of adsorbents gained in the
above mentioned way and adsorption kinetic were conducted using kinetic methods of pseudo
first and pseudo second-order, and Weber-Morris diffusion model. It was also monitored whether
the effect can be stimulated under the influence of two different types of mixing, in the magnetic
stirrer and ultrasonic bath. The selected method of analysis, regarding the nature of the analyte,
was the atomic absorption spectroscopy
Effect of temperature on antimony leaching from PET and glass bottled water
No full textThe leaching of elements from packaging into bottled water is a key factor in assessing product safety, with antimony used as a catalyst in PET packaging production, which is particularly significant due to its potential toxicity.1,2 This study aimed to investigate the leaching of antimony and other elements (Ba, Cd, Cr, Cu, Li, Pb, Sr, B, Mn, K, Mg, Na, Ca) from PET and glass packaging into bottled water at different temperatures (-20°C, 25 °C, and 40 °C). In July 2024, six commercial Serbian brands of bottled water (Knjaz Miloš, Voda Voda, Rosa, Aqua viva, Life, Vrnjci) were analyzed to quantify element leaching using the ICP-MS technique. Additionally, plastic bottles were analyzed to determine the antimony content within the packaging itself. The results showed a similar antimony content in all plastic bottles (160±17 mg/kg). The concentrations of macroelements (Ca, Mg, Na, K, Li, Ba) in the water remained constant across all samples, regardless of packaging type or storage temperature. However, at 40 °C, the leaching of antimony from PET packaging into the water was observed, indicating increased element leaching at elevated temperatures. The increased antimony concentration observed in Voda Voda bottled in glass can be attributed to the PET-containing plastic polymer used for the bottle cap. No antimony leaching was detected in water from glass packaging without plastic components. These findings underscore the critical need for careful consideration of packaging materials and storage conditions in ensuring bottled water safety, particularly concerning elevated temperatures and packaging components containing PET
Enhanced adsorption of emerging contaminant diclofenac sodium by zeolite modified with cationic surfactant
No full textOctadecyldimethylbenzylammonium (ODMBA) chloride was used as a surfactant to modify the natural zeolite for the preparation of organozeolites. The natural zeolite was modfied with surfactant in amounts equal to 20, 50, 75 and 100% of the zeolite's external cation exchange capacity (ECEC). Obtained organozeolites, denoted as OZ-20, OZ-50, OZ-75 and OZ-100, were tested as adsorbents for non-steroidal anti-inflammatory drug diclofenac sodium (DS), a common contaminant of water systems. Results showed that with the increase of the amounts of surfactant in organozeolite, as well as with the increase of the amounts of solid phase in the suspension, DS adsorption increased. The material with the highest surfactant amount (OZ-100) showed capability to remove 90.7% of DS from buffer solution. Characterization of the organozeolites, before and after DS removal, performed using FTIR method confirmed successful modification of zeolite and presence of DS in organozeolites after adsorption
Biochar as an Enzyme Immobilization Support and Its Application for Dye Degradation
No full textWastewaters generated by the textile industry often contain significant amounts of harmful (carcinogenic and mutagenic) cationic dyes, whose efficient removal is of crucial importance. This study investigates the laccase immobilization on biochar obtained from sour cherry stones (SCS-B), as a cost effective adsorbent, and evaluates its application for brilliant green (BG) degradation. The successful immobilization of laccase on biochar was achieved via adsorption and confirmed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). An immobilization efficiency of 66% was achieved using 0.274 U/mL of laccase at pH 5 and a temperature of 40 °C. The adsorption kinetics of laccase followed a pseudo-second-order model, indicating that chemical adsorption plays a significant role in the immobilization process. The BG degradation by immobilized system was further optimized by evaluating effects of pH, temperature, dye concentration, and contact time. More than 92% of BG (50 mg/L) was removed within 4 h at pH 5 and temperature of 30 °C. These findings suggest that SCS-B can effectively be used as an enzyme carrier and be further utilized for the removal of emerging pollutants, positioning it as a sustainable solution for wastewater treatment
Lignocellulosic waste from fruit processing industries - valuable resource with wide applications
No full textWith its substantial production volume, Serbia’s fruit industry is one of the leading sectors of the Serbian economy, with the total production of approximately 1.5m tons per year (www. serbiadoesfruit.com). Serbia is one of the top plum-producing countries in the world with the average production of 450 thousand tons per year. Also, there is an increasing trend in the production of sour cherries (with average annual production around 145 thousand tons), and peaches, where the average annual production was about 40 thousand tons) (www.stat.gov.rs).
However, fruit processing industry generates significant amounts of waste (peels, rind, seeds, core, stones, pods, shell, pomace, etc.) which represents 25-30% of processed raw materials (Lopičić et al., 2022). Mostly, this type of waste is landfilled; raising the greenhouse gases (GHGs) and pollutant leachates, wasting of food commodities, land, water, fertilizers, chemicals, energy and labour. The complex bio-structure of this waste type together with various conversion and modification allows their multi-scale application. It can be applied to produce various types of biomaterials (bioplastics, biocomposites), biofuels, resins, adsorbents and sustainable fertilizers with lower carbon footprint than the conventional ones (Izydorczyk et al, 2024).
In this paper three waste biomasses (peach - PS, sour cherry - CS and plum stones - PmS) obtained from Serbian fruit processing industry were analysed and pre-evaluated as a potential starting material for soil treatment to enhance soil fertility. According to chemical analysis this type of waste contains lignocellulosic matrix (LC) made of cellulose (C), hemicellulose (HC) and lignin (L). Proportions of these constituents in each of LC biomass are: PS: 62.94% C, 5.42% HC and 17.93% L (Lopičić et al., 2013); CS: 58.18% C, 2.71% HC and 18.57% L and PmS: 22.93% C, 21.42% HC and 25.41% L (Pap et al., 2017). The results of elemental organic analysis showed the following proportions: PS: 47.42% C, 0.27% N, 6.06% H, 0.21% S and 45.58% O; CS: 47.90% C, 0.0% N, 6.28% H, 0.0% S and 45.82% O and PmS: 48.51% C, 1.48% N, 6.28% H, 0.15% S and 43.57% O. This implies the positive impacts on soil structure by enhancing organic matter. In addition, this type of waste contains macro and micro elements, of which K, Ca, P, Mg are dominant. The content of available (water-soluble) elements in samples ashes, performed by AAS analysis showed that the content of soluble phosphorus was the highest in PmS (93% is water soluble) followed by the PS (78%), and CS (70%) while potassium is almost completely water-soluble in PS (97.2%). Therefore, this is an abundant and affordable source of soluble phosphorus and potassium in the final product, which could affect soil health by enhancing the soil texture, moisture retention, nutrient availability and cation exchange capacity
Poboljšanje adsorpcionih karakteristika divljeg sirka hidrotermalnom karbonizacijom u materijal visokog afiniteta za uklanjanje olova
No full textProces hidrotermalne karbonizacije (HTC) je efikasan za poboljšanje kapaciteta adsorpcije biljnih ostataka. U ovoj studiji, divlji sirak (Sorghum halepenese) je transformisan u ugljenični materijal sa odličnim adsorpcionim svojstvima za tretman olova iz otpadnih voda primenom HTC tretmana na 220°C. Karbonizacija smanjuje sadržaj pepela i isparljivih materija u dobijenom materijalu usred razgradnje biomase. Eksperimentalni podaci su analizirani korišćenjem Lengmirovog, Frojndlihovog i Redlich-Peterson modela izotermi. Rezultati su pokazali da Lengmirov model izoterme najbolje opisuje proces adsorpcije, sa maksimalnim kapacitetom od 28,40 mg/g. Ovo ukazuje da bi divlji sirak tretiran HTC tretmanom mogao biti veoma efikasan adsorbent za prečišćavanje otpadnih voda
Breeding potential of morphological and phytochemical characteristics of landraces and autochthone varieties of Capsicum annuum L. in Republic of Serbia
No full textBy maintaining a large number of local pepper genotypes, it is possible to preserve a large number of desirable genes that can be used in different pepper selection programs. The aim of this study was to classify a part of the collection of 15 genotypes (11 populations and 4 varieties originating from autochthonous populations) of peppers originating from Republic of Serbia. Morphological characteristics (weight, length, width, pericarp thickness, color before fruit ripening, shape and number of fruit chambers) and 10 phytochemical parameters of the fruit (carbohydrates, essential oils, ash, cellulose, beta carotene, potassium, iron, vitamin C, total phenols, antioxidant activity) were studied. Using statistical multivariate techniques (PCA and Cluster analysis), the degree of variation between local populations was assessed and diversity was determined based on the morphological and nutritional characteristics of pepper fruits. Morphological traits were determined using two main components that accounted for 70.3% of the variability. These components accounted for 49.8% of the variation in nutritional traits. The ‘Čokotanka’ population would be suitable for individual selection and reduced divergence within the population, since it has 6 tested traits that resulted in high diversity index. Populations ‘Stojankina kletva’, ‘Lalić’ and ‘Strižanka’ would be suitable for recombination of genes to improve the properties of individual selection programs for this vegetable specie
An overview on the viable methods for textile wastewater treatment
No full textThe textile industry is one of the major polluters of the environment, primarily due to the types and quantities of wastewater it produces. It is estimated that 20% of global water pollution is caused by textile processing, meaning that these processes generate enormous amounts of wastewater. Generally, this wastewater contains high levels of suspended solids, dyes, salts, pesticides, non-biodegradable organic substances, and heavy metals. The decline in water quality, along with increasingly stringent environmental protection regulations, has led the textile industry to turn to sustainable wastewater treatment methods that help reduce the global water footprint. This paper reviews some viable methods used for the treatment of wastewater originating from the textile industry. The focus is on advanced treatment techniques, such as adsorption, membrane-based filtration, electrochemical processes, and advanced oxidation. These methods offer potential solutions to mitigate the environmental impact of textile wastewater and promote sustainable water management practices
Application of Machine Learning for Predicting Mechanical Properties and Designing Novel Biocompatible Titanium Alloys
No full textTitanium alloys are renowned for their exceptional strength, low modulus of elasticity, and excellent
biocompatibility, making them ideal for orthopedic applications. To optimize these properties and
explore new alloy compositions, machine learning was employed to analyze a database of biocompatible alloys. Using the Extra Trees Regressor model, key mechanical properties : Young’s modulus,
tensile strength, and yield strength were predicted. The correlation coefficients for the test set were
0.793, 0.893, and 0.868, respectively, while the mean absolute errors fell within the acceptable range
of values reported in the literature. By designing experiments and constructing relief maps for over
thirty alloying element combinations, approximately 16,000 unique compositions of four-component
alloy systems were discovered, providing a basis for further experimental research