Microstructural Analysis of Thermally Treated Geopolymer Incorporated with Neodymium

The following investigation presents the thermal treatment of geopolymer based on metakaolin, with the addition of 1% and 5% of neodymium in the form Nd2O3, at 300˚C, 600˚C and 900˚C. Six samples were synthesized in total. Samples GT1 and GT2 containing 1% and 5% of Nd2O3, and they were treated at 300˚C, while the samples GT3 and GT4 also had the same percentage composition of Nd2O3 and were treated at 600˚C, and the samples GT5 and GT6 were treated at 900˚C with the same percentage of Nd2O3. Physical and chemical changes in the aluminosilicate geopolymer matrix were monitored. The incorporation of rare earths into the polymer network of aluminosilicates has been proven to disrupt the basic structure of geopolymers, however, with increased temperature, these materials show even more unusual properties. DRIFT was employed to investigate the structural properties of thermally treated geopolymers. Additionally, TEM provided further insight into the structural changes induced by thermal treatment and Nd2O3 doping. SEM was used to observe the effect of thermal treatment temperature (300˚C and 600˚C) on geopolymer porosity, which resulted in the appearance of large pores and cracks in the material. The UV/Vis spectra of the synthesized Nd3+ doped geopolymers exhibited attractive optical properties. The photoexcitation of electrons from the valence band to the conduction band in the geopolymer structure is responsible for the absorbance observed at 260 nm, while the minor peaks at slightly longer wavelengths can be linked to Nd3

Radiological and structural analysis of aluminosilicate materials incorporated with samarium (III)-oxide

This study focused on analyzing samples of aluminosilicate materials in which different percentages of samarium (III)-oxide were incorporated. Basic samples and thermally treated samples at 600 °C were analyzed. Introducing samarium (III)-oxide into the polymer matrix of aluminosilicates has been demonstrated to alter the fundamental structure of aluminosilicate materials. Interestingly, at elevated temperatures, these materials exhibit even more distinctive properties. The gamma ray spectrometric analysis results were used to conduct radiological analysis. Different methods monitor physico-chemical changes within the aluminosilicate materials. By introducing Sm3+ into the aluminosilicate matrix, the basic structure of the aluminosilicate is disturbed. The DRIFT method was used to analyze the structural properties. The analysis of the microstructural properties of the selected samples was carried out using a scanning electron microscope (SEM) and enabled the examination of the fine details of the structure of the materials thermally treated at 600 °C which resulted in the appearance of significant pores and cracks in the material.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Preparation and Performance of Low Content Carbon Geopolymer

Due to the low CO2 emission of geopolymers compared to Portland cement, interest in their use as binding cement has increased in recent years. The main goal of this research is to relate the green and sustainable characteristics to the good mechanical and chemical properties of fly ashbased geopolymers. For those purposes, samples of different ratios of fly ash (FA) and metakaolin (MK) were prepared. Mineralogical characterization of the geopolymer samples conducted using X-ray powder diffraction (XRD) showed that in the geopolymer synthesis reaction new amorphous phase was formed. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) confirmed characteristic bands of Si-O and O-Si-O groups at 1045 cm–1 . Compressive strength analysis revealed that the optimal ratio of FA and MK is 50:50 and exhibits the highest value, while X-ray photoelectron spectroscopy (XPS) analysis revealed the total reduction of carbon content in the alkali activated geopolymer with optimal stoichiometry 50:50. The results of this research indicates the possibility to obtain a geopolymer material with almost complete absence of carbon, which implies further application as a material with very high environmental potential and zero carbon emission

Influence of Thermal Treatment on the Chemical and Structural Properties of Geopolymer Gels Doped with Nd2O3 and Sm2O3

In this research, the influence of the thermal treatment of geopolymer gels at 300 ◦C, 600 ◦C and 900 ◦C when incorporated with 5% rare earth elements (REEs) in the form of (GP-Sm) Sm2O3 and (GP-Nd) Nd2O3 was investigated. Changes in the chemical and structural properties of the geopolymer gels during thermal treatment for 1 h were monitored. Physico-chemical characterization was performed using the following methods: diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). Besides the characterization of the fundamental properties, some practical macroscopic properties were analyzed as well: sorptivity, open porosity, and Archimedean density. The stretching vibrations of Nd–O–Si and Sm–O–Si were confirmed at a value of around 680 cm−1and an Nd–O–Si absorption band at a higher value, together with the most dominant band of Si–O stretching vibration similar for all the samples. No significant chemical changes occurred. Structural analysis showed that for GP-Nd, the largest pore diameter was obtained at 900 ◦C, while for GP-Sm, the largest pore diameter was obtained at 600 ◦C. EDS confirmed the amount of dopant to be about 5%. X-ray photoelectron spectroscopy showed that for GP-Nd, the ratio of Si and Al changed the most, while for GP-Sm, the ratio of Si and Al decreased with increasing temperature. The contributions of both dopants in the GP-gel structure remained almost unchanged and stable at high temperatures. The atomic percentages obtained by XPS analysis were in accordance with the expected trend; the amount of Si increased with the temperature, while the amount of Al decreased with increasing temperature. The sorptivity and open porosity showed the highest values at 600 ◦C, while the density of both geopolymers decreased linearly with increasing temperature

Creating Sustainable Buildings: Structural Design Based on the Criterion of Social Benefits for Building Users

Sustainable building involves reducing negative environmental impacts with a simultaneous increase in life quality. The aim is to optimize building performances while considering all aspects of sustainability: environmental, economic, and social. The building structure determines the building’s performances, and it should be designed and evaluated as a subsystem of the building, in line with the objectives of the system–building. This paper investigates structural design based on integrated design objectives within the criterion of social benefits for users throughout the use phase of the building, focusing on protection and safety, aspects of comfort, spatial organization, spatial adaptability, and maintenance. The problem was studied using integrative literature review methodology and system theory. The main findings of the research are a review and critical analysis of the representative literature and the derived conceptual framework for structural design based on the criterion of social benefits for building users, which should support more comprehensive and more efficient decision-making during systemic design and optimization of buildings. The presented integrated literature review indicates the need for the application of a systemic approach to structural design in order to create sustainable buildings

Microstructural Analysis of Thermally Treated Geopolymer Incorporated with Neodymium

The following investigation presents the thermal treatment of geopolymer at 300 °C, 600 °C and 900 °C. We investigated what happens to the geopolymer base when incorporated with 1% and 5% of neodymium in the form Nd2O3. A total of six samples were synthesized. Geopolymer 1 contained 1% and geopolymer 2 contained 5% Nd2O3, and these samples were treated at 300 °C; then, samples geopolymer 3 and geopolymer 4 also had the same percentage composition of Nd2O3 and were treated at 600 °C, while samples geopolymer 5 and geopolymer 6were treated at 900 °C. Physical and chemical changes in the aluminosilicate geopolymer matrix were monitored. The incorporation of rare earths into the polymer network of aluminosilicates has been proven to disrupt the basic structure of geopolymers; however, with increased temperatures, these materials show even more unusual properties. Diffuse reflectance infrared Fourier transform (DRIFT) analysis showed that the intensity of the vibrational band decreases with the increase in temperature during thermal treatment, suggesting alterations in the chemical structure of the geopolymers. Transmission electron microscopy (TEM) analysis showed that the diameter of the nanoparticles containing Al2O3 is in the range 5–10 nm, while larger crystallites range from 30 to 80 nm. Scanning electron microscopy (SEM) analysis revealed that the temperature of the thermal treatment increases to 300 °C and 600 °C; the porosity of geopolymer increases in the form of the appearance of large pores and cracks in material. X-ray photoelectron spectroscopy (XPS) analysis was used to investigate the surface chemistry of geopolymers, including the chemical composition of the surface, the oxidation state of the elements, and the presence of functional groups. The UV/Vis spectra of the synthesized geopolymers doped with Nd3+ show interesting optical properties at 900 °C; the geopolymer matrix completely disintegrates and an amorphous phase with a rare-earth precipitate appears

Development of periphytic diatoms on different artificial substrates in the Eastern Adriatic Sea

The settling of diatoms as fouling organisms on a certain substrate is greatly influenced by substrate characteristics and the preferences of a diatom community and diatom species. A distinction among substrates can be made by analysing the specific abundance and composition of diatoms on different substrates. In this study, 11 different artificial substrates were exposed to a marine environment for a period of 30 days. Abundance and taxonomic composition of periphytic diatoms was determined on each of the substrates and on shoots of the marine seagrass Posidonia oceanica. The aim was to compare diatom community structure on different newly colonized surfaces. On all surfaces examined, periphytic diatoms were the pioneering organisms with differences in quantitative and qualitative composition on the different substrates. Taxonomic analysis of diatom communities on the substrates examined revealed 41 diatom taxa, with the dominant genera Cylindrotheca, Amphora, Nitzschia, Cocconeis and Navicula. Given that all the examined artificial substrates were solid materials, differences in the abundance and species composition of diatoms found between the materials point to the substrates’ physical and chemical characteristics as a major influence on the final settling of diatoms. Knowledge from investigating the settlement of fouling organisms on anthropogenic substrates can have future use in management of waste materials that end up in the marine environment

Medium chain length polyhyoxyalkanoates (mcl-PHA) model compounds for the discovery of novel PHA depolymerases

PHAs are naturally made microbial polyesters that have been commercialized as biodegradable plastics. However, it has been shown that these materials are not so easily biodegraded in natural environments [1]. PHA depolymerases are key PHA degrading enzymes and their identification and characterization is of great interest and importance. Currently, screening is done on polymeric substrates using techniques such as clear zone assays on agar or weight loss measurements. Results obtained using these different methods cannot be directly compared, since they depend highly on the polymer used, PHA granules preparation and assay conditions [2]. In order to design a more specific test for the determination of PHA depolymerase activity, we synthesized 3-hyoxyalkanoate monomers (3-HA monomer) and 3-hyoxyalkanoic acid dimers (3-HA dimer) and their respective p-nitrophenyl esters, allowing for spectrophotometric determination of their activity [3]. Compounds were characterized using N and FTIR. Para-nitrophenyl labeled substrates were then used in the enzymatic activity assay with the benchmark polyhyoxyoctanoate (PHO) depolymerase from Pseudomonas fluorescens GK13 expressed in Escherichia coli CodonPlus-RIPL hosts. This activity was compared to recombinantly expressed leaf-branch compost cutinase (LCC cutinase) and polyethyleneterephtalate (PET) hyolyzing esterase from Ideonella sakaiensis (IsPETase). Our initial results revealed increased specificity of PHO depolymerase towards newly synthetized substrates, suggesting their suitability for specific screens and isolation of new mcl-PHA depolymerases, as well as in high throughput screening assays designed for guiding their directed evolution.10th International Conference of MIKROBIOKOSMOS, Larissa from 30 Novewmber to 2 December 2023

Surface Modification of high density polyethylene by Au+ ion implantation observed by phase imaging atomic force microscopy

High density polyethylene (HDPE) has been modified by Au+ ions implantation with the energy of 200 keV. The doses of implanted gold ions were: 1 × 1015, 5 × 1015 and 1 × 1016 ions/cm2. Surface topography was observed by atomic force microscopy (AFM), while surface composition changes were detected by phase imaging AFM. Phase analysis of AFM images has shown that both physical and chemical changes occured on the surface of HDPE and that those changes depended on the implantation dose. The implantation of gold ions caused a high degree of physical changes. Breakpoints were observed for the implantation dose of 4.4 × 1015 ions/cm2. Physical changes are confirmed by the analysis of mean square roughness and power spectral density (PSD) slopes as functions of the implantation dose. The position and half-width of peaks in histograms of phase AFM images confirmed the changes in surface composition.I Serbian Ceramic Society Conference - Advanced Ceramics and Application : program and the book of abstracts; May 10-11, 2012; Belgrad

Adsorption Efficiency of Cadmium (II) by Different Alkali-Activated Materials

The objective of this study was to demonstrate the potential utilization of fly ash (FA), wood ash (WA), and metakaolin (MK) in developing new alkali-activated materials (AAMs) for the removal of cadmium ions from waste water. The synthesis of AAMs involved the dissolution of solid precursors, FA, WA, and MK, by a liquid activator (Na2SiO3 and NaOH). In concentrated solutions of the activator, the formation of an aluminosilicate gel structure occurred. DRIFT spectroscopy of the AAMs indicated main vibration bands between 1036 cm−1 and 996 cm−1, corresponding to Si-O-Si/Si-O-Al bands. Shifting vibration bands were seen at 1028 cm−1 to 1021 cm−1, indicating that the Si-O-Si/Si-O-Al bond is elongating, and the bond angle is decreasing. Based on the X-ray diffraction results, alkali-activated samples consist of an amorphous phase and residual mineral phases. The characteristic “hump” of an amorphous phase in the range from 20 to 40° 2θ was observed in FA and in all AWAFA samples. By the XRD patterns of the AAMs obtained by the activation of a solid three-component system, a new crystalline phase, gehlenite, was identified. The efficiency of AAMs in removing cadmium ions from aqueous solutions was tested under various conditions. The highest values of adsorption capacity, 64.76 mg/g (AWAFA6), 67.02 mg/g (AWAFAMK6), and 72.84 mg/g mg/g (AWAMK6), were obtained for materials activated with a 6 M NaOH solution in the alkali activator. The Langmuir adsorption isotherm and pseudo-second kinetic order provided the best fit for all investigated AAMs