Yttrium doped phosphate-based glasses: structural and degradation analyses

This study investigates the role of yttrium in phosphate-based glasses in the system 45(P 2 O 5)-25(CaO)-(30-x)(Na 2 O)-x(Y 2 O 3) (0≤ x≤ 5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spec-troscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31 P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y 2 O 3 content as metaphosphate units (Q 2) decreased with subsequent increase in pyrophosphate species (Q 1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crys-tallised glass samples revealed the presence of calcium pyrophosphate (Ca 2 P 2 O 7) and sodium metaphosphate (NaPO 3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y 2 O 3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y 2 O 3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yt-trium (YO 6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles

Thermal and crystallization kinetics of yttrium-doped phosphate-based glasses

© 2019 The American Ceramic Society and Wiley Periodicals, Inc Yttrium-doped glasses have been utilized for biomedical applications such as radiotherapy, especially for liver cancer treatment. In this paper, the crystallization behavior of phosphate-based glasses doped with yttrium (in the system 45P2O5–(30 − x) Na2O–25CaO–xY2O3—where x = 0, 1, 3 and 5) have been investigated via Differential Scanning Calorimetry (DSC) using nonisothermal technique at different heating rates (5°C, 10°C, 15°C and 20°C/min). The glass compositions were characterized via EDX, XRD, Density and Molar volume analysis. The Moynihan and Kissinger methods were used for the determination of glass transition activation energy (Eg) which decreased from 192 to 118 kJ/mol (Moynihan) and 183 to 113 kJ/mol (Kissinger) with increasing yttrium oxide content. Incorporation of 0 to 5 mol% Y2O3 revealed an approximate decrease of 71 kJ/mol (Ozawa and Augis) for onset crystallization (Ex) and 26 kJ/mol (Kissinger) for crystallization peak activation energies (Ec). Avrami index (n) value analyzed via Matusita–Sakka equation suggested a one-dimensional crystal growth for the glasses investigated. SEM analysis explored the crystalline morphologies and revealed one-dimensional needle-like crystals. Overall, it was found that these glass formulations remained amorphous with up to 5 mol% Y2O3 addition with further increases in Y2O3 content resulting in significant crystallization

Upcycling Glass Waste into Porous Microspheres for Wastewater Treatment Applications: Efficacy of Dye Removal

Each year about 7.6 million tons of waste glasses are landfilled without recycling, reclaiming or upcycling. Herein we have developed a solvent free upcycling method for recycled glass waste (RG) by remanufacturing it into porous recycled glass microspheres (PRGMs) with a view to explore removal of organic pollutants such as organic dyes. PRGMs were prepared via flame spheroidisation process and characterised using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET) and Mercury Intrusion Porosimetry (MIP) analysis. PRGMs exhibited 69% porosity with overall pore volume and pore area of 0.84 cm3/g and 8.6 cm2/g, respectively (from MIP) and a surface area of 8 m2/g. Acid red 88 (AR88) and Methylene blue (MB) were explored as a model source of pollutants. Results showed that removal of AR88 and MB by PRGMs was influenced by pH of the dye solution, PRGMs doses, and dye concentrations. From the batch process experiments, adsorption and coagulation processes were observed for AR88 dye whilst MB dye removal was attributed only to adsorption process. The maximum monolayer adsorption capacity (qe) recorded for AR88, and MB were 78 mg/g and 20 mg/g, respectively. XPS and FTIR studies further confirmed that the adsorption process was due to electrostatic interaction and hydrogen bond formation. Furthermore, dye removal capacity of the PRGMs was also investigated for column adsorption process experiments. Based on the Thomas model, the calculated adsorption capacities at flow rates of 2.2 mL/min and 0.5 mL/min were 250 mg/g and 231 mg/g, respectively which were much higher than the batch scale Langmuir monolayer adsorption capacity (qe) values. It is suggested that a synergistic effect of adsorption/coagulation followed by filtration processes was responsible for the higher adsorption capacities observed from the column adsorption studies. This study also demonstrated that PRGMs produced from recycled glass waste could directly be applied to the next cyclic experiment with similar dye removal capability. Thus, highlighting the circular economy scope of using waste inorganic materials for alternate applications such as pre-screening materials in wastewater treatment applications

Effect of Reinforcement of Hydrophobic Grade Banana ( Musa ornata

This research studied the physicomechanical as well as morphological properties of alkali treated (NaOH and KMnO4) and untreated banana bark fiber (BBF) reinforced polypropylene composites. A detailed structural and morphological characterization was performed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and mechanical properties testing (tensile strength, flexural strength, and microhardness). Chemical treatments improved the hydrophobic property of the fiber and it is found to be better for KMnO4 treatment. Composites with 0, 5, 10, and 15 wt.% loadings were then compared for water uptake studies and revealed that KMnO4 treated fiber composites absorb less water compared to others. KMnO4 treatment with 15% fiber loading improved the tensile strength, flexural strength, and microhardness of the composites compared to raw and NaOH treated fiber loadings. TGA analysis also shows onset temperature at 400~500°C that is associated with the decomposition of the banana fibers constituents including lignin, cellulose, and hemicelluloses which suggests better thermomechanical stability. All of the values suggest that 15% KMnO4 treated banana bark fiber (BBF)/PP composites were found to be better than those of the raw and NaOH treated ones

Adsorption studies and effect of heat treatment on porous glass microspheres

This paper investigates the effect of heat treatment on porous glass microspheres produced via a novel flame spheroidization process, followed by exploring their suitability for dye removal from water. The effect of simple use of smaller porogen (≤5 µm) followed by heat treatment on the overall changes in textural and porosity profiles was quantified. Heat treatment was applied at different temperatures between 510°C and 540°C and cross-sectional SEM and nitrogen adsorption–desorption confirmed pore sizes had narrowed significantly from microporous (55 ± 8 µm) to mesoporous to macroporous range (≥2 nm) yet retained their interconnectivity. This decrease in pore morphologies led to an increased specific surface area and pore volume (by 51%). In addition, dye separation studies were explored using anionic Acid Red 88 (AR88), utilizing batch and column adsorption experimental processes. This study showed that the heat-treated microspheres achieved higher dye adsorption rates (i.e., 125 mg/g in batch adsorption studies, while column adsorption studies revealed 153 mg/g and 76 mg/g for flow rates 2.2 ml/min and 0.5 ml/min, respectively) in comparison with the nonheat-treated microspheres. Furthermore, the dye separation profiles were achieved via electrostatic interaction, hydrogen bonding, and Lewis acid–base interaction, without any internal or external functionalization of the microspheres required

Yttrium doped phosphate-based glasses: structural and degradation analyses

This study investigates the role of yttrium in phosphate-based glasses in the system 45(P2O5)–25(CaO)– (30-x)(Na2O)–x(Y2O3) (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y2O3 content as metaphosphate units (Q2) decreased with subsequent increase in pyrophosphate species (Q1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca2P2O7) and sodium metaphosphate (NaPO3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y2O3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y2O3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yttrium (YO6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles