TGA-DSC Analysis Research Articles

Green Synthesis of TiO2 Nanoparticles Using Acorus calamus Leaf Extract and Evaluating Its Photocatalytic and In Vitro Antimicrobial Activity

Here, we present an innovative and creative sustainable technique for the fabrication of titania (TiO2) using Acorus calamus (A. calamus) leaf extract as a new biogenic source, as well as a capping and reducing agent. The optical, structural, morphological, surface, and thermal characteristics of biosynthesized nanoparticles were investigated using UV, FTIR, SEM, DLS, BET, and TGA-DSC analysis. The phase formation and presence of nanocrystalline TiO2 were revealed by the XRD pattern. FTIR analysis revealed conjugation, as well as the presence of Ti–O and O–H vibrational bands. The nanoparticles were noticed to be globular, with an average size of 15–40 nm, according to the morphological analysis, and the impact of size quantification was also investigated using DLS. The photocatalytic activity of bare, commercial P-25 and biosynthesized TiO2 (G-TiO2) nanoparticles in aqueous solution of rhodamine B (RhB) dye was investigated under visible light irradiation at different time intervals. The biosynthesized TiO2 nanoparticles exhibited strong photocatalytic activity, degrading 96.59% of the RhB dye. Different kinetic representations were utilized to analyze equilibrium details. The pseudo-first-order reaction was best suited with equilibrium rate constant (K1) and regression coefficients (R2) values 3.72 × 10−4 and 0.99, respectively. The antimicrobial efficacy of the prepared nanoparticles was investigated using the disc diffusion technique. Further, biosynthesized TiO2 showed excellent antimicrobial activity against the selected gram-positive staining (B. subtilis, S. aureus) over gram-negative (P. aeruginosa, E. coli) pathogenic bacteria in comparison to bare TiO2.

Mechanical and thermal modification of mordenite-rich tuff and its effect on cement pastes

To overcome performance deficiencies of the raw mordenite-rich tuff in the partial replacement of Portland cement in cement paste, the material was subjected to different treatments: calcination at 300 °C and 500 °C, grinding to very high specific surface areas, co-grinding with Portland cement, and separate or co-grinding with granulate blast furnace slag. The resulting materials were examined by tracking changes in density, particle shapes, and size distributions. The blended cement pastes were examined by monitoring the water demand, setting time, hydration process by isothermal microcalorimetry, degree of hydration, non-evaporable water content and free Ca(OH)2 by TGA-DSC analysis. The findings provide clear evidence that with the activation techniques, the performance of the raw mordenite-rich tuff is improved.

Facile synthesis and electrochemical evaluation characteristics of NiO-CeO2 based inorganic nanocomposite anode material for application in LTSOFC

In this research work, we report the synthesis and characterization of NiO-Ce0.95Nd0.05O2-δ-Ce0.95Gd0.05O2-δ (NiO-CNO-CGO) nanocomposite anode material for LTSOFC. The thermal properties of NiO-CNO-CGO precursor were studied using TGA-DSC analysis which inferred that the formation of pure-phase was completed at around 600 °C. XRD analysis reveals a single fluorite cubic phase structure. FTIR data confirmed the occurrence of stretching vibration of M-O bond in the sample. Presence of nano-sized particles was confirmed by particle size analysis. The surface morphology was studied using SEM resulting in unsmooth grains. Respective atomic weight percentage of Ni, Ce, Nd, Gd and O was confirmed by EDAX studies. The surface roughness was studied using AFM. The sample resulted in a conductance of 4.55 x 10−4 Scm−1 in air atmosphere with activation energy of 0.4483 eV. The obtained results were discussed in order to use the material as an efficient anode for LTSOFC application.

Comparison of Thin Films of Titanium Dioxide Deposited by Sputtering and Sol-Gel Methods for Waveguiding Applications

In this work, TiO2 thin films were deposited onto glass substrate by two different techniques: sol-gel dip-coating (SG) and reactive DC magnetron sputtering (Sput). The prepared samples have been characterized by means of micro-Raman, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) measurements, scanning electron microscopy (SEM), UV-Visible spectrophotometry, and M-Lines spectroscopy (MLS). The micro-Raman results showed an amorphous TiO2-SG phase and the vibrational mode of TiO2-Sput is anatase phase. DSC-TGA analysis was used to investigate the thermal properties of the TiO2 material. SEM spectroscopy has shown that TiO2-SG has a disordered and more porous surface, TiO2-Sput sample is homogeneous and shows uniform distribution of densely packed well-defined grains. The obtained films have an optical transmittance varying from 60 to 88% in the visible region. The optical band gaps deduced from the transmittance are 3.48 and 3.53 eV for TiO2-SG and TiO2-Sput, respectively. The optical waveguiding measurements carried out on TiO2-SG and TiO2-Sput films show single guided modes behavior (TE0 and TM0). These measurements have allowed deducing the refractive index and thickness values that are 2.06 at 216 nm for TiO2-SG and 2.26 at 204 nm for TiO2-Sput thin films. The analysis of waveguiding properties indicates that amorphous TiO2 may prove to be more efficient in photonic device as compared to crystalline TiO2. Keywords: TiO2, thin films, sol-gel, sputtering, anatase, waveguiding.

Mannich reaction as an interesting synthetic route for the development of energetic benzoxazine polymers

In this study, three new energetic benzoxazine monomers were synthesized via a one-step Mannich reaction process involving the incorporation of explosophore nitro groups (NO2) in different positions (ortho, meta and para) into the monomer backbone. The molecular structures of the synthesized monomers were confirmed by FTIR, 1H and 13CNMR techniques. The curing behavior, thermomechanical properties and the thermal stability were assessed by DSC-TGA analyses. All monomers displayed two exothermic peaks related to the polymerization and degradation steps except 4-NBZ that present the polymerization and the degradation phenomena through one unique exotherm pic. The energetic performances were evaluated by the determination of the heat of combustion using a bomb calorimeter in an oxygen atmosphere. The results indicated that the para position provided the benzoxazine monomers with a high calorific value comparable to that of the nitrocellulose (about 10.401 kJ/g). Meanwhile, the aforementioned monomer was found to ignite at a temperature of about 267 °C. Overall, this study showed that the ease of synthesis of the benzoxazine resins via Mannich reaction can be further extended the energetic field and further researches are undergoing to fully unravel the potential of these exceptional materials.

Utilization of crude paper industry effluent for Polyhydroxyalkanoate (PHA) production

Paper industry generates a large amount of effluent which contains unused organic carbon from the raw materials used. Utilization of the unused carbon may lead to remediation of the effluent by lowering the BOD. Polyhydroxyalkanoates are microbial polymers which accumulate in various bacteria in carbon rich conditions. The present study is focused on the utilization of untreated crude paper industry effluent (PIE) as a substrate for Polyhydroxyalkanoates (PHA) production to utilize the unused carbon and develop a feasible production process. To achieve this, indigenous PHA-producing bacterial strains were screened for their ability to utilize different concentrations of PIE as a substrate. One of the isolates, ART_41, was able to utilize different concentrations of PIE for growth. ART_41 was characterizedas a Gram-negative strain belonging to Ancylobacter sp. by 16s rRNA sequencing. Maximum PHA production (41.7%) was achieved when using 30% PIE. FTIR and DSC-TGA analysis validated the extracted polymer as Poly-3-hydroxybutyrate (PHB). Thus, this study concludes that crude paper industry effluent could be utilized as a substrate when the correct bacterial strain is employed; allowing sustainable PHA production.

LCD-SLA 3D printing of BaTiO3 piezoelectric ceramics

Stereolithography-based 3D printing is a promising method to produce complex shapes from piezoceramic materials. In this study, LCD-SLA 3D printing was used to create lead-free piezoceramics based on barium titanate (BaTiO3, BT). Three types of BT powders (micron, submicron and nanoscale) were tested in LCD-SLA 3D printing, and a technique for the preparation of a ceramic slurry suitable for LCD-SLA printing has been developed. Using TGA-DSC analysis, the thermal debinding parameters to obtain crack-free samples were determined, followed by further sintering and the study of the piezoelectric properties (εr = 1965, d33 = 200 pC/N, tan = 1,7 %). The results of the study demonstrate high potential for the production of complex piezoceramic elements that can be used in aviation, in particular, aviation radio equipment; in the marine industry for transceiver modules of hydroacoustic antennas; and in the nuclear industry for pressure control sensors in the steam–water path.

Design and structural characterization of 2-methyl 8-hydroxyl quinolinilium 5-chloro salicylate salt

The enhanced physico chemical properties of 2-methyl 8-hydroxy quinolone was observed by the modified 2-methyl 8-hydroxy quinolinium 5-chloro salicylate crystal structure which were grown by slow evaporation method. The crystal structure was confirmed by single X-ray diffraction analysis. Crystal structure was stabilized through halogen bond interaction in the title crystal. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular hydrogen bonding interactions. FTIR and FT-Raman spectral studies were characterized to reveal the presence of functional groups in the grown crystal. The proton and carbon chemical shift of the title compound were observed by 1H and 13C NMR analysis. Excited energy of the title compound was observed using UV-Visible spectral analysis. The fluorescence solid and solvent spectrum revealed that the green emission was observed in the grown crystal. The melting behavior and stability of the title compound was performed by TGA-DSC analysis. The ability to show the pharmacological behavior of the title crystal was analyzed by anti-oxidant, anti-microbial and anti-cancer studies.

X-ray, Hirshfeld surfaces analyses, DSC-TGA thermal stability, infrared, and optical properties studies of phenylammonium tetrachlorozincate hydrate (C6H5NH3)2ZnCl4.H2O

This paper reports the synthesis, crystal structure reinvestigation at 296 ​K, Hirshfeld surfaces, DSC, TG-dTG, Infrared, and UV studies of (C6H5NH3)2ZnCl4.H2O, which crystalized in the triclinic space group P-1 [Z ​= ​2, a ​= ​7.575(3) Å, b ​= ​9.894(3) Å, c ​= ​13.101(4) Å, α ​= ​95.903(13)°, β ​= ​102.408(14)° and γ ​= ​111.659(13)°]. The crystal structure consists of two cations C6H5NH3+ linked to a distorted ZnCl42− tetrahedron anion, together linked to the water molecule via hydrogen bonds of N-H⋯Cl, N-H⋯O and O-HW···Cl types. The ZnCl42− tetrahedra and H2O molecules form an infinite two-dimensional layer parallel to (0 0 2) plan between the organic sheets. The powder and single-crystal X-ray analyses confirm the pure phase of the synthetized compound. The Hirshfeld surfaces and fingerprint plots, used to analyse quantitatively the interactions in the crystal structure, showed that Cl⋯H/H⋯Cl contacts due to O-H⋯Cl and N-H⋯Cl hydrogen bonding are the major contributor in the total crystal packing surface of (C6H5NH3)2ZnCl4.H2O. The DSC-TGA analyses showed that the compound dehydration made at around 80 ​°C, gives an anhydrous compound thermally stable between 80 ​°C and 120 ​°C. The anhydrous compound decomposition process is predicted, and confirmed by Infrared spectra at various temperatures. The observed bands are assigned and discussed based on the theoretical analyses; the non-fundamental bands resulted in the formation of hydrogen bonding are assigned. The photoluminescence spectra investigated at room temperature showed a red emission line at 2.60 ​eV, which may be associated with radiative recombination of exciton confined within the ZnCl42−. This suggests potential applications for this compound as UV detection and optical materials.

Removal of nitrate and phosphate ions from aqueous solution using zirconium encapsulated chitosan quaternized beads: Preparation, characterization and mechanistic performance

The traditional adsorbents are generally retrieval for reutilizing or direct disposal properties. In this work, a more effective and cost-effective technique is employed for adsorbent materials. Chitosan beads (CS) are recognized to be efficient bio-adsorbent for the remediation of toxic anions from aqueous solutions. In the present study, the zirconium encapsulated chitosan quaternized (Zr@CSQ) beads were prepared and its application for the adsorptive removal of nitrate and phosphate ions from water. The fabricated Zr@CSQ beads were characterized by a sequence of analytical techniques, including XRD, SEM, EDAX, BET, FTIR and TGA–DSC analysis. The different kinetic models and known Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models were used to define the isotherm and kinetic saturations for toxic anions adsorption using Zr@CSQ beads. The Zr@CSQ beads showed superior adsorption capacity at 80.2 and 67.7 mg/g for nitrate and phosphate ions, respectively. Thermodynamic parameters demonstrated that the sorption process is spontaneous, feasible and exothermic nature. The impact of other influencing co-ions like bicarbonate, chloride and sulphate on the removal efficiency of nitrate and phosphate ions were examined. Toxic anions removal by Zr@CSQ beads were found to occur through the adsorption of nitrate and phosphate ions on the surface of beads via electrostatic attraction, ion exchange, and surface complexation mechanism. The obtained results revealed that the removal efficiency of toxic anions, good adsorption–desorption performance and appropriate form, Zr@CSQ beads considered as a promising adsorbent for water/ wastewater purifications.

Comparison of the Properties of Natural Sorbents for the Calcium Looping Process.

Capturing CO2 from industrial processes may be one of the main ways to control global temperature increases. One of the proposed methods is the calcium looping technology (CaL). The aim of this research was to assess the sequestration capacity of selected carbonate rocks, serpentinite, and basalt using a TGA-DSC analysis, thus simulating the CaL process. The highest degrees of conversion were obtained for limestones, lower degrees were obtained for magnesite and serpentinite, and the lowest were obtained for basalt. The decrease in the conversion rate, along with the subsequent CaL cycles, was most intense for the sorbents with the highest values. Thermally pretreated limestone samples demonstrated different degrees of conversion, which were the highest for the calcium-carbonate-rich limestones. The cumulative carbonation of the pretreated samples was more than twice as low as that of the raw ones. The thermal pretreatment was effective for the examined rocks.

Synthesis, characterization and utility of a series of novel copper(II) complexes as excellent surface disinfectants against nosocomial infections.

Nosocomial infections are among the major public health concerns, especially during the ongoing Covid19 pandemic. There is a great demand for novel chemical agents that are capable of killing specific pathogens or augmenting the efficiency of existing disinfectants. Herein, we report the synthesis and comprehensive characterization (through FT-IR, HR-MS, SEM, TGA-DSC, CV, UV and SCXRD analyses) of six novel copper(II) complexes, [CuL(4X-An)] (5a-5d), [CuL(An)] (5e), and [CuL(benzhydrylamine)] (5f), and their evaluation as anti-microbial agents against WHO priority pathogens, confirming their possible use in hospital settings. The compounds were synthesized with a Schiff base (H2L) obtained by the condensation reaction of 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (DHA) and benzohydrazide and further addition of different p-substituted aniline (An) molecules. Single crystal structure analyses revealed that the aniline derivatives are isostructural to the copper atom in a square planar coordination, while the benzhydrylamine complex forms a dimer (5f), with a square pyramidal coordination geometry for the metal. Time-kill kinetics and reduced microbial recovery studies revealed excellent bactericidal action against Staphylococcus aureus and Enterococcus faecalis. Particularly, the novel compound 5f significantly reduced microbial recovery compared to ethanol-based sanitisers. In fact, addition of 5f to 70% ethanol remarkably synergized the killing with >6-log reduction in microbial burden. Overall, our novel compounds would increase the disinfection efficacy in hospitals and industries, thereby improving the efficiency and minimizing the risk of infections.

Microwave absorption and mechanical properties of SiCf/SiOC composites with SiO2 fillers

Owing to the polysiloxane (PSO) characteristic of cheap, healthy, available and low free carbon content, in this research the SiCf/SiOC composites were manufactured by polymer infiltration and pyrolysis (PIP) method with various content of SiO2 fillers. It can be concluded from the DSC-TGA and XRD analysis that SiOC ceramic was formed from PSO when pyrolysis temperature exceeded 800 °C and after pyrolysis at 1000 °C the PSO mainly composed by amorphous SiO2. The effects of SiO2 fillers on morphology of SiOC matrix, flexural strength, complex permittivity, and microwave absorption property of SiCf/SiOC composites were investigated. The results indicated that the SiO2 fillers can enhance the density and reduce the microcracks of matrix. Therefore, the maximum flexural strength 201.09 MPa can be obtained by adding 5 g SiO2 filler into PSO precursor solution. The complex permittivity and flexural strength of composites first increased when content of SiO2 filler enhanced from 0 to 5 g. Nevertheless, with the content of SiO2 filler increased from 5 g to 10 g and 15 g, the complex permittivity and flexural strength of composites decreased. In summary, the SiCf/SiOC composites with 10 g SiO2 fillers not only possess the reflection loss as low as -26.02 dB and the effective absorption bandwidth (EAB) below -10dB up to 3.21 GHz at the thickness of 3.0 mm but also own the flexural strength of 171.71 MPa.

Effective separation of chromium species in technological solutions using amino-immobilized silica prior to their determination

Amino-immobilized (poly(4,9-dioxadodecane-1,12-guanidine, polydiallyldimethylammonium, hexadimethrin bromide, polyhexamethylene guanidine) silicas were proposed for chromium speciation for the first time. Adsorbents surface was characterized by TGA-DSC, FT-IR, CHN, XRD and SEM analysis. Polyamines were strongly fixed on the silica surface and were not washed off with solutions of 3М HNO3 and 20 g L−1 NaCl. Аmino-immobilized silica quantitatively removed (R ≥ 99%) Cr(VI) from solutions at pH 4–7. Cr(III) was not recovered in this pH range, which makes it possible to separate Cr(VI) from Cr(III). The separation factor (КCr(VI)/Cr(III)) was ≥ 1∙104. Silica-based adsorbents layer-by-layer immobilized with polyamines and 2-(1,8-dihydroxy-3,6-disulfo-2-naphthylazo)benzenearsonic acid were proposed for quantitative removal of Cr(III) from aqueous solutions with pH 4–6 at 90 °C. A system of sequentially connected columns filled with selective adsorbents was used to separate the chromium species in stream at рН= 5 and a flow rate of 1 mL min−1. Chromium was determined after its elution with 5 mL of 2 M HNO3 at a flow rate of 1 mL min−1 using ICP-OES or ICP-MS. The pre-concentration factors for Cr(VI) and Cr(III) was 60. A two-column system was used for chromium speciation in technological solutions. The efficiency of chromium speciation was confirmed by state standard procedure.

Removal of phosphate and nitrate via a zinc ferrite@activated carbon hybrid composite under batch experiments: Study of isotherm and kinetic equilibriums

Phosphate and nitrate ions are ubiquitous pollutants in aquatic environments and phosphate and nitrate removal from water have been widely studied. Still, there exists a dilemma in developing highly selective adsorbents for the removal of phosphate and nitrate ions with enhanced removal efficiency. Herein, developed a unique and novel activated carbon-supported zinc ferrite (AC@ZnFe2O4) composite (Activated carbon derived from Muskmelon Peel) via co-precipitation method for removing phosphate and nitrate ions from water. The adsorption capacity of AC@ZnFe2O4 strongly depends on the surface properties, and this system was mainly governed by multilayer adsorption. Besides, AC@ZnFe2O4composite showed a high adsorption efficiency of 91.80 and 75.58 mg/g for phosphate and nitrate ions, respectively at 30 °C (Langmuir isotherm model). The fabricated AC@ZnFe2O4 composite was characterized using FTIR XRD, SEM, BET, EDAX and TGA-DSC analysis. The regeneration experiments revealed that the AC@ZnFe2O4 composite could potentially be reused by maintaining its high removal efficiency. The above findings suggest that AC@ZnFe2O4 composite could act as a potential low-cost adsorbent and applicable for the removal of phosphate and nitrate ions to retain the quality of water after treatments.

Preparation method and performance test of Evotherm pre-wet treatment aluminum hydroxide type warm-mixed flame-retardant asphalt

In order to better improve the flame retardant effect of flame retardant asphalt and the dispersibility of flame retardant. The inorganic flame retardant ATH was previously surface-modified by the traditional road surface active agent warm mix (Evotherm), and a new type of inorganic warm mix flame retardant was developed. The results show that through the wet modification in this experiment, the modification effect of aluminum hydroxide (ATH) after the wet modification at 50℃, 20 min and 8% Evotherm dosage is good and the modification efficiency is high. The inorganic warm-mix flame retardant particles. It can be evenly dispersed in the asphalt, significantly reducing the agglomeration phenomenon. The particles of the warm-mix flame retardant have good adhesion to the asphalt; the prepared warm-mix flame retardant and a certain amount of hydrotalcite are mixed in the ratio of No. 70 In the heavy road matrix asphalt, 12% by mass of hydrotalcite is combined with 12% by mass of Evotherm modified ATH, and the oxygen index can reach 27.8, which is already a self-extinguishing material with obvious flame retardant performance. SEM analysis shows that the dispersibility of ATH is significantly improved after modification: XRD and FT-IR analysis show that Evotherm is physically attached to the surface of ATH: TGA-DSC analysis shows that the thermal stability of Evotherm modified ATH has been improved.

Catalytic performance of cubic ordered mesoporous alumina supported nickel catalysts in dry reforming of methane

In this research, a series of Ni-based catalysts with 10, 15, and 20% nickel content, supported on cubic ordered mesoporous alumina (COMA) for the first time were prepared employing one-pot synthesis and tested in dry reforming of methane reaction. In order to characterize the prepared samples N2 sorption isotherms, powder XRD, TEM, FT-IR, SEM/EDX, H2-TPR, XPS, TPO and TGA-DSC analyses were used. The 15%NiO/COMA catalyst showed the best catalytic performance over which conversions of CH4 = 99 and CO2 = 96% with H2/CO ratio = 0.89 at 850 °C were obtained. Performance stability test were carried out over catalyst of 15 wt% nickel content. Results were very promising as no activity loss was detected after 210 h of DRM reaction at 700 °C with GHSV = 18,000 ml/(g.h). TGA-DSC analysis proved that about 5 wt% carbon deposited onto the structure of endurance-tested catalyst after 210 h demonstrating excellent catalytic stability of COMA structure in DRM reaction.

Fe2O3/CaO-Al2O3 multifunctional catalyst for hydrogen production by sorption-enhanced chemical looping reforming of ethanol

Sorption-enhanced chemical looping reforming of ethanol for hydrogen production was investigated using Fe2O3 as oxygen carrier and modified CaO-based Al2O3 as CO2 sorbent. Combined Fe2O3/CaO-Al2O3 multifunctional catalysts were demonstrated and prepared by different methods including sol-gel, mechanical mixing, and impregnation at different Fe contents (5, 10, and 15 wt%). The results showed that the multifunctional catalyst prepared by impregnation method with 5 wt% Fe loading provided the highest H2 purity of 70% in the pre-breakthrough period which lasted for 60 min at 600 °C. This was attributed to the preserving of Ca12Al14O33 inert support in the structure during the preparation as shown by XRD results, leading to higher surface area as determined by N2 physisorption and to prevention of particle agglomeration as evidenced by SEM-EDX. Although the H2 production was inhibited by the presence of Ca2Fe2O5 phase, a stable performance was found for at least 5 repeated cycles both for sorption capacity and oxygen carrier. The ease of decarbonation was also observed with this material as confirmed by DSC-TGA analysis. This highlighted the mutual advantages of Fe in CaO sorption stability and Ca in Fe oxygen carrier stability which could offset their intrinsic weak robustness.

Biopolymeric Membrane Enriched with Chitosan and Silver for Metallic Ions Removal.

The present paper synthesized, characterized, and evaluated the performance of the novel biopolymeric membrane enriched with cellulose acetate and chitosan (CHI)-silver (Ag) ions in order to remove iron ion from the synthetic wastewater using a new electrodialysis system. The prepared membranes were characterized by Fourier Transforms Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), Thermal Gravimetric Analysis (TGA) and Differential Thermal Analysis (DSC), contact angle measurements, microscopy studies, and electrochemical impedance spectroscopy (EIS). The electrodialysis experiments were performed at the different applied voltages (5, 10, and 15 V) for one hour, at room temperature. The treatment rate (TE) of iron ions, current efficiency (IE), and energy consumption (Wc) were calculated. FTIR-ATR spectra evidenced that incorporation of CHI-Ag ions into the polymer mixture led to a polymer-metal ion complex formation within the membrane. The TGA-DSC analysis for the obtained biopolymeric membranes showed excellent thermal stability (>350 °C). The contact angle measurements demonstrated the hydrophobic character of the polymeric membrane and a decrease of it by CHI-Ag adding. The EIS results indicated that the silver ions induced a higher ionic electrical conductivity. The highest value of the iron ions treatment rate (>60%) was obtained for the biopolymeric membrane with CHI-Ag ions at applied voltage of 15 V.

Improvement of the performance and microstructural development of alkali-activated slag blends

This study investigated the performance and microstructural development of alkali-activated slag (AAS) blends containing hydromagnesite seeds. AAS blends with and without seeds were assessed by isothermal calorimetry, porosity, setting time and compressive strength measurements. The formation of hydrate phases was further investigated via XRD, TGA-DSC, FTIR and SEM analyses. AAS blends incorporating 2% hydromagnesite seeds revealed the best performance in terms of hydration kinetics, strength and microstructural development. The positive influence of seeds was highlighted via increased hydration rates and degrees, shortened setting times, higher compressive strengths and denser microstructures. These improvements were attributed to the provision of additional nucleation sites in the presence of seeds that enabled the increased formation of hydrate phases (e.g. C-(A)-S-H with more crosslinks forming between adjacent silicate chains) within the pore structure.