Thermogravimetry-differential Thermal Analysis Research Articles

Heavily vanadium-doped LiFePO4 olivine as electrode material for Li-ion aqueous rechargeable batteries

Since LiFePO4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe0.9V0.1PO4/C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li3V2PO4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO3 and NaNO3 electrolytes amounting to around 100 mAh g−1 at 20 mV s−1. Still, the material is only stable in LiNO3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries.

CaCu3Ti4O12 ceramic via oxalate route: Synthesis, characterization and electrical properties

In this manuscript, a new method for the synthesis of CaCu3Ti4O12 (CCTO) perovskite was adopted via co-precipitation followed by calcination processes. The co-precipitation route was employed to synthesize calcium and copper oxalates precipitated on the TiO2 surfaces and the calcination technique at different temperatures was utilized to follow the single-phase formation. Differential thermal analysis-thermogravimetry (DTA-TG) were used to estimate the proper calcination temperatures and to follow the precursor′s decomposition stages. X-ray diffraction (XRD) revealed the initiation of titanate formation at 700 °C. The complete formation of single-phase was achieved at 1100 °C. In agreement with the XRD measurements, FT-IR spectra confirmed the formation the different phases at different calcination temperatures. The prepared titanate showed giant dielectric properties with values higher than reported in literature. The conductivity measurement indicated semi-conducting properties and revealed a transition agreed well with that obtained in the dielectric properties measurements vs. temperature, attributed to the orientional polarization or change in the entire conduction mechanism from hopping to ionic conduction. The obtained electrical properties enhances the utilization of the entire titanate as capacitors.

Controlled dual activity of an organometallic antibiotic through micelle formulation

Sodium Lauryl Sulphate (SLS) and Cetyltrimethylammonium bromide (CTAB) were employed to create micelles (SLS@CIPTIN and CTAB@CIPTIN) of the organometallic antibiotic Ph2Sn(CIP)2 (CIPTIN) (where HCIP= ciprofloxacin). The characterization of the micelles was conducted in the solid-state using melting point, Attenuated Total Reflectance-Fourier Transform Infra-Red (ATR-FTIR), 119Sn Mössbauer and X-ray Fluorescence (XRF) spectroscopies, and Thermogravimetry/Differential Thermal Analysis (TG-DTA), while in solution, by Ultra violet-Visible (UV–Vis) and Nucleus Magnetic Resonance (1HNMR ) spectroscopic techniques were employed. The compounds were tested for their antiproliferative activity against human breast adenocarcinoma cells: MCF-7 (hormone depended (HD)) and MDA-MB-231 (hormone independent (HI)). The in vitro and in vivo non-genotoxicity was confirmed with micronucleus (MN) and Artemia salina assay. The antiproliferative mechanism of action of SLS@CIPTIN and CTAB@CIPTIN was studied by cell morphology and cell cycle arrest. The antibacterial activity was evaluated using Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Inhibition Zones (IZ) against Minimum Bactericidal Concentration (MBC) against Gram-negative strains P. aeruginosa, E. coli, as well as Gram-positive strains S. epidermidis and S. aureus. The results indicate that both the investigated CIPTIN and its supramolecular assembly (SLS@CIPTIN) exhibit activity. Therefore, the encapsulation of antimicrobial compounds can indeed be regarded as an attractive strategy for the development of new dual-active agents. These agents offer concurrent anticancer and antibacterial attributes without inducing toxicity.

Historical lime‐based flooring mortars from the Church of Santa Maria de Alcobaça monastery (12th century), Portugal: A multi‐analytical approach

AbstractThe Monastery of Alcobaça houses in reserve the ceramic tiles that adorned the floor of the church's apse. These tiles were removed during rehabilitation works and many preserve part of their original fixing mortars. A comprehensive analysis of 21 samples was conducted using a multi‐analytical approach (X‐ray fluorescence, X‐ray diffraction, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, μ‐Raman spectroscopy, thermogravimetry–differential thermal analysis, optical microscopy, and colorimetry). Results suggest compositional variations in the samples from the back and sides of the ceramic tiles; however, the mineralogy and general characteristics of the aggregates remained consistent between the samples and are coherent with the local geology, suggesting a shared historical origin.

Adsorption of copper (II) from aqueous solutions using adsorbent obtained with sodium hydroxide activation of biochar prepared by microwave pyrolysis

AbstractMicrowave heating is one of the leading methods that save energy, time, and cost for the conversion of bio-waste into biochar in the agricultural sector. In this study, in the first stage, economical biochar production from pistachio green hulls by microwave heating method is in question. In the second step, sodium hydroxide(NaOH) activation was followed to improve the surface properties of biochar. This adsorbent obtained was applied to remove copper ions(Cu(II)) from wastewater. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetry differential thermal analysis (TG/DTG), and nitrogen adsorption/desorption methods were used to characterize the biochar samples. In adsorption studies, kinetic, isotherm, and thermodynamic parameters were investigated. Cu(II) adsorption capacity on modified biochar obtained by Langmuir isotherm was found to be 227.27 mg/g. In addition, the mechanism of Cu(II) adsorption on modified biochar has been proposed. Biochar, which is obtained from the green shells of pistachios, which is widely available and grown in Turkey, by microwave method and then NaOH activation, is a potential solution for both the improvement of water pollution caused by heavy metals and the disposal of related wastes with an appropriate method.

Flame Spray Pyrolysis Synthesis of Vo-Rich Nano-SrTiO3-x.

Engineering of oxygen vacancies (Vo) in nanomaterials allows diligent control of their physicochemical properties. SrTiO3 possesses the typical ABO3 structure and has attracted considerable attention among the titanates due to its chemical stability and its high conduction band energy. This has resulted in its extensive use in photocatalytic energy-related processes, among others. Herein, we introduce the use of Flame Spray Pyrolysis (FSP); an industrial and scalable process to produce Vo-rich SrTiO3 perovskites. We present two types of Anoxic Flame Spray Pyrolysis (A-FSP) technologies using CH4 gas as a reducing source: Radial A-FSP (RA-FSP); and Axial A-FSP (AA-FSP). These are used for the control engineering of oxygen vacancies in the SrTiO3-x nanolattice. Based on X-ray photoelectron spectroscopy, Raman and thermogravimetry-differential thermal analysis, we discuss the role and the amount of the Vos in the so-produced nano-SrTiO3-x, correlating the properties of the nanolattice and energy-band structure of the SrTiO3-x. The present work further corroborates the versatility of FSP as a synthetic process and the potential future application of this process to engineer photocatalysts with oxygen vacancies in quantities that can be measured in kilograms.

Removal of paracetamol from aqueous solution with zinc oxide nanoparticles obtained by green synthesis from purple basil (Ocimum basilicum L.) waste

In this study, environmentally friendly zinc oxide nanoparticles (OB-ZnO NPs) were synthesized using Ocimum basilicum (OB) plant waste extract, and the removal of paracetamol (PCM) from pharmaceutical wastes with toxic effects on the ecosystem was investigated. The characteristic structure of synthesized OB-ZnO NPs was determined by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM) and energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), Zetasizer, thermogravimetry-differential thermal analysis (TGA-DTA), and UV-vis spectroscopy. The effect of the obtained OB-ZnO NPs on PCM removal was determined by batch adsorption tests. In the study in which 6 different kinetic and isotherm models were examined, error analysis functions were used to determine the most suitable model. Accordingly, the crystal structure of biosynthesized OB-ZnO NPs has a particle size of 30.39 nm, a surface area of 13.826 m2/g, and a pore volume of 0.0475 cm3/g. Since OB-ZnO NPs have a zeta potential of − 22.1 mV and a mass loss of 33% at about 750 °C, these NPs show that they are durable at high temperatures. When the PCM removal mechanisms with OB-ZnO NPs were examined, it was determined that the most suitable kinetic and isotherm model was the Elovich model with an R2 value of 0.989 and the Redlich-Peterson model with an R2 value of 0.999. In the study, which reached 23 mgPCM/gOB-ZnO NP removal efficiency, it was revealed that OB-ZnO NPs obtained from waste plants have the potential to be used in the removal of pharmaceutical wastes.Graphical abstract

Comparative e-waste plastics biodegradation efficacy of monoculture Pseudomonas aeruginosa strain PE10 and bacterial consortium under in situ condition.

A significant amount of electronic obsoletes or electronic waste (e-waste) is being generated globally each year; of these, ~20% of obsolete electronic items have plastic components. Current remediation practices for e-waste have several setbacks due to its negative impact on the environment, agro-ecosystem, and human health. Therefore, comparative biodegradation studies of e-waste plastics by monoculture Pseudomonas aeruginosa strain PE10 and bacterial consortium consisting of Achromobacter insolitus strain PE2 (MF943156), Acinetobacter nosocomialis strain PE5 (MF943157), Pseudomonas lalkuanensis PE8 (CP043311), and Stenotrophomonas pavanii strain PE15 (MF943160) were carried out in situ. Biological treatment of e-waste with these candidates in soil ecosystems has been analyzed through diversified analytical techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric-derivative thermogravimetry-differential thermal analysis (TG-DTG-DTA), and scanning electron microscopy (SEM). Both P. aeruginosa strain PE10 and the bacterial consortium have a tremendous ability to accelerate the biodegradation process in the natural environment. However, FTIR analysis implied that the monoculture had better efficacy than the consortium, and it was consistent until the incubation period used for the study. Some polymeric bonds such as ν C=C and δ C-H were completely removed, and ν C=C ring stretching, νasym C-O-C, νsym C-H, etc. were introduced by strain PE10. Furthermore, thermal analysis results validated the structural deterioration of e-waste as the treated samples showed nearly two-fold weight loss (WL; 6.8%) than the untreated control (3.1%) at comparatively lower temperatures. SEM images provided the details of surface disintegrations. Conclusively, individual monoculture P. aeruginosa strain PE10 could be explored for e-waste bio-recycling in agricultural soil ecosystems thereby reducing the cost, time, and management of bioformulation in addition to hazardous pollutant reduction.

Synergistic effects of microencapsulated bacterial spores and superabsorbent polymer on self-healing performance in mortar

This study explores the feasibility of utilizing a superabsorbent polymer (SAP) to improve the self-healing performance of microbial-induced calcium carbonate precipitation (MICP) in cement-based materials. The amount of microencapsulated bacterial spores was varied from 0.25–1 % by cement weight. The SAP content was set to either 0 or 4 % by cement weight. As additives, the impact of SAP and MICP bacteria on mortar properties, including flowability and compressive strength, was assessed. The self-healing performance was evaluated based on crack-healing percentage and water permeability recovery. Microstructural analyses, including thermogravimetry/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), were performed to investigate the microstructural and chemical changes during the healing process. The findings revealed that specimens exclusively mixed with 4 % SAP exhibited a slightly lower crack-closure efficiency compared to those mixed exclusively with 1 % MICP bacteria. However, the SAP-containing specimens exhibited a higher degree of permeability recovery. Meanwhile, in the binary additive system with 0.5 % MICP bacteria and 4 % SAP, the specimens exhibited the highest crack-closure percentage of 91 % and a final water discharge rate of 15 mL/min after 45 days of healing. In contrast, specimens mixed exclusively with 1 % MICP bacteria showed a crack-closure percentage of 76 % and a final water discharge rate of 59 mL/min. These results suggest that incorporating SAP into the MICP system enables a reduction in MICP bacterial content without compromising self-healing performance.

Thermodynamic, spectroscopic, and molecular characterization of rice straw biomass for use as biofuel feedstock

AbstractIndia is one of the leading producers of rice in the world. Gasification and pyrolysis are two thermochemical processes. In the gasification process, biomass is transformed into syngas, which serves as an energy source. This conversion occurs under high temperatures with a carefully regulated and restricted air supply. On the other hand, pyrolysis, which transpires at lower temperatures without the presence of air, generates pyrolysis oil as a by‐product. This oil can be further refined into liquid fuels. For the purpose of investigating the feasibility of biofuel production, the current study involved the characterization of rice straw biomass using various techniques such as thermogravimetry differential thermal analysis (TG/DTA), Fourier transform infrared (FTIR), carbon, hydrogen, nitrogen, sulphur and oxygen (CHNS/O), inductively coupled plasma optical emission spectroscopy (ICP‐OES), among others. These analytical methods were employed to assess the potential of rice straw biomass for the production of biofuels. The existence of a significant amount of cellulose (32.1%), volatiles (approximately 67.06%), and high heating value (HHV) (13.18 MJKg−1) in rice straw inferred their capability to be used as feedstocks in the production of biofuel. The activation energy of approximately 173.20 KJ/Mol (Flynn Wall Ozawa [FWO]) indicated the viability of the burning process. From master plot (Z(α)) analysis, the experimental curve was seen passing through different theoretical curves, indicating the complex nature of the pyrolysis process for rice straw.

Polyethylenimine Grafted onto Nano-NiFe2O4@SiO2 for the Removal of CrO42-, Ni2+, and Pb2+ Ions from Aqueous Solutions.

Polyethyleneimine (PEI) has been reported to have good potential for the adsorption of metal ions. In this work, PEI was covalently bound to NiFe2O4@SiO2 nanoparticles to form the new adsorbent NiFe2O4@SiO2-PEI. The material allowed for magnetic separation and was characterized via powder X-ray diffraction (PXRD), showing the pattern of the NiFe2O4 core and an amorphous shell. Field emission scanning electron microscopy (FE-SEM) showed irregular shaped particles with sizes ranging from 50 to 100 nm, and energy-dispersive X-ray spectroscopy (EDX) showed high C and N contents of 36 and 39%, respectively. This large amount of PEI in the materials was confirmed by thermogravimetry-differential thermal analysis (TGA-DTA), showing a mass loss of about 80%. Fourier-transform IR spectroscopy (FT-IR) showed characteristic resonances of PEI dominating the spectrum. The adsorption of CrO42-, Ni2+, and Pb2+ ions from aqueous solutions was studied at different pH, temperatures, metal ion concentrations, and adsorbent dosages. The maximum adsorption capacities of 149.3, 156.7, and 161.3 mg/g were obtained for CrO42-, Ni2+, and Pb2+, respectively, under optimum conditions using 0.075 g of the adsorbent material at a 250 mg/L ion concentration, pH = 6.5, and room temperature.

A novel foaming additive derived from waste polyethylene terephthalate (PET) for low-carbon warm mix asphalt

Plastic pollution is growing relentlessly due to the careless disposal of waste plastic products. This study focuses on converting waste plastic bottles into a foaming additive for the production of eco-friendly warm mix asphalt (WMA) for paving purposes. The additive, namely PET-TETA, was synthesized from waste polyethylene terephthalate (PET) via an aminolysis process. Its chemical and physical properties were characterized by the scanning electron microscope (SEM), X-ray diffractometer (XRD), and thermogravimetry-differential thermal analyzer (TG-DTA) tests. The WMA mixtures were prepared using PET-TETA and a commercial foaming additive, and their properties were studied and compared to a conventional hot mix asphalt mixture. The performances of the asphalt mixtures were characterized through the indirect tensile stiffness modulus, moisture susceptibility, and immersion Hamburg wheel-tracking tests. The findings revealed that PET-TETA was a semicrystalline material containing approximately 26 % hydration water, which could be released gradually during the preparation of asphalt pavements. The performance of the WMA mixture utilizing PET-TETA was comparable to the other two asphalt mixtures, and it exhibited higher strengths and better resistance to stripping. Therefore, it is promising to apply PET-TETA as a sustainable and effective WMA additive for paving purposes, providing a solution to the issue of waste plastic disposal.

Structural properties and photocatalytic activity of amorphous-crystalline TiO2 thin films

TiO2-coated glass plates were prepared by dip coating using TiO2 coating sol with a mixed amorphous and crystalline structure. These samples were dried at 100°C or calcined at 500°C, which were referred to as MT and CT, respectively. The TiO2 thin films on glass plates were characterized by X-ray diffraction, thermogravimetry-differential thermal analysis, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, Brunauer-Emmett-Teller surface area measurement, scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectra. The TiO2 thin films of MT samples had mixed amorphous and crystalline structures, while those of CT samples had only crystalline structures. The photocatalytic activity of the samples was investigated on the basis of methylene blue (MB) decomposition under ultraviolet and visible light irradiation. In the dark stabilization, MT samples had a higher MB adsorption capacity than CT samples. MT samples had a smaller amount of anatase TiO2 than CT samples, but both glass plate samples showed the same MB photocatalytic activity under ultraviolet light irradiation. We presumed that these results were because the amorphous-crystalline TiO2 thin films had a high specific surface area, so they had more adsorption and active sites. Under visible light irradiation, only the MT samples had photocatalytic activity, which can be attributed to their high visible light absorbance, which may be due to their peroxo groups, disordered structure, and larger specific surface area.

Synthesis, characterization, sorption, and antibacterial properties of a new polystyrene-supported o-hydroxyacetophenonediethylenetriamine polymer

A new polystyrene-supported Schiff base resin, o-hydroxyacetophenonediethylenetriamine-polystyrene (PS-HAPDA), has been synthesized via a reaction between the commercially available chloromethyl polystyrene polymer and the Schiff base o-hydroxyacetophenonediethylenetriamine (HAPDA). The structure of the synthesized polymer has been determined by Fourier transform infrared spectroscopy and thermogravimetry differential thermal analysis (TG/DTA). The chelating properties of the new polymer toward some divalent metal ions were studied by a batch equilibration technique under different experimental conditions. Results revealed that the metal-ion uptake follows the order Cu+2 > Zn+2 > Ni+2 > Co+2 > Pb+2. The antibacterial activity of complexed PS-HAPDA was tested against Gram-negative strains and Gram-positive strains.

Selection and thermophysical assessment of phase change materials (PCMs) for space cooling applications in buildings

Phase change materials are gaining more attention in building comfort applications because of their latent heat thermal energy storage (TES) capacity. Identifying the best PCM candidate is a pivotal factor that significantly impacts the thermal performance of a building. This study delves into assessing prospective PCM candidates for potential utilization in cooling systems within buildings in hot subtropical climates. Extending the application of multicriteria decision-making (MCDM) methodologies, this research scrutinizes various commercial PCMs by conducting an exhaustive analysis of pertinent literature in the context of this specific application objective. Thermophysical properties are integrated into the MCDM framework to identify the most fitting candidates with optimal properties and attributes. The properties and attributes of PCMs are subjected to scoring and weighting through the AHP based on their significance in the given application context. TOPSIS and VIKOR techniques select the suitable PCM from the identified PCMs. The results showed that latent heat receives the highest weightage, amounting to 50.2%, due to its paramount importance. Furthermore, OM37 emerged as a promising choice for building space cooling, considering the prescreened temperature range of 30 °C–40 °C and for the specific location under consideration. Following PCM selection, thorough characterization was performed to evaluate the suitability of the chosen PCM for integration within building envelopes. The thermal conductivity of OM37 was determined to be 0.20 W/mK, while the morphology by a Field Emission Scanning Electron Microscope (Fe-SEM) intricate porous structure. Furthermore, a differential scanning calorimeter (DSC) suggests melting and solidification temperatures of 40 °C and 34 °C with a total enthalpy of 197.04 j/g, and a Thermogravimetry Differential Thermal Analysis (TG/DTA) showed a substantial weight loss of approximately 98.9% at around 247.3 °C. The presented experimental test results agree with the literature data and other researchers’ results.

Effect of Na versus Ca Sulfate Salts on the Hydration of Calcium Sulfoaluminate Clinker.

This paper examined how the amount (5% or 20%) and type (CaSO4 or Na2SO4) of sulphate salt affect the hydration of calcium sulphoaluminate clinker (KCSA). The mechanical behavior of the pastes was determined at 1, 3, 28, and 90 days, the heat flow and total heat were measured with isothermal conduction calorimetry, and the reaction products were characterized using X-ray diffraction (XRD), differential thermal analysis/thermogravimetry (DTA/TG) and scanning electron microscopy (SEM). The results obtained indicated that both the amount of sulphate salt (5% or 20%) and its type (CaSO4 or Na2SO4) affect the hydration kinetics, type of reaction products formed, and development of mechanical strength. The incorporation of CaSO4 has a positive effect on the development of the mechanical strength of KCSA. However, Na2SO4 can also produce adverse side effects at older ages. The presence of Na2SO4 increases pH values, which partly destabilizes the ettringite formed, thereby favoring carbonation and thenardite precipitation, which can cause the specimens to crack and break.

Integrated experimental assessment and validation of oxidation with real-scale SiC fuel compact in HTGR

Air ingress is a critical accident in HTGR design, caused by a rupture in the coolant pipe. It leads to the oxidation of hot graphite at high temperatures, resulting in mechanical degradation of graphite structures. To address this issue, the authors propose a novel approach of substituting graphite fuel compacts with polycrystalline reaction-sintered SiC (RS-SiC) fuel compacts due to their superior oxidation resistance. The adoption of SiC based fuel compact will eliminate the graphite sleeves currently used in the pin-in-block type HTGR designs. It will also make it possible to achieve the high-power density due to the absence of graphite sleeves. There is limited understanding of the oxidation kinetics and transition behavior in RS-SiC. To address this knowledge gap, integrated experiments are conducted to investigate the thermal and oxidation behavior of SiC under varying oxygen concentrations. These experiments aim to provide insights into SiC's performance in HTGR environments using similar temperature and flow velocity conditions. Experimental data obtained will be utilized to develop a numerical model for enhanced understanding. In this study, both experimental and computational fluid dynamics (CFD) analyses were performed to compare the temperatures obtained from simulations with experimental measurements. The results demonstrated good agreement between experimental and numerical data. Passive oxidation was observed in real scale SiC fuel compacts at both 900 °C and 1100 °C, with slightly lower weight gain at the higher temperature. This suggests the possibility of damage to the SiO2 oxide layer at elevated temperatures. These results are important as the experiments are done in an integrated test facility using the air ingress accident boundary conditions of HTGR with the SiC fuel compact of real scale. These experiments validate the earlier findings from thermogravimetry differential thermal analysis (TG/DTA) conducted in a smaller-scale facility. They play a role in extending our understanding of SiC oxidation behavior, thereby assisting in the advancement of HTGR designs for enhanced safety and performance.

Aluminium dross waste utilization for phosphate removal and recovery from aqueous environment: Operational feasibility development

The need to minimize eutrophication in water bodies and the shortage of phosphate rock reserves has stimulated the search for sequestration and recovery of phosphate from alternative sources, including wastewater. In this study, aluminium dross (AD), a smelting industry waste/by-product, was converted to high-value material by encapsulation in calcium alginate (Ca-Alg) beads, viz. Ca-Alg-AD and utilized for adsorptive/uptake removal and phosphate recovery from an aqueous environment. Encapsulation of AD in alginate beads solves serious operational difficulties of using raw AD material directly due to density difference constraining efficient contact of AD with pollutants present in water and post-treatment recovery of AD material. The phosphate removal was evaluated in both batch and continuous flow operation modes. The batch adsorption study revealed 96.86% phosphate removal from 10 mg L−1 of initial phosphate concentration in 70 min of optimal contact time. Further, the phosphate removal potential of Ca-Alg-AD beads turned out to be independent of solution pH, with an average of 95.93 ± 1.40 % phosphate removal in the 2–9 pH range. The result reflects phosphate adsorption on Ca-Alg-AD beads following a second-order pseudo-kinetic model. Ca-Alg-AD beads-based adsorption followed Freundlich and Langmuir isotherm models. Further, a continuous packed bed column study revealed a total phosphate adsorption capacity of 1.089 mg g−1. The chemical composition, physical stability, and surface properties of Ca-Alg-AD beads were analyzed by means of state-of-the-art analytical techniques, such as Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetry/Differential Thermal Analysis (TG/DTA). These characterization techniques comprehend the mechanism and influence of surface properties and morphology on the phosphate adsorption behaviour, which induce the involvement of multiple mechanisms such as ligand complexation, ion exchange, and electrostatic attraction for phosphate adsorption on Ca-Alg-AD beads.

Rapid Photocatalytic Activity of Crystalline CeO2-CuO-Cu(OH)2 Ternary Nanocomposite

The development of a heterojunction nanocomposite leads to improved optoelectronic properties. Herein, ceria (CeO2), copper oxide (CuO), and ceria–copper–copper hydroxide (CeO2-CuO-Cu(OH)2) nanocomposites were prepared via a facile chemical method and their structural, morphological, and optical properties were studied using various characteristic techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), ultra-violet visible light absorption (UV-visible), photoluminescence, and thermogravimetry differential thermal analysis (TG-DTA). In the integration of CeO2 and CuO with Cu(OH)2, the band gap is modified to 2.64 eV; this reduced band gap can improve the photocatalytic efficiency of the nanocomposite. The CeO2 can increase light absorption in the nanocomposite, while CuO acts as an electron trap in the composite and this leads to a good enhancement of the optical properties of the CeO2-CuO-Cu(OH)2 nanocomposite. In addition, the heterojunction combination at the interfaces of the CeO2-CuO-Cu(OH)2 nanocomposite facilitates the photo-generated charge separation in the composite, which increases the charge participation in the catalyzed conversion reactions of the prepared composite. The highest photocatalytic degradation efficiencies of 96.4% and 92.7% were achieved for fast green (FG) and bromophenol blue (BP), respectively, using the CeO2-CuO-Cu(OH)2 nanocomposite.

Influence of multi-stage processing and mechano-chemical treatments on the hydration and microstructure properties of recycled aggregate concrete

On account of the shortage of naturally occurring coarse aggregate, recycled aggregate (RA) made from crushed concrete debris is now used in the construction industry. With this rise in the utilisation of recycled aggregate in the construction sector, there has been extensive research into ways to improve its quality. The significant fraction of mortar remains that are left on the RA surface is the primary factor that affects its quality. Concrete made from RA loses strength and mechanical performance due to the attached mortar's increased porosity and water absorption values and the frailer transition region between the new mortar and aggregates. In order to minimise the old cement fractions and increase the quality, this paper studies the effect of concrete incorporating multi-stage processed RA from demolished concrete waste, followed by treatment with mechanical abrasion and sodium silicate immersion. The recycled aggregates were produced through multi-stage jaw crushing, followed by utilising natural aggregate, recycled aggregate, and recycled aggregate obtained after mechanical abrasion, followed by sodium silicate treatment for concrete mix design at various substitution percentages as coarse aggregates. The experimental investigation further progresses with the evaluation of mechanical and durability properties of concrete mixes, which is additionally followed by microstructural studies such as scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Thermogravimetry-differential thermal analysis (TG-DTA). The outcomes demonstrate that two-stage treatment, such as mechanical abrasion followed by sodium silicate immersion, yields superior-quality RA. Recycled aggregate concrete (RAC) made with these treated aggregates illustrated an increase in workability and density with respect to an untreated RAC mix. Furthermore, comparable strengths in compression, flexure, and tension are found in treated RAC mixes, particularly at 35% replacement levels, with respect to concrete mixes comprised of natural aggregates. A similar trend is detected in the chloride penetration tests and water sorptivity tests. In addition, the microstructural investigation confirmed the formation of additional calcium silicate hydrate for treated RAC mixes, particularly for the 35% substituted RA mix. On the basis of the results, it is suggested that multi-stage jaw crushing followed by treatment through mechanical abrasion and sodium silicate can potentially enhance the mechanical, microstructural, and durability performance of RAC.