XRD Results Research Articles

Solvent-Free in Situ Synthesis of a CsPbBr3 Nanocrystal/ZrO2 Hybrid Phosphor with Excellent Thermal Stability for White Light-Emitting Diodes.

All-inorganic cesium lead halide perovskite CsPbX3 (X = Cl, Br, I, or mixed) nanocrystals (NCs) are emerging as promising candidates in light-emitting diodes (LEDs) owing to their excellent luminescent properties. However, CsPbX3 NCs are extremely susceptible to the elevated temperature associated with prolonged LED operation due to their low formation energy and soft ionic crystal structure. Here, CsPbBr3 NCs hybridized with ZrO2 were in situ synthesized by a rapid solvent-free method under an ambient environment for the first time, which was also suitable for large-scale production. The as-prepared CsPbBr3/ZrO2 hybrid phosphor not only presented enhanced photoluminescence (PL) properties but also exhibited improved thermal stability. For example, the PL intensity of the CsPbBr3/ZrO2 hybrid phosphor could retain 70% of the initial value at 130 °C, obviously higher than that of 34% for pure CsPbBr3. The exceptional thermal stability of the CsPbBr3/ZrO2 hybrid phosphor could be attributed to the introduction of ZrO2, which effectively preserved the initial perovskite structure of CsPbBr3 during heat treatment, as confirmed by XRD results. The as-prepared CsPbBr3/ZrO2 hybrid phosphor had great practical applications verified by the construction of white LEDs (WLEDs) with a luminance degradation of only 9% after continuous operation for 24 h at the initial luminance of 2000 cd m-2, which was significantly better than that of 63% for control WLEDs. The proposed thermally stable hybrid phosphor is expected to greatly contribute to the industrialization process of perovskites.

A Novel BiOBr/CAU-17 Composite with Enhanced Photo-Catalytic Performance for Dye Degradation and Removal of Tetracycline Antibiotic Under Visible Light.

In order to improve the low specific surface area and high recombinant light generation carriers of BiOBr, loading BiOBr onto suitable Metal Organic Frameworks (MOFs) is an effective strategy to unleash its efficient visible light response and intrinsic catalytic activity. In this study, using classic MOF CAU-17 as a precursor, using a straightforward co-precipitation technique, four BiOBr/CAU-17 composites with distinct MOF contents values BCAU-1, BCAU-2, BC, AU-3, and BCAU-4 were created, and their photo-catalytic characteristics were examined. The BCAU-2 composite exhibited much higher photo-catalytic degradation efficiency for Rhodamine B (RhB) and Tetracycline (TC) than the pristine materials, counter compositions, and early reported materials. XRD, SEM, TEM, XPS, and EDX results revealed the strong synergistic photo-catalytic effect of BiOBr and CAU-17. The photocatalytic degradation of TC was significantly enhanced by the BiOBr bimetal modification, with the 2 wt.% BiOBr/CAU-17 nanocomposite achieving an 87.2 % degradation of TC and 82 % Total Organic Carbon (TOC) removal within 60 min. The high photo-degradation efficiency of BCAU-2 composite should be attributed to the efficient transfer of photo-generated carriers at interfaces and the synergistic effect between BiOBr/CAU-17. Furthermore, the experiments on the capture of the active species proved that the main active free radicals involved in the degradation of RhB and TC are attributed to the photo-induced holes h+ and ⋅ O2 - under visible light. The catalyst's efficacy is corroborated by the outcomes of photoluminescence spectroscopy and photo current response. This study offers a new understanding for the design of green synthesis schemes for photo-catalytic dye degradation and removal of certain antibiotics from the aquatic environment.

Enhanced Hg(II) reduction activity over two-dimensional n-n heterojunction MoS2/Bi2WO6 nanocomposites under visible light illumination

The engineering of band structure acts as an effective avenue to promote photocatalytic redox reactions, which can be achieved by fabricating heterojunction photocatalysts. Herein, MoS2 NPs were anchored on the surface of the mesoporous Bi2WO6 network through a facile sol-gel process to form heterostructure MoS2/Bi2WO6 nanocomposites. HR-TEM and XRD results of the obtained MoS2/Bi2WO6 nanocomposite verified the formation of the hexagonal phase of MoS2 and the orthorhombic one for Bi2WO6. The MoS2/Bi2WO6 nanocomposites displayed enhancemed harvest for the visible light domain and photocatalytic ability in comparison with the pristine Bi2WO6. The photocatalytic ability of MoS2/Bi2WO6 nanocomposites was assessed by the Hg(II) reduction upon visible light irradiation. The optimal 12 % MoS2/Bi2WO6 photocatalyst displayed the superior reduction of Hg(II) about 99 % after 50 min, and the rate constant reached 0.1220 min−1 according to pseudo-first-order kinetic, where it was larger three folds than pristine Bi2WO6 (0.0418 min−1). The outstanding photocatalytic ability of n-n heterojunction MoS2/Bi2WO6 photocatalyst was attributed to the huge surface area, wide photoabsorption, and high separation efficiency of photocarriers. The reduction ability of MoS2/Bi2WO6 photocatalyst remained at 94 % after five times recycle, indicating its good reusability and high stability. The obtained heterojunction with the S-scheme mechanism could inhibit the recombination of the photocarriers, thus leading to superb photocatalytic ability. This work emerges an efficient route to design S-scheme heterojunction Bi2WO6-based photocatalytic methods for energy conversion and environmental purification.

Synthesis, characterization and electrochemical performance of Bi2S3/rice husk-based activated carbon composites as lithium ion battery anodes

This study investigates the impact of hydrothermal duration on bismuth sulfide/activated carbon composites (Bi2S3/AC) by varying the duration to 8, 24, and 48 h. The primary aim is to delineate the composite characteristics and electrochemical performance of Bi2S3/AC composites, aiming to produce anodes for lithium-ion batteries with high capacity, excellent cyclic stability, and minimal volume expansion. Activated carbon derived from rice husks was synthesized via a carbonization process and chemical activation using H3PO4 as an activator. Subsequently, the synthesis of Bi2S3/AC composites used bismuth nitrate pentahydrate and thiourea precursors through the hydrothermal method that involved three variations of hydrothermal duration: 8, 24, and 48 h, denoted as BC8, BC24, and BC48, respectively. The FTIR test indicates the presence of Bi-S, C=C, and CO groups in the three composite products, signifying the existence of bismuth sulfide and activated carbon. The XRD result reveals orthorhombic crystal forms in the composites, while the SEM-EDX mapping illustrates particle morphologies resembling flower-like shapes. These compositions comprise Bi 74.16 %, S 11.37 %, and C 10.43 %. The GSA test suggests a mesoporous pore size in these composites. In final result, BC24 exhibits the highest electrical and ionic conductivity, measuring 2.12 × 10−3 S.cm−1 and 2.057 × 10−4 S.cm−1, respectively. The CV data of the BC24 composite indicates two reduction and oxidation peaks in the first cycle. Charge-discharge test on the BC24 composite exhibits a specific charge capacity of 445.51 mA.h.g-1 and a discharge capacity of 364.24 mA.h.g-1.

Physical Properties of HfO2 Nano Structures Deposited using PLD

On Quartz substrates, high purity transparent conductive the Di-Oxide of the (HfO2) Nano and micro-structure films were successfully coated. The method of (PLD) Deposition using Pulsed Laser, and the influence of laser energy was investigated. The XRD results revealed two distinct phases, cubic and monoclinic crystal shapes. Peaks in the Fourier-transform infrared (FTIR) spectra showed that HfO2 nanofilm was forming.The findings of the optical characteristics reveal an excellent transparency of nearly 80% (89 percent). As the laser wavelength decreases, the optical energy band gap values for Nanostructure of HfO2 were prepared, with values ranging from 5.24 to 5.53 eV. Also, the EDX results showed the appearance of hafnium peaks and oxygen peaks in varying proportions, which confirms that hafnium oxide is definitely obtained The results of the AFM reveal that when the pulsed laser intensity increases, the average grain diameter values increase from 52.96 to 74.54 nm. With regard to optimum pulsed laser energy, the based on I-V characterization, the generated factor ideality for created diodes was discovered to be decreasing, and the corresponding values of the barrier height grew. The ideality factor of the diode made the optimum pulsed laser energy (1800 mJ) was greater (n=3.1).

Preparation of Ni-Cu-C composite catalysts prepared from mixed nickel and copper hydroxides for selective hydrogenation of 4-nitrophenol

A high-performance Ni-Cu-C composite catalyst was prepared from mixed nickel hydroxide and copper hydroxide, which were obtained by coprecipitation, by thermal treatment with acetylene-containing gas at 120 °C followed by hydrogen reduction at 180 °C. The characterization results of XRD, TEM, XPS, and H2-TPR measurements confirmed the presence of nickel carbide (Ni3C), copper carbide (CuxC), Cu, and Ni in the matrix of amorphous carbon in the composite catalyst. The mild preparation temperature and the porous carbon shell layers prevented the nano-sized particles from aggregation. The formation of interstitial Ni3C and CuxC significantly enhanced the dissociation of molecular hydrogen, accelerating the selective hydrogenation of 4-nitrophenol (4-NP) to yield 4-aminophenol (4-AP) at relatively mild conditions (80 °C and 1.0 MPa hydrogen pressure). The catalytic performance of the composite catalysts depended strongly on the Ni/Cu molar ratio, with an optimal Ni/Cu molar ratio of 4. In addition, the composite catalyst showed high conversion and selectivity to the corresponding aniline in the selective hydrogenation of other nitroarenes, including nitrobenzene, 4-nitrotoluene, 4-nitrochlorobenzene, 4-nitrobenzaldehyde, 4-nitroacetophenone, and 2-nitroaniline. The catalyst offers a novel approach to rational design and preparation of high-performance abundant metal catalysts for selective hydrogenation of nitroarenes.

Physical and chemical characteristics and activity of nickel-modified cobalt-iron-containing catalysts in the reaction of dry reforming of methane

In the process of dry reforming of methane (DRM), the activity of low-percentage catalysts based on cobalt and iron oxides and their modification with nickel oxide was studied. It has been established that the addition of nickel oxide into the Fe2O3/γ-Al2O3 catalyst increases the degree of methane conversion from 14 to 89%, and also increases the yield of target reaction products H2 to 43.0 vol.%, CO to 46.1 vol.% at 850 °C. On a Co3О4-NiО/γ-Al2O3 catalyst at 850 °C, methane conversion reaches to 88.1%, the yield of H2 and CO is 44.8%. TPR-H2 analyzes showed that the introduction of nickel oxide into Fe2O3/γ-Al2O3 composition, in contrast to the Co3O4/γ-Al2O3 catalyst, the temperature peaks of Fe2O3-NiО/γ-Al2O3, reduction shift towards lower temperatures and weaken the interaction of metals with the support - γ-Al2O3 and thereby the amount of active reduced particles of iron and nickel oxides increases, which ensures good catalytic activity of Fe2O3-NiО/γ-Al2O3. According to the XRD results, spinel-like form - NiFe2O4, NiAl2O4 and CoAl2O4, also phase as Fe2O3 were obtained on the Fe2O3-NiО/γ-Al2O3 catalyst. This indicates that the developed catalysts form new phases that are active at high temperatures to produce synthesis gas in reduction-oxidation processes during the DRM reaction.

Sustained-release composite films incorporated with cinnamon essential oil: Characterization, release kinetics and application for cherry tomato preservation

Food spoilage waste accelerated the development of bio-based active food packaging. Sustained-release composite films based on oxidized corn starch/pullulan were prepared by incorporating cinnamon essential oil (CEO) nanoemulsion. The SEM, ATR-FTIR and XRD results showed that CEO was successfully encapsulated in film matrixes. The composite films exhibited the increase of thermal stability, UV-shielding, flexibility and water vapor resistance properties. The films containing CEO nanoemulsion (≥10%) showed excellent antimicrobial activities against S. aureus, E. coli and B. cinerea (the maximum inhibition zones achieving 27.23 ± 2.31 mm). The release kinetics results showed sustained release of CEO from the films with high content of CEO nanoemulsion, and the dominant release mechanism was Fickian diffusion. The composite films effectively maintained cell structure, weight, firmness and total soluble solids content of fruits during storage. Therefore, the sustained-release composite films could be a prospective packaging material for fruits preservation.

Photocatalytic degradation of Diuron in water – Impact of Rh impregnation on P25 visible light activity

Significant efforts have lately been dedicated to the development of visible light activated photocatalysts for the degradation of emerging pollutants in water. This study shows the impact of Rh addition on the photocatalytic performance of TiO2 in Diuron degradation through various experimental approaches and modelling. Three samples with different Rh loading (0.5 %, 1 %, and 2 %) were synthesized, characterized, and their activities were evaluated. It was observed that the activity of RhP25 improved under white light irradiation with increasing Rh content. At low Rh loadings the Rh atoms interact with Ti and may be stabilized in the TiO2 lattice. At higher loadings Rh interacts with the O atoms forming two different clusters Rh3O4 and Rh4O6 on the TiO2 surface. This phenomenon was evidenced by DFT, XPS and XRD results. The addition of Rh induce new electronic states in the TiO2 enhancing the visible light absorption. Photocatalytic experiments revealed a threefold increase in Diuron removal under white light irradiation for 2%RhP25 compared to P25, achieving 23 % degradation in comparison with the 7 % observed for the P25 without the Rh addition. Furthermore, repeated experiments did not show significant deterioration of the activity.

Controllable mechanism of hazardous jarosite transformation into recyclable hematite in the leaching solution of secondary zinc oxide powder

The controlled synthesis of recyclable hematite in the leaching solution of secondary zinc oxide powder is an urgent problem in the chemical industry and metallurgy fields. In this paper, the effects of the temperature, agitation speed, and seed addition on the contents of iron, sulfur, potassium, sodium, and zinc in the iron removal residues, as well as the iron concentration in the supernatant after iron removal were systematically studied. In addition to the temperature control already reported, we found that the agitation speed can also control the transformation between jarosite and hematite phases. The content of jarosite in the residues can be effectively controlled by adjusting the agitation speed, thereby significantly improving the quality of hematite product, as indicated by SEM-EDS and XRD results. Under temperature of 185 °C, an agitation speed of 500 rpm, and a seed addition of 15 g/L, the iron, sulfur and zinc contents in the filter residues and the iron concentration in the supernatant were 59%, 3.22%, 0.92%, and 4.182 g/L, respectively. Kinetic studies show that the rapid oxidation kinetics is not conducive to the formation of high-quality hematite products. These results can directly guide the process of transformation of harmful jarosite into recyclable hematite from the leaching solution of secondary zinc oxide powder, which is of great practical significance for the controlled and waste-free removal of iron from aqueous solutions in the chemical industry and metallurgy fields.

Enhanced NIR reflectance black pigments based on CuCr2-xTixO4: Synthesis and properties

Ti-doped CuCr2O4 is an excellent black cool pigment for preventing surface overheating. Ti was introduced into the precursor in the form of tetrabutyl titanate(C16H36O4Ti) and calcined to obtain a CuCr2-xTixO4 black pigment. XRD, XPS, and EDS results showed that a portion of Ti entered the lattice of CuCr2O4, while the remaining Ti existed in the form of TiO2. The absence of TiO2 reduced the absorption of visible light. As the x value increased, the absorption of visible light by CuCr2-xTixO4 decreased and L∗ increased. CuCr1.1Ti0.9O4 has a maximum reflectance of 23.0 % for NIR solar reflectance, and the mechanism could be determined by the following three reasons: 1) Small particles help to reflect NIR; 2) TiO2 improves the NIR reflectivity of the black pigment; and 3) According to the Drude free-electron theory, the substitution of Ti4+ for Cr3+ increases the concentration of free carriers in CuCr2O4, which increases the NIR reflectance. Application studies indicated that the CuCr1.1Ti0.9O4 coating on an alumina plate was approximately 3 °C lower than the CuCr2O4 coating after 40 min of irritation by an IR lamp. Therefore, CuCr1.1Ti0.9O4 pigments exhibited potential applications in insulating materials.

Physical properties and hydration behaviors of paste casting brick containing coal gasification slag (CGS): Effect of curing condition and CGS dosage

In the process of developing coal chemical technologies, it is necessary to address environmental pollution and resource waste caused by the associated solid waste coal gasification slag (CGS). This study investigated the feasibility of using CGS as a substitute for fly ash (FA) in the preparation of paste casting bricks. The effects of curing conditions and CGS dosages on the physical properties of the specimens were investigated and related to the hydration behaviors through various microscopic techniques. The results showed that the occurrence of electrostatic flocculation and the enrichment of active substances increased the yield stress of the slurry as the CGS replacement rose, which manifested as decreased fluidity at the macroscopic level. The secondary hydration reaction was facilitated with the increased CGS replacement rate due to the desirable hydraulic activity of CGS. XRD, FTIR and TG results corroborated that the content of hydration products which contributed to strength development were enhanced with the addition of CGS under different curing conditions. XRD and SEM-EDS results indicated that the doping of elements such as Mg and Al under autoclaved condition led to a reduction in the grain size of tobermorite, and the micro-morphology tended to concentrate stresses under pressure. The results of this study promote the resourceful utilization of CGS in building materials and lay the foundation for further scale-up industrial application.

Structural Phase Transitions and Metallization in Zirconium Disulfide (ZrS2) under High Pressure.

The high-pressure study on zirconium disulfide (ZrS2) has been conducted up to ∼33.9 GPa by using in-situ synchrotron X-ray diffraction at room temperature and electrical transport measurements, aiming to investigate the pressure-induced structural phase transitions and the metallization of the material. The experiments indicated that a progressive structural evolution occurs as the sequence below: hexagonal (space group (SG): P3̅m1) → monoclinic (SG: P21/m) started at 2.8 GPa → orthorhombic (SG: Immm) started at 9.9 GPa → tetragonal (SG: I4/mmm) started at 30.4 GPa. The lattice parameters and bulk modulus of the phases at high pressure are calculated. The decompression results demonstrate the coexistence of ZrS2 stability in monoclinic (SG: P21/m) and orthorhombic (SG: Immm) structures. The electrical transport results demonstrate a significant enhancement in the conductivity of ZrS2 at 8 GPa, and metallization occurs at ∼29.8 GPa. Combined with XRD results, the metallization is coincident with the phase transition to the tetragonal (SG: I4/mmm) structure. Our study presents a more precise phase transition sequence, calculates the cell parameters and bulk modulus of ZrS2 under high-pressure conditions based on experimental results, and confirms that metallization is induced by the structural phase transition. These findings provide an experimental basis for the further utilization of transition metal sulfides (TMDs) under high pressure.

Preparation and Photocatalytic Performance of In2O3/Bi2WO6 Type II Heterojunction Composite Materials.

Bismuth-based photocatalytic materials have been widely used in the field of photocatalysis in recent years due to their unique layered structure. However, single bismuth-based photocatalytic materials are greatly limited in their photocatalytic performance due to their poor response to visible light and easy recombination of photogenerated charges. At present, constructing semiconductor heterojunctions is an effective modification method that improves quantum efficiency by promoting the separation of photogenerated electrons and holes. In this study, the successful preparation of an In2O3/Bi2WO6 (In2O3/BWO) II-type semiconductor heterojunction composite material was achieved. XRD characterization was performed to conduct a phase analysis of the samples, SEM and TEM characterization for a morphology analysis of the samples, and DRS and XPS testing for optical property and elemental valence state analyses of the samples. In the II-type semiconductor junction system, photogenerated electrons (e-) on the In2O3 conduction band (CB) migrate to the BWO CB, while holes (h+) on the BWO valence band (VB) transfer to the In2O3 VB, promoting the separation of photoinduced charges, raising the quantum efficiency. When the molar ratio of In2O3/BWO is 2:6, the photocatalytic degradation degree of rhodamine B (RhB) is 59.4% (44.0% for BWO) after 60 min illumination, showing the best photocatalytic activity. After four cycles, the degradation degree of the sample was 54.3%, which is 91.4% of that of the first photocatalytic degradation experiment, indicating that the sample has good reusability. The XRD results of 2:6 In2O3/BWO before and after the cyclic experiments show that the positions and intensities of its diffraction peaks did not change significantly, indicating excellent structural stability. The active species experiment results imply that h+ is the primary species. Additionally, this study proposes a mechanism for the separation, migration, and photocatalysis of photoinduced charges in II-type semiconductor junctions.

Study of patterns and mechanisms of combustion of powdered and granulated T-C-B system

Experimental studies of the combustion patterns of the ternary system (100 – x)(Ti + C) – x(Ti + 2B) of bulk density in powder and granular form used for the synthesis of composite ceramics TiC–TiB2 were carried out. The study shows that the dependence of the powder mixture combustion rate on the Ti + 2B content has a non-monotonic character, which is associated with the influence of impurity gas release on the combustion process. By removing the influence of impurity gas by granulation, a monotonic dependence with two characteristic sections was obtained. For the granulated mixture, an increase in the Ti + 2B content 60 wt. % leads to a change from the conductive combustion mode to the convective one, accompanied by a sharp increase in the combustion rate. For the conductive combustion mode, the combustion rate of the substance inside the granule and the combustion transfer time from the granule to the granule were determined, which allowed us to estimate the inhibitory effect of impurity gas release on the combustion rate of powder mixtures of different composition. For the convective combustion mode, it was shown that a decrease in the content of the gasifying additive in the mixture (granulation with ethyl alcohol) led to an unexpected result: an increase in the combustion rate of the mixture. For compositions with (Ti + 2B) 60 wt. % the combustion rate with counter filtration of impurity gases was determined for the first time, which made it possible to estimate the front rate increase according to the filtration combustion theory. According to XRD results, the combustion products of all compositions contain only two main phases TiC and TiB2.

Enhancement of carrier concentration in chemical bath deposited copper sulfide (CuxS) thin film by post-growth annealing treatment

Copper sulfide thin films (CuxS, 1 ≤ x ≤ 2), owing to their unique optical and electrical properties, have attracted enormous attention in recent research. As one of the chalcogenide semiconductors, CuxS is used in several applications such as chemical sensors, photo-absorbing layers, photovoltaics, and lithium-ion batteries. In this study, copper sulfide thin film (CuxS; where 1 ≤ x ≤ 2) has been deposited by the chemical bath deposition method (CBD) at 27 °C with the molar ratio for copper and sulfur as 1:5, respectively. The structural, compositional, morphological, optical, and electrical properties of as-deposited and annealed CuxS thin films are investigated. From XRD plots, the presence of a mixture of two co-existing polycrystalline phases is observed, i. e. covellite phase with CuS stoichiometry and digenite phase with Cu1.8S stoichiometry up to an annealing temperature of 200 °C. At higher annealing temperatures, i.e. at 300 °C and 400 °C, the phase of CuxS thin film gets completely converted to digenite phase with Cu1.8S stoichiometry and chalcocite phase with Cu2S stoichiometry respectively. There is an enhancement in the crystallinity of CuxS thin film with an increase in annealing temperature as confirmed by XRD and Raman results. The optical bandgap of CuxS thin film is found to be decreased from 2.81 eV to 1.66 eV with an increase in the annealing temperature. The CuxS thin films are found to be p-type in nature, and the film annealed at 400 °C possesses the highest carrier concentration as revealed from the Hall effect measurement. This study aims to investigate the improvement of electrical properties of CuxS thin film with the variation in annealing temperature for optoelectronic applications such as photodetector.

Hydrothermal Synthesis of ZnO Nanoflowers: Exploring the Relationship between Morphology, Defects, and Photocatalytic Activity

Two forms of flower-like ZnO nanostructures were synthesized using hydrothermal methods at various growth times/temperatures and zinc precursors. The morphology, structure, chemical composition, and optical properties of these ZnO nanoflowers were studied using a scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy, and UV–Vis spectroscopy. The SEM images revealed two forms of flower-like nanostructures, namely lotus- and tulip-like flower ZnO nanostructures. The XPS analysis revealed the oxidation state of the Zn and O elements, as well as the presence of OH groups on the surface of the lotus-like flower ZnO nanostructure. The XRD results revealed less crystallinity of the lotus-like ZnO nanoflowers (NFs) compared with the tulip-like ZnO NFs. The XRD results revealed the presence of Zn (OH)2 in the ZnO NFs. The Raman results confirmed less crystallinity of the lotus-like ZnO NFs. The estimated optical bandgap was 2.92 and 3.0 eV for the tulip- and lotus-like ZnO NFs, respectively. The tulip-like ZnO NFs showed superior photocatalytic degradation of methylene blue dye, verified via UV–Vis radiation, compared with the lotus-like ZnO NFs, which show the impact of the structure defects and OH- impurities on the photocatalytic performance of ZnO nanoflowers.

Utilization of circulating fluidized bed coal ash in autoclaved aerated concrete manufacture by mineral carbonation

Using circulating fluidized bed combustion (CFBC) ash discharged from thermal power plants, we identified factors affecting mineral carbonation to sequester CO2 and produced autoclaved aerated concrete (AAC). To use CFBC ash as a raw material for AAC, free-CaO, which causes volume expansion, was replaced through hydration and carbonation. During the raw material replacement process, carbonation behavior was confirmed through pH and temperature. A Ca(OH)2 to liquid ratio similar to a fly ash to liquid ratio of 0.25 is considered to provide sufficient diffusion distance, and the reaction rate may increase due to the rise in water temperature caused by Ca2+ leaching. Additionally, the results of XRD, XRF, TG-DTA, and SEM analyses indicate that hydration and carbonation reactions were stably achieved in the materials, suggesting that CO2 sequestration allows the materials to be used as alternative raw materials. After identifying the characteristics of the CFBC ash and the substituted material, AAC was manufactured through pressurized carbonation. The weight change rate, carbonation depth, ventilation rate, pore structure, and compressive strength of the manufactured AAC were measured. As a result, the alternative raw material exhibited higher permeability and a larger pore size range in the specimens compared to the original material, indicating easier CO2 penetration into the specimens. Consequently, this experiment suggests the potential of using the material in AAC production by providing a theoretical basis for solving volume expansion issues associated with concrete admixtures and CO2 sequestration in waste materials.

Effect of Hexamethylenetetramine concentration on the structural, morphological, optical and bactericidal action of Eu-doped TiO2 quantum dots derived through wet chemical method

Recently, it has been established that bacteria are quickly developing resistance to traditional antibiotics; as a result, one of the most significant challenges facing the healthcare sector is treating illnesses linked to bacterial infections. In this work, we used a simple wet chemical approach to easily prepare pure TiO2 and Eu-doped TiO2 quantum dots (QDs) with different hexamethylenetetramine (HMT) concentrations: 0.1, 0.15, and 0.2 M. As indicated by XRD results, the pure TiO2 possesses the tetragonal anatase phase, while the Eu-doped TiO2 samples prepared with the support of HMT content during sample synthesis promotes the amorphous phase. The Eu-doped TiO2 sample prepared at 0.1 M HMT has an almost uniform distribution of ultra-fine QDs, with an average particle size distribution of 2.05 ± 0.17 nm, according to the TEM image. The Eu 3d core level doublet at 1134.29 and 1164.21 eV, which correspond to Eu3+3d5/2 and Eu3+3d3/2, respectively, is displayed in the XPS data for the sample prepared at 0.1 M HMT. Based on the findings of the Tauc plot, the sample prepared at 0.2 M HMT is found to have a larger optical band gap than the pure TiO2 and Eu-doped TiO2 samples prepared at different HMTA concentrations. According to antibacterial tests, the zone of inhibition for E. coli increases from 7 ± 0.55 to 12 ± 0.60 when the concentration of the Eu-doped TiO2 sample prepared at 0.15 M HMT is increased from 100 to 300 µg/mL. In the field of biomedical application, this enhanced antibacterial activity of Eu-doped TiO2 QDs can be utilized to create a potent medication for bacterial resistance.

Evaluation of the Nitrogen Release Properties of Chitosan-Bentonite Beads

In this study, chitosan-bentonite beads were prepared by using bentonite and chitosan as fertilizer carrier materials and urea as fertilizer components. The prepared samples were named BUC0.2, BUC0.4 and BUC0.6 based on the bentonite ratios of 0.2%, 0.4% and 0.6% (weight/volume). In the FT-IR and XRD results, it was seen that the characteristic peaks of the bentonite structure became evident in the BUC0.6 sample, while chitosan peaks were dominant in the BUC0.2 sample, as expected. As the amount of bentonite increased, the swelling ratio generally increased from 31.6% to 48.6. In the nitrogen release experiments, a very rapid nitrogen release occurred in the first hours of release. It was thought to be due to the rapid dissolution of urea in water. The cumulative release percentage showed a slightly decreasing trend in the days following the release experiment. When nitrogen release profiles of the samples containing different amounts of bentonite were compared, it was observed that the nitrogen release curves were quite close to each other due to the lower bentonite ratio. Release percentages of the samples containing different amounts of bentonite were obtained between 61.2-67.7. Observations supported the efficient degradation of fertilizers in the soil environment. As a result, it was evaluated that the prepared materials were promising as environmentally friendly nitrogen fertilizer.