Smaller Average Particle Size Research Articles

Textile dyes removing from the wastewater by green synthesized Cu-doped ZnO photocatalysts under the simulated sunlight illumination

Herein, Cu-doped ZnO photocatalysts were prepared via green synthesis method with utilization of Cannabis Sativa leaves. The catalytic activity was evaluated through the degradation of methylene blue (MB) and rhodamine B (RhB) under the simulated sunlight illumination. XRD, FESEM, EDAX, FTIR, BET-BJH and DRS were used for characterizations of Cu-doped ZnO. The results showed that, 3 wt % Cu-doped ZnO (CuZn3) displayed the excellent characterizations such as uniform dispersion, lower energy bandgap, smaller average particle size and greater surface area. For the photocatalysts with higher Cu loading (more than 3 wt %), non-uniform dispersion with larger particles, lower specific surface area and higher energy bandgap were found. The average particle size and energy bandgap for CuZn3 were 37.7 nm and 2.9 eV, respectively. Due to the superior properties, CuZn3 presented the highest amount of dyes degradations. After 180 min test, MB and RhB degradations by CuZn3 were 92.1 and 94.2 %, respectively. Moreover, it was found that optimum amount of CuZn3 was 100 ppm. Furthermore, applying of various scavengers revealed that hydroxyl radicals, superoxide radicals, and photo-generated electrons were the primary forms of radicals involved in dyes degradation using Cu-doped ZnO photocatalysts.

Electro-spinnability study of polymer slurry system for proton exchange membrane fuel cell

The electro-spinnability of catalyst slurry determines fabrication availability and the catalyst layer's quality. It was affected by the ink composition, ambient condition, and electrospinning parameters. Abnormal electrospinning behaviors, including blocking, dripping, dripping with spinning, semi-floating fibers, and standing fibers, were observed under the unfavorable combination of the factors. The high blocking frequency can be avoided by using a slurry with higher ionomer content, lower solid content and smaller average particle size. Dripping and dripping with electrospinning phenomena can be solved by restricting the applied voltage above 10 kV. Semi-floating fibers can be avoided by limiting the ambient temperature between 20-30°C and relative humidity between 15-25%. Standing fibers can be prevented by restricting the total applied voltage (the difference between the positive voltage on the needle and the negative voltage on the drum) to a level lower than 15 kV.

Preparation and characterization of hydrophobic waterborne polyurethane self‐matting coating

AbstractA green method to synthesize self‐matting waterborne polyurethane acrylic hybrid emulsion with hydrophobic function is introduced in this study. A reactive waterborne polyurethane (RWPU) dispersion containing unsaturated CC double bonds was prepared from epoxidized soybean oil. Subsequently, the RWPU dispersion was copolymerized with fluorinated monomers of different carbon chain lengths to prepare polyurethane acrylic hybrid emulsion (PUF). The results revealed the gloss levels of PUF films to be as low as 12.4 gloss units at 60°. The morphology of PUF films was observed by scanning electron microscope and three‐dimensional surface profilometer, and the relationship between surface roughness and gloss was discussed in detail. In addition, thermal gravimetric analysis was conducted to determine the thermal stability of the PUF films, and the results denoted that these PUF films exhibited excellent thermal stability. Comprehensive performance tests indicated that the RWPU dispersion, which was copolymerized with hexafluorobutyl methacrylate at a weight of 10%, exhibited a low gloss, a high contact angle of 120°, and a high elongation percentage of 423%. Furthermore, the dynamic light scattering results showed small average particle size, revealing the excellent storage stabilities.

Assessment of hemostatic ability of biomaterial based on chitosan and Eclipta prostrata L. extract

The biomaterials based on chitosan and Eclipta prostrata L. extract have been prepared by microemulsion method and solution method (with and without sodium tripolyphosphate (STPP) as a cross-linking agent). The main component in Eclipta prostrata L. extract is flavonoid groups. The structure of the chitosan/extract biomaterials was studied by infrared spectroscopy. The chitosan/extract biomaterial using STPP cross-linker appeared an absorption band at 1152 cm−1 attributed to the vibrations of C–O–P bonds, which proved that chitosan has crosslinked with STPP. The morphology of the biomaterials was investigated by the dynamic light scattering technique and field emission scanning electron microscopy. The obtained results showed that the particle size of the chitosan/extract biomaterials prepared by microemulsion method and solution method with STPP ranged from 68.06 nm to 1484 nm, with an average particle size of 304.9–1019 nm. The microemulsion method produced biomaterials with much smaller average particle size than the solution method using cross-linkers. The hemostatic ability of the biomaterials was better than that of the control sample based on the time of blood clotting formation and glomerular aggregation ability. The sample with the ratio of E. prostrata L. extract: chitosan of 1:30 had the lowest hemostasis time (6 min 46 s) and its glomerular aggregation rate after 5 min was 13.05%. This indicated that the biomaterials based on chitosan and E. prostrata L. extract are promising for application in biomedicine as hemostatic materials.

Morphology, Crystal Structure and Thermal Properties of Nano-Sized Amorphous Colemanite Synthesis

It is important to utilize the raw colemanite (RC) mineral, which has abundant reserves in the world, and to reduce its particles to smaller sizes for nanotechnology. However, not only the particle size of the produced colemanite powder but also its other properties need to be elucidated. By using the Taguchi design, the RC mineral was ground in a high-energy ball mill. From signal-to-noise (S/N) ratio, the smallest average particle size was found to be 3.10 µm for the experiment E04/nano-sized amorphous colemanite (NAC) powder. The characteristics of as-received RC mineral and synthesized NAC material were investigated using laser particle size analyzer, optical microscopes, SEM–EDS, XRD, TEM, HRTEM, and TGA–DTA devices. It was found that the NAC powder was not homogeneous, a small peak within the 300–20 nm range appeared, and d90, d50, d10, and dmin values were, respectively, 14.6 µm, 3.08 µm, 232 nm, and 26 nm. In the XRD analysis, the pure colemanite, calcite, and silica minerals were determined. The crystal structure of the NAC powder almost turned amorphous, and the crystallite size of (031) peak was reduced to 7.3 nm. It was deduced that the average particle size was 8.29 nm (R2 = 0.86), and the d-spacing value was 0.307 nm. This significant finding was attributed to the mobility of balls and moreover it was interpreted with an equation. An unknown transition in TGA–DTA was referred to the calcite mineral. Finally, it is believed that the synthesized NAC material will be beneficial to engineering studies as a natural/mineral additive.

Enhancement of N2O decomposition performance by co-doping of Ni and Y to Co3O4 catalyst

Co3O4, Y2O3-Co3O4 and NiO-Y2O3-Co3O4 samples were prepared by the simple co-precipitation method, and their N2O catalytic decomposition performance was evaluated. Experimental results disclose that the order of catalytic activity among the three catalysts is NiO-Y2O3-Co3O4 > Y2O3-Co3O4 >> Co3O4. N2O conversion over NiO-Y2O3-Co3O4 catalyst reached 100 % at 360 °C, which was 20 °C and 60 °C lower than those over Y2O3-Co3O4 and Co3O4, respectively. In addition, NiO-Y2O3-Co3O4 catalyst shows better water resistance compared with Co3O4 and Y2O3-Co3O4. Systems-based characterization techniques, it is confirm that Y and Ni were successfully doped into Co3O4, where Y was on the surface and Ni was mainly in the bulk phase. Due to the co-doping of Y and Ni, NiO-Y2O3-Co3O4 catalyst has smaller average particle size and reinforced surface alkalinity. Furthermore, the surface modification of Y enhances the electron-donating capacity of Co2+ and oxygen desorption ability, while bulk phase doping of Ni facilitates the reduction of Co3+ to Co2+ and weakens Co-O bond in Co3O4, which endow NiO-Y2O3-Co3O4 sample with lower Ea for N2O decomposition. Therefore, NiO-Y2O3-Co3O4 catalyst exhibits the best N2O catalytic decomposition performance.

Experimental Study on Dispersion Stability and Polishing Performance of Polishing Solution Based on Micro-Abrasive Water Jet Polishing

In micro-abrasive water jet polishing (MAWJP) technology, where abrasive particles serve as polishing tools, particles tend to form large clusters, leading to increased nozzle wear and diminished material polishing quality. Achieving a polishing solution with good dispersion stability is crucial for enhancing polishing accuracy and minimizing nozzle wear. Therefore, this study employed three dispersants with distinct dispersion mechanisms to examine the impact of each dispersant’s concentration on the dispersion stability of the polishing solution across various abrasive concentrations. Through experimentation, the optimal dispersant type and concentration ratio of abrasive to dispersant were determined, and the effect of the selected dispersant on jet polishing performance was validated. The results of the dispersion stability experiment indicated that, in comparison to Na(PO3)6 and polyethylene glycol (PEG), the polishing solution containing 1.0–2.0 wt% phosphoric ester compounds exhibited a more stable dispersion effect (zeta potential < −50 mV) and superior dispersibility, characterized by a smaller average particle size. Furthermore, K9 optical glass was subjected to fixed-point and local polishing using phosphoric ester compounds as the dispersant. The fixed-point polishing experiment revealed that, at a dispersant concentration of 1.0 wt% and an abrasive concentration of 20 wt%, a smooth and symmetrical material removal profile could be achieved. In the local polishing experiment, the reduction rate of the root mean square of the surface roughness (RMS) increased from 54.33% to 82.24%, and the reduction rate of peak-to-valley height difference in surface (PV) increased from 38.84% to 68.97%. In conclusion, the incorporation of a dispersant proves effective in enhancing the dispersion stability of the polishing solution and dispersibility of the abrasive particles, thereby improving the surface quality of the materials in MAWJP.

Exploring the synergistic effect of palladium nanoparticles and highly dispersed transition metals on carbon nitride/super-activated carbon composites for boosting electrocatalytic activity

In the present work, multifunctional electrocatalysts formed by palladium nanoparticles (Pd NPs) loaded on Fe or Cu-containing composite supports, based on carbon nitride (C3N4) and super-activated carbon with a high porosity development (SBET 3180 m2/g, VDR 1.57 cm3/g, and VT 1.65 cm3/g), were synthesised. The presence of Fe or Cu sites favoured the formation of Pd NPs with small average particle size and a very narrow size distribution, which agreed with Density Functional Theory (DFT) calculations showing that the interaction of Pd clusters with C3N4 flakes is weaker than with Cu- or Fe-C3N4 sites. The electroactivity was also dependent on the composition and, as suggested by preliminary DFT calculations, the Pd-Cu catalyst showed lower overpotential for hydrogen evolution reaction (HER) while bifunctional oxygen reduction reaction/ oxygen evolution reaction (ORR/OER) behaviour was superior in Pd-Fe sample. The Pd-Fe electrocatalyst was studied in a zinc-air battery (ZAB) for 10 h, showing a performance similar to a commercial Pt/C + RuO2 catalyst with a high content of precious metal. This study demonstrates the synergistic effect between Pd species and transition metals and shows that transition metals anchored on C3N4-based composite materials promote the electroactivity of Pd NPs in HER, ORR and OER due to the interaction between both species.

Self-motivated photoaging of microplastics by biochar-dissolved organic matter under different pyrolysis temperatures

Dissolved organic matter (DOM) released from biochar (BDOM) can interact with microplastics (MPs) in the environment, inevitably affecting their environmental behaviour. Information regarding the influence of BDOM on MPs during photoaging and associated variations in the MP aging mechanism remains unclear. This study evaluated the effect of BDOM on the aging of polystyrene (PS) MPs. The results showed that among three pyrolysis temperatures, low-temperature BDOM significantly enhanced the photoaging process of PS MPs, with the smallest average particle size and highest carbonyl index value after 15 days of aging under light conditions. The DOM level decreased after 5 days, increased after 5–10 days, and stabilised after 15 d. BDOM accelerates PS MPs aging, leading to more DOM released from PS, which can be transformed into 1O2 via triplet-excited state (3DOM⁎ and 3PS⁎) to further enhance PS MPs aging, resulting in the realisation of the self-accelerated aging process of PS MPs. 1O2 plays a crucial role in the self-motivated accelerated aging process of PS MPs. These findings provide new insights into the effects of the DOM structure and composition on reactive oxygen species generation during MPs aging.

Fabrication of an amino-modified MWCNTs grafted with chlorosulfonated PMIA nanofibrous membrane via electrospinning for efficient high-temperature dust filtration

The development of nanofibrous membrane with exceptional filtration efficiency, excellent mechanical properties, and high-temperature resistance poses a significant challenge in the field of industrial dust removal. Incorporating multi-walled carbon nanotubes (MWCNTs) into poly(m-phenylene isophthalamide) PMIA enhances the mechanical properties of nanofibrous membrane fabricated via electrospinning. However, the application of MWCNTs is limited due to their poor dispersion and self-aggregation in solvents. Herein, amino-modified MWCNTs (MWCNTs-NH2) grafted with chlorosulfonated PMIA (PMIA-SO2Cl) nanofibrous membrane was fabricated via electrospinning. The results demonstrated that the coupling effect of PMIA-SO2Cl and MWCNTs-NH2 significantly enhanced the stability of MWCNTs in the PMIA electrospinning solution, resulting in a more homogeneous dispersion of MWCNTs and a smaller average particle size (D50 = 198.03 nm). The filtration efficiency of the most penetrating particle size (MPPS) and the tensile strength of PMIA-SO2Cl/MWCNTs-NH2 nanofibrous membrane were 99.990 % and 57.514 MPa, respectively. The tensile strength retention rates in 30 wt% H2SO4 and 10 wt% NaOH were 52.56 % and 80.25 %, respectively. The MWCNTs-NH2/PMIA-SO2Cl nanofibrous membrane exhibited significantly enhanced mechanical property, filtration efficiency and high-temperature resistance (approximately 250 °C) compared to the unmodified nanofibrous membranes. This study was instructive for the application of electrospinning nanofibrous membranes in the field of high-temperature dust removal.

PH-Sensitive Acrylic Terpolymers for the Coating of Orally Administered Drugs Used for Colonic Release.

Polymeric coatings are a promising option for the development of delivery systems for orally administered drugs. However, the gastrointestinal conditions to which they are subjected, which include low pH and solubility as well as peristaltic movements, can limit their applications. In this work, different formulations of polymeric coatings were produced using pH-sensitive materials consisting of copolymers of methyl acrylate, methyl methacrylate, and methacrylic acid. The polymers were synthesized by the emulsion polymerization technique, obtaining small average particle sizes (56-190 nm), molecular weights between 200,000 and 400,000 g/mol, and a glass transition temperature above 35 °C, which are suitable for film formation at room temperature. Thus, they were assessed as coatings for hydroxypropyl methylcellulose capsules (HPMC) using the immersion method, showing adequate capacity to protect the capsule at gastric pH (pH 1.2) and dissolve at the simulated intestinal pH (pH= 7.2). In particular, the higher the content of the acidic monomer, the higher the release time of the test molecule contained in the acrylic terpolymer-coated HPMC capsules proposed, which was a curcuminoid derivative due to their bright color and potential medical benefits. In addition, a minimum number of immersions was required for coating the HPMC capsules at high acidic concentrations, which further facilitates the delayed release needed for colonic treatment. However, too high proportions of methacrylic acid may result in cytotoxicity issues. Consequently, a biocompatible formulation containing a proportion of methyl acrylate, methyl methacrylate, and methacrylic acid of 7:3:3 is proposed as the most adequate for colonic release. Thus, by chemically modulating the molar percentages of the acrylic monomers, it was possible to obtain tailored acrylic terpolymer coatings with different characteristics and desired properties in order to modulate the release kinetics of an active substance in a colonic environment.

Synthesis of biphenyl via sustainable Suzuki-Miyaura coupling reaction using mesoporous MCF-supported tin-palladium nanoparticles

The current work presents a novel approach to synthesizing monometallic palladium (Pd) and bimetallic tin-palladium (Sn-Pd) nanoparticles anchored to mesostructured cellular foam silica (MCF). The monometallic catalyst Pd@MCF was prepared by the impregnation method, whereas the bimetallic catalyst Pd@MCF(Sn) was prepared by a green electroless reduction method. Our findings demonstrate that the bimetallic Sn-Pd nanoparticles produced through green electroless reduction exhibit no aggregation or clustering, and possess high and uniform dispersion, smaller average particle size and a narrower distribution of particle size than Pd nanoparticles obtained via impregnation. The synthesis of Pd@MCF(Sn) used tin as one of the metallic components of the catalyst and also as a reducing agent rather than conventionally used harmful reducing agents in the electroless reduction method. Remarkably, the introduction of tin into the catalyst system also displays a synergistic effect in the Suzuki-Miyaura coupling (SMC) reaction. The monometallic Pd@MCF catalyst was outperformed by the bimetallic Pd@MCF(Sn) catalyst in terms of catalytic activity for SMC reaction of phenylboronic acid with iodobenzene to produce biphenyl without using toxic reagents, organic solvents, costly phosphine ligands or protective atmospheres. This study also explored and optimized the factors controlling the reaction rate, offering insightful information to improve the production of biphenyl. The reaction follows a second-order kinetics with an apparent activation energy of 8.2 Kcal/mol by applying the Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism. Here, we present a promising strategy for formulating a highly effective and eco-friendly catalyst for sustainable production of biphenyl using Suzuki-Miyaura coupling reaction.

Effect of in situ ultrasonic wave and influent ammonia nitrogen fluctuation on stability of aerobic granular sludge

ABSTRACT This study elucidates the impact of fluctuating influent conditions and in situ ultrasonic wave exposure on the stability of aerobic granular sludge (AGS) in the treatment of simulated wastewater emanating from rare earth mining operations. During a stable influent period spanning from Day 1 to Day 95, the seed granules underwent an initial disintegration followed by a re-granulation phase. The secondary granulation was achieved on Day 80 and Day 40 for the ultrasonic reactor (R1) and the control reactor (R2), respectively. Notably, granules formed in R1 exhibited a more porous structure compared to those generated in R2. Subsequently, when the ammonia nitrogen in the influent oscillated between 100 and 500 mg/L during Days 96-140, both reactors yielded compact and densely structured granules. Nitrogen removal profiles were comparable between the two reactors: the removal efficiencies for ammonia nitrogen and total inorganic nitrogen escalated from 95% and 80%, respectively, during Days 1-95, to 95% and 90%, respectively, post-Day 140. A suite of performance metrics indicated that steady-state granules from R1 outperformed those from R2 across several parameters. Specifically, the nitrification/denitrification rates, and relative abundance of denitrifying bacteria were all higher in granules from R1. Conversely, the relative abundance of nitrifying bacteria was comparable between granules from both reactors. However, R1 granules demonstrated lower sludge concentration and smaller average particle size than their R2 counterparts. In conclusion, the AGS system demonstrated robust resilience to fluctuating ammonia nitrogen, and the application of ultrasonic waves significantly enhanced granular activity while achieving in situ sludge reduction.

Anomalous Temperature-Induced Particle Size Reduction in Manganese Oxide Nanoparticles.

The intricate role of temperature in the structure-property relationship of manganese oxide nanoparticles (Mn3O4 NPs) remains an open question. In this study, we successfully synthesized Mn3O4 NPs using the hydrothermal method with two differing temperatures, namely, 90 and 150 °C. Interestingly, a smaller average particle size is found when Mn3O4 NPs are synthesized at 150 °C compared to 90 °C, corresponding to 46.54 and 63.37 nm, respectively. This was confirmed by the time variation of temperature setting of 150 °C where the size evolution was insignificant, indicating a competing effect of nucleation and growth particles. Under varying NaOH concentrations (2-6 M) at 150 °C, a reduction in the particle size is found at the highest NaOH concentration (6 M). The particle grows slightly, indicating that the growth state is dominant compared to the nucleation state at low concentrations of NaOH. This finding implies that the high nucleation rate originates from the excessive monomer supply in the high-temperature reaction. In terms of crystallinity order, the structural arrangement of Mn3O4 NPs (150 °C) is largely decreased; this is likely due to a facile redox shift to the higher oxidation state of manganese. In addition, the higher ratio of adsorbed oxygen and lattice oxygen in Mn3O4 NPs at 150 °C is indirectly due to the higher oxygen vacancy occupancies, which supported the crystallinity decrease. Our findings provide a new perspective on manganese oxide formation in hydrothermal systems.

Preparation of surface modified nano-hydrotalcite and its applicaiton as a flow improver for crude oil

The poor fluidity of crude oil under low-temperature is one of the key issues affecting crude oil extraction and transportation, which requires a large amount of chemicals or energy. In order to solve this problem, anionic surfactants modified hydrotalcite was prepared in this study, its performance as flow improver was investigated, and the mechanism of improving the flowability of crude oil caused by the interaction between modified hydrotalcite and wax and resin in crude oil was explored. Anionic surfactant modified hydrotalcite has a high viscosity reduction effect on crude oil, and sodium dodecyl sulfate modified hydrotalcite (12S-MNH) has the most significant effect on the viscosity of poplar oil sample (YL). Further research was conducted on the viscosity reducing effect of 12S-MNH can reduce the viscosity of YL crude oil by 96.6% (31 °C) and depress the pour point by 14.0 °C at most. The modification of hydrotalcite was characterized by Fourier Infrared (FTIR), zeta potential particle size analysis, scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffraction (XRD) and contact angle, which confirms the modification of hydrotalcite by sodium lauryl sulphate can prepare surface hydrophobic nanoparticle with smaller average particle size. Combined with DSC analysis and optical microscopy analysis of oil samples added with 12S-MNH, the mechanism of 12S-MNH on viscosity and pour point of crude oil was discussed.

Microfluidic assisted preparation of soybean hydrolyzed protein-curcumin nanocomplexes: Evaluation of structure, functional properties, and interaction mechanism

The instability and low bioavailability of curcumin are the main reasons that limit its application. In this study, soy protein hydrolysate was used as a carrier to prepare soy hydrolysate curcumin nanocomposites assisted by microfluidization to improve the practical application of curcumin. Preparation of nanocomplexes through microfluidization increased the stability, intestinal targeting and bioavailability of curcumin (74 %). The nanocomposite exhibits high encapsulation efficiency (98 %) and loading capacity (10 mg/g), as well as smaller average particle size (100 nm) and polydispersity index (0.25) and good oxidation resistance. In addition, Fourier transform infrared spectroscopy and fluorescence spectroscopy showed that curcumin and soy protein hydrolysate were combined mainly through hydrophobic interactions and hydrogen bonds. The introduction of curcumin changed the secondary structure of hydrolysate. This study provides a new method to increase the stability and bioavailability of curcumin, and provide a new strategy for the application of curcumin and soy protein in related foods and functional beverages.

Effect of different concentrations of gellan gum with/without 0.50% basil essential oil on the physicochemical properties of gellan gum-rice bran oil coating emulsions and their application in egg preservation.

This work investigated the effects of different concentrations (0.10%, 0.15% or 0.20%, w/v) of gellan gum (GG) with/without 0.50% (v/v) basil essential oil (BEO) on physicochemical properties of gellan gum-rice bran oil (GG-RBO) emulsions. The results showed that GG-RBO emulsions with 0.15% or 0.20% GG were more stable than GG-RBO emulsion with 0.10% GG (as evidenced by higher apparent viscosity and absolute zeta potential, but smaller average particle size and lower turbidity), thus displaying better coating performances (as evidenced by bigger contact angle but lower moisture content). The presence of BEO further improved their stability and coating performances. Coating with GG-BRO or GG-RBO-BEO emulsion with 0.15% GG significantly delayed the increase in weight loss, and the decrease in haugh unit, yolk index and albumen pH of eggs during 42days storage; moreover, GG-RBO-BEO emulsion caused lower total aerobic plate count. Therefore, GG-RBO, especially GG-RBO-BEO emulsion has potential in egg preservation.

Screen-Printing of NiO-ScSZ on YSZ Substrate Using Solid-State Reaction and Glycine-Nitrate Process Precursors for Solid Oxide Electrochemical Cells

Solid oxide electrochemical cells (SOCs) consisting of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are widely studied for the development of high-efficiency energy generation and storage devices. To investigate the effect of precursor particle size on the microstructural and morphological properties of the electrode, glycine nitrate process and solid-state reaction ball-milling were utilized as synthesis methods for Nickel oxide-scandia stabilized zirconia (NiO-ScSZ) powders. The synthesized powders were then screen-printed on commercial YSZ solid electrolyte substrates. The structure and morphology of the sintered electrodes were investigated. Particle size analysis (PSA) revealed that NiO-ScSZ precursor powders obtained from GNP ball-milled had a smaller average particle size than solid-state reaction ball-milled powders. For the sintered NiO-ScSZ films, cubic structures of both NiO and ScSZ have been observed from the X-ray diffraction (XRD) patterns. A better porous morphology with less agglomeration and better dispersion of NiO and ScSZ phases was revealed by the scanning electron microscopy (SEM) micrographs and elemental mapping for the GNP-ball-milled synthesized powders.

In situ self-assembly preparation and characterization of CaO–ZrO2 nanopowders under vacuum

CaO–ZrO2 nanocomposite powders were prepared by in situ self-assembly method under vacuum. The effects of calcium oxide content on the physical phase composition and microscopic morphology of the as-prepared nanopowders were investigated. The results showed that the content of the tetragonal phase in the powders gradually increased with increasing calcium oxide content. When the calcium oxide content reached 10 wt%, the prepared CaO–ZrO2 nanopowders were a pure tetragonal phase with good dispersion and average particle size about 57 nm. In comparison to the situation in air, the amorphous carbon particles formed by the pyrolysis of organic matter under vacuum were evenly distributed on the surface of the nanocomposite particles or between them. In this way, direct contact of the nanoparticles was avoided, thus inhibiting their rapid growth at high temperatures and facilitating the formation of fine grains with high surface energy. The preliminary results indicated that the smaller average particle size and narrower particle size distribution of the nanocomposite powders prepared in vacuum were significantly beneficial for improving the bending strength of the nanoceramic products compared to that in air. It is expected to provide valuable information for further optimization of the controllable preparation of high-quality nanoceramic powders.

Synthesis of sulfur-chlorine-doped fluorescent carbon quantum dots from leachate membrane concentrate as a selective probe for Pd2+ detection

In this work, humic acid-based sulfur-chlorine-doped carbon quantum dots (L-CQDs) were synthesized by using a polyethylene glycol (PEG)-assisted hydrothermal technique using landfill leachate concentrate (LLC) as a carbon source. The prepared L-CQDs contain many oxygen-containing functional groups on the surface with a small average particle size of 4–6 nm, resulting in excellent hydrophilicity and dispensability. The three-dimensional fluorescence spectrum shows that the characteristic peak for humic acid for LLC is redshifted after adding PEG as an inactivator, indicating that L-CQDs are synthesized by PEG encapsulation and linkage. The optimum condition for preparing L-CQDs involves the addition of 0.5 g PEG (MW = 2000) into 20 mL LLC and reaction at 200 °C for 5 h, with the optimal L-CQD quantum yield reaching 5.32%. L-CQDs were used to prepare fluorescent nanoprobes for the detection of palladium ions (Pd2+). The obtained nanoprobe shows admirable performance in detecting Pd2+, with high selectivity, excellent water solubility and stability. The fluorescence intensity of the nanoprobe is selectively quenched through static quenching by Pd2+ in the concentration range of 5–40 μmol L−1. This work provides a simple, easy, and fast detection method for Pd2+ and opens up a way for the resource utilization of LLC.