Effects Of Preparation Parameters Research Articles

Synthesis optimization and separation mechanism of ZSM-5 zeolite membranes for pervaporation dehydration of organic solvents

Pervaporation (PV), as an energy-efficient mixture separation technology, plays an important role in the chemical industry. In this work, no organic templates were needed to produce high-performance ZSM-5 membranes with an extremely low Si/Al ratio of 3.3 on α-Al2O3 tubular supports using 100 nm nanoseeds. The effects of preparation parameters on the crystalline phase structures, micromorphologies, and PV separation performance of ZSM-5 membranes were comprehensively investigated. The results revealed that the Si/Al ratio of gels significantly affected both the Si/Al ratio and the crystal orientation of the final ZSM-5 membrane. The optimized ZSM-5 membrane with a thickness of 1.8 μm was utilized to dehydrate various organic solvents via PV, and the influence of the operating parameters on PV dehydration performance was evaluated and is described herein. Furthermore, the permeation behaviors of single gases and PV were examined using permeate molecules within a similar size range to reveal the PV mechanism of the ZSM-5 membrane. The results demonstrated that gas permeation followed Knudsen diffusion, while PV permeation was decreased with decreases in the affinity of molecules, revealing an adsorption-diffusion mechanism that dominated PV dehydration through the ZSM-5 membrane. Moreover, the as-synthesized ZSM-5 membrane had good water permselectivity for water/acetone (e.g., total flux = 1.03 kg/(m2 h), α = 307) and for water/isopropanol (e.g., total flux = 1.49 kg/(m2 h), α = 1070) mixtures compared with other membranes reviewed in the literature. The synthesized ZSM-5 membrane also exhibited excellent reproducibility, high stability, and attractive PV separation performance, demonstrating its significant potential application in the PV dehydration of organic solvents.

In-situ spray impregnation of poly(pentamethylene oxamide) onto carbon fibers and their composites

Polyoxamides are a class of polyamides that exhibit superior mechanical, chemical, UV light resistance, and low water absorption properties than their conventional counterparts. In this study, a novel in-situ spray polycondensation techniques is developed and used to impregnate poly (pentamethylene oxamide) (PA52) prepolymer into carbon fibers (CF). The prepolymer impregnated CFs are subjected to solid state polycondensation to increase the molecular of PA52 resin thus obtain prepregs for fabrication of carbon fiber reinforced polyoxamide composites. The effects of preparation parameters on the mechanical properties of PA52/CF composites are studied and reported. The results showed that, PA52/CF composites prepared at molding temperature of 325°C, pressure of 3.0 MPa, and time of 10 min exhibits good tensile strength at break, flexural strength, and interlaminar shear strength (ILSS) of 435 MPa, 364 MPa, and 51 MPa, respectively. SEM results suggest good adhesion between the PA52 and CF which is supported by the high storage modulus results obtained from dynamic mechanical analysis (DMA) results, depicting the potential of in-situ spray impregnation in preparation of carbon fiber reinforced polyoxamide composites.

Preparation of morph-genetic aluminum-doped calcium oxide templated from cotton and the calcium looping performance for energy storage in the presence of steam

Calcium looping (CaL), which can be combined with concentrated solar power (CSP) plants, is considered a promising technology for energy storage. To overcome the deactivation of calcium based materials with increasing cycles, a novel morph-genetic aluminum doped calcium oxide was prepared by a biomass template method using limestone, aluminum nitrate and cotton as raw materials. The effects of preparation parameters and heat storage conditions (especially in presence of steam) on the energy storage performance were studied. The results showed that the hollow tubular structure of the biomass template was preserved in the synthesized material and stabilized by the support of Ca12Al14O33. The presence of the hollow microtubular structure resulted in an increased pore volume of the synthesized materials and a change of the pore distribution, promoting the diffusion of CO2. This phenomenon also explained the superior performance of the synthesized material in terms of the apparent kinetic properties and resistance to sintering. The optimal synthesized material had a high energy storage density and carbonation fraction, which were more than three times those of limestone. The presence of steam during calcination served to reduce the calcination temperature and mitigate the sintering effect of CaO. An optimization route combining solar steam system and CaL-CSP system was proposed based on the positive effect of steam, which was promising for high-efficiency energy storage.

Ball-milled sulfide iron-copper bimetals based composite permeable materials for Cr (VI) removal: Effects of preparation parameters and kinetics study

Zero-valent iron (ZVI) and modified ZVI have been investigated extensively for groundwater remediation. However, ZVI based powder was difficult to be applied directly as permeable reactive barrier (PRB) materials due to their low water permeability and usage rate. In this study, sulfide iron-copper bimetal was prepared by ball milling, which is environment-friendly without second contamination. The optimal preparation parameters of sulfide iron-copper bimetal for Cr(VI) removal were determined (Cu/Fe ratio (w/w), 0.018; FeS/Fe ratio (w/w), 0.1213; ball milling speed, 450 rpm; ball milling time, 5 h). A composite permeable material was prepared by sintering a mixture of sulfide iron-copper bimetal, sludge, and kaolin. The parameters for composite permeable material preparation including sludge content and particle size, and sintering time were optimized, which were 60%, 60–75 mesh, and 4 h, respectively. The optimal composite permeable material was characterized by SEM-EDS, XRD, and FTIR. The results demonstrated preparation parameters can affect the hydraulic conductivity and hardness of composite permeable material. High sludge content, small particles size, and moderate sintering time resulted in high permeability of composite permeable material and were beneficial for Cr(VI) removal. The dominant Cr(VI) removal mechanism was reduction, and the reaction followed pseudo-first order kinetics. Conversely, low sludge content and large particle size, and long sintering time lead to low permeability of composite permeable material. Chromate removal was mainly by chemisorption following pseudo-second order kinetics. The hydraulic conductivity and hardness of the optimal composite permeable material achieved 1.732 cm/s and 50, respectively. The results of column experiments indicated that its Cr(VI) removal capacity was 0.54 mg/g, 0.39 mg/g and 0.29 mg/g at pH 5, 7 and 9, respectively. The ratio of Cr(VI) to Cr(III) on composite permeable material surface was similar under acidic and alkaline conditions. This study will provide an effective reactive material of PRB for field application.

Preparation and Application of Fe-Al-SiO2 Poly-Coagulants for Removing Microcystis aeruginosa from Water

Novel Fe-Al-SiO2 (FAS) poly-coagulants were prepared by the ball milling method using ferrous sulfate, aluminum sulfate, hydrophobic silica, and sodium carbonate as raw materials. The optimal preparation conditions and effects of preparation parameters on removal efficiencies were obtained by Response Surface Methodology (RSM) and Analysis of Variance (ANOVA). Removal efficiencies were investigated by employing FAS as the poly-coagulant for algae-laden water. Furthermore, obtained FAS samples were characterized by SEM, FTIR, XRD, and TGA. Results showed that the optimal preparation conditions were n(Fe):n(Al) of 2:1, m(Si):m(Fe+Al) of 1:2, and n(CO32−):n(Fe+Al) of 1.75:1, and the most significant influencing factor was n(CO32−):n(Fe+Al). FAS13 prepared under the above condition had the highest coagulation efficiency for simulated algae-laden water. Removal efficiencies for OD680, TP, and residual Al and Fe concentrations were 92.86%, 90.55%, 0.142 mg/L, and 0.074 mg/L, respectively. Nano-sized spherical particles, excellent thermal stability, and functional groups such as Al–O–Si, Fe–O–Si, and Fe–OH, corresponding to Al2Si2O5(OH)4, Fe7Si8O22(OH)2, and Fe2(OH)2CO3, were observed in FAS13. The coagulation performance of FAS13 was splendid when applied in real algae-laden water. The removal rates of TP, OD680, turbidity, and Chl-α were above 93.87%. The residual Al concentration was at the range of 0.057–0.128 mg/L.

Effects of Preparation Parameters on the Structural and Morphologic Properties of SnO2-Sb Coatings

Sb-doped SnO2 (SnO2-Sb) coatings show superiority in degrading toxic and refractory organic pollutants. SnO2-Sb coatings can be prepared by oxidizing electrodeposited Sn-Sb coatings through an annealing process. The properties and structure of SnO2-Sb coatings can be tailored by adjusting the preparation parameters. This study examines the effects of crucial preparation parameters on the performance of SnO2-Sb coatings, with the aim of enhancing their properties.Determining the coatings’ cross-sectional and surface characteristics was accomplished using various characterization techniques. A thorough investigation of the prepared samples’ phase and element components was also carried out. Based on the findings, the surface roughness of the prepared Sn-Sb precoating changed with increasing current density, yet the primary surface features of the SnO2-Sb coatings were hardly altered by the annealing process. Without lowering the coating thickness, the appropriate current density of 30 mA/cm2 produced a rough and active coating surface. Our study’s proper annealing temperature of 600 °C transformed Sn-Sb precoating into SnO2-Sb coating and achieved excellent coating quality.While changes in the Sb content affected the morphology of the prepared SnO2-Sb coatings, the mixed oxide coatings’ cassiterite SnO2 phase was unaffected. These results may provide insights into the optimized use of SnO2-Sb coatings in various applications.

Fabrication of Black Silicon Microneedle Arrays for High Drug Loading.

Silicon microneedle (Si-MN) systems are a promising strategy for transdermal drug delivery due to their minimal invasiveness and ease of processing and application. Traditional Si-MN arrays are usually fabricated by using micro-electro-mechanical system (MEMS) processes, which are expensive and not suitable for large-scale manufacturing and applications. In addition, Si-MNs have a smooth surface, making it difficult for them to achieve high-dose drug delivery. Herein, we demonstrate a solid strategy to prepare a novel black silicon microneedle (BSi-MN) patch with ultra-hydrophilic surfaces for high drug loading. The proposed strategy consists of a simple fabrication of plain Si-MNs and a subsequent fabrication of black silicon nanowires. First, plain Si-MNs were prepared via a simple method consisting of laser patterning and alkaline etching. The nanowire structures were then prepared on the surfaces of the plain Si-MNs to form the BSi-MNs through Ag-catalyzed chemical etching. The effects of preparation parameters, including Ag+ and HF concentrations during Ag nanoparticle deposition and [HF/(HF + H2O2)] ratio during Ag-catalyzed chemical etching, on the morphology and properties of the BSi-MNs were investigated in detail. The results show that the final prepared BSi-MN patches exhibit an excellent drug loading capability, more than twice that of plain Si-MN patches with the same area, while maintaining comparable mechanical properties for practical skin piercing applications. Moreover, the BSi-MNs exhibit a certain antimicrobial activity that is expected to prevent bacterial growth and disinfect the affected area when applied to the skin.

Molecular dynamics study of the effect of substrate temperature on the barrier behavior in aluminum oxide Josephson junctions

Although the quality and reliability of Josephson junctions have been improved considerably, the effect of preparation parameters on the structure and nanochemical properties of the barrier layer remains elusive. Here, we use molecular dynamics to study the relationship between the structure and morphology of tunnel barriers and the substrate temperature. We find that substrate temperature affects the atomic arrangement of the barrier, especially in the lower interface region. We also confirm the importance of the lower interface for studying the properties of Josephson junctions and the disordered properties of aluminum oxidation. This work will improve the Josephson junction physical vapor deposition process and lead to the development of a lower noise and more reliable quantum computer.

Preparation of magnetic biochar and its catalytic role in degradation of Cu-EDTA by heterogeneous Fenton reaction.

In this study, magnetic biochar (Fe-BC) was synthesized from phoenix tree leaves and FeSO4·7H2O by impregnation-pyrolysis method, and was used to activate H2O2 to degrade Cu-EDTA. The effects of preparation parameters on the degradation of Cu-EDTA by Fe-BC/H2O2 system were investigated by degradation experiments and characterization methods (SEM, BET, FTIR, XRD and XPS). The results showed that the magnetic biochar prepared under the pyrolysis temperature of 400 °C, pyrolysis time of 3 h and iron content of 3 wt% had the best catalytic activity. Within 120 min, the breaking efficiency of Cu-EDTA binding, precipitation efficiency of Cu2+ and removal efficiency of TOC could reach 78.48, 71.65 and 46.54% at the conditions of adding 1.0 g/L magnetic biochar and 25 mM H2O2 and the iron dissolution was only 0.32 mg/L. The characterization results and comparison experiments demonstrated that the catalytic effect of magnetic biochar not only depends on the transfer of electrons to H2O2 by the loaded iron oxides, but also the active oxygen functional groups (OFGs) and persistent free radicals (PFRs) contained on the surface can transfer electrons to H2O2 or even dissolved oxygen to produce an amount of hydroxyl radicals (·OH) and superoxide anion radicals (O2·-).

Preparation of copper-based biochar adsorbent with outstanding H2S adsorption capacity and study on H2S removal

In this study, a H2S adsorbent with outstanding adsorption capacity and low cost based on the hybrid of biochar and copper was prepared for the removal of gaseous H2S. The effects of preparation parameters and process parameters on desulfurization performance on the developed adsorbent, and the mechanism and kinetics of H2S removal were studied systematically. The regeneration performance of Cu2.56WRS300 adsorbent after H2S adsorption and its mercury removal performance after deactivation were also tested. The results show that although copper loading is not conducive to the development of physical structure of the adsorbent, it promotes the formation of a large number of copper oxide adsorption sites on surface of the adsorbent, which greatly increasing H2S adsorption capacity. Under the optimized tested conditions, the best H2S adsorption capacity on the Cu2.56WRS300 adsorbent is up to 1191.1 mg/g, which is far more than most similar adsorbents. The chemisorption are the decisive step of the H2S adsorption process. The inactivated Cu2.56WRS300 adsorbent shows good regeneration ability and better Hg0 removal performance than commercial activated carbon. This study provides a new idea for the development of cost-effective H2S adsorbent.

Structural Aspects of Materials in Optimization of Fuel Cell Electrodes.

Today's energy problems, caused by the irrational consumption of fossil fuels and, as a result, terrible environmental consequences, require the global population to quickly introduce clean energy sources. Electrochemical power sources, which include the fuel cell, provide the technological basis for electrical energy production. While proton exchange membrane fuel cells (PEMFC) rely on platinum based catalysts, obtaining stable and earth abundant catalytic materials for the oxygen reduction reaction (ORR) is an important step towards large scale integration. Our work focusses on FeNC noble-metal free catalysts in PEMFC conditions. The reaction conditions are much more complex in comparison to half cells, as transport processes and e.g. carbon oxidation affect the performance data. Thus, it turns out to be extremely difficult to determine the most important factors affecting the catalytic activity and stability of the material and to optimize the structure of the membrane-electrode assembly as several factors are overlaying each other: For example, the pyrolysis temperature affects the surface area, degree of graphitization and iron-related composition as well as extent of surface functional groups [1]. The metal loading, pyrolysis temperature and a use of possible precursor templates effects the structure, surface area as well as ORR activity and selectivity of catalysts [2], [3].In our recent work, it was shown that in contrast to the electrochemical characteristics observed in rotating disc electrode (RDE) measurements, the best performing catalyst was prepared at the highest investigated temperature for both FC activity and stability [1]. In contrast, the dwell time had only a limited impact at low pyrolysis temperature, whereas a variation from 30 min to 90 min gave significant destruction of molecular FeNx moieties for the high temperature pyrolysis. [1]To gain further insights on the effect of preparation parameters on FC performance and in specific stability, we coupled a quadrupole mas-spectrometer to the cathode exhaust to follow possible release of CO2 depending on the applied conditions. The data are interpreted together with the structural characterization of the materials. We will discuss how the dwell time and pyrolysis temperature effected on morphology changes of the catalyst and to what extent this impacts the FC activity and short-term stability.AcknowledgementsA.O. would like to thank you the TU Darmstadt for the Future talent scholarship, UIK gratefully acknowledges financial support by the BMBF young research group StRedO (03XP0092), and we thank Y. Ostroverkh, and Z. L. Müller, for the consultation and assistance with the fuel cell setup.[1] J. Scharf, M. Kübler, V. Gridin, W.D.Z. Wallace, L. Ni, S.D. Paul, U.I. Kramm, Relation between half-cell and fuel cell activity and stability of FeNC catalysts for the oxygen reduction reaction, (2022) SusMat, accepted (doi: 10.1002/sus2.84).[2] P.Theis, W.D. Z. Wallace, L. Ni, M. Kübler, A. Schlander, R. W. Stark, N. Weidler, M, Gallei, U. I. Kramm. Systematic study of precursor effects on structure and oxygen reaction activity of FeNC catalysts, (2021) Philos. Trans. Royal Soc. A PHILOS T R SOC A, (doi: 10.6084/m9.figshare.c.5506708).[3] P. Boldrin, D. Malko, A. Mehmood, U. I. Kramm, S. Wagner, S. Paul, N. Weidler, A. Kucernak. Deactivation, reactivation and super-activation of Fe-N/C oxygen reduction electrocatalysts: Gas sorption, physical and electrochemical investigation using NO and O2., (2021) Appl. Catal. B, Vol. 292, 120169, (doi: 10.1016/j.apcatb.2021.120169).

Effect of preparation parameters on properties of metakaolin-based geopolymer activated by silica fume- sodium hydroxide alkaline blend

In this study, metakaolin was activated using an alkali activator containing silica fume and sodium hydroxide to obtain a metakaolin-based geopolymer. Silica fume was used to partially substitute metakaolin (0 to 25 wt% of metakaolin). Enough reactive silica was introduced using silica fume, which was added to sodium hydroxide solution before being mixed with metakaolin. The Na2O/Al2O3 molar ratio was adjusted in the range of 0.8 to 1.2 by varying the sodium hydroxide concentration, and the geopolymer paste specimens were cured at three different temperatures, i.e., 60, 70, and 80 °C. The specimens were analyzed by X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscopy, mercury intrusion porosimetry, energy dispersion spectroscopy, and compressive strength measurement techniques. The results revealed that geopolymer-zeolite composites were produced in the presence of less than 10 wt% silica fume and Na2O/Al2O3 molar ratios higher than 1. When the SF content was raised above 10%, a significant increase in the formation of the geopolymer phase developed, resulting in increased compressive strength. Mercury intrusion porosimetry measurements show the geopolymer composite with 10 wt% silica fume and a Na2O/Al2O3 molar ratio of 1. It contained large zeolite crystals embedded in its macroporous geopolymer matrix and had a pore size of 400 nm. Maximum compressive strength of 33 MPa was achieved at 15 wt% silica fume, Na2O/Al2O3 molar ratio of 1, and curing temperature of 70 °C.

Development of Composite Thin-Film Nanofiltration Membranes Based on Polyethersulfone for Water Purification

The development of thin-film composite membranes has gained more importance as they exhibit higher permeability, higher solute rejection and improved antifouling behavior. The incorporation of hydrophilic nanomaterials within the composite thin film has reported to effectively increase the hydrophilicity and improve the membrane performance. In this study novel thin-film composite nanofiltration membranes were prepared by interfacial polymerization of trimesoyl chloride, polyvinylpyrolidone (PVP) and montmorillonite (MMT) composite on the porous polyethersulfone membrane. The effect of preparation parameters was studied as; reaction time, PVP concentration and MMT content. The properties of the prepared composite thin-film membranes were analyzed in terms of their chemical structure, surface morphological features, pure water contact angle, zeta potential, pure water permeation flux (PWP) and solutes rejection. The prepared composite thin-film membranes showed smoother surfaces, different surfaces functionality and amphoteric surfaces with points of zero charge at pH 7–7.5. The PWP was found to increase with increasing MMT content up to 0.10 wt%. The rejection of crystal violet dye (CV) was studied using the prepared membranes. The membrane with 0.5% PVP, 0.10% MMT and 6 min reaction time showed PWP of 18.1 L/m2 h bar and CV rejection of 80.01%. The rejection of Na2SO4 and MgCl2 increased with increasing MMT content and reached 96% and 35.4%, respectively. The steady state flux was decreased by 5% with increasing MMT content from 0.10 to 0.12 wt% indicating improved antifouling behavior with MMT.

Enhanced fine flake graphite flotation and reduced carbon emission by a novel water-in-oil kerosene emulsion

Kerosene is a frequently-used collector in graphite flotation; however, its consumption substantially increases due to its poor dispersibility in water and the depletion of graphite resources. We prepared a novel water-in-oil type kerosene emulsion as a more efficient collector for graphite flotation. The effect of preparation parameters on the emulsion stability was investigated by particle size analysis, stratification test, and electrical conductivity test. The results indicated that particle size played a dominant role in the stability of emulsified kerosene. The smaller emulsified kerosene droplets contribute to a more stable emulsion dispersion. Optical microscope and Cryo-SEM techniques visualized a stable and homogenous emulsion with an average particle size of 1–2 µm. Furthermore, batch flotation and adsorption tests indicated that the emulsified kerosene outperformed pristine kerosene as a collector in fine flake graphite flotation, increasing the flotation recovery by approximately 3%, with 26%− 34% kerosene consumption reduction. Our study provides a valuable pathway for developing emulsified collectors for clean flotation of graphite ores, especially for reducing carbon emission.

Effect of operating variables on functions of sodium alginate granules based on drinking water treatment residues

Drinking water treatment residues (DWTR) have been regarded as a promising adsorbent for phosphorus control. The granulation of DWTR is a crucial step for its application in the filtration system. Traditional granulation processes could not achieve the balance between stable structures and adsorption capacities. Encapsulation of DWTR powders into alginate beads overcame these drawbacks. However, previous studies ignored the effect of preparation parameters on the properties of DWTR particles. In this study, the effects of sodium alginate (SA) concentrations, alginate types, Fe3+ concentrations, and gelation times on structures and mechanical stabilities of DWTR granules were investigated in depth based on their morphologies and pore structures, and compressive strength. The results showed that SA concentrations influenced the viscosity of DWTR-SA solution, and that granulation of DWTR with low SA concentration resulted in incomplete crosslinking, but granulation of DWTR with high SA concentration could change the shape of final granules. 2% SA was chosen as an optimum concentration for DWTR granules preparation. The ratios of M/G in SA affected the microstructures and mechanical strength of resultant granules. The presence of high G-block content in SA resulted in the formation of a dense crosslinking structure, which increased mechanical strength but decreased specific surface area. The morphologies of DWTR granules did not change as Fe3+ concentrations increased, and the granules with excellent mechanical strength were obtained at FeCl3 concentrations of 2% (w/v). The DWTR spheres could maturate quickly and are stable after 4 h. The resulting granular DWTR exhibited a comparable P adsorption capacity (26.89 mg-P/g) to the original powder, which was better than traditional P adsorption materials and pellet DWTR produced by high-temperature calcination. The results should be helpful for engineers to choose the best granulation parameters for their applications.

Effects of preparation parameters on growth and properties of β-Ga2O3 film

The Ga2O3 films are deposited on the Si and quartz substrates by magnetron sputtering, and annealing. The effects of preparation parameters (such as argon–oxygen flow ratio, sputtering power, sputtering time and annealing temperature) on the growth and properties (e.g., surface morphology, crystal structure, optical and electrical properties of the films) are studied by x-ray diffractometer (XRD), scanning electron microscope (SEM), and ultraviolet-visible spectrophotometer (UV-Vis). The results show that the thickness, crystallization quality and surface roughness of the β-Ga2O3 film are influenced by those parameters. All β-Ga2O3films show good optical properties. Moreover, the value of bandgap increases with the enlarge of the percentage of oxygen increasing, and decreases with the increase of sputtering power and annealing temperature, indicating that the bandgap is related to the quality of the film and affected by the number of oxygen vacancy defects. The I–V curves show that the Ohmic behavior between metal and β-Ga2O3 films is obtained at 900 °C. Those results will be helpful for the further research of β-Ga2O3 photoelectric semiconductor.

Factors Influencing the Droplet Size of Asphalt Emulsion during Fabrication

The size distribution of asphalt droplets greatly affects the overall technical properties of asphalt emulsion, while it did not obtain much concern previously. In order to fabricate a good-quality asphalt emulsion with a small droplet size distribution, the effect of preparation parameters on the asphalt droplet size distribution, such as emulsifier dosage, asphalt temperature, shear time, pH value, and soap solution temperature, were systematically studied. All preparation parameters can affect the droplet size distribution of asphalt emulsion as well as the representative droplet diameters for the 10th, 50th and 90th cumulative volume percentile (D10, D50, and D90). The order of preparation parameters are ranked as: emulsifier dosage > temperature of soap solution > pH of soap solution > shear time > asphalt temperature. Therefore, the emulsifier dosage, the temperature and pH of the soap solution should be carefully controlled to obtain asphalt emulsion with good droplet size distribution during fabrication. Compared to D10, the D50 and D90 are more easily affected by the fluctuant preparation parameters, which are recommended to be utilized to evaluate the emulsifying effect of asphalt emulsion and judge the asphalt droplet size distribution.

Re-utilization of Chinese medicinal herbal residue: waste wormwood rod-derived porous carbon as a low-cost adsorbent for methyl orange removal.

A cost-effective approach was applied to prepare porous carbon samples by the simple carbonization of wormwood rod followed by salt activator (NaCl) activation. The effect of preparation parameters on the characteristics of the wormwood rod-based porous carbons (WWRs) were studied. The properties of these samples were investigated by SEM, BET surface area, X-ray diffraction, FT-IR spectra and X-ray photoelectron spectrometer. The prepared WWRs were applied as new adsorbent materials to remove methyl orange (MO). The experimental results indicated that WWR-800 activated at 800 °C possesses the best adsorption performance. Several factors that affected the adsorption property of the system such as the solution pH, dosing of adsorbent, initial dye concentration and ionic strength were examined. In addition, the thermodynamic parameters and kinetic parameters of MO with WWR-800 were studied. The results indicated that the adsorption of MO on WWR-800 was an endothermic process and non-spontaneous under standard conditions. The maximum equilibrium adsorption capacity of MO on WWR-800 was 454.55 mg/g. After five adsorption/desorption cycles, the adsorption capacity of MO on WWR-800 remained at 94%, which indicated that wormwood rod-based porous carbon possessed good reusability.

Nanoporous Membranes Prepared from Homogeneous Lamellar Structure Developed via Biaxial Melt‐Drawing of Ultra‐High Molecular Weight Polyethylene/Normal Molecular Weight Polyethylene Blend Films

AbstractBiaxial melt‐drawing of blend films composed of ultra‐high molecular weight polyethylene and normal molecular weight polyethylene produced a unique network structure consisting of 30‐nm thick homogeneous folded chain crystals. Subsequent biaxial solid‐drawing produced a nanoporous structure covering a large area of the membrane surface (120 mm × 120 mm). Effects of preparation parameters, including annealing and subsequent solid‐drawing, on resultant nanoporous morphology are also testified to achieve the desirable membrane. The higher gas permeability coefficients of the nanoporous membranes indicate that these nanopores are interconnected along the thickness direction. Despite such excellent porosity, the tensile strength reached 30 MPa, which is similar to that for the initial non‐porous film. Consistence of membrane porousness and robustness is highly desirable for various separation applications, including filtration, water purification, dialysis, and lithium‐ion batteries.

Controllable preparation of boron nitride quantum dots with small size and strong blue photoluminescence

As a new type of quantum dots (QDs), boron nitride QDs (BNQDs), show promising potentials in disease diagnosis, fluorescence imaging and bio-sensing due to its good biocompatibility, low cytotoxicity and excellent photoluminescence performance. However, there are still challenges in preparing BNQDs with uniform and small size. In this paper, the BNQDs with uniform and small size have been prepared through a hydrothermal process with the exfoliated hexagonal boron nitride nanosheets (h-BNNSs) as precursor. The as-prepared BNQDs were characterized by transmission electron microscope (TEM), high-resolution TEM, fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis and photoluminescence spectra (PL) for morphology, surface functional groups, element composition and optical properties. The as-prepared BNQDs have uniform particle size distribution with an average lateral size of 1.65 nm, and a PL quantum yield of 2.49 %. In addition, the as-prepared BNQDs exhibit strong blue fluorescence under UV-vis (365 nm) irradiation and nanosecond luminescent decay. Furthermore, the effect of preparation parameters on the fluorescence performance of BNQDs was investigated which provides an optimal condition for the preparation of BNQDs with excellent fluorescence performance. Together with other advantages, such as excellent physical/chemical properties, good biocompatibility and low cytotoxicity, the as-prepared BNQDs have great potentials in medical diagnosis, biosensing, photoelectric devices and other fields in the future.