Semi-wet Method Research Articles

Aerosol fluidized bed coating: Exploring the impact of process conditions on process yield, coating coverage and thickness

Aerosol droplets are used to coat fluidized particles in this work. Coating experiments utilizing aerosol droplets (with a mean diameter of around 1μm) were performed under different process conditions to explore their impact on process yield, as well as on coating coverage. Core materials were glass and porous γ-Al2O3, which had mean diameters of 653μm and 610μm, respectively. Sodium benzoate (NaB) solution and silicon dioxide (SiO2) nanosuspension were used as the coating liquid. After sampling, particle pictures were taken by a scanning electron microscope and analyzed using image processing to determine the coating coverage. To simulate the coating process and determine, for each experiment, a factor for preferential deposition on already occupied positions, Monte Carlo simulations were used. Also, some particles were cut in the middle to measure coating layer thickness. Intraparticle coating thickness distribution from Monte Carlo simulations coarsely matches the measured thickness from cut particles. Results show that the process yield, coating coverage, and preference factor are affected by experimental conditions such as expanded bed height, fluidization air temperature, atomizing pressure, the number of aerosol inlets, as well as the surface potential of core particles. This study is first to examine the impact of surface charge of different core materials on droplet deposition. In an experiment with SiO2 nanosuspension, γ-Al2O3 cores could be coated quite uniformly with SiO2 nanoparticles with a layer thickness of ca. 1.1μm. This shows the potential of aerosol droplet deposition as a novel semi-wet method for coating large particles with nanoparticles without using any binders.

Semi-wet synthesis of high-performance Li1.6Mn1.6O4 for selective lithium extraction from Salt Lakes Brine

Among the manganese-based lithium-ion sieves, Li1.6Mn1.6O4 has a high theoretical lithium adsorption capacity as a spinel ion sieve material. Small particle size orthogonal phase purity LiMnO2 powders were prepared by a semi-wet method and calcined in air at 400 °C to obtain Li1.6Mn1.6O4 a lithium-ion sieve precursor. The synergistic effects of oxygen atmosphere, heat treatment conditions and lithium/manganese molar ratio on the crystal structure of LiMnO2 and the lithium adsorption/desorption characteristics of Li1.6Mn1.6O4 were comprehensively investigated with XRD, SEM, TEM, XPS, Raman, DTA-TG and capacity retention study. Notably, when the initial lithium/manganese molar ratio was set at 1.1, and the sample underwent a calcination at 120 °C for 48 h under carefully controlled deoxygenation conditions, we observed the exclusive presence of the desired orthorhombic phase in the LiMnO2 sample. In contrast, when the synthesis conditions deviated from the optimized parameters led to the presence of the monoclinic phase of Li2MnO3. This highlights the sensitivity of Li1.6Mn1.6O4 properties to the synthesis conditions. The results of adsorption-desorption cycles show that the ion sieve Li1.6Mn1.6O4 prepared by heat treatment of ordered o-LiMnO2 is more stable, the structural stability of Li1.6Mn1.6O4 were characterized by high-temperature in-situ XRD experiments during heating from 30 to 800 °C. The equilibrium adsorption capacity was 34 mg g−1 in Qarhan Salt Lake brine at 10th cycle, and a remarkably low Mn dissolution loss rate of 0.6 %. The results have significant potential to advance the development of high-performance adsorbent in the Li-Mn-O system and contribute to the advances in lithium separation technology.

Studies on Impedance and Dielectric Properties of Bi2/3Cu3Ti4−xSixO12 (x = 0.05 and 0.1) Ceramics Synthesized by the Semi-wet Method

Studies on Impedance and Dielectric Properties of Bi2/3Cu3Ti4−xSixO12 (x = 0.05 and 0.1) Ceramics Synthesized by the Semi-wet Method

The effect of several postharvest processing on the quality of Robusta Coffee (Coffea canephora)

Postharvest processing, especially in picking, is an essential factor affecting the quality of Robusta coffee (Coffea canephora). This study was aimed to compare the effect of Postharvest processing on the quality of Robusta coffee. The Postharvest methods used in this research were the farmer’s metods, natural process, semi-wet, and wet methods. The observed parameters in this study were physical quality, caffeine content and chlorogenic acid content. The results showed that the physical quality of the farmer’s process, the dirt content exceeded 0.5%, had black seeds, cracked black, cocoa beans, cracked seeds, and hollow seeds which were higher than SNI (Indonesian National Standard) with quality number four based on the defect value. While the quality of the natural, semi-wet and wet methods was in accordance with SNI with quality number two. The results of further testing for the farmer method obtained caffeine content of 1.80% and chlorogenic acid content of 1.00%, natural method of 1.79 % caffeine and chlorogenic acid of 1.32%, the semi-wet method caffeine of 1.92% and chlorogenic acid of 1.28 %, wet method of the caffeine of 1.83% and chlorogenic acid of 1.25%. This shows that the processing with the lowest quality is shown in the processing method of farmers.

POTENCY OF YEAST AS A BIOCONTROL AGENT OF OCHRATOXIN A-PRODUCING FUNGI AND ITS EFFECT ON ARABICA COFFEE TASTE

Biocontrol agents can be used to control mycotoxigenic fungi, which include different species of yeast. The objectives of this research were to select yeast isolates that can inhibit the growth of ochratoxin A (OTA)-producing fungi (Aspergillus ochraceus BIO 37310) and to increase the taste of Arabica coffee processed using wet and semi-wet methods. Twenty-two yeast isolates (KA, KA2, KB, KB2, KC, KD, Endomyces decipiens BIO 131215, E. fibuliger BIO 132216, BIO 132217, BIO 13218, BIO 132219, BIO 132220, Candida krusei (= Issatchenkia orientalis) BIO 211285, BIO 211286, BIO 211287, BIO 211288, BIO 211289, BIO 211290, BIO 211291, Saccharomyces cerevisiae BIO 341363, BIO 341364, and BIO 341365) were screened for their antagonistic property against A. ochraceus BIO 37310 in vitro using well (dip) test method. The results showed that C. krusei (BIO 211287, BIO 211288, and BIO 211289) inhibited A. ochraceus BIO 37310. In vivo the highest yeast population was found in coffee beans processed using a semi-wet method inoculated with C. krusei BIO 211288 (46,222 ± 9,576 cfu/g), which was not significantly different from that of the coffee beans inoculated with C. krusei BIO 211287 (36,333 ± 14,000 cfu/g). The three yeast isolates were also able to grow either in coffee beans processed using wet or semi-wet methods inoculated with A. ochraceus BIO 37310 and each yeast isolate. Interaction between the three yeast isolates and A. ochraceus BIO 37310 resulted in E-type interaction, i.e. the fungus was not able to grow anymore, while the yeasts grew further. The total cupping scores of coffee beans inoculated with the three yeast isolates were higher than those of coffee beans uninoculated and inoculated with commercial lactic acid bacteria. The three yeast isolates could be used as biocontrol agents of A. ochraceus BIO 37310 and increase the sensorial quality of coffee beverages.

Physical properties of Sidikalang robusta coffee beans medium roasted from various colors of coffee cherries

The purpose of the present study is to investigate the physical properties of medium roasted Sidikalang robusta coffee beans that originated from various colors of coffee cherries. A semi-wet method has been applied for each coffee cherry with a range of fruit ripeness (green, yellow, orange, bright red and dark red). The physical properties measurements include mass loss, mass density, porosity, and water content. After roasted for medium level, the coffee density is difference for each coffee cherries colors namely 0.42 g/cm3 (green cherries), 0.31 g/cm3 (yellow cherries), 0.40 g/cm3 (orange cherries), 0.34 g/cm3 (bright red cherries), and 0.25 g/cm3 (dark red cherries). The mass declined after medium roasted is 16.82% (green cherries), 17.00% (yellow cherries), 18.70% (orange cherries), 18.32% (bright red cherries) and 16.76% (dark red cherries). The coffee beans porosity difference before and after medium roasted is decreases by 13.56% for green cherries and 16% for yellow cherries and increased by 12.22 (orange cherries), 3.44% (bright red cherries), and 6.88% (dark red cherries). Finally, the water content of coffee beans was 8.38% (green cherries), 9% (yellow and orange cherries), 7.91% (bright red cherries), and 10.83% (dark red cherries). The present study concludes that cherries colors have influenced the coffee bean’s physical properties before and after medium roasting.

Influence of Zn doping on microstructure, dielectric, and electric properties in Bi2/3Cu3Ti4O12 ceramic synthesized by the semi-wet method

Influence of Zn doping on microstructure, dielectric, and electric properties in Bi2/3Cu3Ti4O12 ceramic synthesized by the semi-wet method

KAJIAN PENERAPAN PRODUKSI BERSIH DI AGROINDUSTRI KOPI WULAN, KECAMATAN MAESAN, KABUPATEN BONDOWOSO

Wulan Coffee Agroindustry is one of agroindustries in region of Bondowoso that applies the semi-wet method and it has potential to be certified by Geographical Indications (IG). The wastes of arabica coffee processing at Wulan Coffee Agroindustry is directly thrown to the surrounding environment without being repaired first, because of that, it is worried that can affect human health and the environment. Therefore, further treatment is necessary to reduce the impact of waste pollutions and improve the efficiency of processing by using cleaner production technology. This study aimed to examine the priority alternative of cleaner production at Wulan Coffee Agroindustry. The method used in this study is descriptive quantitative with mass balance analysis, energy balance analysis, feasibility analysis, and priority analysis of cleaner production application using the method of AHP (Analytical Hierarchy Process). The waste management alternative in the Wulan Coffee Agroindustry were coffee pulp waste processing i.e. cascara tea, briquettes, and animal feed, also the waste water of coffee processing as biogas. The cleaner production applied in the Wulan Coffee Agroindustry had alternatives likes coffee green bean, coffee powder, and cascara tea. It was the priority scale to be applied because technically factor and financial factor consist of NPV, IRR, B/C ratio, and PBP were Rp 1.211.88.689; 49%; 6.27, and 0.76 or 9 month. Therefore, the result of AHP analysis using expert choice application showed that cascara tea was the priority alternative of cleaner production application with value of 15,4. Keyword: arabica coffee, assessment, Bondowoso, feasibility analysis, waste utilization

Preparation, microstructure, dielectric and electrical analysis of Fe-modified PZT piezoceramics

PZT-based piezoceramics have been widely explored for electronic device applications. In this study, iron (Fe)-modified PZT abbreviated as Pb1-3x/2 Fex(Zr0.53Ti0.47)O3 ceramics (PFZT) for x ≤ 0.05 were prepared by a semi-wet method. The effects of Fe doping on the crystal structure, surface morphology, dielectric and electrical behavior of PFZT ceramics were investigated systematically. Room temperature XRD patterns show a perovskite structure with a minor pyrochlore phase. FE-SEM demonstrates uniform and dense microstructures. Temperature and frequency-dependent dielectric constant and dielectric loss establish its importance for the purpose of device applications. During the experimentation, it has been shown that PFZT ceramics with x ≤ 0.05 are frequency-dependent in nature, whereas PFZT ceramics for x = 0.04 exhibits improved dielectric properties (er~6045 at Tc~325 °C). The impedance spectroscopy studies show that electrical properties are highly influenced by the grain and grain boundaries.

Studies of sintering temperature on the microstructure, magnetic and dielectric behavior of CaCu3Ti3.5Mn0.5O12 ceramic synthesized by semi-wet route

The CCTMO (CaCu3Ti3.5Mn0.5O12) ceramic has been prepared by using the semi-wet method and sintered at 1223 K, 1323 K, and 1373 K, respectively for 8 h. The XRD, as well as TEM, have been to confirm the phase formation of CCTMO ceramics. The crystalline size of CCTMO was found in the range of 38–70 nm at different sintering temperatures. The route-mean square, as well as average roughness, was occurred by AFM technique 7.55 nm and 9.23 nm, respectively, sintered at 1373 K. The P-E hysteresis loop shows the ferromagnetic behavior of CCTMO at room temperature for all samples. The zero-field cooled (ZFC), field cooled (FC) and Magnetic hysteresis (M-H) curve shows temperature-dependent ferromagnetic behavior of CCTMO ceramic. The dielectric constant (ɛr) at 10 kHz decreases with increasing sintering temperature due to semiconducting grains and insulating boundaries supported by internal barrier layer capacitance modal (IBLC) in Mn-doped CCTO ceramic.

Direct electrocaloric, structural, dielectric, and electric properties of lead-free ferroelectric material Ba0.9Sr0.1Ti1-xSnxO3 synthesized by semi-wet method

By using the semi-wet synthesis method, lead-free ferroelectric materials Ba0.9Sr0.1Ti1-xSnxO3 with x = 0, 0.02, 0.05, and 0.10 (abbreviated as BSTS) were prepared and their structural, electric and electrocaloric properties were investigated. The X-ray diffraction (XRD) patterns show that the samples calcined at 950 °C have well crystallized into perovskite structure suggesting the substitution of Ti4+ by Sn4+ in BST lattice. With increasing content of Sn, the enhancement of the dielectric permittivity was observed for (0 ≤ x ≤ 0.05) and the ferroelectric transition temperature (TC) was found to shift towards the room temperature (TC = 20 °C for x = 0.10). Direct measurements of the electrocaloric effect (ECE) were performed on all samples by using the high-resolution calorimeter. It is found that Ba0.9Sr0.1Ti0.95Sn0.05O3 exhibits a high ECE temperature change of ΔTEC = 0.188 K at an applied electric field of only 7 kV/cm. Impedance spectrum analysis of all the samples performed in the temperature range of 300–360 °C reveals the existence of two relaxation contributions related to the grain and grain boundaries that are well separated in frequency. Activation energies of conduction and relaxation processes were deduced for both contributions in order to determine the conduction mechanism of the studied compositions.

The effect of cobalt-doping on microstructure and dielectric properties of CaCu3Ti4O12 ceramics

Ceramics of CaCu3-xCoxTi4O12 (CCCTO, x = 0, 0.2, 0.4 and 0.6), with cubic lattice structure, were fabricated using a semi-wet method. The dielectric properties of the prepared samples were studied at 1 kHz frequency in the temperature range of 300–600 K, as well as in the frequency range of 50 Hz–200 kHz at room temperature. The results showed that the dielectric constants of the as-prepared samples in the frequency range of 50 Hz–200 kHz, at room temperature, are reasonably high (1.7 × 104 ≤ ε ≤ 6 × 104). It was also found out that the dielectric loss (tanδ) of the prepared samples decreased by increasing the cobalt concentration at low and middle frequencies. The dielectric loss decreased from 0.87 for an undoped sample CaCu3Ti4O12 (CCTO), to 0.15 for a doped sample (CCCTO) with x = 0.6, at 50 Hz frequency. However, the dielectric constant (ε) values for the samples doped with cobalt were found to be higher than that of for the undoped sample. Moreover, the XRD patterns as well as the SEM images and EDX results revealed that the Cu-rich phase (CuO) decreased at the CCTO grain boundaries, while at the same time Co2TiO4 and CaTiO3 phases with good dielectric insulating behavior having been formed at the boundaries. This causes the increase of the resistance at the grain boundaries leading to lower leakage current which in turn results in a decrease of the dielectric loss. These results were confirmed by using the impedance spectroscopy analysis. Our results indicate that the cobalt doped CCTO ceramics can be suggested as good candidates to be used in fabricating microelectronic and memory devices with high dielectric constant and low dielectric loss.

A novel chitosan 3-amino-1,2,4-triazole hybrid: Preparation and its effects on cotton fabric properties

A hybrid of chitosan and 3-amino-1,2,4-triazole was prepared using the semi-wet method, which allows for the adsorption of the triazole molecules on the chitosan surface. Moreover, an easy method for applying this hybrid to cotton fabric was established. The tensional strength, uniformity and compatibility of the hybrid components in forming of a strong film were studied using different variables, including the chitosan 3-amino-1,2,4-triazole ratio, fixation temperature and time. The loading of the hybrid onto the fabric in the absence and presence of cross linker (butane tetra carboxylic acid) was also studied. The best conditions for preparing the hybrid was a 1:4 molar ratio of chitosan to 3-amino-1,2,4-triazole at 60°C for 240min, and those for the application of the hybrid to cotton fabric were a 1:1 molar ratio at 150°C with a 5min curing time. Both hybrid and treated cotton fabrics were characterized using FTIR, SEM, TGA, and DSC as well as the nitrogen content and tensional strength of the treated cotton. Finally, the antibacterial activities of the treated cotton fabric display 100% activity and excellent effects against gram-positive bacteria, Staphylococcus aureus and gram-negative Escherichia coli.

Water Effect on Preparation of Ag/Al2O3 Catalyst for Reduction of NOx by Ethanol

Alumina-supported silver catalysts (Ag/Al2O3) derived from wet impregnation, a semiwet method, and water-free ball-milling were investigated for the selective catalytic reduction of NOx by ethanol. It was found that Ag/Al2O3 catalysts with the highest NOx reduction efficiency can be obtained via wet impregnation and the semiwet method but not by water-free ball milling. To optimize the preparation parameters and discern the effect of water in the production of Ag/Al2O3 catalysts, the resulting series of alumina-supported silver samples were characterized by means of XRD, BET, XAS (XANES and EXAFS), in situ DRIFTS, and NMR. The results indicated that silver species were oxidized and highly dispersed on the large surface area Al2O3 obtained from wet impregnation and the semiwet method. In situ DRIFTS revealed that the vital intermediate enolic species were correspondingly predominant on the surfaces of catalysts prepared by these methods, while the inactive intermediate acetate species were significantly fo...

Preparation of CuCrO2 and the photocatalytic properties of its composites

Delafossite CuCrO2 was prepared with Cr(NO3)3 and Cu(NO3)2 by the semi-wet method via two different routes. The samples were characterized with thermogravimetry-differential scanning calorimetry, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy techniques. It was shown that addition of Cr(OH)3 precipitated with aqueous ammonia solution into aqueous Cu(NO3)2 solution is a suitable route to synthesize CuCrO2. In the calcination process, the precursor transformed into CuCrO2 in the sequence: Cr(OH)3 → CuCrO4 → CuCr2O4 → CuCrO2, as verified by the TG-DSC and XRD results. The composites of CuCrO2-WO3 and CuCrO2-ZnO prepared by the grinding method show higher activity than CuCrO2 in the photocatalytic splitting of water into hydrogen under the irradiation of a high-pressure mercury lamp or a xenon lamp.

DIELECTRIC PROPERTIES OF ULTRAFINE Zn-DOPED CaCu3Ti4O12 CERAMIC

Ultrafine powder of CaCu2.80Zn0.20Ti4O12 ceramic was prepared using a novel semi-wet method. DTA/TG analysis of dry powder gives pre-information about formation of final product around 800°C. The formation of single phase was confirmed by X-ray diffraction analysis. The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm, respectively. Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic. Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

Synthesis and Photocatalylic Activity of SrCu<sub>2</sub>O<sub>2</sub> for Water Decomposition to Hydrogen

P-type semiconductor SrCu2O2 was synthetized by semi-wet method. The precursor was analyzed by TGA and the calcined samples SrCu2O2 were characterized using XRD and SEM. N-P heterogeneous complex CdO/SrCu2O2 and WO3/SrCu2O2 were prepared using equal volume impregnation method. The photocatalylic activity of SrCu2O2, CdO/SrCu2O2, WO3/SrCu2O2, CdO and WO3 under ultraviolet light irradiation was investigated. The experimental results showed that SrCu2O2, CdO and WO3 did not exhibit any activity when they were used alone, but CdO/SrCu2O2 and WO3/SrCu2O2 were efficient photocatalysts for water decomposition to hydrogen. The conclusion could be drawn that the combination of N-type semiconductor and P-type semiconductor is very important for the photocatalysis.

Dielectric properties of lanthanum-doped CaCu 3Ti 4O 12 synthesized by semi-wet route

Effect of La 3+ doping at Ca 2+ site in CaCu 3Ti 4O 12 has been examined. Compositions with x=0.10, 0.20 and 0.30 were synthesized in the system Ca (1−3 x /2)La x Cu 3Ti 4O 12 by semi-wet method. Powder X-ray diffraction confirmed the formation of monophasic compounds. The structure remains cubic similar to CaCu 3Ti 4O 12. Lattice parameter increases slightly with increasing La 3+ concentration. Microstructure has been studied using scanning electron microscopy (SEM). Average grain size is in the range 2–4 μm for various compositions. Energy-dispersive spectrometer (EDS) studies confirm the stoichiometry of the synthesized materials. Dielectric constant, dielectric loss and conductivity of the samples decrease with increasing lanthanum concentrations.

Polysialylated Neuropilin-2 Is Expressed on the Surface of Human Dendritic Cells and Modulates Dendritic Cell-T Lymphocyte Interactions

Polysialic acid (PSA) is a unique linear homopolymer of alpha2,8-linked sialic acid that has been identified as a posttranslational modification on only five mammalian proteins. Studied predominantly on neural cell adhesion molecule (NCAM) during development of the vertebrate nervous system, PSA modulates cell interactions mediated by NCAM and other adhesion molecules. An isoform of NCAM (CD56) on natural killer (NK) cells is the only protein known to be polysialylated in cells of the immune system, yet the function of PSA in NK cells remains unclear. We show here that neuropilin-2 (NRP-2), a receptor for the semaphorin and vascular endothelial growth factor families in neurons and endothelial cells, respectively, is expressed on the surface of human dendritic cells and is polysialylated. Expression of NRP-2 is up-regulated during dendritic cell maturation, coincident with increased expression of ST8Sia IV, one of the key enzymes of PSA biosynthesis, and with the appearance of PSA on the cell surface. PSA on NRP-2 is resistant to digestion with peptide N-glycosidase F but is sensitive to release under alkaline conditions, suggesting that PSA chains are added to O-linked glycans of NRP-2. Removal of polysialic acid from the surface of dendritic cells or binding of NRP-2 with specific IgG promoted dendritic cell-induced activation and proliferation of T lymphocytes. Thus, this newly recognized polysialylated protein on the surface of dendritic cells influences dendritic cell-T lymphocyte interactions through one or more of its distinct extracellular domains.

Phase evolution by thermal treatment of equimolar cobalt–magnesium cordierite glass powders

Abstract The structural evolution with annealing time at temperatures between 900 and 1100 °C of loosely compacted equimolar cobalt–magnesium cordierite glass powder was reported. The glass, with composition MgCoAl4Si5O18, was prepared by melting a glass precursor, previously synthesized by a semiwet method, at 1650 °C. Field emission scanning electron microscopy (FESEM) of isothermally heated glasses at 900 and 950 °C revealed increased phase separation with thermal treatment. X-ray diffraction (XRD) results of these powders indicated that the first crystalline phase formed was μ cobalt-containing cordierite which transformed to α cordierite with longer annealing. At the beginning of the μ to α transformation, mullite and cobalt–magnesium aluminate spinel were detected but on further annealing they disappear. Infrared (IR) spectroscopy after long annealing at 1100 °C showed that some ordering for aluminium and silicon in tetrahedral sites had taken place, indicating some transformation to the orthorhombic crystalline form, β, of cordierite. FESEM examination revealed that the μ-cordierite grew by a dendritic mechanism along the particle surface and that the nucleation and growth of α-cordierite occurs within the μ-cordierite dendrites. Finally, after short annealing at 1100 °C the fully crystallized microstructure developed was α-cordierite with columnar or linear features.