Dynamic absorption efficiency of paracetamol powder in microwave drying

Zhai, Di; Zhang, Fucheng; Wei, Chu; Shang, Xiaobiao; Chen, Junruo; Liu, Meihong; Peng, Jinhui

doi:10.1515/htmp-2019-0015

Cited by 7 publications

(3 citation statements)

References 26 publications

(30 reference statements)

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“…This thin oxide layer is considered a dielectric ceramic layer [ 29 ] that covers an electrically conductive metallic particle, so those particles are actually similar to a composite material structure. Several studies have investigated microwave heating of metal powders [ 26 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Furthermore, several recent theoretical studies were performed using effective-medium approximation models, where MW heating of electrically conductive powder particles surrounded by insulating oxide layer was investigated [ 33 , 36 , 40 ].…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Mahmoud

2022

Materials

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The native oxide layer that forms on copper (Cu) metal spherical particle surfaces under ambient handling conditions has been shown to have a significant effect on sintering behavior during microwave heating in a previous study, where an abnormal expansion was observed and characterized during sintering of Cu compacts using reducing gases. Because microwave (MW) heating is selective and depends greatly on the dielectric properties of the materials, this thin oxide layer will absorb MW energy easily and can consequently be heated drastically starting from room temperature until the reduction process occurs. In the current study, this oxide ceramic layer was qualitatively and quantitatively characterized using the carrier gas hot extraction (CGHE) method, Auger electron spectroscopy (AES), and a dual-beam focused ion beam (FIB)/scanning electron microscope (SEM) system that combines both FIB and SEM in one single instrument. Two different commercial gas-atomized spherical Cu metal powders with different particle sizes were investigated, where the average oxygen content of the powders was found to be around 0.575 wt% using the CGHE technique. Furthermore, AES spectra along with depth profile measurements were used to qualitatively characterize this oxide layer, with only a rough quantitative thickness approximation due to method limitations and the electron beam reduction effect. For the dual-beam FIB-SEM system, a platinum (Pt) coating was first deposited on the Cu particle surfaces prior to any characterization in order to protect and to preserve the oxide layer from any possible beam-induced reduction. Subsequently, the Pt-coated Cu particles were then cross-sectioned in the middle in situ using an FIB beam, where SEM micrographs of the resulted fresh sections were characterized at a 36° angle stage tilt with four different detector modes. Quantitative thickness characterization of this native oxide layer was successfully achieved using the adapted dual-beam FIB-SEM setup with more accuracy. Overall, the native Cu oxide layer was found to be inhomogeneous over the particles, and its thickness was strongly dependent on particle size. The thickness ranged from around 22–67 nm for Cu powder with a 10 µm average particle size (APS) and around 850–1050 nm for one with less than 149 µm.

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Section: Introductionmentioning

confidence: 99%

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Mahmoud

2022

Materials

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“…Therefore, during the experiment, we will discover that in pure microwave under dry conditions, a surprising number of solid-state bubbles will form on the surface due to the rapid evaporation of water. The polar molecules will be affected by the alternating electromagnetic field when the dielectric material is in an alternating electromagnetic field [20,28],. Because polar molecules' charge distribution is nonuniform and asymmetric, their positive and negative charge centers do not overlap, rotate under the influence of the electromagnetic field, and collide with molecules in random thermal motion within the material, converting microwave energy into heat energy that can be used to heat the object.…”

Section: Mechanical Strength Testmentioning

confidence: 99%

Hydrogel-Crosslinked Microneedles Based on Microwave-Assisted Drying Method

Chen

Zhang

Chen

et al. 2022

Advances in Polymer Technology

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We present a method and several applications for the synthesis of hydrogel-crosslinked microneedle arrays utilizing microwave-assisted drying, ensuring a significant reduction in reaction preparation time while maintaining quality. We demonstrate the feasibility of drying hydrogels using microwaves and thus extend to crosslinked microneedle fabrication. Crosslinking was performed using 1,4-butanediol diglycidyl ether (BDDE) as a crosslinking agent. Infrared spectra of the microneedle arrays were measured with attenuated total reflection-Fourier transform infrared (ATR-FTIR). The surface morphology of the microneedle arrays was observed with scanning electron microscopy (SEM). The microneedle arrays were evaluated in terms of mechanical strength, swelling kinetics, rheological properties, degradation rate, and glucose iontophoresis. The results show that this method can shorten the reaction preparation time by 5 hours, and the prepared crosslinked microneedle array has better crosslinking efficiency, swelling effect, and greater mechanical strength than traditional methods.

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“…Microwave radiation is applied in multiple industrial processes that require a heating source, such as drying, pyrolysis, and catalysis. [1,2] A reason for this variety of applications is the microwave interaction ability with different types of materials at the molecular level. Based on this interaction, materials can be classified in three categories: opaque or conductors, transparent, and absorbers.…”

Section: Introductionmentioning

confidence: 99%

Investigation of charcoal and activated charcoal for microwave absorbers

2022

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The effects of the microwave heating process and the behaviour as absorbent materials of charcoals obtained from Eucalyptus urograndis wood, macauba endocarp, and lignin, in the activated and non-activated forms, were investigated. The dielectric properties were measured with the coaxial probe method, and the values of loss tangent obtained for all the materials characterize them as absorbers. Heating tests were performed with materials in the raw form and also mixed with sand, a transparent material to microwave radiation. A factorial design of experiments was performed, and the effect of microwave power and mass concentration of materials over heating rate was studied. Both factors had a significant and positive influence on the heating rate of the seven analyzed materials. The carbon activation process increased the absorption and heating potential, due to the greater surface area and porosity generated

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Dynamic absorption efficiency of paracetamol powder in microwave drying

Cited by 7 publications

References 26 publications

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Hydrogel-Crosslinked Microneedles Based on Microwave-Assisted Drying Method

Investigation of charcoal and activated charcoal for microwave absorbers

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