Application of microwave heating to the determination of free, combined and total sulphur in rubber

Puacz, Wojciech; Szahun, Wieslaw; Kopras, Mariusz

doi:10.1016/0039-9140(95)01680-5

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…156 Removal of other sulfur species is firstly needed for the extraction of sulfur in OM or kerogen, i.e., water soluble sulfur (WSS), S 0 , CAS, pyrite, and other sulfurbearing minerals. 141,157 The organic sulfur in the barite-free residue is transformed into BaSO 4 or Ag 2 S by Eschka, [158][159][160][161] tube furnace combustion, 162 bomb washing, 163 Raney nickel hydrodesulfurization, 164,165 Kiba reduction, 166 and microwaveassisted digestion [167][168][169] hydrodesulfurization method is rarely used because activating the Raney nickel-aluminum alloy is difficult and deoxygenated water is needed (see Tables S7-S8). [172][173][174] Samples are broken down using H 2 O 2 with microwaves, where sulfur compounds are oxidized to sulfate and collected as BaSO 4 with a 98% recovery rate.…”

Section: Kerogen or Organic Sulfur Extractionmentioning

confidence: 99%

“…Removal of other sulfur species is firstly needed for the extraction of sulfur in OM or kerogen, i.e., water soluble sulfur (WSS), S 0 , CAS, pyrite, and other sulfur‐bearing minerals 141,157 . The organic sulfur in the barite‐free residue is transformed into BaSO 4 or Ag 2 S by Eschka, 158–161 tube furnace combustion, 162 bomb washing, 163 Raney nickel hydrodesulfurization, 164,165 Kiba reduction, 166 and microwave‐assisted digestion 167–169 methods. As to samples containing barite, the residue is digested in 40% NaOH, then boiled with 100% H 2 O 2 repeatedly.…”

Section: Chemical Treatmentmentioning

confidence: 99%

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Procedures from samples to sulfur isotopic data: A review

Zhao,

Guo,

Zhang

et al. 2024

Rapid Comm Mass Spectrometry

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RationaleSulfur isotopes have been widely used to solve some key scientific questions, especially in the last two decades with advanced instruments and analytical schemes. Different sulfur speciation and multiple isotopes analyzed in laboratories worldwide and in situ microanalysis have also been reported in many articles. However, methods of sampling to measurements are multifarious, and occasionally some inaccuracies are present in published papers. Vague methods may mislead newcomers to the field, puzzle readers, or lead to incorrect data‐based correlations.MethodsWe have reviewed multiple methods on sulfur isotopic analyses from the perspectives of sampling, laboratory work, and instrumental analysis in order to help reduce operational inhomogeneity and ensure the fidelity of sulfur isotopic data. We do not deem our proposed solutions as the ultimate standard methods but as a lead‐in to the overall introduction and summary of the current methods used.ResultsIt has been shown that external contamination and transformation of different sulfur species should be avoided during the sampling, pretreatment, storage, and chemical treatment processes. Conversion rates and sulfur isotopic fractionations during sulfur extraction, purification, and conversion processes must be verified by researchers using standard or known samples. The unification of absence of isotopic fractionation is needed during all steps, and long‐term monitoring of standard samples is recommended.ConclusionThis review compiles more details on different methods in sampling, laboratory operation, and measurement of sulfur isotopes, which is beneficial for researchers' better practice in laboratories. Microanalyses and molecular studies are the frontier techniques that compare the bulk sample with the elemental analysis/continuous flow–gas source stable isotope ratio mass spectrometry method, but the latter is widely used. The development of sulfur isotopic measurements will lead to the innovation in scientific issues with sulfur proxies.

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Section: Kerogen or Organic Sulfur Extractionmentioning

confidence: 99%

Section: Chemical Treatmentmentioning

confidence: 99%

Procedures from samples to sulfur isotopic data: A review

Zhao,

Guo,

Zhang

et al. 2024

Rapid Comm Mass Spectrometry

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“…Microwave heating is widely used for processing food [1], chemicals [2], wood [3], rubber [4], and ceramics [5], [6]. This method of heating is faster and more efficient than conventional heating methods because microwaves do not require a medium for heat transfer [7].…”

Section: Introductionmentioning

confidence: 99%

Uniform Microwave Heating via Electromagnetic Coupling Using Zeroth-Order Resonators

TAKAHARA,

MITANI,

SHINOHARA

2024

IEICE Trans. Electron.

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We propose microwave heating via electromagnetic coupling using zeroth-order resonators (ZORs) to extend the uniform heating area. ZORs can generate resonant modes with a wavenumber of 0, which corresponds to an infinite guide wavelength. Under this condition, uniform heating is expected because the resulting standing waves would not have nodes or antinodes. In the design proposed in this paper, two ZORs fabricated on dielectric substrates are arranged to face each other for electromagnetic coupling, and a sample placed between the resonators is heated. A single ZOR was investigated using a 3D electromagnetic simulator, and the resonant frequency and electric field distribution of the simulated ZOR were confirmed to be in good agreement with those of the fabricated ZOR. Simulations of two ZORs facing each other were then conducted to evaluate the performance of the proposed system as a heating apparatus. It was found that a resonator spacing of 25 mm is suitable for uniform heating. Heating simulations of SiC and Al 2 O 3 sheets were performed with the obtained structure. The heating uniformity was evaluated by the width 𝐿 50% over which the power loss distribution exceeds half the maximum value. This evaluation index was equal to 0.397𝜆 0 for SiC and 0.409𝜆 0 for Al 2 O 3 , both of which exceed 𝜆 0 /4, the distance between a neighboring node and antinode of a standing wave, where 𝜆 0 is the free-space wavelength. Therefore, the proposed heating apparatus is effective for uniform microwave heating. Because of the different electrical parameters of the heated materials, SiC can be easily heated, whereas Al 2 O 3 heats little. Finally, heating experiments were performed on each of these materials. Good uniformity in temperature was obtained for both SiC and Al 2 O 3 sheets.

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