Kinetics of thermal decomposition of ammonium persulfate
01 Mar 1996-Russian Chemical Bulletin (Kluwer Academic Publishers-Plenum Publishers)-Vol. 45, Iss: 3, pp 539-542
TL;DR: In this article, the authors studied the thermal decomposition of ammonium persulfate by calorimetry and Raman spectroscopy and estimated the activation energies of the overall reaction and its individual stages.
Abstract: Kinetics of thermal decomposition of ammonium persulfate was studied by calorimetry and Raman spectroscopy. The values of activation energies of the overall reaction and its individual stages were estimated.
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TL;DR: A hierarchical anode consisting of a nickel–iron hydroxide electrocatalyst layer uniformly coated on a sulfide layer formed on Ni substrate was developed, affording superior catalytic activity and corrosion resistance in seawater electrolysis.
Abstract: Electrolysis of water to generate hydrogen fuel is an attractive renewable energy storage technology. However, grid-scale freshwater electrolysis would put a heavy strain on vital water resources. Developing cheap electrocatalysts and electrodes that can sustain seawater splitting without chloride corrosion could address the water scarcity issue. Here we present a multilayer anode consisting of a nickel–iron hydroxide (NiFe) electrocatalyst layer uniformly coated on a nickel sulfide (NiSx) layer formed on porous Ni foam (NiFe/NiSx-Ni), affording superior catalytic activity and corrosion resistance in solar-driven alkaline seawater electrolysis operating at industrially required current densities (0.4 to 1 A/cm2) over 1,000 h. A continuous, highly oxygen evolution reaction-active NiFe electrocatalyst layer drawing anodic currents toward water oxidation and an in situ-generated polyatomic sulfate and carbonate-rich passivating layers formed in the anode are responsible for chloride repelling and superior corrosion resistance of the salty-water-splitting anode.
399 citations
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...4C) (30), with the peaks around 1,230 cm, 1,440 cm, and 1,590 cm assigned to S–O vibration (31)....
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TL;DR: In this article, a one-pot green procedure for the treatment of cellulosic biomass with ammonium persulfate (APS) was developed for the synthesis of highly crystalline carboxylated nanocrystalline cellulose (NCC-COOH), an emerging nanomaterial with a plethora of diversified applications.
Abstract: A one-pot green procedure for the treatment of cellulosic biomass with ammonium persulfate (APS) was developed for the synthesis of highly crystalline carboxylated nanocrystalline cellulose (NCC–COOH), an emerging nanomaterial with a plethora of diversified applications. Raman spectroscopy proved applicable for monitoring the fate of APS and its two byproducts during the production of NCC–COOH from microcrystalline cellulose (MCC). The two main byproducts were then identified and quantified as ammonium sulfate (AS) and H2SO4 with the latter accounted for 60% of the total sulfate ions in solution. On the basis of such findings, one-step neutralization of H2SO4 and NCC with NH4OH immediately after reaction was implemented for the formation of additional AS, followed by its quantitative recovery by precipitation. This was a very effective and critical step in waste stream management and cost reduction for the large scale production of NCC. In addition, the process resulted in highly crystalline NCC with COO–...
57 citations
TL;DR: In this paper, the analysis of thermal decomposition of selected organic additives, which are commonly used in shaping of ceramic materials by colloidal methods, was performed on an apparatus coupled with a mass spectrometer.
Abstract: The paper presents the analysis of thermal decomposition of selected organic additives, which are commonly used in shaping of ceramic materials by colloidal methods. Shaping of ceramics requires using different additives which then are burned out during sintering process. For this reason, the knowledge about thermal degradation of organics used, as well as decomposition products, seems to be very important from the application point of view. The analyzed substances were as follows: diammonium hydrocitrate, citric acid, ammonium salt of acrylic polymer, l-ascorbic acid, N,N,N′,N′-tetramethylethylenediamine, and ammonium persulfate. The thermal analysis has been done on the apparatus coupled with mass spectrometer what allowed to observe what types of gasses are released to the atmosphere during heating. The obtained results showed important differences in thermal degradation of organic additives. It was possible to determine at what temperature regions harmful gases like N2O, NO2, or SO2 are released from the organics and which additives can be treated as environmentally friendly.
33 citations
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...The thermally activated decomposition of persulfate ion leads to the formation of sulfate radical ion [29], which then can be oxidized to SO2, as shown on MS spectra....
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20 citations
TL;DR: The HNO3-free mixtures might allow to replace KOH/i-propanol and similar alkaline solutions for texturization of monosilicon wafers at room temperature with less surface contamination with significant economic and ecological advantages.
Abstract: The wet-chemical treatment of silicon wafers is an important production step in photovoltaic and semiconductor industries. Solutions containing hydrofluoric acid, ammonium peroxodisulfate, and hydrochloric acid were investigated as novel acidic, NOx-free etching mixtures for texturization and polishing of monocrystalline silicon wafers. Etching rates as well as generated surface morphologies and properties are discussed in terms of the composition of the etching mixture. The solutions were analyzed with Raman and UV/vis spectroscopy as well as ion chromatography (IC). The silicon surfaces were investigated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), diffuse reflection infrared spectroscopy (DRIFT), and X-ray photoelectron spectroscopy (XPS). Surprisingly, pyramidal surface structures were found after etching SiC-slurry as well as diamond wire-sawn monocrystalline Si(100) wafers with hydrochloric acid-rich HF-(NH4)2S2O8-HCl mixtures. Acidic etching solutions are generally not known for anisotropic etching. Thus, the HNO3-free mixtures might allow to replace KOH/i-propanol and similar alkaline solutions for texturization of monosilicon wafers at room temperature with less surface contamination. Besides, common HNO3-based etching mixtures may be replaced by the nitrate-free system, leading to significant economic and ecological advantages.
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01 Jan 1967
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01 Nov 1985
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TL;DR: In this paper, the solid state thermal decomposition of the alkali metal peroxydisulphates M2[S2O8], M = Na, K, Rb, Cs, have been studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and in situ high temperature Raman spectroscopic studies.
Abstract: The solid state thermal decompositions of the alkali metal peroxydisulphates M2[S2O8], M = Na, K, Rb, Cs, have been studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), in situ high temperature Raman spectroscopic studies, and by recording the infrared and Raman spectra of the products formed when the salts are heated to various temperatures. In addition to detecting the exotherm associated with the decomposition of peroxydisulphate to pyrosulphate and the endotherm associated with the fusion of pyrosulphate, the DSC study detected previously unreported solid state phase changes of Cs2[S2O8] and K2[S2O7]. These phase changes are also detectable using Raman spectroscopy. The TGA study indicates the formation of an intermediate in the decomposition of pyrosulphate to sulphate, but it is not possible to determine its stoichiometry from the TGA study.
13 citations