scholarly journals Generation of active Co(III) and peroxodiphosphate by synergistic electrocatalytic system with phosphate and the mediator cobalt(II) and its degradation performance

2021 ◽  
Vol 83 (4) ◽  
pp. 841-853
Author(s):  
Dongmei Li ◽  
Wenjie Li ◽  
Quan Zhang ◽  
Yizhi Wang ◽  
Hongyu Lin ◽  
...  
Keyword(s):  
Sulfonic Acid ◽  
Degradation Mechanism ◽  
Degradation Process ◽  
Oxidation Products ◽  
Oxidation Of Co ◽  
Active Oxidation ◽  
Benzene Sulfonic Acid ◽  
Titanium Electrode ◽  
Electrocatalytic Degradation ◽  
Inorganic Substances

Abstract The promising synergistic electrocatalytic system of phosphate (PO43−) with the mediator cobalt(II) (for short E-Co(II)-PO43−) was employed to degrade cationic dye methylene blue (MB). The exploration in the electrocatalytic process revealed that the main intermediate active oxidation products were Co(III), accompanied with hydroxyl radicals and peroxodiphosphates (P2O84−). Their synergistic electrocatalytic degradation rate to MB and total organic carbon (TOC) was up to 100 and 60% in 40 min, respectively, which was 5 times and 2.6 times that in a direct electrocatalytic system, correspondingly. The degradation process of the E-Co(II)-PO43− system on MB started with the bond being broken at the N-C junction of the MB molecule and intermediate active oxidation substances being generated, such as phenothiazine, 2-amino-5-(N-methylformamide) benzene sulfonic acid and N1,N1-dimethyl-1,4 diaminobenzene. Then, the intermediates were degraded into aniline, phenol and benzene sulfonic acid, and eventually decomposed into inorganic substances like CO2 and water. The electrocatalytic degradation mechanism of E-Co(II)-PO43− system on MB was the combination of indirect oxidation of the intermediate oxidants like Co(III), P2O84− and the hydroxyl radical with direct electrocatalysis on the platinum titanium electrode, where the electrocatalytic oxidation of Co(III) was dominant.

scholarly journals Investigation of the β-pinene photooxidation by OH in the atmosphere simulation chamber SAPHIR

2016 ◽  
Author(s):  
Martin Kaminski ◽  
Hendrik Fuchs ◽  
Ismail-Hakki Acir ◽  
Birger Bohn ◽  
Theo Brauers ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Degradation Process ◽  
Product Distribution ◽  
High Reactivity ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Emission Rates ◽  
Photochemical Degradation ◽  
Atmosphere Simulation Chamber ◽  
Simulation Chamber

Abstract. Beside isoprene, monoterpenes are the non-methane volatile organic compounds (VOC) with the highest global emission rates. Due to their high reactivity towards OH, monoterpenes can dominate the radical chemistry of the atmosphere in forested areas. In the present study the photochemical degradation mechanism of β-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR. The focus of this study is on the OH budget in the degradation process. Therefore the SAPHIR chamber was equipped with instrumentation to measure radicals (OH, HO2, RO2), the total OH reactivity, important OH precursors (O3, HONO, HCHO), the parent VOC beta-pinene, its main oxidation products, acetone and nopinone, and photolysis frequencies. All experiments were carried out under low NOx conditions (≤ 2 ppb) and at atmospheric beta-pinene concentrations (≤ 5 ppb) with and without addition of ozone. For the investigation of the OH budget, the OH production and destruction rates were calculated from measured quantities. Within the limits of accuracy of the instruments, the OH budget was balanced in all β-pinene oxidation experiments. However, even though the OH budget was closed, simulation results from the Master Chemical Mechanism 3.2 showed that the OH production and destruction rates were underestimated by the model. The measured OH and HO2 concentrations were underestimated by up to a factor of two whereas the total OH reactivity was slightly overestimated because of the poor reproduction of the measured nopinone by the model by up to a factor of three. A new, theory-derived first-generation product distribution by Vereecken and Peeters was able to reproduce the measured nopinone time series and the total OH reactivity. Nevertheless the measured OH and HO2 concentrations remained underestimated by the numerical simulations. These observations together with the fact that the measured OH budget was closed suggest the existence of unaccounted sources of HO2.

THE SULFURIC ACID SOLVENT SYSTEM: PART VII. SOLUTIONS OF SOME TIN(IV) AND LEAD(IV) COMPOUNDS

1966 ◽  
Vol 44 (10) ◽  
pp. 1197-1202 ◽  
Author(s):  
R. J. Gillespie ◽  
R. Kapoor ◽  
E. A. Robinson
Keyword(s):  
Sulfuric Acid ◽  
Sulfonic Acid ◽  
Solvent System ◽  
Lead Tetraacetate ◽  
Benzene Sulfonic Acid ◽  
Tin Compounds ◽  
Cationic Species ◽  
Stannic Acid ◽  
System Part

Solutions of tetramethyl tin trimethyl tin sulfate, di-n-butyl tin diacetate, tetraphenyl tin, and triphenyl tin hydroxide in. 100% sulfuric acid have been investigated by cryoscopic and conductimetric methods. Tetramethyl tin reacts with sulfuric acid with the evolution of methane and the formation of trimethyl tin hydrogensulfate. Trialkyl tin hydrogensulfates and dialkyl tin dihydrogensulfates behave as strong bases. It is probable that the cationic species formed are protonated hydrogensulfates rather than "stannonium" ions. Phenyl-substituted tin compounds are cleaved in sulfuric acid with the formation of benzene sulfonic acid and the complex hexa(hydrogensulfato) stannic acid, H2Sn(HSO4)6, and its anions. Lead tetraacetate gives yellow solutions containing hexa(hydrogensulfato) plumbic acid, H2PB(HSO4O6, and its anions.

scholarly journals Effects of pH on aquatic biodegradation processes

2009 ◽  
Vol 6 (1) ◽  
pp. 491-514 ◽  
Author(s):  
R. F. Krachler ◽  
R. Krachler ◽  
A. Stojanovic ◽  
B. Wielander ◽  
A. Herzig
Keyword(s):  
Organic Matter ◽  
Lake Water ◽  
Decomposition Rate ◽  
Degradation Mechanism ◽  
Ph Dependence ◽  
Degradation Process ◽  
Plant Litter ◽  
Lake Basin ◽  
Causal Connection ◽  
Ph Values

Abstract. To date, little is known about the pH-stimulated mineralization of organic matter in aquatic environments. In this study, we investigated biodegradation processes in alkaline waters. Study site is a large shallow soda lake in Central Europe (Neusiedler See/Ferto). The decomposition rate of plant litter was measured as a function of pH by incubating air-saturated lake-water samples in contact with Phragmites litter (leaves) from the littoral vegetation. All samples showed high decomposition rates (up to 32% mass loss within 35 days) and a characteristic two-step degradation mechanism. During the degradation process, the solid plant litter was dissolved forming humic colloids. Subsequently, the humic colloids were mineralized to CO2 in the water column. The decomposition rate was linearly related to pH. Increasing pH values accelerated significantly the leaching of humic colloids as well as the final degradation process. The observed two-step mechanism controls the wetland/lake/air carbon fluxes, since large quantities of humic colloids are currently produced in the reed belt, exported through wind-driven circulations and incorporated into the open lake foodweb. At present, the lake is rapidly shrinking due to peat deposition in the littoral zone, whereas it has been resistant to silting-up processes for thousands of years. In order to investigate the cause of this abrupt change, the chemical composition of the lake-water was measured during 1995–2007. A thorough analysis of these data revealed that major lake-water discharges through the lake's artificial outlet channel led to a decline in salinity and alkalinity. According to our estimates, the lake's original salinity and alkalinity was 70–90% higher compared to the present conditions, with the consequence of substantially lower pH values in the present lake. The observed pH dependence of reed litter biodegradation rates points to a causal connection between low pH values and accumulation of peat in the lake basin. Our results suggest that the pH stimulated remineralisation of organic matter plays a major role in maintaining the long-term integrity of saline lake/wetland systems.

scholarly journals Effect of Rejuvenator Containing Dodecyl Benzene Sulfonic Acid (DBSA) on Physical Properties, Chemical Components, Colloidal Structure and Micro-Morphology of Aged Bitumen

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1476 ◽  
Author(s):  
Dongliang Kuang ◽  
Zhou Ye ◽  
Lifeng Yang ◽  
Ning Liu ◽  
Zaihong Lu ◽  
...  
Keyword(s):  
Thin Film ◽  
Physical Properties ◽  
Sulfonic Acid ◽  
Chemical Components ◽  
Structure Transformation ◽  
Colloidal Structure ◽  
Benzene Sulfonic Acid ◽  
Oven Test ◽  
Dodecyl Benzene Sulfonic Acid ◽  
Micro Morphology

DBSA was used as a solubilizer together with conventional rejuvenator (CR) to produce a solubilized rejuvenator (SR), two kinds of aged bitumen involving TFOT aged bitumen and PAV aged bitumen were obtained by thin film oven test (TFOT) and pressurized aging vessel (PAV), respectively. Effects of CR and SR on the physical properties, chemical components, colloidal structure and micro-morphology of TFOT aged bitumen and PAV aged bitumen were investigated. Testing results of physical properties and chemical components indicated that CR and SR can replenish aged bitumen with necessary aromatics, TFOT aged bitumen that chemical component variation deteriorates its physical properties. With regard to PAV aged bitumen, of which the performance attenuation lies in chemical components variation and colloidal structure transformation, even if the content of CR reached up to 10 wt %, the regenerated bitumen cannot meet the regeneration requirement yet due to its definite influence on colloidal structure transformation, comparatively, sulfonic group in SR can react with the superficial atoms of asphaltenes to reform a solvation layer to facilitate the colloidal structure transformation of PAV aged bitumen, performance and beelike structure of regenerated PAV aged with bitumen with 10 wt % SR were approximated to that of virgin bitumen.

scholarly journals Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4778
Author(s):  
Natalia P. Mishchenko ◽  
Elena A. Vasileva ◽  
Andrey V. Gerasimenko ◽  
Valeriya P. Grigorchuk ◽  
Pavel S. Dmitrenok ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Degradation Products ◽  
Lethal Dose ◽  
Oxidative Degradation ◽  
Degradation Process ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Ionization Mass ◽  
Echinochrome A ◽  
Esi Ms

Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome®), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O2 in air-equilibrated aqueous solutions were identified, isolated, and structurally characterized. An HPLC method coupled with diode-array detection (DAD) and mass spectrometry (MS) was developed and validated to monitor the Ech A degradation process and identify the appearing compounds. Five primary oxidation products were detected and their structures were proposed on the basis of high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 7-ethyl-2,2,3,3,5,7,8-heptahydroxy-2,3-dihydro-1,4-naphthoquinone (2), 6-ethyl-5,7,8-trihydroxy-1,2,3,4-tetrahydronaphthalene-1,2,3,4-tetraone (3), 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (4), 2,3,4,5,7-pentahydroxy-6-ethylinden-1-one (5), and 2,2,4,5,7-pentahydroxy-6-ethylindane-1,3-dione (6). Three novel oxidation products were isolated, and NMR and HR-ESI-MS methods were used to establish their structures as 4-ethyl-3,5,6-trihydroxy-2-oxalobenzoic acid (7), 4-ethyl-2-formyl-3,5,6-trihydroxybenzoic acid (8), and 4-ethyl-2,3,5-trihydroxybenzoic acid (9). The known compound 3-ethyl-2,5-dihydroxy-1,4-benzoquinone (10) was isolated along with products 7–9. Compound 7 turned out to be unstable; its anhydro derivative 11 was obtained in two crystal forms, the structure of which was elucidated using X-ray crystallography as 7-ethyl-5,6-dihydroxy-2,3-dioxo-2,3-dihydrobenzofuran-4-carboxylic acid and named echinolactone. The chemical mechanism of Ech A oxidative degradation is proposed. The in silico toxicity of Ech A and its degradation products 2 and 7–10 were predicted using the ProTox-II webserver. The predicted median lethal dose (LD50) value for product 2 was 221 mg/kg, and, for products 7–10, it appeared to be much lower (≥2000 mg/kg). For Ech A, the predicted toxicity and mutagenicity differed from our experimental data.

scholarly journals β-Glucosidase genes differentially expressed during composting

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xinyue Zhang ◽  
Bo Ma ◽  
Jiawen Liu ◽  
Xiehui Chen ◽  
Shanshan Li ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Environmental Changes ◽  
Cellulose Degradation ◽  
Degradation Mechanism ◽  
Degradation Process ◽  
Global Scale ◽  
Expression Of Genes ◽  
Glucose Tolerant ◽  
Cooling Phase ◽  
And Function

Abstract Background Cellulose degradation by cellulase is brought about by complex communities of interacting microorganisms, which significantly contribute to the cycling of carbon on a global scale. β-Glucosidase (BGL) is the rate-limiting enzyme in the cellulose degradation process. Thus, analyzing the expression of genes involved in cellulose degradation and regulation of BGL gene expression during composting will improve the understanding of the cellulose degradation mechanism. Based on our previous research, we hypothesized that BGL-producing microbial communities differentially regulate the expression of glucose-tolerant BGL and non-glucose-tolerant BGL to adapt to the changes in cellulose degradation conditions. Results To confirm this hypothesis, the structure and function of functional microbial communities involved in cellulose degradation were investigated by metatranscriptomics and a DNA library search of the GH1 family of BGLs involved in natural and inoculated composting. Under normal conditions, the group of non-glucose-tolerant BGL genes exhibited higher sensitivity to regulation than the glucose-tolerant BGL genes, which was suppressed during the composting process. Compared with the expression of endoglucanase and exoglucanase, the functional microbial communities exhibited a different transcriptional regulation of BGL genes during the cooling phase of natural composting. BGL-producing microbial communities upregulated the expression of glucose-tolerant BGL under carbon catabolite repression due to the increased glucose concentration, whereas the expression of non-glucose-tolerant BGL was suppressed. Conclusion Our results support the hypothesis that the functional microbial communities use multiple strategies of varying effectiveness to regulate the expression of BGL genes to facilitate adaptation to environmental changes.

scholarly journals Synergistic Effects of Multiple Environmental Factors on Degradation of Hydrogenated Nitrile Rubber Seals

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 897 ◽  
Author(s):  
Weitao Lou ◽  
Weifang Zhang ◽  
Tingzhu Jin ◽  
Xuerong Liu ◽  
Wei Dai
Keyword(s):  
Environmental Factors ◽  
Elevated Temperatures ◽  
Synergistic Effects ◽  
Degradation Process ◽  
Nitrile Rubber ◽  
Oxidation Products ◽  
Compression Stress ◽  
Hydraulic Systems ◽  
Hydraulic Oil ◽  
Higher Temperature

Degradation tests of hydrogenated nitrile rubber seals, often used as sealing components in hydraulic systems, were conducted under the free and compression state in air and hydraulic oil at three elevated temperatures for several days to investigate the synergistic effects among three factors. The crosslinking and chain scission reactions both occurred simultaneously at higher temperature during the degradation process, and crosslinking predominated for most cases. Additionally, the synergistic effect between compression stress and hydraulic oil further slowed the degradation rate by limiting oxygen access. However, the higher temperature and hydraulic oil both promoted the formation of oxidation products, whereas the compression stress restrained the formation of amide groups. The fracture morphology results show that the defects gradually formed on the fracture surface, especially for the uncompressed specimens. The increase of the compression set aged in air was more than that in hydraulic oil, implying the more serious degradation. Moreover, rubber seals under the synthetic effect of three environmental factors presented the minimum degradation level. The degradation of the compressed and uncompressed specimens exposed to hydraulic oil is more serious than that of specimens exposed to air.

scholarly journals Initial steps in the degradation of benzene sulfonic acid, 4-toluene sulfonic acids, and orthanilic acid in Alcaligenes sp. strain O-1

1990 ◽  
Vol 1 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Thomas Thurnheer ◽  
Daniel Z�rrer ◽  
Otmar H�glinger ◽  
Thomas Leisinger ◽  
Alasdair M. Cook
Keyword(s):  
Sulfonic Acid ◽  
Sulfonic Acids ◽  
Benzene Sulfonic Acid ◽  
Orthanilic Acid
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