The atmospheric chemical reaction of 4-tert-butylphenol initiated by OH radicals

2013 ◽  
Vol 10 (2) ◽  
pp. 111 ◽  
Author(s):  
Chen Gong ◽  
Xiaomin Sun ◽  
Chenxi Zhang
Keyword(s):  
Rate Constants ◽  
Degradation Mechanism ◽  
Degradation Process ◽  
State Theory ◽  
Oh Radicals ◽  
Atmospheric Lifetime ◽  
Computational Theory ◽  
Developmental Problems ◽  
First Order ◽  
First Order Kinetics

Environmental context 4-tert-Butylphenol, an environmental endocrine disruptor, can be taken in by humans and animals resulting in reproductive and developmental problems. We report a theoretical study on the degradation mechanism of 4-tert-butylphenol in the atmosphere, and calculate the atmospheric lifetime of this chemical. The data will help our understanding of the behaviour of 4-tert-butylphenol in the environment and thereby provide valuable information about its possible effect on human health. Abstract 4-tert-Butylphenol (TBP) is a typical environmental endocrine. In this paper, the OH-initiated degradation mechanism of TBP in the atmosphere is studied at the MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level of computational theory. A profile of the potential energy surface is constructed and reaction pathways are analysed. The addition reactions of TBP with OH radicals are more important than abstraction reactions in the atmosphere. In subsequent reactions, O2 and NO may play an important role in the degradation process of TBP. The rate constants are calculated using the transition state theory and a canonical variational transition with small-curvature tunnelling correction. The Arrhenius equations of rate constants in the temperature range of 200–500K are fitted. The rate constant of the degradation of the TBP at 298.15K is 3.56×10–14cm3 molecule–1s–1 and the atmospheric lifetime is 10.8 months according to the pseudo-first-order kinetics.

Kinetic study on the linalool ozonolysis reaction in the atmosphere

2012 ◽  
Vol 90 (4) ◽  
pp. 353-361 ◽  
Author(s):  
Xiaomin Sun ◽  
Chenxi Zhang ◽  
Yuyang Zhao ◽  
Jing Bai ◽  
Maoxia He
Keyword(s):  
Rate Constants ◽  
Transition State Theory ◽  
State Theory ◽  
Oxidation Products ◽  
Tunneling Effect ◽  
Total Rate ◽  
Variational Transition State Theory ◽  
Atmospheric Lifetime ◽  
Ozone Addition ◽  
First Time

In the atmosphere, linalool ozonolysis will generate a series of oxidation products and then form particles through nucleation. In this study, the linalool ozonolysis mechanisms were studied and some of the main products detected from experiment are verified. The Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition state theory (CVT) with small curvature tunneling effect (SCT) are used to calculate rate constants over the temperature range of 200∼800 K. The total rate constant for the reaction of ozone with linalool is 4.50 × 10−16 cm3 molecule–l s–l, and the addition of ozone to (CH3)2C=CH– is the main ozone addition position. Furthermore, the Arrhenius formulas are fitted and the lifetimes of reaction species in the troposphere are discussed for the first time. The total atmospheric lifetime of linalool relative to O3 is 2.30 h. The O3-initiated atmospheric lifetimes of P1, P3, and P6 are 2.64 months, 16.67 days, and 15.5 h, respectively.

Removal of sulfonamides from wastewater in the UV/TiO2 system: effects of pH and salinity on photodegradation and mineralization

2019 ◽  
Vol 79 (2) ◽  
pp. 349-355 ◽  
Author(s):  
C. H. Wu ◽  
C. Y. Kuo ◽  
C. D. Dong ◽  
C. W. Chen ◽  
Y. L. Lin
Keyword(s):  
Rate Constants ◽  
Inhibitory Effect ◽  
Chloride Ions ◽  
Mineralization Rate ◽  
Direct Photolysis ◽  
First Order ◽  
First Order Kinetics ◽  
Lower Reactivity ◽  
Chlorine Radicals ◽  
Effects Of Ph

Abstract The effects of salinity on the photodegradation and mineralization of sulfonamides in the UV/TiO2 system were investigated. The goals of this study were to analyze the effects of pH and salinity on the sulfonamide concentration and total organic carbon (TOC) during the removal of sulfonamides in a UV/TiO2 system. Four sulfonamides – sulfadiazine (SDZ), sulfamethizole (SFZ), sulfamethoxazole (SMX) and sulfathiazole (STZ) - were selected as parent compounds. The photodegradation and mineralization rates of sulfonamides in the UV/TiO2 system satisfy pseudo-first-order kinetics. Direct photolysis degraded sulfonamides but sulfonamides cannot be mineralized. The photodegradation and mineralization rate constants in all experiments followed the order pH 5 > pH 7 > pH 9. At pH 5, the mineralization rate constants of SMX, SFZ, SDZ and STZ were 0.015, 0.009, 0.012 and 0.011 min−1, respectively. The addition of NaCl inhibited the mineralization of the four tested sulfonamides more than it inhibited their photodegradation. The inhibitory effect of chloride ions on the removal of sulfonamides in the UV/TiO2 system was attributed to the scavenging by chloride ions of hydroxyl radicals (HO•) and holes and the much lower reactivity of chlorine radicals thus formed, even though the chlorine radicals were more abundant than HO•.

Skeletal isomerization of cyclohexene on Al2O3 and AlPO4–Al2O3 catalysts

1984 ◽  
Vol 62 (8) ◽  
pp. 1455-1458 ◽  
Author(s):  
J. M. Campelo ◽  
A. Garcia ◽  
J. M. Gutierrez ◽  
D. Luna ◽  
J. M. Marinas
Keyword(s):  
Rate Constants ◽  
Reaction Pathway ◽  
Acid Sites ◽  
Skeletal Isomerization ◽  
Irreversible Adsorption ◽  
First Order ◽  
First Order Kinetics ◽  
Selectivity Studies ◽  
Apparent Activation Energies ◽  
Competitive Products

Cyclohexene skeletal isomerization, in a microcatalytic pulse reactor, was investigated using Al2O3 and AlPO4–Al2O3 as catalysts. Apparent rate constants and apparent activation energies were calculated according to the kinetic model of Bassett–Habgood. Selectivity studies concluded that 1-MCP and 3-MCP were competitive products with a first-order kinetics. The rate constants as well as the selectivity at 1-MCP increase with an increase in the number and strength of stronger acid sites, measured by means of the irreversible adsorption of aniline in cyclohexane, at 298 K, using a spectrophotometric method. The parallel reaction pathway, proposed for AlPO4 catalysts, agrees with both the observed rates and selectivities using Al2O3 and AlPO4–Al2O3 catalysts.

Photocatalytic removal of taste and odour compounds for drinking water treatment

2009 ◽  
Vol 9 (5) ◽  
pp. 477-483 ◽  
Author(s):  
H. Tran ◽  
G. M. Evans ◽  
Y. Yan ◽  
A. V. Nguyen
Keyword(s):  
Drinking Water ◽  
Sodium Bicarbonate ◽  
Photocatalytic Degradation ◽  
Rate Constants ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Drinking Water Treatment ◽  
Degradation Process ◽  
Negative Effects ◽  
Reaction Rate Constants

Photocatalytic degradation of geosmin and 2-methylisoborneol (MIB), which are two taste and odour compounds commonly found in drinking water supply sources, was investigated using an immobilised TiO2 photoreactor. It was found that the degradation of geosmin and MIB followed similar pseudo-first-order kinetics with reaction rate constants being approximately 0.025 min−1 for typical geosmin and MIB concentrations of 250 and 500 ng/L. The normalised formal quantum efficiency was calculated to be in the range of 162–182 L/mol. Influence of additives (i.e. sodium bicarbonate and alcohols) on the degradation process was also investigated. It was found that there was a small reduction in the degradation rate constants of geosmin and MIB with increasing sodium bicarbonate concentration. At 50 mg/L sodium bicarbonate the degradation rate constants decreased by approximately 5%. Similarly, for methanol and ethanol concentrations up to 35 and 50 mg/L, respectively, these constants were found to also decrease. While addition of sodium bicarbonate and alcohols was seen to have relatively small negative effects on the photocatalytic degradation performance, the magnitude of their influence was consistent with the hypothesis that the degradation mechanism of geosmin and MIB was predominately that of attack involving HO∙ radicals.

Azides. Part V. A kinetic study of the formation of N-(p-toluenesulphonyl)-1H-azepine by thermolysis of p-toluenesulphonylazide in benzene under nitrogen pressure

1985 ◽  
Vol 63 (4) ◽  
pp. 887-890 ◽  
Author(s):  
Nagaraj R. Ayyangar ◽  
Ramesh B. Bambal ◽  
Dattatraya D. Nikalje ◽  
Kumar V. Srinivasan
Keyword(s):  
Kinetic Study ◽  
Rate Constants ◽  
Nitrogen Pressure ◽  
Time Profile ◽  
First Order ◽  
First Order Kinetics ◽  
Concentration Time

The course of thermolysis of p-toluenesulphonylazide (A) in benzene at 160 °C and 40.1 atm of nitrogen pressure was followed by analysis of the reactants and products in the reaction mixture by hplc. The rate measurements indicate that the reaction follows first-order kinetics with respect to the formation of N-(p-toluenesulphonyl)-1H-azepine (B) and p-toluencsulphonamide (D). The concentration–time profile is consistent with the formation of p-toluenesulphonylanilide (C) from the azepine (B). The rate constants indicate that the azepine (B) decomposes to the anilide (C) at the same rate at which it is formed.

Effects of oxidant concentration and temperature on decolorization of azo dye: comparisons of UV/Fenton and UV/Fenton-like systems

2012 ◽  
Vol 65 (11) ◽  
pp. 1970-1974 ◽  
Author(s):  
C. Y. Kuo ◽  
C. Y. Pai ◽  
C. H. Wu ◽  
M. Y. Jian
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Azo Dye ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Decolorization Efficiency ◽  
Pseudo First Order ◽  
Reactive Red 2

This study applies photo-Fenton and photo-Fenton-like systems to decolorize C.I. Reactive Red 2 (RR2). The oxidants were H2O2 and Na2S2O8; Fe2+, Fe3+, and Co2+ were used to activate these two oxidants. The effects of oxidant concentration (0.3–2 mmol/L) and temperature (25–55 °C) on decolorization efficiency of the photo-Fenton and photo-Fenton-like systems were determined. The decolorization rate constants (k) of RR2 in the tested systems are consistent with pseudo-first-order kinetics. The rate constant increased as oxidant concentration and temperature increased. Activation energies of RR2 decolorization in the UV/H2O2/Fe2+, UV/H2O2/Fe3+, UV/Na2S2O8/Fe2+ and UV/Na2S2O8/Fe3+ systems were 32.20, 39.54, 35.54, and 51.75 kJ/mol, respectively.

A theoretical insight into atmospheric chemistry of HFE-7100 and perfluoro-butyl formate: reactions with OH radicals and Cl atoms and the fate of alkoxy radicals

2016 ◽  
Vol 40 (7) ◽  
pp. 6148-6155 ◽  
Author(s):  
Bhupesh Kumar Mishra ◽  
Makroni Lily ◽  
Ramesh Chandra Deka ◽  
Asit K. Chandra
Keyword(s):  
Global Warming ◽  
Atmospheric Chemistry ◽  
Global Warming Potential ◽  
Rate Constants ◽  
Oh Radicals ◽  
Atmospheric Lifetime ◽  
Alkoxy Radicals ◽  
Cl Atoms ◽  
Theoretical Insight ◽  
Insight Into

The calculated rate constants for C4F9OCH3 + OH/Cl reactions are found to be 1.94 × 10−14 and 1.74 × 10−12 cm3 molecule−1 s−1, respectively, at 298 K. The atmospheric lifetime and global warming potential for HFE-7100 are computed to be 2.12 years and 155.3, respectively.

Bioconcentration factors and kinetics of chlorobenzenes in a juvenile crab (Portunus pelagicus (L))

1993 ◽  
Vol 44 (4) ◽  
pp. 565 ◽  
Author(s):  
MR Mortimer ◽  
DW Connell
Keyword(s):  
Rate Constants ◽  
Aquatic Organisms ◽  
Aqueous Solubility ◽  
Portunus Pelagicus ◽  
Lipophilic Compounds ◽  
First Order ◽  
First Order Kinetics ◽  
Log Kow ◽  
Wet Weight ◽  
Depuration Rate

The uptake- and depuration-rate constants (k1 and k2 respectively), according to first-order kinetics, were measured for a series of chlorobenzenes with juvenile crabs, Portunus pelagicus. These constants were found to be related to the lipophilicity of the chlorobenzenes as expressed by the octanol-water coefficient (log Kow), giving relationships similar to those observed with fish. However, the actual magnitude of k1 and k2 on a lipid basis ranged from 720 to 5880 h-1 and from 0.492 to 0.0102 h-1 respectively, which is about ten times faster than those for fish. The bioconcentration factor (KB in wet weight units) obtained from these rate constants was related to Kow, by the following expression. log KB=-2.88+1.09 log Kow. The empirical constants in this equation are similar to those observed with other aquatic organisms except that the value of -2.88 is lower than that reported with the other organisms. This is probably due to the relatively low lipid content of the crabs. It is suggested that the bioconcentration of essentially nonbiodegradable lipophilic compounds occurs as a result of partitioning between biota lipid and water. Other physicochemical properties (molar volume and aqueous solubility) and two molecular descriptors (zero- and first-order Randik indices) exhibited good correlations with the bioconcentration characteristics described above.

scholarly journals Efficient degradation of naproxen by persulfate activated with zero-valent iron: performance, kinetic and degradation pathways

2020 ◽  
Vol 81 (10) ◽  
pp. 2078-2091
Author(s):  
Shuyu Dong ◽  
Xiaoxue Zhai ◽  
Ruobing Pi ◽  
Jinbao Wei ◽  
Yunpeng Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydroxyl Radical ◽  
Rate Constants ◽  
Zero Valent Iron ◽  
Degradation Pathways ◽  
First Order ◽  
First Order Kinetics ◽  
Degradation Rates ◽  
Initial Ph ◽  
Pseudo First Order

Abstract Degradation of naproxen (NAP) by persulfate (PS) activated with zero-valent iron (ZVI) was investigated in our study. The NAP in aqueous solution was degraded effectively by the ZVI/PS system and the degradation exhibited a pseudo-first-order kinetics pattern. Both sulfate radical (SO4•−) and hydroxyl radical (HO•) participate in the NAP degradation. The second-order rate constants for NAP reacting with SO4•− and HO• were (5.64 ± 0.73) × 109 M−1 s−1 and (9.05 ± 0.51) × 109 M−1 s−1, respectively. Influence of key parameters (initial pH, PS dosage, ZVI dosage, and NAP dosage) on NAP degradation were evaluated systematically. Based on the detected intermediates, the pathways of NAP degradation in ZVI/PS system was proposed. It was found that the presence of ammonia accelerated the corrosion of ZVI and thus promoted the release of Fe2+, which induced the increased generation of sulfate radicals from PS and promoted the degradation of NAP. Compared to its counterpart without ammonia, the degradation rates of NAP by ZVI/PS were increased to 3.6–17.5 folds and 1.2–2.2 folds under pH 7 and pH 9, respectively.

Macrokinetics and Mechanism of Phenol Solution Degradated by Fe3+/Ce4+ Doped TiO2 Particles

2014 ◽  
Vol 955-959 ◽  
pp. 411-414
Author(s):  
Yu Fei Wang ◽  
Long Yan ◽  
Jian Li
Keyword(s):  
Degradation Process ◽  
Isobutyric Acid ◽  
Phenol Solution ◽  
First Order ◽  
Degradation Reactions ◽  
First Order Kinetics ◽  
Before And After ◽  
Mechanism Of Degradation ◽  
Butanedioic Acid ◽  
Dynamic Cycle

Fe3+/Ce4+doped TiO2particles was prepared and used for degradation of phenol solution, the macrokinetics and mechanism of degradation process was proposed by GC-MS, and Fe3+/Ce4+-doped TiO2particles before and after treated phenol was also compared by TEM. The experimental results showed that COD degradation reactions in static and dynamic cycle process are in accordance with first-order kinetics from the macro effects, phenol can be oxidized to intermediates, such as isobutyric acid, malonic acid, para-benzoquinone, butenic acid, ethanedioic acid, maleic acid, butanedioic acid, o-dihydroxybenzene, paradioxybenzene and dioxybenzene, indicating that Fe3+/Ce4+-doped TiO2particles are beneficial to some oxidation formation. Moreover, the shapes of Fe3+/Ce4+-doped TiO2particles after treated phenol displays aggregated.

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