Thermal decomposition rate constant of peroxybenzoyl nitrate in the gas phase

1981 ◽  
Vol 15 (10) ◽  
pp. 1229-1232 ◽  
Author(s):  
Tomohiro. Ohta ◽  
Isao. Mizoguchi
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Decomposition Rate Constant

Decomposition rate constants of Picea abies logs in southeastern Norway

1999 ◽  
Vol 29 (3) ◽  
pp. 372-381 ◽  
Author(s):  
Erik Næsset
Keyword(s):  
Picea Abies ◽  
Rate Constant ◽  
Cross Sections ◽  
Decomposition Rate ◽  
Rate Constants ◽  
Initial Density ◽  
Decomposition Rate Constant ◽  
Negative Exponential Function ◽  
Standing Trees ◽  
Negative Exponential

Decomposition rate constants were estimated from 384 cross sections of Norway spruce (Picea abies (L.) Karst.) logs with base diameter >7.0 cm collected in open areas at five different study sites in southeastern Norway. Fresh wood core samples were taken from 95 standing trees adjacent to the logs to estimate the initial density of these cross sections. Based on this chronosequence, a simple negative exponential function of time showed an average decomposition rate constant for all cross sections of 0.033 per year. Cross-section diameter, ground contact, soil moisture, and aspect were all found to have significant impacts on the decomposition rate constant. For different combinations of these characteristics the decomposition rate constant ranged from a minimum of 0.0165 per year to a maximum of 0.0488 per year.

The thermal decomposition of cyclobutane-1,2-dione

1985 ◽  
Vol 63 (11) ◽  
pp. 2945-2948 ◽  
Author(s):  
J.-R. Cao ◽  
R. A. Back
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Vapor Pressure ◽  
Gas Phase ◽  
Rate Constant ◽  
Surface Reaction ◽  
Order Rate Constant ◽  
Reaction Vessel ◽  
Arrhenius Parameters ◽  
First Order

The thermal decomposition of cyclobutane-1,2-dione has been studied in the gas phase at temperatures from 120 to 250 °C and pressures from 0.2 to 1.5 Torr. Products were C2H4 + 2CO, apparently formed in a simple unimolecular process. The first-order rate constant was strongly pressure dependent, and values of k∞ were obtained by extrapolation of plots of 1/k vs. 1/p to1/p = 0. Experiments in a packed reaction vessel showed that the reaction was enhanced by surface at the lower temperatures. Arrhenius parameters for k∞, corrected for surface reaction, were log A (s−1) = 15.07(±0.3) and E = 39.3(±2) kcal/mol. This activation energy seems too low for a biradical mechanism, and it is suggested that the decomposition is probably a concerted process. The vapor pressure of solid cyclobutane-1,2-dione was measured at temperatures from 22 to 62 °C and a heat of sublimation of 13.1 kcal/mol was estimated.

Kinetic parameters of the thermal decomposition of cobalt hydroxide nanopowder under isothermal conditions

2020 ◽  
Author(s):  
T.H. Nguyen
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Decomposition Rate ◽  
Cobalt Hydroxide ◽  
Average Particle ◽  
Co3o4 Nanoparticles ◽  
Decomposition Rate Constant ◽  
Isothermal Conditions ◽  
Nano Powder ◽  
Research Show

The paper focuses on the kinetic parameters of synthesizing Co3O4 nano-powder by thermal decomposition of hydroxide Co(OH)2 under isothermal conditions. The thermal decomposition of Co(OH)2 nano-powder under isothermal conditions was carried out in a tube furnace in the temperature range from 150 to 200 °C. Findings of research show that the thermal decomposition rate constant at 200 °C is approximately 2.7 times higher than that at 150 °C. Accordingly, for 80 min of thermal decomposition, the process accelerates 1.8 times. The activation energy of this process is approximately 33 kJ/mol, which indicates a mixed reaction mode. The study shows that Co3O4 nanoparticles obtained at the temperature of the maximum thermal decomposition rate, i.e. 180 °C, mainly consist of elongated ovoid and acicular aggregates with an average particle value of 47 nm and the length of up to 200 nm.

Kinetics and mechanism of the oxidation of oxalate ion by tris(acetylacetonato)-manganese(III) and its hydrolytic derivatives in aqueous perchlorate media

1993 ◽  
Vol 71 (12) ◽  
pp. 2155-2159 ◽  
Author(s):  
Subrata Mukhopadhyay ◽  
Swapan Chaudhuri ◽  
Rina Das ◽  
Rupendranath Banerjee
Keyword(s):  
Free Radicals ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Rate Constants ◽  
Kinetics And Mechanism ◽  
Unimolecular Decomposition ◽  
Decomposition Rate Constant ◽  
Mixed Complexes ◽  
Ph Range ◽  
Oxalate Ion

In the pH range 6.6–8.6, [MnL2(H2O)2]+ and [MnL2(H2O)(OH)] (HL = acetylacetone) oxidize oxalate ion (ox2−) to CO2 through the inner-sphere intermediates [MnL2(ox)]− and [MnL2(OH)(ox′)]2−, where ox′ is a half-bonded (unidentate) oxalate ion. Their rate constants of decomposition are 1.0 × 10−4 s−1 and 11.2 × 10−2 M−1 s−1 at 30 °C and at I = 1.0 M (NaClO4). Decomposition of these mixed complexes produces free radicals, presumably CO2−, which is further oxidized to CO2 by another Mn(III) in a fast step. At pH 4.2, [Mn(ox)3]3− is produced quantitatively when [ox]0 ≥ 0.12 M, which has been characterized spectrally, and its unimolecular decomposition rate constant k (= 2.7 × 10−4s−1 at 30 °C and I = 1.0 M) compares well with that reported earlier (2.44 × 10−4 s−1 at 25 °C and I = 1.0 M).

scholarly journals Leaf-litter decomposition and nutrient dynamics of five selected tropical tree species

2020 ◽  
Vol 30 (1) ◽  
pp. 32-38
Author(s):  
S. Bhattarai ◽  
B. Bhatta
Keyword(s):  
Weight Loss ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Tree Species ◽  
Nutrient Dynamics ◽  
Decomposition Rate Constant ◽  
Tropical Tree Species ◽  
One Year

Leaf-litter decomposition in terrestrial ecosystems has a major role in recycling the nutrients to the soil. Nutrient dynamics is the way nutrients cycle in an ecosystem. The present study was conducted for five selected tropical tree species viz. Shorea robusta, Ficus hookeri, Mallotus philippensis, Artocarpus lakoocha and Dillenia pentagyna at Hetauda, Makawanpur. This paper aims to determine the litter decomposition rate-constant and nutrient mineralization pattern of the selected species. The litter-bag method was used to assess the decomposition and nutrient dynamics for one year. Both decomposition rate-constant and weight loss were highest for M. philippensis (% weight loss = 73.49; k = 0.33) and lowest for S. robusta (% weight loss = 54.01; k = 0.18). In general, weight remaining showed a strong negative correlation with N and P concentration but a slightly negative with K. However, the remaining weight of litter showed a strong positive correlation with C : N ratio, thus indicating a good predictor of mass loss and mineralization. The study showed that there was no net release of nitrogen during the one-year study period; however, the net P release was found to be highest for S. robusta followed by D. pentagyna and the net K release was highest in F. hookeri followed by A. lakoocha.

scholarly journals Modelling the temperature of a compost microreactor in isolation

2020 ◽  
Author(s):  
◽  
Mitchell Hawse
Keyword(s):  
Rate Constant ◽  
Decomposition Rate ◽  
Dry Mass ◽  
Small Scale ◽  
Conductive Heat ◽  
Wood Biomass ◽  
Decomposition Rate Constant ◽  
Plastic Container ◽  
Waste Wood ◽  
Municipal Biosolids

A mixture of waste-wood biomass and municipal biosolids waste was composted in a plastic container inside of an insulated chamber. The mixture of biomass and biosolids was approximately 50:50 and weighed 82.6 kg. The peak temperature of the compost was 32.4◦C. The small scale of the compost system allowed the lower limit of the compost decomposition rate to be studied. A model was successfully developed to predict the core temperature of the compost using the ambient temperature in the insulated chamber. A literature review was conducted to determine literature values for the overall convective and conductive heat transfer coefficient, the dry mass fraction, and heat of combustion for both biomass and biosolids. The model used an optimization algorithm to calculate the rate constant for the experimental setup. The calculated decomposition rate constant was 0.0525 Day−1.

scholarly journals Patterns of Leaf Litter Decomposition as Related to Litter Traits in the Sudano-Guinea Savannahs of Ngaoundere, Cameroon

2019 ◽  
pp. 1-19
Author(s):  
A. Ibrahima ◽  
P. Souhore ◽  
A. A Mang A Menick
Keyword(s):  
Phenolic Compounds ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Plant Species ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Dry Mass ◽  
Specific Mass ◽  
Decomposition Rate Constant ◽  
Litter Mass

Litter decomposition processes are poorly studied in the savannahs. Leaf litter decomposition of the twenty-four contrasting plant species including trees, shrubs and grass species, was studied in the sudano-guinea savannahs of Ngaoundere, Cameroon. The litterbag technique was used to assess litter mass loss and single exponential model was adopted to estimate decay rate constants. Initial litter thickness varied from 0.02 to 1.11 mm, area from 4.27 to 245.89 mm2, sclerophyllous index from 0.01 to 1.75 mg.mm-2, density from 0.21 to 87.50 mg.mm-3, and specific mass area from 0.57 to 185.46 mm2.mg-1. Litter cellulose content varied from 3.79 to 11.84%; lignin from 2.84 to 8.12%, NDF from 21.35 to 80.41%, and total phenolic compounds from 0.47 to 17.76%. During the 52 weeks of the field experiment, mean dry mass remaining of litter samples was significantly between 8.05 and 75.22% of initial litter dry mass for C. papaya and C. regidus respectively. Litter decomposition rate constant (k) significantly ranged from 0.003 (C. regidus) to 0.121 %.week-1 (C. papaya). Litter mass remaining (LMR) was positively related to thickness (R2 = 0.605, P<0.01), Sclerophyllous index (R2 = 0.446, P<0.05), Specific mass area (R2 = 0.569, P<0.001), lignin (R2 = 0.631, P<0.01) and phenolic compounds (R2 = 0.618, P<0.001). The litter decomposition rate constant (k) was negatively related to thickness (R2 = 0.602, P<0.01, n=12), Sclerophyllous index (0.542; P<0.05), Specific mass area (0.419; P<0.05) and phenolic compounds (0.530; P<0.01). It can be concluded that litter decomposition is affected by plant species diversity, plant groups and physico-chemical traits of litters in the sudano-guinea savannahs of Ngaoundere, Cameroun. These preliminary results would contribute to understanding the mechanism of litter decomposition in general and in these savannahs in particular.

Sign in / Sign up

Export Citation Format

Share Document