scholarly journals Frustrated Lewis Pair Stabilized Phosphoryl Nitride (NPO), a Mono Phosphorus Analogue of Nitrous Oxide (N2O)

2021 ◽  
Author(s):  
André Eckhardt ◽  
Martin-Louis Riu ◽  
Peter Müller ◽  
Christopher Cummins
Keyword(s):  
Nitrous Oxide ◽  
Half Life ◽  
Negative Charge ◽  
Activation Enthalpy ◽  
Activation Entropy ◽  
Order Kinetic ◽  
Reactive Intermediate ◽  
First Order ◽  
Frustrated Lewis Pair ◽  
Good Agreement

Phosphoryl nitride (NPO) is a highly reactive intermediate, and its chemistry has only been explored under matrix isolation conditions so far. Here we report the synthesis of an anthracene (A) and phosphoryl azide-based molecule (N3P(O)A) that acts as a molecular synthon of NPO. Experimentally, N3P(O)A dissociates thermally with a first order kinetic half-life that is associated with an activation enthalpy of ΔH⧧ = 27.5 ± 0.3 kcal mol–1 and an activation entropy of ΔS⧧ = 10.6 ± 0.3 cal mol–1 K–1 that are in good agreement with calculated DLPNO-CCSD(T)/cc-pVTZ//PBE0-D3(BJ)/cc-pVTZ energies. In solution N3P(O)A undergoes Staudinger reactivity with tricyclohexylphosphine (PCy3) and subsequent complexation with tris(pentafluorophenyl)borane (B(C6F5)3, BCF) to form Cy3P-NP(A)O-B(C6F5)3. Anthracene is cleaved off photochemically to form the frustrated Lewis pair (FLP) stabilized NPO complex Cy3P⊕-N=P-O-B⊖(C6F5)3. Intrinsic Bond Orbital (IBO) analysis suggests that the adduct is zwitterionic, with a positive and negative charge localized on the complexing Cy3P and BCF, respectively.

scholarly journals Thermal decomposition of 3,6-diphenyl-1,2,4,5-tetroxane in nitromethane solution

2018 ◽  
Vol 15 (2) ◽  
pp. 6306-6310
Author(s):  
Nelly Lidia Jorge ◽  
Alexander German Bordón ◽  
Andrea Natalia Pila ◽  
Mariela Ines Profeta ◽  
Maria Josefa Jorge ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Benzoic Acid ◽  
Activation Enthalpy ◽  
Decomposition Reaction ◽  
Activation Entropy ◽  
Order Kinetic ◽  
Stepwise Mechanism ◽  
First Order ◽  
Mechanism Of Decomposition ◽  
Organic Products

The thermal decomposition reaction of benzaldehyde diperoxide (DFT; 0.001 mol L-1) in nitromethane solution studied in the temperature range of 130.0-166.0 °C, follows a first-order kinetic law up to at least 60% DFT conversion. The organic products observed were benzaldheyde and benzoic acid. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DFT in nitromethane were calculated (DH# = 106.3 ± 1.0 kJ mol-1 and DS# = -58.6 ± 1.1 J mol-1K-1) and compared with those obtained in other solvents to evaluate the solvent effect.

Characterization of Dioctyl terephthalate biodegradation by food waste composting

2019 ◽  
Vol 33 (14n15) ◽  
pp. 1940048 ◽  
Author(s):  
Sung Tse Lee ◽  
Huu Tuan Tran ◽  
Chitsan Lin ◽  
Hong Giang Hoang ◽  
Thi Dieu Hien Vo ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Food Waste ◽  
Half Life ◽  
Order Kinetic ◽  
Aerobic Composting ◽  
First Order ◽  
Competitive Process ◽  
Plastic Products

Dioctyl terephthalate (DOTP), a plasticizer is used as an additive in many plastic products. Disposal of DOTP into environment has been of concern because it is hardly biodegradable in nature. Therefore, the aim of this study is to investigate the biodegradation of DOTP by aerobic composting processes without bioaugmentation. The initial DOTP concentration in the compost mixture was 11,882 mg/kg, after 35-day incubation, the removal efficiency of the compost reactor was 98%. The degradation was found to follow the first-order kinetic with the half-life of 5.2 days. Food waste composting was demonstrated as a technically robust and economically competitive process for the degradation of DOTP, and that of other similar plasticizers are expected.

Kinetic of Self-Reducing Mixtures of Iron Ore and Biomass of Elephant Grass

2016 ◽  
Vol 869 ◽  
pp. 1007-1012 ◽  
Author(s):  
E.P. Rocha ◽  
José Adilson de Castro ◽  
Flavia de Paula Vitoretti ◽  
F.V. Junior
Keyword(s):  
Reaction Mechanisms ◽  
Iron Ore ◽  
Arrhenius Plot ◽  
Order Kinetic ◽  
Elephant Grass ◽  
First Order ◽  
Fraction Versus ◽  
Dsc Method ◽  
Pellet Feed ◽  
Good Agreement

In this work, kinetic runs of self-reducing mixtures composed by pellet feed, BOF dust and biomass of elephant grass were performed using TGA-DSC method, for the temperatures, 900, 950, 1000, 1050 and 1100°C, and carbon percentages (15, 20 and 30% of carbon). The converted fraction versus time was calculated, and the different regions of the reactions progress were selected to analyze the reactions kinetics that occur in the mixture (devolatilization of biomass, Boudouard and sequence of reduction reactions). The kinetic behavior for the different steps showed good agreement with the first-order kinetic law. Using Arrhenius plot, was possible to estimate the apparent activation energy values obtained for the reaction mechanisms corresponding to Fe3O4→FeO and FeO→Fe. The kinetic constants for the 1100°C temperature and mixture containing 30% of carbon were the higher values: 0.0037 s-1 for the reaction Fe3O4 → FeO and 0.0258 s-1 for the mechanism FeO →Fe.

UV Protectants for the Biopesticide Based on Photostabilization of Ecdysone

2011 ◽  
Vol 183-185 ◽  
pp. 401-405 ◽  
Author(s):  
Hua Nan Guan ◽  
De Fu Chi ◽  
Jia Yu
Keyword(s):  
Ultraviolet Light ◽  
Larvicidal Activity ◽  
Half Life ◽  
Moderate Degree ◽  
Order Kinetic ◽  
Synthetic Compounds ◽  
First Order ◽  
Glass Slides ◽  
Life Values ◽  
Order Kinetic Equation

The ultraviolet protectant (UV protectant) properties of different natural and synthetic compounds were investigated for a biopesticide based on ecdysone. This study examined the photostabilization of ecdysone when exposed to ultraviolet light in the presence of some ultraviolet protectants. Ecdysone solutions with and without UV protectants in methanol were applied onto the surface of glass slides. At particular intervals, the remaining concentration of ecdysone was analyzed by HPLC. Using first-order kinetic equation, the dissipation half-life values (DT50) for the degradation of ecdysone under ultraviolet radiation were obtained. The larvicidal activity was evaluated against the larvae of Martianus dermestoides Chevrolat. It indicated that the addition of congo red, yeast, starch and arabia gum provided moderate degree of photostabilization of ecdysone and that addition of lignin provided the best photostabilization of ecdysone, among these UV protectants studied. Toxicity of the ecdysone with UV protectants was higher to the larvae of M. dermestoides Chevrolat compared to the ecdysone alone as indicated by the lower EC50 value. The dissipation half-life values of ecdysone after irradiation under ultraviolet light and the larvicidal activity suggested that the addition of lignin (in 1:l mol ratio) can provide better photostabilization of ecdysone molecule.

scholarly journals Removal of Ibuprofen From Synthetic Wastewater Using Photocatalytic Method in the Presence of Feo Photocatalyst Supported on Modified Iranian Clinoptilolite

2021 ◽  
Author(s):  
Majid Mohadesi ◽  
Ashkan Gouran ◽  
Kiarash Seifi
Keyword(s):  
Iron Oxide ◽  
Synthetic Wastewater ◽  
Process Time ◽  
Order Kinetic ◽  
Optimal Conditions ◽  
Initial Concentration ◽  
First Order ◽  
Order Kinetic Model ◽  
Ft Ir ◽  
Good Agreement

Abstract This study investigated the removal of an organic drug called ibuprofen from the wastewater containing this drug. Iron oxide supported on modified Iranian clinoptilolite was used as the photocatalyst in the presence of the light of a solar lamp. XRD, SEM, EDAX and FT-IR analyses were performed to detect the prepared photocatalyst. The results of photocatalytic identification analyses proved the suitable loading of iron oxide supported on modified Iranian clinoptilolite. This study investigated the effect of initial concentration of ibuprofen (5–25 mg/L), photocatalyst concentration (100–300 mg/L), and process time (10–240 min) on the removal from ibuprofen from wastewater containing this drug. The experiments were performed in a setup in the presence of a solar lamp with a flux of 300 W/m2. The results indicated that with the initial ibuprofen concentration of 25 mg/L, photocatalyst concentration of 300 mg/L, and time of 210 min, the highest percentage of ibuprofen removal was 99.80%. Kinetic modeling was then performed using the Langmuir-Hinshelwood model, and a quasi-first-order kinetic model showed a good agreement with the results obtained. Finally, the recovery of the photocatalyst was investigated and the results showed that under optimal conditions about 91% of ibuprofen was removed after five re-uses of the photocatalyst.

scholarly journals Sorptive behaviour of chromium on polyethylene microbeads in artificial seawater

2018 ◽  
Vol 250 ◽  
pp. 06001 ◽  
Author(s):  
Nur Farhan Zon ◽  
Ammar Iskendar ◽  
Shamila Azman ◽  
Shazani Sarijan ◽  
Razali Ismail
Keyword(s):  
Potential Role ◽  
Adsorption Process ◽  
Artificial Seawater ◽  
Order Kinetic ◽  
Heavy Metal Adsorption ◽  
First Order ◽  
Pseudo First Order ◽  
Aquatic Food ◽  
Good Agreement

This study investigates the interactions between chromium (Cr) and microplastic under controlled laboratory conditions using low density polyethylene microbeads as plastic particles. Chromium was added to suspensions of in artificial seawater to investigate heavy metal adsorption on microbeads surface. Polyethylene microbeads proved to have affinity in providing surface area for chromium. It served as an effective sorption surface thus lowering amounts of chromium in seawater through adsorption process. The best percentage of heavy metals adsorbed to microbeads and adsorption capacity was 1.7 µg/g and 8.5 % at 1.0 µg/mL respectively. The maximum adsorption was monitored for 180 hours. Kinetic study was performed and fitted well in pseudo-first-order kinetic. In term of isotherm, dataset was in good agreement with both Langmuir and Freundlich with correlation at 0.977 and 0.9606 respectively. Adsorption of chromium to polyethylene microbeads had important implications for the potential role of microplastics, in this case microbeadschromium contaminated act as a quantified link in aquatic food webs.

scholarly journals STABILITY OF CHITOSAN-TRIPOLYPHOSPHATE COMPLEX-ENCAPSULATED ANTHOCYANIN AT HIGH WATER ACTIVITY

2020 ◽  
Vol 31 (2) ◽  
pp. 171-179
Author(s):  
Umi Laila ◽  
◽  
Rochmadi Rochmadi ◽  
Sri Pudjiraharti ◽  
Rifa Nurhayati ◽  
...  
Keyword(s):  
Water Activity ◽  
Half Life ◽  
Incubation Temperature ◽  
Kinetic Constant ◽  
Food Product ◽  
High Water ◽  
Order Kinetic ◽  
Degradation Kinetic ◽  
First Order ◽  
The Stability

Previous study successfully conducted encapsulation of the purple-fleshed sweet potato’s anthocyanin but the study has yet to reveal the stability of encapsulated anthocyanin. Therefore, this research aims to observe the stability of encapsulated anthocyanin regarding the characteristic of low anthocyanin stability, which depends on environmental factors, such as temperature, pH, humidity, and water activity. The kinetic parameters of stability, including kinetic constant (k), reaction order, and half-life (t1/2), were also studied. Stability testing was conducted in high water activity of 0.75 and various in-cubation temperatures at 16, 25, 35, and 45°C. Un-encapsulated anthocyanin extract was also tested for its stability in the same condition in order to be compared with encapsulated anthocyanin. This study re-vealed that the encapsulated anthocyanin had lower stability than un-encapsulated anthocyanin extract. It was proven by higher kinetic constant and lower half-life of encapsulated anthocyanin for every incubation temperature which was induced by higher pH of encapsulated anthocyanin compared with anthocyanin extract. Besides, high water activity reduced glass transition temperature (Tg), in which encapsulated anthocyanin was in rubbery state. Both encapsulated anthocyanin and anthocyanin extract were degraded following the first order kinetic. Using the Arrhenius equation, it was obtained that the degradation kinetic constant of encapsulated anthocyanin was stated as k= 420.44 exp (-23.33/RT). Meanwhile, k= 1.12x106 exp (-46.70/RT) described degradation of kinetic constant of anthocyanin extract. The stability test re-vealed that the application of encapsulated anthocyanin was not suitable for wet-type food product.

Kinetics and Mechanism of Degradation of Aqueous Promecarb Insecticide Studied by UV Spectrophotometry and HPLC

2017 ◽  
Vol 42 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Hayet Bakhti ◽  
Najib Ben Hamida
Keyword(s):  
Degradation Mechanism ◽  
Aqueous Media ◽  
Reversed Phase ◽  
Activation Entropy ◽  
Uv Spectrophotometry ◽  
Order Kinetic ◽  
First Order ◽  
Mechanism Of Degradation ◽  
Order Kinetic Model

The present paper deals with the degradation mechanism of the insecticide promecarb, or 3-isopropyl-5-methylphenyl- N-methylcarbamate, in aqueous media. The reaction kinetics have been investigated using UV spectrophotometry and reversed phase HPLC. The determination of 3-isopropyl-5-methylphenol as the main product of promecarb hydrolysis gives evidence for the significant reactivity of this insecticide in alkaline solution. The rate constants were determined following a proposed first-order kinetic model. The positive activation entropy obtained Δ S≠ = +66.82 J mol−1 K−1 and the absence of general basic catalysis indicates an E1cB mechanism involving unimolecular collapse of the promecarb via a methylisocyanate intermediate. These results were confirmed by the fact that promecarb fits well into Brønsted and Hammett plots obtained for a series of substituted N-methylcarbamates for which the decomposition in aqueous media was established to follow an E1cB mechanism.

Photodegradation of some Furocoumarins in Ethanol under UV Irradiation

2016 ◽  
Vol 683 ◽  
pp. 402-405
Author(s):  
Natalya G. Bryantseva ◽  
Olga N. Tchaikovskaya ◽  
Vlada S. Kraiukhina ◽  
Maria Gómez ◽  
Jose Luis Gómez
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Kinetic Model ◽  
Kinetic Parameter ◽  
Bulk Solution ◽  
Order Kinetic ◽  
First Order ◽  
Operational Variables ◽  
Pseudo First Order ◽  
Good Agreement

Photodegradation of 5-Methoxypsoralen (5-MOP), 4', 5'-dimethyl-3,4-cyclogeksilpsoralen (KC5) and 4'-methyl-3,4 cycloheptylpsoralen (KC4) has been carried out in an XeBr exilamps, both in the presence of H2O2, and a kinetic model, which explains the dependence of the pseudo-first order kinetic parameter on the substrate concentration and other operational variables, has been developed. In the development of the model, mass transfer of 5-MOP, KC5 and KC4from the bulk solution to the wall of the vessel was assumed as the step determining the rate of the photodegradation process, which successfully explains some singularities observed in the experimental results.By fitting the experimental data to the model, a detailed study of the influence of all operational variables on the pseudo-first order kinetic parameter has been done, in good agreement with the model hypotheses.

The in vivo regeneration of goldfish rhodopsin and porphyropsin

1986 ◽  
Vol 122 (1) ◽  
pp. 269-275
Author(s):  
A. T. Tsin ◽  
J. M. Flores
Keyword(s):  
Body Weight ◽  
Rate Constant ◽  
Half Life ◽  
Visual Pigment ◽  
Initial Period ◽  
Direct Result ◽  
Order Kinetic ◽  
Kinetic Rate Constant ◽  
First Order

Goldfish with retinas rich in either rhodopsin or porphyropsin were illuminated with bright light and then placed in the dark room to allow visual pigment regeneration. The kinetics of this in vivo pigment regeneration were followed by sampling these animals at regular time intervals. The first-order kinetic rate constant for the initial period of porphyropsin regeneration at 20 degrees C was 8.3 X 10(−3) nmol kg-1 body weight min-1 and the half-life of this reaction was 83 min. At 30 degrees C, the rate constant was increased to 1.4 X 10(−2) nmol kg-1 body weight min-1, yielding a reduced half-life of 49 min. This suggests that the Q10 of porphyropsin regeneration is about 1.7. In goldfish retinas enriched with rhodopsin (62% rhodopsin and 38% porphyropsin), the initial phase of visual pigment regeneration (at 30 degrees C) proceeded at a slower rate (first-order rate constant: 6.5 X 10(−3) nmol kg-1 body weight min-1; half-life of reaction = 106 min) than the rate of porphyropsin regeneration. This suggests that the high proportion of rhodopsin in the retina of goldfish held at 30 degrees C is not a direct result of a faster rate of regeneration of rhodopsin than of porphyropsin.

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