Kinetic Investigations of the Reaction of Phenyl Radicals with Ethyl Acetate in the Gas Phase: An Experimental and Computational Study

Research on the kinetics and degradation pathways of gaseous acetic acid ester organics

ABSTRACTDesigned to meet the specific needs of the printing industry exhaust gas emissions, this paper proposes a method for the degradation of gaseous acetic acid ester organics that is environmentally friendly, safe, and simple to use: micro-nano cavitation technology. In the process of using micro-nano cavitation technology to degrade acetic acid ester organics, the products in the degradation process were analyzed by gas chromatography-mass (GC-MS) spectrometry, and the degradation pathways of acetic acid ester organics were identified. Under high temperatures and high pressure caused by cavitation collapse, the C-C bond and C-O bond on the main chain of organic matter are cleaved to form low molecular products. Low-molecular intermediate products are continuously produced as the reaction advances, and these intermediate products are further oxidized and decomposed into carbon dioxide and water. Besides, the factors that influence the degradation rate of acetic acid ester organics were investigated. Based on the experimental data, acetic acid esters can degrade with the greatest efficiency when their initial concentration is 200 ± 50 mg/m3 and their treatment time is 20∼30 min. Moreover, the experiment was optimized using the response surface method. The results suggested that for an initial concentration of 155.544 mg/m3 and a reaction time of 21.961 min, the best degradation rate was 0.251 min-1. Micro-nano cavitation technology is a novel and promising technology for the degradation of volatile organic compounds, with a wide range of practical applications.

Kinetics of IO radicals with C1, C2 aliphatic alcohols in tropospherically relevant conditions

Kinetics of the reaction of IO radicals with methanol (MeOH) and ethanol (EtOH) were experimentally studied in the gas phase using pulsed laser photolysis-cavity ring-down spectroscopy (PLP-CRDS). IO radicals were produced in situ at the reaction zone by photolysing a mixture of precursors (CH₃I + O₃ + N₂) at 248 nm and thereby electronically excited at 445.04 nm. The rate coefficients for the reactions of (IO + MeOH) and (IO + EtOH) were measured at a total pressure of 60 Torr/N₂ in the range of 258-360 K. At room temperature, the experimental rate coefficients of the title reactions were measured to be [Formula: see text] and [Formula: see text]. Dependencies of the kinetics with photolysis laser fluence and experimental pressures were verified. Effects of pressure over the kinetic behaviour of the studied systems were observed to be insignificant within the statistical uncertainties when studied in the range of ~ 30-150 Torr/N₂, whereas a minor and linear fluence dependency was observed within the studied limit. From the measured kinetic parameters, the atmospheric lifetimes of MeOH and EtOH were calculated in the tropospherically relevant conditions regarding their reactions with important atmospheric oxidants like Cl atom, OH and IO radicals. To complement experimental results, kinetics and thermochemistry for the title reactions were investigated theoretically via canonical variational transition state (CVT) theory in combination with small curvature tunnelling (SCT) corrections with a dual-level Interpolated Single Point Energy (ISPE) approach at the CCSD(T)/def2-QZVPP//M06-2X/def2-TZVPP level of theory/basis set in the temperatures between 200 and 400 K. Good degree of agreement was encountered between experimentally measured and theoretically calculated rate coefficients. This article also discusses the thermochemical parameters and kinetic branching ratios (BRs) of all the pathways involved in the title reactions.

Influencing factors and kinetics study on the degradation of gaseous ethyl acetate by micro-nano bubbles

As an eco-friendly technology, micro-nano bubbles have gained extensive attention due to their excellent properties. We carried out the experiments to investigate the degradation performance of micro-nano bubbles on ethyl acetate at ambient temperature and pressure. The effects were deeply analyzed by studying the treatment time, initial concentration, and mixed components on ethyl acetate. Treatment time at 30 min had the best results, with a removal efficiency of 86.07 % and a degradation rate of 0.340 ± 0.021 min^-1. With the increase of the initial ethyl acetate concentration, the degradation extent first increased and then decreased. The best efficiency of 94.61% and the maximum reaction rate of 8.79×10^-3 min^-1 were achieved at an initial concentration of 265.6 mg/m³. In addition, ethyl acetate degradation was inhibited by the presence of butyl acetate, and removal efficiency of mixed components was lower than that of single components. The GC-MS results showed that possible intermediates, such as ethanol and acetone, were produced during the decomposition process, which was expected to eventually decompose into CO₂ and H₂O as the reaction progresses. This work presents a new method for the degradation of ethyl acetate and provides valuable information for the degradation of organic matter by micro-nano bubbles.

Kinetics of IO radicals with ethyl formate and ethyl acetate: a study using cavity ring-down spectroscopy and theoretical methods

The gas-phase kinetics of the reactions of IO radicals with ethyl formate (EF) and ethyl acetate (EA) were investigated experimentally using cavity ring-down spectroscopy (CRDS). IO radicals were generated in situ in the CRD reaction zone by photolyzing a mixture of (CH₃I + O₃ + N₂) at 248 nm and thereby probed at 445.04 nm. The rate coefficients for the reactions (IO + EF) and (IO + EA) were measured at a total pressure of 65 Torr of N₂ in the temperature range of 258-358 and 260-360 K, respectively. The rate coefficients for the reactions (IO + EF) and (IO + EA) were measured experimentally at room temperature to be kExpt,298KIO+EF = (3.38 ± 0.67) × 10^-14 and kExpt,298KIO+EA = (1.56 ± 0.30) × 10^-13 cm³ molecule^-1 s^-1, respectively. The effects of pressure and photolysis laser fluence on the kinetics of test reactions were found to be negligible within the experimental uncertainties for the studied range. To complement our experimental findings, the kinetics of the title reactions were investigated theoretically using canonical variational transition state theory (CVT) with small curvature tunnelling (SCT) at the CCSD(T)//M06-2X/def2-SV(P) level of theory in temperatures between 200 and 400 K. Very good agreement was observed between the experimentally measured and theoretically calculated rate coefficients for both the reactions at 298 K. The thermochemical parameters as well as the branching ratios for the title reactions are also discussed in this study.

Investigation of kinetics of phenyl radicals with ethyl formate in the gas phase using cavity ring-down spectroscopy and theoretical methodologies

The gas-phase kinetics of phenyl radical (^·C₆H₅) with ethyl formate (HCO₂Et, EF) was investigated experimentally using ultrasensitive laser-based cavity ring-down spectroscopy (CRDS). Phenyl radicals were generated by photolyzing nitrosobenzene (C₆H₅NO) at 248 nm and thereby probed at 504.8 nm. The rate coefficients for the (phenyl radical + EF) reaction were investigated between the temperatures of 260 and 361 K and at a pressure of 61 Torr with nitrogen (N₂) as diluent. The temperature-dependent Arrhenius expression for the test reaction was obtained as: [Formula: see text]=(1.20  ±  0.16) × 10^-13 exp[-(435.6  ±  50.0)/T] cm³ molecule^-1 s^-1 and the rate coefficient at room temperature was measured out to be: [Formula: see text]=(4.54  ±  0.42) × 10^-14 cm³ molecule^-1 s^-1. The effects of pressure and laser fluence on the kinetics of the test reaction were found to be negligible within the experimental uncertainties. To complement the experimental findings, kinetics for the reaction of phenyl radicals with EF was investigated theoretically using Canonical Variational Transition State Theory (CVT) with Small Curvature Tunnelling (SCT) at CCSD(T)/cc-pVDZ//B3LYP/6-31 + G(d,p) level of theory in the temperatures between 200 and 400 K. The theoretically calculated rate coefficients for the title reaction were expressed in the Arrhenius form as: [Formula: see text]= (1.48  ±  0.56) × 10^-38 × T^8.47 × exp[(2431.3  ±  322.0)/T] cm³ molecule^-1 s^-1 and the corresponding rate coefficient at room temperature was calculated to be: [Formula: see text]= 4.91 × 10^-14 cm³ molecule^-1 s^-1. A very good agreement was observed between the experimentally measured and theoretically calculated rate coefficients at 298 K. Thermochemical parameters as well as branching ratios for the reaction of (phenyl radical + EF) are also discussed in this manuscript.