Study on detoxification property of alkaline-modified MoO42--H2O2 decontaminants against PhSMe under subzero environment

The decontaminant activated by MoO42- (MoO42--H2O2) suitable for subzero environment shows strong oxidizing ability and weak nucleophilicity due to its acid. In this paper, in order to improve nucleophilicity and retain oxidation of MoO42--H2O2 as far as possible, NH3 and NaOH were used as alkaline modifiers, and PhSMe was used as a simulant of HD to study the oxidation rate and products of sulfides by alkaline-modified MoO42--H2O2 below zero. Results showed that the reaction rate constants decreased with the increase of pH in both NH3 and NaOH modified MoO42--H2O2 at -20°C, and the relative ratio of sulfone to sulfoxide increased especially at pH>9. The reaction activation energy Ea of PhSMe oxidation in the alkaline-modified MoO42--H2O2 decontaminants was lower than that in the MoO42--H2O2 decontaminant, which indicated that the sensitivity of the oxidation reaction rate to temperature in MoO42--H2O2 was reduced after modification.

Electrochemical Oxidation of 4-Chlorophenol Over a Carbon Paste Electrode Modified with ZnAl Layered Double Hydroxides

A study is presented on the electrochemical oxidation of 4-chlorophenol (4cp) in aqueous solution using a bare carbon paste electrode, CPE, and another one that was modified with ZnAl layered double hydroxides (CPE/ZnAl-LDH). The electro-oxidation was effected at pH values ranging from 3 up to 11. It was found through cyclic voltammetry that this process was irreversible, namely, there were no reduction peaks, and that depending on the nature of the electrode, the anodic current was limited either by adsorption (CPE) or diffusion (CPE/ZnAl-LDH). The energy required and the oxidation reaction rate depended on the pH and on the nature of the electrode, such that the greater rates were obtained when the CPE/ZnAl-LDH electrode and acid pHs were used.

Pulsed corona discharge: the role of ozone and hydroxyl radical in aqueous pollutants oxidation

Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition and treated water contact surface was the objective for the experimental research undertaken for aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were carried out in the reactor, where aqueous solutions showered between electrodes were treated with 100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy efficiency surpassing that of conventional ozonation.

Photo-Oxidation of PVC-Coated Membrane Material

To study photo-oxidation behavior of PVC-coated membrane material under different UV radiation intensities, three intensities of Ultraviolet (UV) irradiation were carried out. The yellowness indexes under different weathering conditions were measured, as well as UV-Vis spectrometry. Result shows that the photo-oxidation mechanism doesn’t change under different UV intensities, but the photo-oxidation reaction rates are not equal when the cumulative UV radiation energy is same. A conclusion is obtained that photo-oxidation reaction rate under different intensities is out of proportion to UV intensity. And according to Schwarzschild’s law, an equation form is established to predict material’s life.

High-Temperature Oxidation Kinetics of Galvalume-Coated Steel Sheet

The high-temperature oxidation kinetics of Galvalume-coated steel sheet and Q235 steel sheet were studied by thermogravimetric analysis (TGA). A new diffusion equation was deduced and used to investigate their kinetic mechanism. The characteristic time (tc) in the equation can be expressed as a function of temperature T, diffusion coefficient D0, thickness of the steel sheet H, etc. The calculated result showed that the oxidation reaction rate of Galvalume-coated steel sheet was slower than that of Q235 steel sheet through comparing the values of tc. Besides, the oxidation reaction rate increased with the temperature rising from 750 to 850 °C. Compared our experimental data with the theoretical value calculated by the new function, a good agreement has been obtained.

Research on Oxidation Reaction of AlN Powder

The process of non-isothermal oxidation of AlN powder (d50=15μm, 5μm and 0.5μm) were studied by TG-DTA and XRD in atmosphere of 80%N2and 20%O2mixture at flowrate of 55ml/min and heating rate of 10 /min. The experimental results reveal that the AlN powder obviously began to be oxidated and its weight increased at 900-1000°С . The process of dynamics of oxidation reaction between AlN and O2was controlled alternately by reaction and diffusion. Non-isothermal oxidation dynamic parameters (activation energy E, reaction orders n and pre-exponential factor A) of d50=5μm AlN powder were obtained by the experimental data. E equals about 417.4kJ/mol, n about 2.9 and A about 3.47×1012. Due to smaller activation energy E and larger pre-exponential factor A in dynamic parameters of AlN powder non-isothermal oxidation, powdery AlN is easily oxidated at high temperature and in air and has a larger oxidation reaction rate. If AlN material with high thermal conductivity characteristics is introduced to prepare composite with high thermal shock resistance, the AlN powder must be treated for oxidation resistance.