Hydrogen evolution on a steel surface and subsequent hydrogen diffusion into the steel matrix are evaluated using an electrochemical permeation test with no applied cathodic current on the hydrogen charging side. In particular, cyclic operation in the permeation test is also conducted to clarify the corrosion-induced hydrogen evolution behavior. In contrast to the conventional perception that the cathodic reduction reaction on the steel in neutral aqueous environments is an oxygen reduction reaction, this study demonstrates that atomic hydrogen may be generated on the steel surface by the corrosion reaction, even in a neutral environment. Although a much lower permeation current density and significant slower diffusion kinetics of hydrogen are observed compared to the results measured in acidic environments, they contribute to the increase in the embrittlement index. This study suggests that the research on hydrogen embrittlement in ultra-strong steels should be approached from the viewpoint of corrosion reactions on the steel surface and subsequent hydrogen evolution/diffusion behavior.

The chemical kinetics of steam reforming of polystyrene (PS) and polypropylene (PP) pyrolysis oil were studied using a ruthenium-based catalyst. The experiments were performed in a tubular flow reactor at temperatures of 530-680°C, Weight Hourly Space Velocities (WHSVs) of 0.453-7.916 h−1, and different steam and pyrolysis oil gas-phase concentrations. The activation energy of steam reforming of polypropylene oil and polystyrene oil is 136 and 142 kJ/mol, respectively. The reaction orders of polypropylene and polystyrene oils were 0.42 and 0.37, respectively. Conversions of polypropylene and polystyrene oils were 2.0-50.3 and 1.9-45.3%, respectively. Indeed, a Langmuir-Hinshelwood (LH) mechanism requiring the dissociative adsorption of pyrolysis oil and steam at two different sites on plastics appeared to be the most plausible pathway for the steam reforming reaction.

This study aimed to describe the mechanism and reaction characteristics of the adhered mortar removal of recycled aggregate (RA) using microwave irradiation (700 W) and a mixed solution of HCl and H2O2. The HOCl concentration increased to 29.7 M at 35oC and 40 min of reaction time without RA in the mixed solution, which shows that HCl reacts with H2O2 to form HOCl and water. However, after nitrogen purging, the HOCl concentration decreased to 2.71 M in 20 min, which proves indirectly that HOCl reacts with HCl to form Cl2 and water. The HOCl concentration decreased from 29.7 M to 1.88 M at 35oC in 40 min with RA in the mixed solution, and the Ca2+ concentration increased to 9,750 mg/L, which demonstrates indirectly that mortar mainly composed of Ca(OH)2 reacts with Cl2 to form Ca(OCl)2 and CaCl2. The reaction rate (k) with microwave heating was about 2.3 times faster than that with conventional heating, and k at a reaction temperature of 50oC was about 1.3 times faster than that at 35oC. The treated RA was improved in density, water absorption, abrasion loss, and absolute volume.

The purpose of this study is to explore the time dependant behaviors of chloride ions adsorption with cement hydrates, focused on its mechanism. AFt phase and CH phase were not able to absorb chloride ion, however, C-S-H phase and AFm phase had a significant chloride adsorption capacity. Based on the results, this study suggested theoretical approach to depict chloride adsorption behavior with elapsed time of C-S-H phase and AFm phase effectively. AFm phase showed a slow chemical adsorption in 40 days, while C-S-H phase showed binding behavior with 3 stages including the stage of instantaneous physical adsorption other stages.

In the present study, lab-scale fast pyrolysis reactor (1kg/hr) using lignocellulosic waste biomass was numerically modeledwith various reaction mechanism and the calculation results were compared. Three kinds of reaction mechanisms were appliedsuch as three-step mechanism, two-stage, semi global mechanism and Broido-Shafizadeh mechanism to simulate chemicalreactions in the fast pyrolysis reactor. The fast pyrolysis reactor was modeled as function of mass fraction and reactiontemperature following each reaction mechanism. Especially, the reaction temperature is one of important factors to determinebio-oil yield. Hence, in this study, reaction rates and yield of fast pyrolysis products were compared with varying reactiontemperature for the three kinds of reaction mechanism. The variation of reaction rate for two-stage, semi global mechanismand Broido-Shafizadeh mechanism showed very similar pattern but, three-step mechanism has different trend because theeffect of secondary reaction was missing. The yield of tar was increased before reaching maximum tar yield at 430oC and520oC for two-stage, semi global mechanism and Broido-Shafizadeh mechanism, respectively then decreased as temperaturerises more. But, the yield of tar was increased continuously for three-step mechanism as temperature rises. The yield of non-condensable gas and char was increased as temperature rises for three kinds of reaction mechanisms.

A magenta azomethine dye(D) was synthesized from the reaction of 3-methyl-1-phenyl-2-pyrazoline-5-one with N,N-diethyl-1,4-phenylenediamine. The magenta azomethine dye was identified on the basis of elemental analysis, 13C-NMR, infrared, and GC/MS studies. The magenta azomethine dye was decomposed in a basic solution. Rate constants of the fading reaction of magenta azomethine dye in ethanol-water solvent were measured spectrophotometrically at 540 nm. Reaction rate was increased with the increase of [OH-] and [H2O] in the region of [H2O]= 11～40 M. The reaction was governed by the following rate law. -d[D]/dt = {ko + kOH[OH-][H2O]}[D] A possible mechanism consistent with the empirical rate law has been proposed.