• Applied Chemistry for Engineering
• /
• v.21 no.2
• /
• pp.183-187
• /
• 2010

Activated carbons (ACs) have been prepared from pitch by the combination of a chemical oxidation with different $H_2O_2$ concentrations i.e., 5, 15, and 25 wt% and a chemical activation with KOH at a constant KOH/pitch ratio of 3/1. The influence of $H_2O_2$ solution on the microporous properties of the pitch and the final activated carbons were invested using XRD, FT-IR, XPS, $N_2$-adsorption, and SEM. XRD indicated that the value of interplanar distance $d_{002}$ increased by chemical oxidation. FT-IR and XPS results showed that the chemical oxidation promoted the formation of surface oxygen functionalities. Also, the specific surface area of the resulting ACs was increased with increasing the concentration of $H_2O_2$ chemical oxidation and showed a maximum value of $2111m^2/g$ at 25 wt% $H_2O_2$ concentration.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.6
• /
• pp.1665-1668
• /
• 2010

The spin exchange interactions of $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$ were examined by spin dimer analysis based on extended Huckel tight binding method. The strongest spin exchange interaction occurs through the super-superexchange path $J_2$ and the second strongest spin exchange interaction occurs through the superexchange interaction path $J_1$. There are two strongly interacting spin exchange paths in $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$. Therefore, magnetic susceptibility curve of $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$ can be well reproduced by an alternating onedimensional antiferromagnetic chain model rather than an isolated spin dimer model.

• Resources Recycling
• /
• v.11 no.2
• /
• pp.3-13
• /
• 2002

The characteristics of cyanide decomposition in aqueous phase by hydrogen peroxide have been explored in an effort to develop a process to recycle waste water. The self-decomposition of $H_2O$$_2$at pH 10 or below was minimal even in 90 min., with keeping about 90% of $H_2O$$_2$undissociated. On the contrary, at pH 12 only 9% of it remained during the same time. In the presence of copper catalyst at 5 g Cu/L, complete decomposition of $H_2$O$_2$was accomplished at pH 12 even in a shorter time of 40 min. The volatility of free cyanide was decisively dependent on the solution pH: the majority of free cyanide was volatilized at pH 8 or below, however, only 10% of it was volatilized at pH 10 or above. In non-catalytic cyanide decomposition, the free cyanide removal was incomplete in 300 min. even in an excessive addition of $H_2$$O_2$at a $H_2$$O_2$/CN molar ratio of 4, with leaving behind about 8% of free cyanide. On the other hand, in the presence of copper catalyst at a Cu/CN molar ratio of 0.2, the free cyanide was mostly decomposed in only 16 min. at a reducedH202/CN molar ratio of 2. Ihe efnciency of HBO2 in cyanide decomposition decreased with increasing addition of H2O2 since the seu-decomposition rate of $H_2$$O_2$increased. At the optimum $H_2$$O_2$/mo1ar ratio 0.2 of and Cu/CN molar ratio of 0.05, the free cyanide could be completely decomposed in 70 min., having a self-decomposition rate of 22 mM/min and a H$_2$$O_2$ efficiency of 57%.

• Analytical Science and Technology
• /
• v.18 no.2
• /
• pp.112-119
• /
• 2005

This study reports on the efficiency of cleaning enameled magnet wire using a sulfuric acid $H_2SO_4$ and removal of dissolved organic material using hydrogen peroxide $H_2O_2$ and nitric acid $HNO_3$ at $80^{\circ}C$. The method involves the addition of pure $H_2SO_4$ and $H_2O_2$ or $HNO_3$. Layers of enameled organic material were dissolved by 90% $H_2SO_4$ and the solution was maintained as 35% $H_2O_2$ or 60% $HNO_3$. $H_2O_2$ content in aqueous $H_2O_2$ was maintained as 8.8 : 1.0. An initial concentration of $H_2SO_4$ in dissolution conditions was accomplished within 15 min, with a stripping time of about 2 h. The concentrations of $H_2O_2$ and $HNO_3$ in the processing bath were relatively low, but sufficient enough to produce an effective amount of power in the bath for the removal of the enamel material. The cleaning effect of enameled organic material involves the dehydration by $H_2SO_4$ and the oxidation by $H_2O_2$ or $HNO_3$.

• Journal of Soil and Groundwater Environment
• /
• v.7 no.1
• /
• pp.25-31
• /
• 2002

This study attempts to elucidate the possibility of treating landfill leachate by steelers' dust/${H_2}{O_2}$ system in a well-mixed batch reactor. Experiments were conducted to investigate the effects of operating variables such as pH, dust and ${H_2}{O_2}$ dosages and ${H_2}{O_2}$ injection method on the treatment efficiency, Contaminant concentrations were identified by TOC (Total Organic Carbon) analyzer. Experimental observations showed the possibility of steelers' dust as a catalytic reagent in the ${H_2}{O_2}$/dust system. The batch experiments showed that the optimal $H_2O$$_2$ and dust dosage, 20g/L dust. 2,000mg/L ${H_2}{O_2}$ removed about 75% of initial TOC concentration (250mg/1) within 60 min. And the TOC removal in the ${H_2}{O_2}$/dust system effectively proceeded only within a limited pH range of 3-4. The stealers' dust-catalyzed oxidative treatment of landfill leachate was more efficient compared with the $FeSO_2$catalyzed system (Fenton oxidation) for the removal rate and the cost.

• Journal of the Korean Ceramic Society
• /
• v.27 no.5
• /
• pp.638-644
• /
• 1990

The C3H8 gas sensitivities of SnO2, Pd-SnO2, Pt-SnO2 gas sensor are looked over with the impregnation method of PdCl2, H2PtCl6 solution on SnO2. The Cl- ion due to incomplete decomposition of PdCl2 at 80$0^{\circ}C$ for 30 min decrease the C3H8 gas sensitivity of SnO2, and the sensitivity is increased by the impreganation of H2PtCl6 solution on SnO2 because of its lower decomposition temperature compared with PdCl2. The C3H8 gas sensitivities of Pd-SnO2, Pt-SnO2 impregnated slightly after 1st sintering are larger than that of pure SnO2 sensor because very small amount of Cl- ion exist in sample due to smaller amount of impregnaiton.

• Journal of Environmental Science International
• /
• v.12 no.7
• /
• pp.775-782
• /
• 2003

The photodegradations of pyrene, chrysene and benzo[a]pyrene that were similar in structure among polycyclic aromatic hydrocarbons (PAHs) were investigated with a low-pressure mercury lamp(the wavelength of 253.7 nm and UV output of 1.35${\times}$10$\^$-3/J/s). The optimum concentrations of TiO$_2$ and H$_2$O$_2$ on the photodegradation of pyrene, chrysene and benzo[a]pyrene were 1 g/L and 1.5${\times}$10$\^$-3/ M, respectively. By these optimum concentrations, their rates increased with increasing the concentration of TiO$_2$ and H$_2$O$_2$ because the amounts of OH radical formed increased, but for the higher concentrations than the optimum, their rates decreased with increasing those concentrations because the white turbidity phenomena occurs in case of TiO$_2$ and H$_2$O$_2$ acts as an OH radical inhibitor. The photodegradation rates among the photodegradation processes such as UV, UV/TiO$_2$, UV/H$_2$O$_2$, and UV/H$_2$O$_2$/TiO$_2$ decreased in the following sequences.: UV/H$_2$O$_2$/TiO$_2$> UV/H$_2$O$_2$> UV/TiO$_2$> UV.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.1
• /
• pp.100-109
• /
• 2016

In this study, the NO oxidation using dry oxidant produced by catalytic $H_2O_2$ conversion was conducted. It was shown that Mn-based $Fe_2O_3$ support catalyst has the best performance in the catalytic $H_2O_2$ conversion and its combined-NO oxidation. The reaction characteristics of NO oxidation was investigated by the various operation conditions such as $H_2O_2$ amount, oxidation temperature and space velocity. As a results, the oxidation efficiency of NO greatly depends on the oxidation reaction temperature, $H_2O_2$ amount and space velocity. The performance of NO oxidation was increased with increasing the oxidation temperature and $H_2O_2$ amount. Also, the performance of NO oxidation was decreased with increasing the space velocity.

• Journal of the Korean GEO-environmental Society
• /
• v.7 no.4
• /
• pp.5-13
• /
• 2006

This study was conducted to evaluate the application of $UV/TiO_2/H_2O_2$ process for treating humic acid and heavy metals in surface water. Removal efficiency of $UV/TiO_2/H_2O_2$ process was much more efficient than that of $UV/TiO_2$ process for humic acid and heavy metals removal. The removal rate of humic acid and heavy metals increased with the increase of $TiO_2$ dosage and UV intensity, however decreased with more than 0.3 g/L of $TiO_2$ dosage. The addition of $H_2O_2$ as an oxidant was a positive effect for the removal rate of humic acid and heavy metals especially in the concentration of 50 mg/L $H_2O_2$.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05b
• /
• pp.186-191
• /
• 1998

$UO_2$-5wt%CeO$_2$ 분말에서 소결온도(1600, 1$700^{\circ}C$), 소결분위기(H$_2$, $N_2$-7vol.%H$_2$) 및 Li$_2$O 첨가량(0.05-2wt%)에 따른 소결성의 변화를 관찰하였다. $UO_2$-5wt%CeO$_2$를 attrition mill에서 2 시간까지 분쇄한 후, 1$700^{\circ}C$에서 H$_2$, N2-7vol.%H$_2$ 분위기에서 소결하면 소결밀도가 각각 10.46, 10.36 g/㎤이지만, 각 분위기에서 소결체내의 결경립크기가 일정하지 않고 Ce agg1omerate도 소결체내의 여러 곳에 분포되어 있어 분말처리만으로 소결성을 개선하는데는 한계가 있었다. 반면에, $UO_2$-5wt%CeO$_2$에 0.lwt%Li$_2$O를 첨가하여 1 시간동안 분쇄란 후, 1$600^{\circ}C$에서 H$_2$$N_2$-7vol.%H$_2$ 분위기로 소결하면 밀도는 각각 10.51, 10.48 g/㎤이었고, 결정립크기는 각각 8.9, 42.1 $\mu\textrm{m}$이었다. 즉, Li$_2$O의 첨가에 의해 밀도와 결정립크기가 모두 증가했으며, H$_2$ 분위기보다는 $N_2$-7vol.%H$_2$ 분위기에서 결정립이 더 크게 성장하였고, 1$700^{\circ}C$에서도 유사한 경향을 나타내었다. $UO_2$-5wt%CeO$_2$와 이 조성에 0.lwt%Li$_2$O를 첨가한 분말들을 H$_2$ 및 $N_2$-7vol.%H$_2$ 분위기에서 소결하여 기공크기 및 기공부피의 변화를 관찰한 결과, H2 분위기에서 소결하였을 때는 Li$_2$O의 첨가에 의해 치밀화가 주로 일어났고, 반면에 $N_2$-7vol.%H$_2$ 분위기에서 소결하면 Li$_2$O의 첨가에 의해 작은 기공은 소멸되고 큰 기공이 생성되었다.