• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1683-1685
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• 2003

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1075-1077
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• 2004

• Corrosion Science and Technology
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• v.7 no.6
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• pp.315-318
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• 2008

The atmospheric corrosion performance of Al-alloying, Si-alloying and Al-Si-alloying steel were studied by wet/dry cyclic corrosion tests (CCT) at $30^{\circ}C$ and 60% relative humidity (RH). The corrosion electrolyte used for CCT was 0.052 wt% $NaHSO_{3}$ (pH~4) solution. The result of gravimetry demonstrated that Al-Si-bearing steels showed lower corrosion resistance than other rusted steels. But the rusted 0.7%Si-alloying steel showed a better corrosion resistance than rusted mild steel. Polarization curves demonstrated that Al-/Si-alloying and Al-Si-alloying improved the rest potential of steel at the initial stage; and accelerated the cathodic reduction and anodic dissolution after a rust layer formed on the surfaces of steels. XRD results showed that Al-Si-alloying decreased the volume fraction of $Fe_{3}O_{4}$ and $\alpha-FeOOH$. The recycle of acid accelerated the corrosion of steel at the initial stage. After the rust layer formed on the steel, the leak of rust destabilized the rust layer due to the dissolution of compound containing Al (such as $FeAl_{2}O_{4}$, $(Fe,\;Si)_{2}(Fe,\;Al)O_{4}$). Al-Si-alloying is hence not suitable for improving the anti-corrosion resistance of steel in industrial atmosphere.

• Journal of the Korean institute of surface engineering
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• v.13 no.1
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• pp.8-15
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• 1980

The critical voltage of hard coat range of Al alloys (K 186, 43S) at various electrolytes and the effects of voltage, temperature of electrolytes and concentration of sulfric acid were investigated, m the hope that to find the adequate voltage. Two kind of A1 alloys were anodized in three typical electrolytes and micro vickers hardness of the films were measured. With respect to the relationship between the hardness of the film and the voltage The result of this experiment are as fallows. 1. The critical voltage of hard coat rangs for the electrolytes $H_2SO_4\;10%,\;H_2SO_4\;10%\;+\;H_2C_2O_4\;2H_2O\;10g/l,\;H_2SO_4\;10%\;+\;NaHSO_4\;5%$ was 20V 22V 24V respectively. 2. $H_2SO_4\;10%\;+\;NaHSO_4$ 5% electrolyte was most adventageous among the three electrolyte in the respect of hardness. 3. The effect of concentration of sulphuric acid was not appeared.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.19-25
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• 2010

Traditional Kr$\ddot{o}$ger-Vink (K-V) notation defines sites in ionic crystals as interstitial or belonging to host ions. It enables description and calculations of combinations of native and foreign defects, including dopants and substituents. However, some materials exhibit inherently disordered partial occupancy of ions and vacancies, or partial occupancy of two types of ions. For instance, the high temperature disordered phases of $Bi_2O_3$, $Ba_2In_2O_5$, $La_2Mo_2O_9$, mayenite $Ca_{12}Al_{14}O_{33}$, AgI, and $CsHSO_4$ are all good ionic conductors and thus obviously contain charged point defects. But traditional K-V notation cannot account for a charge compensating defect in each case, without resorting to terms like "100% substitution" or "Frenkel disorder". the former arbitrary and awkward and the latter inappropriate. Instead, a K-V compatible nomenclature in which the partially occupied site is defined as the perfect site, has been proposed. I here introduce it thoroughly and provide a number of examples.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.671-678
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• 2000

Reaction characteristics of simultaneous removal of SOx and NOx have been investigated in a thermogravimetric analyzer and tubular fixed bed reactor using the $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst. Sulfur removal capacity of $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst is largely enhanced above both the temperature of $450^{\circ}C$ and the loading of 6wt% due to the participation of alumina support in a sulfation reaction. The NO reduction efficiency of 8wt% $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst shows the maximum value at $370^{\circ}C$ and then decreases with the increase of reaction temperature due to the oxidation of $NH_3$ gas. The presence of sulfate on the surface of sorbent/catalyst enhances the optimum reaction temperature showing the maximum deNOx efficiency. In the simultaneous removal of SOx and NOx at $250^{\circ}C$. deNOx activity of $CuO/{\gamma}-Al_2O_3$ sorbent/catalyst is rapidly decreased due to the formation of ammonium salts such as $NH_4HSO_4$. In the simultaneous removal reaction of SOx and NOx, the optimum temperature showing the maximum deNOx efficiency increases to $400^{\circ}C$ due to the presence of $SO_2$ gas.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.321-322
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• 2001

대기중 과산화수소($H_2O$$_2$)는 기상과 액상에서 peroxy radicals 간의 결합 (HO$_2$ㆍ+ HO$_2$ㆍ $\longrightarrow$$H_2O$$_2$+O$_2$)에 의해 생성된다. 만약 수소 원자 하나가 organic group으로 치환되면 organic peroxides가 생성된다(Calvert et al., 1985). 이러한 과산화수소($H_2O$$_2$)와 methylhydroperoxide(MHP, $CH_3$COOH), hydroxymethylhydroperocide(HMHP, HOC$H_2O$OH)등의 organic peroxides는 대기 중에서 주요 산화제로 작용한다. 이들 peroxide 물질들은 pH 5 이하의 aqueous phase (cloud, fog and rain water)에서 sulphuric acid (HSO$_4$$^{2-}$ ) 형성에 중요한 역할을 한다(Calvert et al., 1985). (중략)

• Membrane and Water Treatment
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• v.13 no.2
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• pp.105-110
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• 2022

Al₂O₃ positively charged nanofiltration composite membrane was successfully prepared with aluminate coupling agent (ACA) as modifier, sodium bisulfite (NaHSO₃) and potassium persulfate (K₂S₂O₈) as initiator and methacryloyloxyethyl trimethylammonium chloride (DMC) as crosslinking monomer. The surface of the membrane before grafting and after polymerization were characterized by SEM and FT-IR. Three factor and three-level orthogonal experiments were designed to explore the optimal conditions for membrane preparation, and the optimal group was successfully prepared. The filtration experiments of different salt solutions were carried out, and the retention molecular weight was determined by polyethylene glycol (PEG). The results showed that the polymerization temperature had the greatest effect on the rejection rate, followed by the reaction time, and the concentration of DMC had the least effect on the rejection rate. The rejection rates of CaCl₂, MgSO₄, NaCl and Na₂SO₄ in the optimal group were 83.8%, 81.3%, 28.1% and 23.6% (average value), respectively. The molecule weight cut-off of 90% (MWCO) of the optimal group was about 460, which belongs to nanofiltration membrane.

• Clean Technology
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• v.20 no.2
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• pp.108-115
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• 2014

Various metal chlorides and acid catalysts in ionic liquid solvent were investigated to directly convert cellulose into 5-hydroxymethylfurfural (5-HMF). Metal chlorides containing Sn(II), Zn(II), Al(III), Fe(III), Cu(II), and Cr(III) were used and acidic ionic liquid immobilized on silica gel as an acid catalyst and commercial acid catalysts (sulfuric acid, chloric acid, Amberlyst-15,DOWEX50x8) were used for comparison studies. The acid strength and amount of acid catalysts were probed with Hammett indicator. The selectivity and yield of 5-HMF were determined with reaction temperature, reaction time and catalyst ratio. A catalyst containing $CrCl_3-6H_2O$ and $SiO_2-[ASBI]HSO_4$ showed the highest selectivity and it was found that this catalyst had higher activity than commercial solid acid catalysts such as Amberlyst-15 and DOWEX50x8. The selectivity of 5-HMF appeared to be mainly dependent on the acid strength and catalyst ratio, it was found that levulinic acid was produced from 5-HMF by rehydration.