• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.18-23
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• 1992

Three solid acid catalysts developed recently are reviewed. Cloverite is a gallophosphate molecular sieve with very large pore, titanium silicate has a specific structure compared with conventional molecular sieves, and Envirocat is prepared for the replacement of aluminium chloride catalyst.

• Resources Recycling
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• v.25 no.3
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• pp.3-10
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• 2016

The passive treatment was required a large area for the treatment of acid mine drainage (AMD), and pollutants were discharged with mine drainage by the increased flow rate in summer. This study was performed to improve the turbidity and to precipitate the pollutants quickly using coagulants and flocculants in AMD of abandoned mine sites that were difficult to build the passive treatment system. The coagulant PAC (Poly aluminium chloride) and flocculant PAM (Polyacrylamide) were selected to improve turbidity in W mine waters. We also tested the particle size analysis, ICP-OES and/or SEM-EDS for water and sludge samples.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.203-207
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• 2009

The concern of seriousness and harmful effects of environmental pollution is rising by the various water pollutions, appearances of new micro-noxious substances and increase of sustainable pollutants. The method is suggested that can effectively increase the removal of organic substances and several pollutants using a coagulation process. The experiment for characteristics of $ZrSiO_4$ (zirconium silicate) as a coagulation-aid was carried out for application to coagulation process with domestic wastewater and lake water, and the removal rate of the organic substances depending on a dosage was evaluated by PDA (Photometric Dispersion Analyzer) in this study. Zeta-potential of zirconium silicate solution was -32.22 mv at pH 7 and the lower negative(-) charge was detected in the more acidic conditions. Absorbance on $UV_{254}$ presented higher when zirconium silicate was added than in a domestic wastewater itself. Besides, the results by PDA experiment represented that injection of zirconium silicate could promote growing of floc. Tests for coagulation process were conducted by three ways which are pre-injection, co-injection and post-injection of zirconium silicate with alum. Accordingly, removal efficiency of organic substances increased over 15% in co-injection than in using of alum as a sole reagent. When a 20 mg/L of alum was used with a 10 mg/L of zirconium silicate, the removal efficiency was high up to 90%. Removal efficiency of $COD_{Cr}$ was improved more than 15% in case of dosage of coagulant either PAC (Poly aluminium chloride) or PACS (Poly aluminium chloride Silicate) together with zirconium silicate. As a result, the removal efficiency of $COD_{Cr}$ were 5~10% higher in a co-injection of zirconium silicate with a coagulant than a pre-injection and a post-injection but it of soluble substances was lower in a co-injection.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.167-167
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• 2012

Aluminium-zinc-tin oxide (AZTO) 박막 트랜지스터는 Spin-coating 방법으로 제작되었다. AZTO용액의 용매는 2-Methoxyethanol, 용질은 각각 Aluminium nitride, Zinc acetate dihydrate, Tin chloride가 사용되어 제작되었다. 용액의 안정성을 위해서 미량의 Mono ethyl amine이 첨가되었다. 용액의 Zn:Sn의 몰 비율은 1 : 1로 고정 되었으며 Al의 mole비를 다양하게 늘리면서 실험을 진행하였다. 이렇게 만들어진 AZTO용액은 3,000 rpm으로 30초간 Spin-coating하였으며 이후 Furnace system을 통하여 $500^{\circ}C$의 온도로 1시간 동안 후열처리 공정을 진행하였다. AZTO박막을 활성층으로 제작된 박막 트랜지스터는 Al의 비율이 늘어남에 따라 처음엔 이동도가 증가하였으나 이후 이동도가 낮아지며 소자특성이 나빠지는 것을 보였다. 이러한 현상의 원인을 알아보고자 물리적, 전기적, 광학적 분석을 통해서 Al양의 변화가 박막트랜지스터 구동에 미치는 영향을 해석하였다. 먼저 AZTO용액은 열중량측정/시차열분석법(Thermo Gravimetry/Differential Thermal Analysis)을 이용하여 spin-coating 이후 후 열처리 온도 결정 및 박막의 변화를 관찰하였으며, X-선 분광(X-ray photoelectron spectroscopy)을 이용하여 박막의 조성 및 전자구조의 변화를, 타원분광해석법(Spectroscopic Ellipsometry)분석을 통하여 밴드 갭과 전도대 이하 밴드 갭 내에 존재하는 결함상태변화를 관찰하였다. AZTO 박막 내의 Al양을 조절하는 것은 박막내의 에너지 준위의 변화를 야기하고 그로인해 박막트랜지스터의 특성을 변화킨다는 결과를 도출하였다.

• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.311-318
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• 2014

The purpose of this study is to investigate the effect of various types of coagulant on dewaterability and settleability of sewage sludge for the application of dewatering process. Cationic organic coagulants and inorganic coagulants of the aluminium base were used; PAC (Poly Aluminium chloride, $Al_2O_3$ 17%) and C-210P (0.2%). After Jar test, PAC 26 mg/L and 0.2% C-210P 55 mg/L was decided as the optimum concentration of the coagulant according to zeta potential measurement. pH, alkalinity and viscosity were measured in all experiments and the data on sedimentation characteristics is analyzed by SDI, SVI sedimentation rate and solid flux. The SRF(Specific Resistance of Filtration) experiment was conducted with the result of single and dual injection system as the dewaterability experiment. As a result, the organic coagulant making large floc has good characteristics of sedimentation and agglutination. Also, it is observed that the organic coagulants injection has a better dewaterability efficiency of coagulants under the condition of the lowest SRF value, followed by dual and inorganic coagulants injection.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.253-259
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• 2004

The Jeju Island in Korea is the clean area which the tradition culture is preserved locally well with the nature environment of Heaven's blessing. An air pollution is becoming recently serious problem as the industrial development is proceeded with the urbanization. This study investigates that the atmosphere environment at Jeju area influences on the metal corrosion. A study of the atmosphere corrosion for carbon steel, copper, zinc ana aluminium exposed on five test sites indoors and outdoors. Corrosion results are treated statistically and adjusted to a model previously proposed for carbon steel, copper, zinc and aluminium based on the influence of environmental parameters and main pollutants($SO_2$ and chlorides) on tire atmosphere corrosion of metals. Through this study, we try to set the standards atmosphere corrosion at Jeju Island.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2321-2327
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• 2015

Three coagulants, alum sulfate(alum), poly aluminum chloride(PAC) and poly aluminum silicate chloride (PASC), were used to remove low to high turbidity and TOC in surface and ground blended water. Laboratory experiments and pilot plant experiments were carried out to evaluate the optimal coagulant and its dosage. To determine the optimized coagulant and its dosage, the turbidity, TOC and pH were measured. The experimental results showed the best removal performance using PASC. The optimal dosage of PASC between 3-20 NTU was found to be 15 mg/L in the jar test. In the pilot test, a 15 mg/L PASC dosage was applied and resulted in the efficient removal of turbidity and TOC between 3.6-27 NTU. The removal efficiency of PASC increased with increasing turbidity and TOC.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.425-438
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• 2016

This study carried out zeta potential measurements of the Microcystis sp. under various solutions condition and investigated the characteristics of Microcystis sp. through the size control of microbubbles to eliminate algae that causes problems in aquatic ecosystems and human activities. DAF process was adopted and several coagulants were used to remove the Microcystis sp. CCD Camera was used to measure and analyze the size of microbubble, and fluorescent microscope was used to observe the particle, algae species and community. Zeta potential behavior of the algae was analyzed by using ELS-Z. Lab-scale and pilot-scale experiments were conducted to test flotation process. Polyaluminium chloride(PAC) coagulant was used, and the removal efficiency of the algae was assessed through Chlorophyll-a analysis. In the Lab-scale experiment, 2.2 ppm, 11 ppm, 22 ppm, and 44 ppm of polyaluminium chloride was injected to coagulate the algae. The coagulated algae was floated by the microbubble. The microbubbles in the experiments were generated at a air pressure of 450 ~ 550 kPa. The microbubble size was controlled in $36{\mu}m$, $100{\mu}m$, and $200{\mu}m$, respectively by using different diffuser. The results of lab-scale experiments on flotation plant indicated that the average removal rate was about 90% or above for 11 ppm, 22 ppm, and 44 ppm of polyaluminium chloride. On the other hand, in the pilot-scale experiment, the removal efficiency was in the range of 85% to 95% in all dose ranges of polyalumium chloride and aluminium sulfate coagulants.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.523-532
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• 2010

Co-application of organic coating and cathodic protection has not provided enough durability to low-alloyed steels inseawater ballast tank (SBT) environments. An attempt has made to study the effect of alloy elements (Al, Cr, Cu, Mo, Ni, Si, W) on general and localized corrosion resistance of steels as basic research to develop new low-allowed steels resistive to corrosion in SBT environments. For this study, we measured the corrosion rate by the weigh loss method after periodic immersion in synthetic seawater at $60^{\circ}C$, evaluated the localized corrosion resistance by an immersion test in concentrated chloride solution with the critical pH depending on the alloy element (Fe, Cr, Al, Ni), determined the permeability of chloride ion across the rust layer by measuring the membrane potential, and finally, we analyzed the rust layer by EPMA mapping and compared the result with the E-pH diagram calculated in the study. The immersion test of up to 55 days in the synthetic seawater showed that chromium, aluminium, and nickel are beneficial but the other elements are detrimental to corrosion resistance. Among the beneficial elements, chromium and aluminium effectively decreased the corrosion rate of the steels during the initial immersion, while nickel effectively decreased the corrosion rate in a longer than 30-day immersion. The low corrosion rate of Cr- or Al-alloyed steel in the initial period was due to the formation of $Cr_2FeO_4$ or $Al_2FeO_4$, respectively -the predicted oxide in the E-pH diagram- which is known as a more protective oxide than $Fe_3O_4$. The increased corrosion rate of Cr-alloyed steels with alonger than 30-day exposure was due to low localized corrosion resistance, which is explained bythe effect of the alloying element on a critical pH. In the meantime, the low corrosion rate of Ni-alloyed steel with a longer than 30-day exposure wasdue to an Ni enriched layer containing $Fe_2NiO_4$, the predicted oxide in the E-pH diagram. Finally, the measurement of the membrane potential depending on the alloying element showed that a lower permeability of chloride ion does not always result in higher corrosion resistance in seawater.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.197-202
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• 2003

Phosphorus is one of the major plant growth limiting nutrients, despite being abundant in soils in both inorganic and organic forms. Phosphobioinoculants in the form of microorganisms can help in increasing the availability of accumulated phosphates for plant growth by solubilization. Penicillium oxalicum CBPSTsa, isolated from paddy rhizosphere, was studied for its phosphate solubilization. The influence of various carbon sources like glucose, sucrose, mannitol and sorbitol and nitrogen sources like arginine, sodium nitrate, potassium nitrate, ammonium chloride and ammonium sulphate were evaluated using liquid media with tricalcium phosphate (Ca-P), ferric phosphate (Fe-P) and aluminium phosphate (Al-P). Maximum soluble phosphate of 824 mg/L was found in the amendment of sucrose-sodium nitrate from 5 g/L of Ca-P. Mannitol, sorbitol, and ariginine were poor in phosphate solubilization. While sucrose was better carbon source in solubilization of Ca-P and Al-P, glucose fared better in solubilization of Fe-P. Though all the nitrogen sources enhanced P solubilization, nitrates were better than ammonium In the amendments of ammonium chloride and ammonium sulphate, higher uptake of available phosphates by the fungus was found, and this resulted in depletion of available P in Fe-P amendment Phosphate solubilization was accompanied by acidification of the media, and the highest pH decrease was observed in glucose amendment Among the nitrogen sources, ammonium chloride favored greater pH decrease.