• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.196-204
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• 2005

The objective of this study is to evaluate the possibility to apply pre-ozone and membrane system for drinking water. This system is improved in fouling control by pre-ozone system. It is composed of ultrafiltration hollow fiber type membrane and ozone reactor. The result of this study is that the flux is increased about 10.7% and decreased in TMP by the pre-ozone. Also, backwashing pressure decreased about 18%. The optimum concentration of residual ozone is 0.3~0.5 ppm. During the period, the recovery ratio of this system was turned out to be 90% as the flowrate of effluent is $67.1m^3/day$. When the TMP and backwashing pressure was $0.85kg/cm^2$ and $1.10kg/cm^2$, this system was stable without sudden fouling. Finally, the quality of effluent is satisfied the guidelines for potable water quality such as turbidity, color, E.coli, Mn, Al, Fe and so on.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.80-84
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• 1991

Lignocellulosic biomass including acetosolv ricestraw and spruce lignin were liquefied and converted into liquid hydrocarbons by catalytic hydroliquefaction reaction. These experimental works were carried out in 1-liter-capacity autoclave using 50% tetralin and m-cresol solution respectively as soluble solvent and Ni. Pd. Fe and red mud as catalyst. $H_2$ gas was supplied into the reactor for escaltion of deoxhydroenolysis reaction. Catalyst concentrations were 1 % of raw material based on weight. The ratio between raw materials and soluble solvent are 1g and 10cc. The reaction conditions are 400-$700^{\circ}C$ of reaction temperature, 10-50 atms of reaction pressure. The highest yield of hydrocarbon, so called "product oil" showed 32% and 5.5% of lowest char formation when red mud was used as catalyst. The product oil yields from those of other catalysts were in the range of 20-29%. The influence of different initial hydrogen pressures was examined in the range d 30-50 atms. A minimum pressure of 35 atms was necessary to obtain a complete recovery of souble solvent for recycling.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.312-313
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• 2015

무전해 도금은 석출응력이 낮고 작업하기가 용이하기 때문에 산업분야에 있어서 중요한 역할을 한다. 무전해 도금 공정에 있어서, 니켈금속은 차아인산염, 아미노보레인 혹은 수소화붕소 화합물($HBF_4$)에 의한 니켈이온의 화학적 환원에 의해 도금된다. 환원반응이 진행함에 따라서 도금액 중에서 니켈과 차아인산염 이온은 감소한다. 이에 이러한 이온을 보충하기 위하여 도금액 중에 황산니켈과 차아인산나트륨이 일반적으로 첨가된다. 하지만 축적된 인산염, 황산염, 나트륨과 이외의 물질이 전착 박막의 품질을 떨어뜨리고 도금액은 폐기되기도 한다. 니켈회수 속도는 종래의 50% 이하였던 것이 90%이상으로 향상되었다. 이온교환법은 니켈도금 폐액으로부터 니켈회수에 필요한 친환경적이고 원가절감의 기술이라고 사료된다. 특히, 갈탄이 저렴하고 양이온 교환성능이 뛰어나다. 이유는 -COOH, -OH 등의 기능성 그룹을 갖기 때문이다. Fe-P 화합물은 식물에 유용하지 못하고 마그네슘과 칼슘 기반의 석출물은 저렴하고 취급이 용이하며 비료와 같이 재활용이 가능하기 때문에 일반적인 인의 제거 수단이 될 수 있다. 본고에서는 니켈도금 폐액으로부터 인을 제거하는 데 $Ca(OH)_2$, $CaCl_2$와 $CaCO_3$를 채택하여 인이 제거되는 정도를 비교하였고 니켈회수율을 높이기 위하여 갈탄을 사용하였다.

• Korean Journal of Microbiology
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• v.31 no.1
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• pp.54-62
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• 1993

Intracellular adenosine deaminase (ADA) from Aspergillus oryzae was purified using ammonium sulfate fractionation, a DEAE-Sephadex A-50 anion exchange chromatography, an ultrafiltration using a PM 10 membrane and two times of Sephadex G-100 gel filtration chromatography. The enzyme was purified 151 fold with a 9% recovery. Purified enzyme gave a single protein band with a molecular weight of 105,000 delton. The enzyme was reasonably stable. The enzyme activity was kept even after 1 hr incubation at 55.deg.C, but decreased significantly at 60.deg.C. The pH optimum was found to be from 6.5 to 7.5. Among tested compounds, the substrate activity was found with adenosine, adenine arainofuranoside, formymcin A, 2'-deoxyadenosine, 3'-deoxyadenosine, 2', 3'-isopropylidene adenosine, 2,6-diaminopurine deoxyriboside, .betha.-nicotinamide adenine dinucleotide (reduced form), 6-chloropurine riboside, 2'-adenine monophosphate (AMP), 3'-AMP and 5'-AMP. The values of Km of adenosine and 2'-deoxyadenosine were calculated to be 500 and .$710\mu$m, respectively. ADA was sensitivite to $Zn^{2+}$, $^Cu{2+}$ and $Fe^{3+}$, p-chloromercuribenzoate and mersalyl acid inactivated the enzyme. The activity of enzyme was not changed when ADA was incubated with dithiothreititol, 2-mercaptoethanol, N-ethylmaleimide, iodoacetic acid and iodoacetamide.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.43-46
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• 2011

Zinc consumption in a continuous galvanizing line is one of the highest operating cost items in the facility and minimizing zinc waste is a key economic objective for any operation. One of the primary sources of excessive loss of zinc is through the formation of top dross and skimmings in the coating pot. It has been reported that the top skimmings, manually removed from the bath, typically consist of more than 80% metallic zinc with the remainder being entrained dross particles ($Fe_2Al_5$) along with some oxides. Depending on the drossing practices and bath management, the composition of the removed top skimmings may contain up to 2 wt% aluminum and 1 wt% iron. On-going research efforts have been aimed at in-house recovery of the metallic zinc from the discarded top skimmings prior to selling to zinc recycling brokers. However, attempting to recover the zinc entrapped in the skimmings is difficult due to the complex nature of the intermetallic dross particles and the quality and volume of the recycled zinc is highly susceptible to fluctuations in processing parameters. As such, an efficient method to extract metallic zinc from top skimmings has been optimized through the use of a specialized thermo-mechanical process enabling a continuous galvanizing facility to conserve zinc usage on-site. Also, through this work, it has been identified that filtration of discrete dross particles has been proven effective at maintaining the cleanliness of the zinc. Future efforts may progress towards expanded utilization of filters in continuous galvanizing.

• Resources Recycling
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• v.11 no.3
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• pp.31-36
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• 2002

Magnetic separation was carried out in order to improve the magnetite grade of the spent iron oxide catalyst, that was composed with magnetite, ceria and soluble alkaline salt. The recovery of magnetite from the spent iron oxide catalyst was over 99%, and the magnetite contents was upgraded to about 80% from 70% via wet type magnetic separation at 500 Gauss. This improvement was due to the removal of alkaline salt by water instead of the magnetic separation.

• Resources Recycling
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• v.22 no.6
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• pp.26-32
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• 2013

In order to recover Pt from the hydrochloric acid leaching solution of spent catalysts, bench scale Karr reciprocating column was employed. At an optimum flow rate and vibration frequency, iron and Pt was completely extracted by using TBP and Aliquat 336. At the same vibration frequency, iron and Pt was completely stripped by HCl and $HClO_4$ after adjusting the flow rate. In the case of extraction of HCl from the raffinate with TEHA, it was difficult to maintain the stability of the column extractor. A comparison of the operation results between column extractor and mixer-settler is reported.

• Analytical Science and Technology
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• v.20 no.1
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• pp.55-60
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• 2007

A sensitive technique for the determination of trace Cu(II) in various samples after the column preconcentration by adsorbing its N-benzoylphenylhydroxylamine (BPHA) onto benzophenone was developed. Several experimental conditions such as the pH of the sample solution, the amount of chelating agent, the amount of benzophenone, and the flowrate of sample solution and so forth were optimized. The interfering effects of diverse concomitant ions were investigated. Fe(III) and $CN^-$ interfered with more seriously than any other ions. However, the interference by these ions could be overcome sufficiently by adjusting the added volume of 0.01M BPHA to 10 mL. The dynamic range, the correlation coefficient ($r^2$) and the detection limit obtained by this proposed technique were 5.0~120 ng/mL, 0.9974, and 2.1 ng/mL, respectively. For validating this proposed technique, the aqueous samples (stream water, reservoir water, and wastewater), the plastic sample and the diluted brass sample were used. Recovery yields of 93~102% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. This method was also validated by the rice flour CRM (normal, fortified) samples. Based on the results from the experiment, it was found that this proposed technique could be applied to the determination of Cu(II) in various real samples.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.257-264
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• 2006

This study investigated the effects of hybrid process(chemical coagulation, Fenton oxidation and ceramic UF(ultrafiltration)) on COD and color removals of commercial reactive dyestuffs. In the case of chemical coagulation, the optimal concentrations of $Fe^{3+}$ coagulant for COD and color removals of RB49(reactive blue 49) and RY84(reactive yellow 84) were determined according to the different coagulant dose at the optimal pH. They were 2.78 mM(pH 7) in RB49 and 1.85 mM(pH 6) in RY84, respectively. In the case of Fenton oxidation, the optimal concentrations of $Fe^{3+}\;and\;H_2O_2$ were obtained. Optimal $[Fe^{2+}]:[H_2O_2]$ molar ratio of COD and color removals of RB49 and RY84 were 4.41:5.73 mM and 1.15:0.81 mM, respectively. In the case of ceramic UF, the flux and rejection of supernatant after Fenton oxidation were investigated. After ceramic UF for 9 hr, the average flux of RB49 and RY84 solutions were $53.4L/m^2hr\;and\;67.4L/m^2hr$ at 1 bar, respectively. In addition, the permeate flux increased and the average flux recovery were 98.5-99.9%(RB49) and 91.0-97.3%(RY84) according to adopting off-line cleaning(5% $H_2SO_4$). Finally, COD and color removals were 91.6-95.7% and 99.8% by hybrid process, respectively.

• Resources Recycling
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• v.25 no.2
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• pp.33-41
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• 2016

A scale up tests (380 kg/day) using a continuous solvent extraction and electro-winning system was carried out to separate and recover cobalt from a solution containing 1.91 g/L Co and 14.65 g/L Ni. The solution was obtained during a process including solvent extraction and precipitation stages for removal of Cu and Fe from a synthetic sulfuric acid solution of manganese nodule matte. The optimal condition for solvent extraction was : solvent concentration of 0.22M Na-Cyanex 272 (45% saponified with NaOH) and O:A phase ratios of 1:1.5, 10:1 and 1.5:1 used in extraction, scrubbing and stripping stages, respectively. The extraction and stripping efficiencies were found to be 99.8% and 99.88%, respectively. The stripped solution contained 40.27 g/L Co with 4 ppm Ni. Cobalt metal of 99.963% purity was yielded with current efficiency of 67% and current density of $0.563A/dm^2$ during the electro-winning process.