• Korean Chemical Engineering Research
• /
• 제45권6호
• /
• pp.554-559
• /
• 2007

본 연구에서는 메탄올과 이산화탄소를 이용한 디메틸카보네이트(dimethyl carbonate, 이하 DMC) 의 직접 합성에서 수율 증대를 위하여 주입된 다양한 첨가제의 영향을 살펴보았다. 그리고 첨가제의 주입과 동시에 반응조건을 달리하여 얻어진 반응특성을 살펴봄으로써 필요한 반응조건의 최적화를 살펴보았다. Citric complexation method에 의해 제조된 복합금속산화물 $Ce_{1-x}Zr_xO_2$ 촉매들 가운데, 가장 높은 성능을 지니고 있는 $Ce_{0.8}Zr_{0.2}O_2$ 촉매가 DMC 합성에서 사용되었다. 황산염(sulfate) 계열, 질산염(nitrate) 계열, 인산염(phosphate) 계열 및 제올라이트 등의 다양한 첨가제가 사용된 가운데 DMC 생성량의 변화가 관찰되었다. 그 결과, $-SO_4$를 지니는 황산염 계열의 $K_2SO_4$ 및 $Na_2SO_4$ 등의 첨가제가 $Ce_{0.8}Zr_{0.2}O_2$ 촉매와 함께 사용됨으로써 가장 높은 DMC 생성량을 얻었다. 기존의 첨가제 없이 $Ce_{0.8}Zr_{0.2}O_2$ 촉매가 사용된 경우, 약 0.6 mmol의 DMC 생성량을 얻을 수 있었으며, $K_2SO_4$ 첨가제가 동시에 주입된 경우 가장 높은 0.91 mmol의 향상된 DMC 생성량을 얻었다.

• Journal of Pharmaceutical Investigation
• /
• 제31권2호
• /
• pp.81-87
• /
• 2001

The purpose of this study was to investigate the effect of additives on the powder characteristics of peonja dry elixir. Peonja dry elixirs were prepared with various amounts of dextrin using a spray-dryer, and their powder characteristics such as flow, cohesion and compressibility were evaluated as an angle of repose, cohesion index and compressibility index, respectively. Their powder characteristics were not significantly different from one another, indicating that the hydrophilic dextrin, a base of dry elixir hardly affected their powder characteristics. Peonja dry elixirs were prepared with 10% dextrin and various amounts of additives such as mannitol (hydrophilic excipient), sodium lauryl sulfate (surfactant), colloidal silica (hydrophobic excipient) and HPMC (polymer), respectively, and their angle of repose, cohesion index and compressibility index were measured. The powder characteristics of peonja dry elixirs prepared with mannitol were not significantly different from one another, indicating that the mannitol scarcely improved the powder characteristics of peonja dry elixirs. The angle of repose and cohesion index of peonja dry elixirs significantly decreased with increasing amount of sodium lauryl sulfate to 0.3% followed by no significant changes in them. The cohesion index of peonja dry elixir significantly decreased with increasing amount of colloidal silica. The angle of repose and cohesion index of peonja dry elixir significantly decreased with increasing amount of HPMC to 0.3% followed by an abrupt increase in them. However, the compressibility index of peonja dry elixir significantly increased with increasing amount of HPMC to 0.3% followed by an abrupt decrease in them. Our results suggested that a small amount of sodium lauryl sulfate, colloidal silica and HPMC improved markedly the powder characteristics of peonja dry elixirs due to forming stronger and less hygroscopic shell of peonja dry elixirs. Among the peonja dry elixirs studied, the peonja dry elixir prepared with 0.3% sodium lauryl sulfate and 0.3% HPMC had the lowest angle of repose of $27^{\circ}$ and cohesion index of 37.8%, and the highest compressibility index of 38.7%, respectively. Thus, sodium lauryl sulfate and HPMC appear to be promising additives for peonja dry elixir, if used in adequate amounts.

• 한국환경과학회지
• /
• 제18권7호
• /
• pp.811-817
• /
• 2009

To determine changes in nitrogen contents and optimal rates as N fertilizer, we investigated nitrogen characteristics in the slurry in the respond to the application of 0, 0.5, and 1 g of ferrous sulfate or alum /25g of dairy slurry. Additions of ferrous sulfate or alum increase total nitrogen, inorganic nitrogen, available nitrogen, and predicted available nitrogen contents in dairy slurry, resulting in reduction in pH. The best results were found in the treatment with 0.5 g of ferrous sulfate or alum /25 g of dairy slurry. In conclusion, the use of ferrous sulfate or alum as on-farm amendment to dairy slurry should be represented an alternative to improve N in dairy slurry.

• 한국표면공학회지
• /
• 제42권5호
• /
• pp.191-196
• /
• 2009

Nanocrystalline Cu thin films were electrodeposited from sulfate baths and investigated systematically the influences of $Cu^{2+}$ concentration and additives on current efficiency, residual stress, surface morphology, and XRD patterns of electrodeposited Cu film. Current efficiency was nearly 100% at from 0.2M to 1.0 M $Cu^{2+}$ concentration. but it was linearly increased with $Cu^{2+}$ concentration at less than 0.2M. The residual stress was observed in range of 7.9 to 18.4 MPa and tensile stress mode. Dendritic and powdered form was obtained at below 0.1 M. As increased with $Cu^{2+}$ concentration in solution, the main peak in the XRD pattern shifted (111) and (220) from (200). In the other hand, all about 100% current efficiency observed in all additive concentration systems, and residual stress observed in range of 20.4 to 26.3 MPa tensile stress. The condition 5(Ultra make-up - 10 ml/l, Ulta A - 0.5ml/l, Ultr B - 0.5 ml/l) was good surface morphology, and fcc(111) peak in XRD patterns increased with increasing additive concentration.

• 펄프종이기술
• /
• 제37권3호
• /
• pp.59-65
• /
• 2005

There are accumulations of remained chemical additives and contaminants in the process water of semi-closed linerboard mill. High temperature of the process water aggravates the anaerobic digestion of contaminated process water and causes the generation of hazardous gases, which are from the biological reaction of varied additives and contaminants. The hydrogen sulfide in the gases easily combine with moisture in the air, and become sulfuric acid, which causes corrosion of paper machinery. This hydrogen sulfide is from the reduction of sulfate ions in the process water, and the sulfate ions are mostly from the alum. We changed the alum to PAC (Poly Aluminum Chloride). The results were preventing generation of hydrogen sulfide, and equivalent sizing effect by the use of PAC.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2001년도 춘계학술발표강연 및 논문개요집
• /
• pp.35-35
• /
• 2001

• 열처리공학회지
• /
• 제37권1호
• /
• pp.16-22
• /
• 2024

The conventional degreasing process involves removing oil and contaminants at temperatures above 80℃, resulting in excessive energy consumption, increased process costs, and environmental issues. In this study, we aimed to find the optimal degreasing conditions for the pre-treatment process of electro-galvanizing cold-rolled steel sheets, conducted efficiently at room temperature without the need for a separate heating device. To achieve this, we developed a room temperature degreasing solution and a brush-type degreasing tool, aiming to reduce energy consumption and normalize the decrease in degreasing efficiency caused by temperature reduction. Alkaline degreasing solution were prepared using KOH, SiO₂, NaOH, Na₂CO₃, and Sodium Lauryl Sulfate, with KOH and NaOH as the main components. To enhance the degreasing performance at room temperature, we manufactured additives including sodium oleate, sodium stearate, sodium palmitate, sodium lauryl sulfate, ammonium lauryl sulfate, silicone emulsion, and EDTA-Na. Room temperature additives were added to the alkaline degreasing solution in quantities ranging from 0.1 to 20 wt.%, and the uniformity of degreasing and the adhesion of the galvanized layer were evaluated through Dyne Test, T-bending Test, OM, SEM, and EDS analyses. The results indicated that the optimal degreasing solution composition consisted of NaOH (30 g/L), Na₂CO₃ (30 g/L), SLS (6 g/L), and room temperature additives (≤1 wt%).

• 환경위생공학
• /
• 제16권2호
• /
• pp.79-90
• /
• 2001

Commercial liquid seeds are used for supplying active microbial flora to organic wastewater treatment plants of high feed-to-microorganism ratio and to maintain optimal microbial condition during unsteady state operation of the biological wastewater treatment plant. In addition to bacterial cells, the liquid weeds contain various additives for special purposes as well as organic substrates for energy supply. The additives give physical stability for the maintenance of microbial decomposition activity and ability to control the overgrowth of seed strains. In this work, the effects of addition of two kinds of typical substrate additives, poly aluminum chloride(PAC) and poly aluminum sulfate(PAS) on the consitutional total cell counts(CFU/ml) of four kinds of reorganization liquid seeds(RLS I, RLS II, RLS III and RLS IV) were studied experimentally. The addition of PAC and PAS gave negative effect on TCC constitution for the four seeds studied.

• 한국표면공학회지
• /
• 제36권5호
• /
• pp.393-397
• /
• 2003

The effects of the composition and additives on the blackening and deposition rate of electroless Ni-Zn plating have been examined. Hydrazine resulted in lower sheet resistance of the deposit than sodium hypophosphite. Zinc concentration more than 15 wt% and small amount of ammonium sulfate in the deposits were needed in obtaining Ni-Zn deposit with a black color. An optimum condition was obtained for the black Ni-Zn deposit at an appreciable deposition rate.

• 공업화학
• /
• 제8권6호
• /
• pp.1041-1047
• /
• 1997

$\omega$-Phenylalkylamine salt의 존재하에서 sodium dodecyl sulfate (SDS)의 임계 미셀농도(CMC)를 전기전도도법으로 구하였다. 유기염의 alky기의 길이가 길어짐에 따라 CMC는 감소하는 경향을 보여주었다. 유기첨가제의 존재하에서 $18^{\circ}C-50^{\circ}C$의 온도 범위에서 SDS의 미셀화 과정에 수반되는 열역학적 파라메터를 구하였다. 이 온도 범위에서 SDS의 미셀화 자유에너지 (${\Delta}G_m^{\circ}$)는 음의 값을 나타내며 미셀화 엔트로피(${\Delta}S_m^{\circ}$)는 큰 양의 값을 나타내었으며 미셀화 엔탈피(${\Delta}H_m^{\circ}$)는 낮은 온도($18^{\circ}C$)에서는 양의 값을 나타내지만 높은 온도($>25^{\circ}C$)에서는 음의 값을 나타내었다. 미셀화는 자발적인 상전이 현상임을 알 수 있었다. 이들 열역학적 파라메터들은 유기염의 소수성 부분의 길이가 길어짐에 따라 감소하는 경향을 보여주었다. 비전도도 값의 차(${\Delta}\kappa$)가 유기염의 mol 비가 증가할수록 큰 값을 나타내었다. 그러므로 유기염의 소수성 부분의 길이가 길어질수록 유기염들은 더 쉽게 SDS 미셀내의 palisade층까지 깊이 침투하여 안정한 혼합 미셀을 형성함을 알 수 있었다.