• 제목/요약/키워드: Pre-oxidation

검색결과 246건 처리시간 0.024초

산화제 과잉 연소기에 활용 가능한 금속재료의 산화 거동에 관한 연구 (A Study on the Oxidation Behavior of Metal Materials Applicable to Oxidizer Rich Pre-Combustor)

  • 신동해;유이상;신민규;고영성;소윤석;한영민
    • 한국추진공학회지
    • /
    • 제23권2호
    • /
    • pp.118-125
    • /
    • 2019
  • 산화제 과잉 예연소기는 고온/고압/산화제 과잉의 환경이며, 이러한 환경에 금속은 급격한 산화가 발생할 수 있다. 본 연구에서는 고온/고압/산화제 과잉의 환경을 모사할 수 있는 설비를 구축하고 여러 금속 재질에 대해 내산화성 평가를 진행하였다. 그 결과, 온도가 높고 압력이 높은 조건에서 금속재질의 변색, 표면 거칠기에 변화와 금속 표면의 박리 현상이 관찰되었고 무게 변화도 확인하였다. 모든 실험 결과를 종합하였을 때 산화제 과잉 예연소기는 금속 재질에 대한 내산화 코팅이 필수적으로 요구되며, 사용 금속으로는 Cr과 Ni의 함유량이 가장 높은 XM-19를 활용하는 것이 좀 더 구조적 안정성을 확보할 수 있을 것으로 판단한다.

Purification and Characterization of Bacillus subtilis Protoporphyrinogen Oxidase and Pre-equilibrium Behavior During Oxidation of Protoporphyrinogen IX

  • Jeong, Eun-Ju;Han, Ok-Soo
    • BMB Reports
    • /
    • 제34권1호
    • /
    • pp.39-42
    • /
    • 2001
  • Previous studies indicate that B. subtilis protoporphyrinogen oxidase is poorly inhibited by diphenyl ether herbicides. To better understand the basis of this insensitivity, the enzyme was overexpressed as a soluble protein in E. coli, purified and characterized. The mechanism of oxidation of B. subtilis protoporphyrinogen IX was studied and the enzyme kinetic parameters were determined for protoporpyrinogen IX; $K_m$, and $k_{cat}$ were $6.3\;{\mu}M$ and $0.028\;h-^1$, respectively. The enzyme required flavin adenine dinucleotide as a cofactor and its activity was enhanced by 1 mM n-octylglucopyranoside. The nonenzymatic oxidation rate was dependent on the concentration of protoporphyrinogen IX, suggesting that the reaction involves a pre-equilibrium step followed by a rate-limiting step.

  • PDF

Preparation, characterization of activated carbon fiber from luffa and its application in CVFCW for rainwater treatment

  • Ahmed, Sanjrani Manzoor;Zhou, Boxun;Zhao, Heng;Zheng, You Ping;Wang, Yue;Xia, Shibin
    • Membrane and Water Treatment
    • /
    • 제11권2호
    • /
    • pp.151-158
    • /
    • 2020
  • ACF preparation from different materials has been attached with great attention during these years. This study was conducted to prepare activated carbon fiber (ACF) from luffa through the processes i.e pre-treatment, pre-oxidation and carbonization activation. Besides, this study also characterizes the ACF and its effect, i.e effect of pre-oxidation time and temperature also activation time and temperature on the compressive strength of ACF were investigated. The results from SEM, BET, FTIR and XRD show that the ACF is very efficient. The products under the optimum conditions had a specific surface area of 478.441 m2 /g with an average pore diameter of 3.783nm, and a pore volume of 0.193 cm3 /g. The surface of the luffa fiber is degummed and exposed, which is beneficial to the subsequent process and the increase of product properties. The compressive strength of HP-ACF was prepared under the optimum conditions, which can reach 0.2461 MPa. ACF is rich in micro-pores and has a good application prospect in the field of environmental protection.

폐 산업용 금속산화물계 촉매를 이용한 휘발성유기화합물의 제거 (Decomposition of Volatile Organic Compounds Using Regenerated Metal Oxide Catalysts)

  • 남승원;심왕근;김상채
    • 한국대기환경학회지
    • /
    • 제22권4호
    • /
    • pp.431-439
    • /
    • 2006
  • Catalytic oxidation of benzene, toluene and xylene (BTX) using regenerated metal oxide catalysts (ZnO-CuO, NiO, $Fe_2O_3$, ZnO, CrO) were investigated in a fixed bed flow reactor to evaluate their feasibility for the purpose of removing volatile organic compounds (VOCs). Four kinds of pre-treatment methods such as gas (air and hydrogen), acid aqueous solution, alkali aqueous solution and cleaning agent were used to find out the optimal regeneration conditions. The physico-chemical properties of the used and regenerated catalysts were characterized by BET and TPR (Temperature Programmed Reduction). The used catalysts showed high conversion ratio and the catalytic ability of toluene oxidation was in the order of ZnO-CuO>$Fe_2O_3$>NiO>ZnO>CrO. We found that the acid aqueous pre-treatment (0.1 N HNO$_3$) was the best way to enhance the catalytic activity of $Fe_2O_3$. In addition, air and hydrogen gas treatment were optimal for NiO and ZnO-CuO catalysts, respectively. Furthermore, the decomposition of BTX depends on the type of a catalyst and a gas molecule.

AZ91 마그네슘 합금의 PEO 피막 형성거동에 미치는 HF전처리의 영향 (Effect of pre-treatment of AZ91 Mg alloy in HF solution on PEO film formation behavior)

  • 권두영;송풍근;문성모
    • 한국표면공학회지
    • /
    • 제54권4호
    • /
    • pp.184-193
    • /
    • 2021
  • This study demonstrates formation behavior and morphological changes of PEO (Plasma Electrolytic Oxidation) films on AZ91 Mg alloy as a function of pre-treatment time in 1 M HF solution at 25 ± 1 ℃. The electrochemical behavior and morphological changes of AZ91 Mg alloy in the pre-treatment solution were also investigated with pre-treatment time. The PEO films were formed on the pre-treated AZ91 Mg alloy specimen by the application of anodic current 100 mA/cm2 of 300 Hz AC in 0.1 M NaOH + 0.4 M Na2SiO3 solution. Vigorous generation of hydrogen bubbles were observed upon immersion in the pre-treatment solution and its generation rate decreased with immersion time. It was also found that 𝛽-Mg17Al12 in AZ91 Mg alloy was dissolved and a protective thin film of MgF2 was formed on the AZ91 Mg alloy surface during the pre-treatment process in the 1 M HF solution. PEO film did not grow on the AZ91 Mg alloy specimen when the surface was not pre-treated and irregular PEO films with nodular defects were formed for the specimens pre-treated up to 1 min. Uniform PEO films were formed when the AZ91 Mg alloy specimen was pre-treated more than 3 min. The growth rate of PEO films on AZ91 Mg alloy increased significantly with increasing pre-treatment time.

전산화 공정을 이용한 조류제거 (The Removal of Algae by Pre-oxidation)

  • 손희종;정철우;배상대;최영익;강임석
    • 한국환경과학회지
    • /
    • 제18권3호
    • /
    • pp.289-298
    • /
    • 2009
  • The blue-green algae which caused odor problem in the tap water are difficult to precipitate in sedimentation basin and clogged the filter void rapidly. The studies of this paper were not only oxidation, coagulation and sedimentation processes for effectively removing blue-green algae but yellow clay and polyamine for verification as coagulants aids. The results of this research are summarized as follows: Higher ozone dose(C) and longer contact time(T) were needed for a high degree of removing blue-green algae efficiency. the removal rate of blue-green algae was proportional to the $C\times T$ value. The removal percent of chlorophyll-a by sedimentation and filter without pre-ozonation was about 75% but 1 mg/L pre-ozonation could increase the removal percent of chlorophyll-a to 99% and more pre-ozonation could remove completely. Though the removal efficiency of turbidity could increased by high dose of chlorination, the dissolved organic carbon was increased. More chlorine dose from 4 to 10 mg/L dissolved organic carbon was decreased. Using yellow clay as coagulant aids increased density of floc so the settling velocity of floc become rising but polyamine could not increase settling velocity of floc though it could formated large floc.

포스트 플라즈마를 이용한 질화의 질화층 형성에 미치는 전처리의 영향에 대한 연구 (A Study on the Effect of Pre-treatment on the Formation of Nitriding Layer by Post Plasma)

  • 문경일;변상모;조용기;김상권;김성완
    • 열처리공학회지
    • /
    • 제18권1호
    • /
    • pp.24-28
    • /
    • 2005
  • New post plasma nitriding can achieve a high uniformity that have been difficult in DC nitriding and have a high productivity comparable to gas nitriding. However, it has not a enough high nitriding potential for a rapid nitriding, because surface activation or ion etching in the general plasma nitriding cannot be expected. Thus, in this study, the effects of pre-treatments with oxidation and reduction gas have been investigated to improve the nitriding kinetics of post plasma nitriding. An effective pre-treatment consisting of oxidation and reduction resulted in the increase of surface energy of STD 11. This induced the surface hardness and the effective nitriding depth of STD 11. It is thought that the increase of the surface energy and the surface area with pre-treatment promote the nucleation of nitriding layer.

조류가 발생한 수질에 과망간산나트륨과 차아염소산나트륨이 세포 손상도 및 부산물 발생에 미치는 영향 비교 (Comparison of sodium permanganate and sodium hypochlorite on algae-containing water: algae cell integrity and byproduct formation)

  • 양보람;홍석원;최재우
    • 상하수도학회지
    • /
    • 제36권5호
    • /
    • pp.249-260
    • /
    • 2022
  • The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO4) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO4. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO4 significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO4 is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.