• Resources Recycling
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• v.29 no.5
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• pp.28-37
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• 2020

In this study, the effect of precipitation temperature, ammonium chloride amount and addition method, vanadium and sodium hydroxide content of the solution on the precipitation of ammonium metavanadate were examined by using the sodium vanadate(NaVO₃) solution in alkali region as a starting material. As the pH of solution decreased, the addition amount of ammonium chloride and the vanadium content of the solution increased, the precipitation rate of ammonium metavanadate increased. In this research condition, the basic conditions for obtaining more than 90% of precipitation yield were 10,000mg/L of vanadium content, 2equivalents of ammonium chloride addition, room temperature, and 2 hours of precipitation time. The size of precipitated particles decreased with increasing precipitation rate. Especially when liquid ammonium chloride was injected into the solution, the precipitation rate was the slowest and the particle size of the precipitate was the largest. After the primary precipitation by adding ammonium chloride as a solid, the secondary precipitation was carried out by adding new reactants. At this time, the precipitation with added ammonium chloride solid was not affected by the precipitates present in the solution. However, when liquid ammonium chloride was added, new precipitate was deposited on the surface of the precipitate present in the solution, increasing its size. Due to the difference in ammonium metavanadate solubility to temperature, the precipitation temperature at the vanadium content of 10,000mg/L in the solution affected the precipitation rate of ammonium metavanadate and the precipitation temperature did not affect the precipitation rate at a high concentration of more than 30,000mg/L vanadium content in the solution.

• KSBB Journal
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• v.11 no.4
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• pp.389-397
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• 1996

The growth of recombinant E. coli and formation of the by-products were investigated. Ammonium phosphate is known to affect the cell growth as well as the enzyme formation. When initial ammonium phosphate concentration was 0.5g/L, cell mass was 4.1g/L. By adding tryptone to the medium, acetic acid formation increased while lactic acid formation decreased. In cultivating recombinant E. coli, lactic acid and acetic acid turned out to be important by-products which affected cell yield and growth rate. Initial ammonium phosphate and tryptone concentration were optimized in our research and can be applied for other culture of recombinant E. coli.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.919-926
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• 2009

Enrichment of anaerobic ammonium oxidation (ANAMMOX) bacteria is the essential step for operating full-scale ANAMMOX bioreactor because adding a significant amount of seeding sludge is required to stabilize the ANAMMOX reactor. In this study, the enrichment of ANAMMOX bacteria from an activated sludge using sequencing batch reactor was conducted and verified by analyzing changes in the microbial community structure. ANAMMOX bacteria were successfully enriched for 70 days and the substrate removal efficiencies showed 98.5% and 90.7% for $NH_4\;^+$ and $NO_2\;^-$ in the activity test, respectively. The phylogenetic trees of Planctomycetes phylum showed that the diverse microbial community structure of an activated sludge was remarkably simplified after the enrichment. All 36 clones, obtained after the enrichment, were affiliated with ANAMMOX bacteria of Candidatus Brocadia (36%) and Candidatus Anammoxoglobus (64%) genera. The quantification using real-time quantitative PCR (RTQ-PCR) revea ed that the 16S rDNA concentration of ANAMMOX bacteria was 74.8% compared to the granular ANAMMOX sludge obtained from an upflow ANAMMOX sludge bed reactor which had been operated for more than one year. The results of molecular analysis supported that the enriched sludge could be used as a seeding sludge for a full-scale ANAMMOX bioreactor.

• Fire Science and Engineering
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• v.24 no.5
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• pp.115-121
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• 2010

This study was performed to test the combustive properties of Pinus rigida-based materials by the treatment of ammonium salts. Pinus rigida plate was soaked in three 20 wt% ammonium salt solutions such as ammonium sulfate (AMSF), monoammonium phosphate (MAPP), and diammonium phosphate (DAPP), respectively, at the room temperature. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). Comparing with virgin pinus rigida plate, specimens treated with the ammonium salts had lower combustive properties and It is supposed that the combustion-retardation properties improved due to the treated ammonium salts in the virgin Pinus rigida. Also, the specimens with treated ammonium salts showed both the lower peak heat release rate (PHRR) and lower total heat release (THR) than those of virgin plate.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.509-515
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• 1994

The interactions of 11 kinds of primary and secondary alkylammonium ions with cyclic (12C4, 15C5, 18C6, DT18C6 and DA18C6) and acyclic$(Q_2O_5)$ polyethers were investigated by NMR titration and conductometry. All of the alkylammonium ions under investigation form the relatively stable 1 : 1 complexes with crown ethers and acyclic polyether by H-bond. The interactions of alkylammonium ions with analogeous hosts having different size were in the order of 18C6 > 15C5 > 12C4, and the strengthes of donor atoms toward the alkylammonium ions were in the order of N > O > S. 18C6 forms more favorable interactions with primary alkylammonium ions than secondary alkylammonium ions, otherwise DA18C6 shows the opposite behaviors. The stability constants for complexations of 18C6 with the alkylammonium ions were determined conductometrically in methanol at 25$^{\circ}C$. The major factors affecting the stability of complexes were the type of alkylammonium ions, the length of alkyl-chain and the steric hindrance due to the structure of alkyl groups on complexation.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1619-1626
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• 2020

In this study, the physical properties of water-dispersible polyurethane resins synthesized with polyammonium phosphate and HMDI were studied by coating film samples and full-grain surfaces. Solvent resistance was found to be unchanged in all samples, and in terms of tensile strength, DPU-AP3 (1.887 kgf/㎟) containing the most ammonium polyphosphate showed the lowest physical properties. The elongation rate was measured as 54 8% in the sample containing a large amount of ammonium polyphosphate. Abrasion resistance was measured as 548 mg.loss of a sample containing a lot of ammonium polyphosphate, and it was confirmed that the physical properties of the blended resin of ammonium polyphosphate and water-dispersible polyurethane were changed.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.158-159
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• 2013

방염제인 인산암모늄에 질산칼륨을 첨가하여 질산칼륨이 인산암모늄의 방염성능에 미치는 영향을 DSC와 실체현미경으로 분석하였다. 활성화에너지는 키싱거방법을 도입하여 분석하였다. 방염성능 실험으로서 셀룰로스를 연료로 사용하였다. 질산칼륨이 일정량 첨가된 방염제를 사용하는 경우 인산암모늄의 활성화에너지를 높이고 탄화면적을 감소시켜 연소확대를 억제하였다. 방염제인 질산칼륨이 첨가된 인산염을 방염제로 사용하는 경우 질산칼륨의 강한 산화력으로 화염발생 온도를 낮추고 탄화형성을 억제하여 화재진행 속도를 낮추는 것으로 나타났다. 적정량 이하의 질산칼륨이 포함된 방염제의 처리는 연소속도를 높이고 탄화물형성을 감소시킬 수 있음을 제시하였다.

• Resources Recycling
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• v.28 no.5
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• pp.42-50
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• 2019

In this study, the precipitation reaction of vanadium and ammonium chloride in aqueous solution was investigated in order to recover vanadium. Ammonium metavanadate having a crystal structure of [$NH_4VO_3$] was precipitated from aqueous solution containing vanadium at pH 9.2 ~ 9.4, and ammonium polyvanadate having a crystal structure of [$(NH_4)_2V_6O_{16}$] was precipitated when the pH of the aqueous solution containing vanadium was adjusted with sulfuric acid. Ammonium polyvanadate [$(NH_4)_2V_6O_{16}$] precipitated at a temperature of $80{\sim}90^{\circ}C$ and pH 2, and at a temperature of $40^{\circ}C$ and pH 6 ~ 8 of aqueous solution. In the acidic region of aqueous solution pH 2, the vanadium content of the aqueous solution should be at least 3,000 mg/L and the precipitation temperature should be maintained at $80^{\circ}C$ or higher in order to obtain a precipitation ratio of 99% or more. When the ammonium vanadate was precipitated in the alkaline region, the vanadium content was more than 10,000 mg/L and the precipitation temperature was maintained at $40^{\circ}C$ to increase the precipitation ratio. Aluminum was not precipitated regardless of the vanadium content and pH of the aqueous solution. However, the iron component reacts with ammonium chloride to precipitate into ammonium jarosite. Therefore, Fe component must be preferentially removed in order to increase the recovery of vanadium.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.29-36
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• 2004

Batch and column tests were performed to develop the design factors for permeable reactive barriers(PRBs) against the contaminated groundwater with ammonium from unsanitary landfill. Clinoptilolite, one of natural zeolites having excellent cation exchange capacity(CEC), was chosen as the reactive material. In batch test, the reactivity of clinoptilolite to ammonium was examined by varying the initial concentration of ammonium and the particle size of clinoptilolites. One gram of clinoptilolite showed removal efficiency about 80% against the ammonium except in very high initial concentration of 80 ppm, but the effect of particle size of clinoptilolite was not noticeable. Permeability test was performed for the specimens made of clinoptilolite and Jumunjin sand with 20 : 80 weight ratio. Flexible wall permeameter was employed far permeability test. The specimen containing the washed 0.42-0.85mm clinoptilolite showed the highest permeability of about $10^{-3}$/s. In column test, the reactivity of mixed materials against ammonium in flowing condition was examined with the landfill leachate. With the test results, clinoptilolite was found to be a suitable material for PRBs against the contaminated groundwater with ammonium.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.751-758
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• 2020

SCR technology, which uses urea-water as a NO_x reducing agent, has been widely used to reduce NO_x in marine diesel engines. However, as an alternative NO_x reducing agent, solid-phase ammonium carbamate has several advantages, such as low-temperature NO_x reduction performance and NH₃ storage capacity. This study presents a method for evaluating the purity of ammonium carbamate using EA, FTIR, and XRD to investigate the change in the material characteristics of ammonium carbamate when it is exposed to various temperature and pressure conditions. In this study, it was found that the purity of ammonium carbamate can be effectively evaluated via EA analysis. The FTIR analysis results confirmed that the properties of ammonium carbamate did not change even after repeated heating and cooling under thermal decomposition temperature conditions, which may be applied to the SCR system of marine diesel engines. Additionally, it was found that when ammonium carbamate was exposed to the atmosphere for a long time, it transformed into ammonium carbonate.