New Design Approaches for Ultrasonic Reactors: Degradation of Naphthalene and Phenol in Water

Her, Nam-Guk,Park, Jong-Sung,Oh, Jeill,Yoon, Yeomin Springer-Verlag 2011 Water, air, and soil pollution Vol.220 No.1

해수용존유기물의 분자량 분포 및 분광학적 특성 이해

남성남 ( Seong-nam Nam ),손미향 ( Mi Hyang Sohn ),허지용 ( Ji Yong Heo ),허남국 ( Nam Guk Her ) 한국물환경학회(구 한국수질보전학회) 2015 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2015 No.-

HPLC-MS/MS를 이용한 TNT, RDX, HMX의 정밀분석 방법 연구

한종훈 ( Jong Hun Han ),허남국 ( Nam Guk Her ) 한국물환경학회(구 한국수질보전학회) 2011 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2011 No.-

UV Absorbance Ratio Index with Size Exclusion Chromatography (URI-SEC) as an NOM Property Indicator

윤여민(Yeo Min Yoon),허남국(Nam Guk Her),Gary Amy 대한환경공학회 2006 대한환경공학회 학술발표논문집 Vol.2006 No.12

An advanced approach is presented for identifying and characterizing biopolymers of natural organic matter (NOM) in water samples. It involves a simple method based on a ratio of peak heights of high performance size exclusion chromatography (HPSEC) chromatograms based on ultraviolet absorbance (UVA) at 210 nm and 254 nm. The HPSECsystem eliminates inorganic interferences and makes it possible to obtain ratio values associated with organic components as a function of molecular weight (MW). Certain biopolymers show a distinctive ultraviolet absorbance ratio index (URI, UVA(210)/UVA(254)) because they contain different compositional proportions of UV-absorbing functional groups and sp2-hybridized carbon. URI values were found to be the lowest for humic acids (1.59 for a humic acid, highest aromaticity), intermediate for fulvic acids (1.88for a fulvic acid, intermediate aromaticity), and highest for proteins (13.50 for BSA, lowest aromaticity). URI increases with eutrophication of natural waters by the increase of microbially derived components that have a high functional group proportion with a low sp2-hybridized carbon, and increases with ozonation by the cleavage of unsaturated bonds (decrease in unsaturated bonds and increase in functional group proportions).

주파수 변화 및 보조제 첨가에 따른 나프탈렌 및 페놀의 초음파 분해효율 비교

박종성(Jong Sung Park),허남국(Nam Guk Her) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.7

최근 초음파를 이용한 유기오염물질의 분해 연구가 진행 중이며, 보다 향상된 초음파 조건을 찾는 연구가 주목을 받고 있다. 본 연구에서는 초음파에 의한 분해 대상물질로 나프탈렌 및 페놀을 선정하여 다양한 주파수(28 kHz, 580 kHz, 1,000 kHz) 및 보조제(TiO₂, H₂O₂, FeSO₄, Zeolite, Cu) 첨가 효과를 비교·분석하여 초음파 처리 시스템의 최적 분해효율 조건을 확인하였다. 주파수 변화에 따른 초음파 분해효율은 나프탈렌과 페놀 모두에서 580 kHz가 가장 우수한 효율을 보였으며, OH 라디칼 역시 동일 주파수에서 가장 많이 발생한 점을 미루어 볼 때, 580 kHz 근처의 초음파 영역에서 최적의 열분해 및 산화분해를 일으킬 수 있는 공동현상 조건이 형성된다는 것을 확인하였다. 100 mg/L의 다양한 보조제를 첨가하여 초음파 분해효율을 비교한 결과 FeSO₄의 분해효율 및 kl값이 무첨가 초음파 반응에 비해 약 1.8배씩 우수하게 조사되었으며, 이것은 초음파와 펜톤 반응이 연계되어 OH 라디칼 생성을 촉진시켜 대상물질의 산화분해를 향상시킨 것으로 판단된다. 그러나 초음파와 펜톤 연계시스템은 배치식 조건에서만 제한적으로 적용 가능할 것이며, 연속식 초음파 시스템에서는 철의 손실, 반옹조의 부식 및 새로운 오염물질을 발생시키는 문제를 야기할 수 있다. 이에 반해 TiO₂를 첨가한 초음파 분해속도가 무첨가 반응보다 약 20%이상 향상된 점을 감안할 때, 초음파와 연계된 연속식 처리 공정에서는 TiO₂가 효과적인 보조제로 사용될 수 있을 것이다. The research seeks to find the optimal conditions for sonodegradation of naphthalene and phenol as exemplary organic pollutants to be subjected to ultrasound in varying frequencies (28 kHz, 580 kHz, and 1,000 kHz) and in the presence of different kinds of additive (TiO₂, H₂O₂, FeSO₄, Zeolite, and Cu). In cases of both naphthalene and phenol, 580 kHz of ultrasound has proven to be the most effective among others at sonodegradation. Based on the observation that OH radicals are also produced in maximum under exposure of 580 kHz of ultrasound, we concluded that this frequency of ultrasound creates hospitable condition for the combined process of degradation by pyrolysis and oxidization. FeSO₄`s degradation rate and k1 value have increased by approximately 1.8 times compared with the results of the solutions without any additives. This seems to be the result of ultrasound reaction which, accompanied by Fenton`s reaction, increased the oxidative degradation and the production of OH radicals. However, application of ultrasound and Fenton`s reaction is limited to the batch type conditions, as its use in continuous system can cause loss of iron or decay of the cistern, thereby creating additional pollutants. When the additive is replaced with TiO₂, on the contrary, the rate of sonodegradation has increased up to 20% compared to when there was no additive. We therefore conclude that TiO₂ could prove to be an effective additive for ultrasound degradation in continuous treatment system.

Arsenic Removal from Water Using Various Adsorbents

Shahnawaz Sinha,Gary Amy,Yeo Min Yoon,Nam Guk Her 대한환경공학회 2011 Environmental Engineering Research Vol.16 No.3

The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four natural types (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxide particles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated microsand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The results showed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determined for a given equilibrium concentration of Ceq = 10 μg/L were 500 mg/L for AA and GFH, 520-1,300 mg/L for MIEX, 1,200 mg/L for HIOPs, 2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbents were 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantly reduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenic in the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbents had lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreased by approximately 60-95%.

HPLC-MS/MS를 이용한 Bisphenol A 분석 및 초음파에 의한 분해 특성 조사

박종성(Jong Sung Park),윤여민(Yeo Min Yoon),허남국(Nam Guk Her) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.6

본 연구는 극미량의 BPA 분석법을 정립하기 위하여 HPLC-MS/MS를 이용한 BPA 분석 조건을 개발하였고, 초음파를 이용한 BPA의 분해 특성을 조사하였다. HPLC-MS/MS에 의한 BPA의 MDL과 LOQ는 각각 0.13 nM과 1.3 nM로 조사되었는데, 이는 기존의 HPLC-UV (MDL: 81.1 nM, LOQ: 811 nM) 및 FLD (MDL: 4.6 nM, LOQ: 46 nM) 보다 약 620배 및 35배 우수하였으며, U.S. EPA의 음용수 권고기준(1.53 μM 혹은 350 ㎍/ℓ)의 약 1,180배 이하까지 정량분석이 가능하였다. 초음파 조사에 따른 BPA의 분해효율은 저주파(28 kHz)를 제외한 중?고주파 조건(580 and 1000 kHz)에서 반응 30분 이내에 95%이상 제거되었다. 특히 BPA의 분해효율 및 k1의 결과는 580 kHz에서 가장 우수하였는데, 이는 580 kHz 근처의 주파수 영역에서 최적의 초음파 공동현상 및 열분해/산화분해가 일어남을 알 수 있었다. 0.01 mM의 CCl₄를 첨가하여 분해효율을 측정한 결과 30분 이내에 BPA 초기농도(1 μM)의 98% 이상까지 제거되었으며, 반응 초기(5분)와 후기(30분)의 k1값은 무첨가 반응에 비해 각각 1.4배 및 1.1배씩 증가하였다. 10 mM의 t-BuOH이 첨가된 결과 무첨가 반응에 비해 약 60% 이상 BPA 분해효율이 감소한 것을 감안할 때 BPA의 주된 초음파 기전은 OH 라디칼에 의한 산화분해임을 알 수 있었다. 그러나 t-BuOH이 첨가된 반응시간 동안(30분) 약 33%의 BPA가 분해가 일어난 것은 OH 라디칼 뿐 아니라 열분해 및 기타 라디칼등에 의한 분해가 진행되었을 것으로 판단된다. The optimal conditions for the analysis of BPA by HPLC-MS/MS was investigated and the ultrasound degradation capacity of the BPA, with the goal to establish the proper directions for analyzing infinitesimal quantities of BPA by HPLC-MS/MS was examined. The MDL and LOQ of BPA analyzed by HPLC-MS/MS were measured 0.13 nM and 1.3 nM respectively, its sensitivity about 620 and 32 times greater than HPLC-UV (MDL: 81.1 nM, LOQ: 811 nM) and FLD (MDL: 4.6 nM, LOQ: 46 nM). In other words, the new method enables the analysis of BPA with the accuracy up to one 1,180th of the amount specified in U.S. EPA guideline for drinking water. Degradation rate of BPA by ultrasound measured over 95% under 580 kHz and 1000 kHz frequency within 30 minutes of treatment, whereas the rate showed some decrease at 28 kHz frequency. At 580 kHz of ultrasound has proven to be the most effective among others at degradation rate and k1 value, so we concluded that this frequency of ultrasound creates hospitable condition for the combined process of degradation by pyrolysis and oxidization. With the addition of 0.01 mM of CCl₄, BPA with the initial concentration of 1 μM was degraded by more than 98% within 30 minutes, the k1 value measured 5 minutes and 30 minutes into the experiment both showed increases by 1.4 and 1.1 times, respectively, compared with BPA without CCl₄. It is also found that the main degradation mechanism of BPA by ultrasound is oxidization process by OH radical, based on the fact that the addition of 10 mM of t-BuOH decreased the rate of BPA degradation by around 60%. However, 33% of BPA degradation rate obtained with the addition of t-BuOH implies further degradation done by pyrolysis or other sorts of radical beside OH radical.

Pretreatment in Reverse Osmosis Seawater Desalination: A Short Review

Ramesh Valavala,Jin Sik Sohn,Ji Hee Han,Nam Guk Her,Yeo Min Yoon 대한환경공학회 2011 Environmental Engineering Research Vol.16 No.4

Reverse osmosis (RO) technology has developed over the past 40 years to control a 44% market share in the world desalting production capacity and an 80% share in the total number of desalination plants installed worldwide. The application of conventional and low-pressure membrane pretreatment processes to seawater RO (SWRO) desalination has undergone accelerated development over the past decade. Reliable pretreatment techniques are required for the successful operation of SWRO processes, since a major issue is membrane fouling associated with particulate matter/colloids, organic/inorganic compounds, and biological growth. While conventional pretreatment processes such as coagulation and granular media filtration have been widely used for SWRO, there has been an increased tendency toward the use of ultrafiltration/microfiltration (UF/MF) instead of conventional treatment techniques. The literature shows that both the conventional and the UF/MF membrane pretreatment processes have different advantages and disadvantages. This review suggests that, depending on the feed water quality conditions, the suitable integration of multiple pretreatment processes may be considered valid since this would utilize the benefits of each separate pretreatment.

토양세척 공정의 환경영향 분석 - 이산화탄소 배출량 및 에너지 사용량을 중심으로

김도형 ( Do Hyung Kim ),황보람 ( Bo Ram Hwang ),허남국 ( Nam Guk Her ),정상조 ( Sang Jo Jeong ),백기태 ( Ki Tae Baek ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.1

총 석유계탄화수소로 오염된 토양을 정화하기 위한 토양세척공정을 부지 내 및 부지 밖 처리로 구분하여 공정 중 발생하는 환경적인 영향을 녹색 및 지속 가능한 정화 평가모델을 사용하여 평가하였다. 각 단계 별 환경부하의 상대적 인 기여도를 평가하기 위해 전체 토양세척공정을 부지조성(1단계), 굴착(2단계), 물리적 선별 및 세척(3단계), 폐수처리 (4단계)의 주요한 4단계로 구분하였다. 부지 내 처리 시에는 1단계에서 CO2 배출량과 에너지사용량의 상대적인 기여도가 각각 87.1%와 80.4%였고, 부지 밖 처리시에는 2단계에서 CO2 배출량과 에너지사용량의 상대적인 기여도가 각 각 82.7%와 80.5%였다. 결론적으로 토양세척공정에서 부지 내 처리의 경우 1단계에서의 세척장치 제작을 위한 철, 스테인리스스틸 등 소비성 재료의 사용이, 부지 밖 처리의 경우 2단계에서의 굴착된 오염토의 운송을 위한 연료의 소비 가 환경부하에 영향을 끼치는 가장 중요한 요소이다. 본 연구의 결과는 토양세척 공정의 적용 시 녹색 및 지속 가능한 정화의 달성을 위한 유용한 정보가 될 것으로 기대된다. This study evaluated the environmental impacts of a soil washing (SW) process, especially, we compared the on-site and off-site remediation of TPH-contaminated soil using green and sustainable remediation (GSR) tool. To assess relative contribution of each stage on environmental footprints in the entire soil washing process, we classified the process into four major stages: site foundation (stage I), excavation (stage II), separation & washing (stage III), and wastewater treatment (stage IV). In on-site SW process, the relative contribution of CO2 emissions and energy consumption were 87.1% and 80.4%, respectively in stage I, and in off-site SW process, the relative contribution of CO2 emissions and energy consumption were 82.7% and 80.5%, respectively in stage II. In conclusion, the major factor contributing environmental impact in the SW process were consumable materials including steel and stainless steel for washing equipment in on-site treatment and fuel consumption for transportation of soil in off-site treatment.

초음파/SWCNT를 이용한 Bisphenol A, 17β-estradiol 처리 연구

이하윤 ( Ha Yun Lee ),한종훈 ( Jong Hun Han ),허남국 ( Nam Guk Her ) 한국물환경학회(구 한국수질보전학회) 2011 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2011 No.-