• Environmental Engineering Research
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• 제13권3호
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• pp.131-135
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• 2008

In this study, Fe(VI) was employed as a multi-functional agent to treat the simulated industrial wastewater contaminated with Cu(II)-EDTA through oxidation of EDTA, decomplexation of Cu(II)-EDTA and subsequent removal of free copper through precipitation. The decomplexation of $10^{-4}\;M$ Cu(II)-EDTA species was performed as a function of pH at excess concentration of Fe(VI). It was noted that the acidic conditions favor the decomplexation of Cu(II)-EDTA as the decomplxation was almost 100% up to pH 6.5, while it was only 35% at pH 9.9. The enhanced degradation of Cu(II)-EDTA with decreasing the pH could be explained by the different speciation of Fe(VI). $HFeO_4^-$ and $H_2FeO_4$, which are relatively more reactive than the unprotonated species $FeO_4^{2-}$, are predominant species below neutral pH. It was noted that the decomplexation reaction is extremely fast and within 5 to10 min of contact, 100% of Cu(II)-EDTA was decomplexed at pH 4.0. However, at higher pH (i.e., pH 10.0) the decomplexation process was relatively slow and it was observed that even after 180 min of contact, maximum ca 37% of Cu(II)-EDTA was decomplexed. In order to discuss the kinetics of the decomplexation of Cu(II)-EDTA, the data was slightly fitted better for the second order rate reaction than the first order rate reaction in the excess of Fe(VI) concentration. On the other hand, the removal efficiency of free Cu(II) ions was also obtained at pH 4.0 and 10.0. It was probably removed through adsorption/coagulation with the reduced iron i.e., Fe(III). The removal of total Cu(II) was rapid at pH 4.0 whereas, it was slow at pH 10.0. Although the decomplexation was 100% at lower pH, the removal of free Cu(II) was relatively slow. This result may be explicable due to the reason that at lower pH values the adsorption/coagulation capacity of Fe(III) is greatly retarded. On the other hand, at higher pH values the decomplexation of Cu(II)-EDTA was partial, hence, slower Cu(II) removal was occurred.

• 대한환경공학회지
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• 제27권5호
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• pp.535-541
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• 2005

본 연구에서는 피트모스(Canadian Sphagnum peat moss)로부터 추출한 피트-휴민 (p-Humin)입자를 충전한 칼럼의 연속흐름 조건하에서의 중금속 이온(Cd, Cu, Pb)의 흡착 및 탈착효율을 조사하였다. p-Humin 충전 칼럼은 단일 성분 및 혼합 중금속 용액 모두에서 높은 중금속 제거효율을 보였으며, 실험 결과는 Thomas 모델식을 적용하여 p-Humin의 중금속 흡착특성에 대한 기초 자료를 산출하였다. 단일 성분 중금속 용액을 대상으로 한 실험 결과, p-Humin 단위 그램당 Cd, Cu 및 Pb의 최대 흡착량($q_0$)은 각각 138.8, 44.66 및 41.61 mg/g으로 나타났다. 혼합 중금속 용액을 대상으로 각 중금속 이온의 경쟁흡착 반응실험 결과, p-Humin에 대한 중금속 이온의 친화력 세기는 Pb $\gg$ Cu > Cd이었다. 흡착된 금속이온은 0.05 N $HNO_3$ 용액을 사용하여 쉽게 탈착시켜 회수할 수 있었으며, 회수율은 약 95% 이상을 나타냈다. 본 연구를 통해 p-Humin은 친환경적이고 경제적인 생흡착제로서 폐수 중 중금속 이온의 제거에 활용 가능함을 확인하였다.

• 대한환경공학회지
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• 제29권3호
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• pp.357-364
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• 2007

본 연구는 폐타이어의 재활용 일환으로 기존의 분말 화된 폐타이어 표면에 특정의 Functional group을 형성시켜 수중의 중금속이온들 과의 Chelate complexes 형성을 유도 함으로서 중금속 제거제로서의 폐타이어 활용방안을 제시 하고자 하였다. 이를 위해 FT-IR을 통하여 Function리 group의 종류 및 XRD, XRF, SEM 용출실험을 통해 개질 변화된 폐타이어 특성 분석하였으며 Kinetics Study를 통해 흡착모델에 적용하여 특정상수 값을 도출 하였다. 결과적으로 중금속 흡착 선호도는 $Pb^{2+}>Cu^{2+}>Cd^{2+}$순으로 확인되었으며, 초기 30분 이내에 흡착평형에 도달 하였고, 흡착반응속도 또한 0.27에서 $1.78\sim3.15(g/mg{\cdot}min)$로 증가하였으며, 80% 이상의 제거효율을 보였다. 이는 기존의 분말폐타이어에 비해 그 효율이 10배가량 증가함을 알 수 있었으며, Functional group을 활용한 폐타이어를 이용할 경우 중금속제거제로서의 뛰어난 효율성을 제시 할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.964-972
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• 2001

The kinetics of copper ion biosorption by Pseudomonas stutzeri cells immobilized in alginate was investigated. During the first few minutes of the metal uptake, the copper biosorption was rapid and then became progressively slower until an equilibium was rapid, and then became progressively slower until an equilibrium was reached. At a biomass concentration of 100g/l, the copper biosorption reaction reached approximately 90% of the equilibrium position within 30 min. A Freundich-type adsorption isotherm model was constructed based on kinetics with different amounts of biomass. When using this model, the experimental values only agreed well with the predicted values in a solution containing less than 200 mg/l Cu(II). Desorption of the bound copper ions was achieved using electrolytic solutions of HCl, $H_2SO_4$, EDTA, and NTA (0.1 or 0.5 M). Metal desorption with 0.1 M NTA allowed the reuse of the biosorbent for at least ten consecutive biosorption/desorption cycles, without an apparent decrease in its metal biosorption capability. A packed-bed column reactor of the immobilized biomass removed approximately 95% of the metal in the first 30 liter of wastewater [containing 100 mg/l Cu(II)] delivered at a rate of 20 L/day, and, thereafter, the rate gradually decreased.

• Environmental Engineering Research
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• 제15권4호
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• pp.183-190
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• 2010

Biogenic Mn oxides are expected to have great potential in the control of water pollution due to their high catalytic activity, although information on biological Mn oxidation is not currently sufficient. In this study, the growth of a Mn oxidizing microorganism, Pseudomonas putida MnB1, was examined, with the Mn oxides formed by this strain characterized. The growth of P. putida MnB1 was not significantly influenced by Mn(II), but showed a slightly decreased growth rate in the presence of Pb(II) and EE2, indicating their insignificant adsorption onto the cell surface. Mn oxides were formed by P. putida MnB1, but the liquid growth medium and resulting biogenic solids were poorly crystalline, nano-sized particles. Biogenic Mn oxidation by P. putida MnB1 followed Michaelis-Menten kinetics, with stoichiometric amounts of Mn oxides formed, which corresponded with the initial Mn(II) concentration. However, the formation of Mn oxides was inhibited at high initial Mn(II) concentration, suggesting mass transfer obstruction of Mn(II) due to the accumulation of Mn oxides on the extracellular layer. Mn oxidation by P. putida MnB1 was very sensitive to pH and temperature, showing sharp decreases in the Mn oxidation rates outside of the optimum ranges, i.e. pH 7.43-8.22 and around 20-$26^{\circ}C$.

• Environmental Engineering Research
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• 제11권1호
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• pp.1-13
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• 2006

In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various adsorbents (e.g., zeolite, sepiolite, dolomite and barite) were synthesized for the biofilter media and their adsorption characteristics of toluene were determined. Adsorption capacity of PU-adsorbent foam was in the order of PU-dolomite ${\approx}$ PU-zeolite > PU-sepiolite > PU-barite. During the biofiltration experiment, influent toluene concentration was in the range of 0-160 ppm and EBRT (i.e., empty bed residence time) was 45 seconds. Pressure drop of the biofilter bed was 4-5 mm $H_2O/m$ column height. The maximum removal capacity was in the order of PU-dolomite > PU-zeolite > PU-sepiolite > PU-barite, while the complete removal capacity was in the order of PU-dolomite > PU-sepiolite > PU-zeolite > PU-barite. The better biofiltration performance in PU-dolomite foam was because PU-dolomite foam had lower density and higher porosity than the others providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-dolomite foam had higher maximum removal rate ($V_m\;=\;11.04\;g$ toluene/kg dry material/day) and saturation constant ($K_s\;=\;26.57\;ppm$) than the other PU foams. This supports that PU-dolomite foam was better than the others for biofilteration of toluene.

• Environmental Engineering Research
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• 제25권3호
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• pp.384-392
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• 2020

The presence of high fluoride concentration (> 1.5 mg/L) in water causes serious health problems such as fluorosis, infertility, brain damage, etc., which are endemic to many places in the world. This study has investigated the fluoride removal capacity of the novel activated biochar (BTS) and hydrochar (HTS) using Teff (Eragrostis tef) straw as a precursor. Activated biochar with mesoporous structures and large specific surface area of 627.7 ㎡/g were prepared via pyrolysis process. Low-cost carbonaceous hydrochar were also synthesized by an acid assisted hydrothermal carbonization process. Results obtained from both adsorbents show that the best local maximum fluoride removal was achieved at pH 2, contact time 120 min and agitation speed 200 rpm. The thermodynamic studies proved that the adsorption process was spontaneous and exothermic in nature. Both adsorbents equilibrium data fitted to Langmuir isotherm. However, Freundlich isotherm fitted best for BTS. The maximum fluoride loading capacity of BTS and HTS was found to be 212 and 88.7 mg/g, respectively. The variation could primarily be attributed to a relatively larger Surface area for BTS. Hence, to treat fluoride contaminated water, BTS can be promising as an effective adsorbent.

• 상하수도학회지
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• 제37권6호
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• pp.375-382
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• 2023

The binary oxide adsorbent using Fe and Mn (Fe-Mn) has been prepared by precipitation method to enhance the removal of phosphate. Different amounts of chitosan, a natural organic polymer, were used during preparation of Fe-Mn as a stabilizer to protect an aggregation of Fe-Mn particles. The optimal amount of chitosan has been determined considering the separation of the Fe-Mn particles by gravity from solution and highest removal efficiency of phosphate (Fe-Mn10). The application of Fe-Mn10 increased removal efficiency at least 15% compared to bare Fe-Mn. According to the Langmuir isotherm model, the maximum uptake (q_m) and affinity coefficient (b) were calculated to be 184 and 240 mg/g, and 4.28 and 7.30 L/mg for Fe-Mn and Fe-Mn10, respectively, indicating 30% and 70% increase. The effect of pH showed that the removal efficiency of phosphate was decrease with increase of pH regardless of type of adsorbent. The enhanced removal efficiency for Fe-Mn10 was maintained in entire range of pH. In the kinetics, both adsorbents obtained 70% removal efficiency within 5 min and 90% removal efficiency was achieved at 1 h. Pseudo second order (PSO) kinetic model showed higher correlation of determination (R²), suggesting chemisorption was the primary phosphate adsorption for both Fe-Mn and Fe-Mn10.

• 한국결정성장학회지
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• 제23권6호
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• pp.325-328
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• 2013

Phosphate has been removed in waste water by chemically synthesized graphene oxide. Removing efficiency of phosphate was investigated using phosphate dispersion aqueous solution, and 70 % of phosphate was removed in phosphate dispersion solution by chemically synthesized graphene oxide solution. Removing efficiency of phosphate was increased from 70 % to 80 % with assistant of iron nano-particle in chemically synthesized graphene oxide solution. Phosphate removing capacity was up to 89.37 mg/g at initial phosphate concentration of 100 mg/l and temperature of 303 K. The Freundlich was applied to describe the equilibrium isotherms and the isotherm constants were determined.

• 한국응용과학기술학회지
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• 제17권2호
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• pp.105-112
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• 2000

Surface tension as a function of concentration and temperature was measured for aquous solution of sodium N-acyl sarcosinate, $RCON(CH_{3})CH_{2}$ COONa, From the intersection points in the (${\gamma}-logC$) curves, the critical micelle concentration (cmc) was determined at 20, 30, 40, and $50^{\circ}C$. Structural effects on the cmc maximum and the minimum area per molecule at the aquous solution/air interface were discussed. The free energy, enthalpy, and entropy of micellization and adsorption of surfactant solution also were investigated. Numberous investigators have dealt with sodium N-acyl sarcosinates and their applications as wettings, flooding and reducing agents and as corrosion inhibitors.