• 수도
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• 통권18호
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• pp.18-30
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• 1979

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.644-646
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• 2014

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3311-3316
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• 2012

In this paper, a layered-carbon-$Fe_3O_4$ (LC-$Fe_3O_4$) hybrid material was synthesized through a facile one-pot solvothermal method and used as the adsorbent for the preconcentration of some phthalate esters (dimethyl phthalate, diethyl phthalate, diallyl phthalate, diisobutyl phthalate and benzyl butyl phthalate) in water samples. The effects of the adsorbent dosage, extraction time, the solution pH and salinity on the adsorption of the phthalate esters (PAEs) were investigated. The magnetic nanocomposite adsorbent could remove and enrich the PAEs from water samples efficiently. After the adsorption, the analytes were desorbed and then determined by high performance liquid chromatography-ultraviolet detection. Under the optimum conditions, the enrichment factors of the method for the analytes were in the range from 161 to 180. A linear response with peak area as the quantification signal was observed in the concentration range from 0.5 to $100ng\;mL^{-1}$. The limits of detection (S/N = 3) of the method were between 0.08 and $0.1ng\;mL^{-1}$. The method was suitable for the determination of trace phthalate esters in environmental water samples.

• 공업화학
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• 제17권3호
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• pp.310-316
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• 2006

본 연구에서는 수중 악취의 원인 물질인 용존 암모니아를 제거하기 위해 분말형태의 활성탄을 사용하였다. 특히, 일반적인 분말활성탄은 암모니아 흡착능이 좋지 않기 때문에 흡착능을 높이기 위해 분말활성탄의 표면을 산 용액으로 함침시킨 산 첨착활성탄을 제조하였다. 이렇게 제조한 산 첨착활성탄을 섬유 재질로 된 다공성 지지막($10{\sim}50{\mu}m$)의 표면에 압력에 의한 분리 활성 여과 층을 형성시켜 흡착과 분리를 동시에 할 수 있는 혼합 공정을 구성하였다. 그 결과 혼합공정에서 암모니아 제거율이 60% 이상 되어, 일반 분말활성탄에 비해 10~15% 더 높은 흡착능을 보였다. 그리고 층이 형성된 동적막의 순수투과성능 실험을 보면 수투과도는 400~700 LMH로 정밀여과(Microfiltration)막 수준의 역할을 한다. 이는 수처리에서 기존의 분리막 공정보다 고효율적인 처리 유량을 유지하는 효과가 기대된다.

• 공업화학
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• 제7권4호
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• pp.794-801
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• 1996

Isopropanol 용매 내에서 titanium isopropoxide($Ti(O-^iPr)_4$)의 가수분해반응에 의하여 $TiO_2$ 미분말을 합성하였고 가수분해 반응 속도를 자외선분광법에 의하여 측정하였다. 반응은 $Ti(O-^iPr)_4$의 농도에 비하여 물 농도를 크게 하여 유사일차반응으로 진행시켰고, 물 농도 및 온도의 변화에 따른 반응속도상수를 Guggenheim method로 계산하였다. 또한 물의 동위원소 효과를 측정하여 반응에 참여하는 물분자의 촉매성을 확인하였다. 입도분석과 미세구조 관찰 결과, 얻어진 $TiO_2$ 미분말은 $0.3{\mu}m$정도의 입자크기를 갖는 구형의 입자로 확인되었다. 또한 반응속도로부터 전이상태에 참여하는 n value와 열역학적 파라메타를 계산한 결과, $Ti(O-^iPr)_4$의 가수분해반응은 이분자 반응인 $S_N2$ mechanism으로 진행하는 것으로 추정되었다.

• 폴리머
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• 제30권6호
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• pp.486-491
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• 2006

본 연구에서는 폐수중에 함유된 암모늄 이온을 전기투석 방법으로 회수하기 위하여 불균질 이온교환막을 압축성형 방법으로 제조하였다. 설폰화 양이온교환수지의 설폰화도는 설폰화제인 chlorosulfonic acid의 함량이 증가함에 따라 증가하였고, 최대 설폰화율은 10 vol%일때 3.32 meq/g이었다. 불균질 이온교환막의 인장강도와 신장률은 이온교환수지의 함량이 증가함에 따라 각각 감소하였으며 인장강도는 LLDPE 막이 가장 높게 나타났으며, 신장률의 경우 EVA 막이 가장 높게 나타났다. 불균질 이온교환막의 함수율은 이온교환수지의 함량이 증가함에 따라 증가하였으며 이온수송수는 PE 막의 경우 최대 0.973이었고, 전기저항값은 LLDPE막이 가장 낮게 나타났으며 수지의 함량 70 wt%일때 $10.36{\Omega}/cm^2$이었다.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2813-2818
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• 2010

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1891-1896
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• 2010

Submicron-sized polymeric colloidal particles can self assemble into 3-dimensional (3D) opal structure which is a useful template for photonic crystal. Narrowly dispersed polymer microspheres can be synthesized by emulsion polymerization in water using water-soluble radical initiator. In this report, we demonstrate a facile and reproducible emulsion polymerization method to prepare various polymeric microspheres within 200 - 400 nm size ranges which can be utilized as colloidal photonic crystal template. By controlling the amount of monomer and surfactant, monodisperse polymer colloids of polystyrene (PS) and acrylates with various sizes were successfully prepared without complicated synthetic procedures. Such polymer colloids self-assembled into 3D opal structure exhibiting bright colors by reflection of visible light. The colloidal particles and the resulting opal structures were rigorously characterized, and the wavelength of the structural color from the colloidal crystal was confirmed to have quantitative relationship with the size of constituting colloidal particles as predicted by Bragg equation. The tunability of the structural color was achieved not only by varying the particle size but also by infiltration of the colloidal crystal with liquids having different refractive indices.

• Corrosion Science and Technology
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• 제18권6호
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• pp.232-242
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• 2019

In this study, hydrophobically modified fumed silica was added to the PVDF coating to improve corrosion protection performance. Two types of silane modifiers, trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ), were used for hydrophobic modification of the fumed silica. The composition of modified fumed silica was analyzed by Fourier transform infrared, X-ray photoelectron spectroscopy, and elemental analysis. The dispersion of modified fumed silica in the PVDF coating was observed by the transmission electron microscopy, and the hydrophobicity of PVDF coating was analyzed by the water contact angle. Surface properties were examined by the field emission scanning electron microscopy and scanning probe microscopy. Potentiodynamic polarization was conducted to confirm corrosion protection performance of PVDF coating in terms of hydrophobically-modified fumed silica contents. As a result, the average surface roughness and the water contact angle of the PVDF coating increased with modifier contents. The results of the potentiodynamic polarization test showed an increase of the E_corr values with increase of the hydrophobicity of PVDF coating. Thus, it clearly indicates that the corrosion protection performance of PVDF coating improved with the addition of the hydrophobic-modified fumed silica that prevents the penetration of moisture into the PVDF coating.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1597-1600
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• 2006

The mononuclear iron complex 1, $Fe^{III}$(Hbida)Cl($H_2O$), was synthesized using a tripodal tetradentate ligand, N-(benzimidazol-2-ylmethyl)iminodiacetic acid (H3bida), which has two carboxylate groups, one benzimida- zoyl group, and one tertiary amine where it serves as a tetradentate chelating ligand for the octahedral Fe(III) ion. The four equatorial positions of the octahedral complex are occupied by two monodentate carboxylates, a benzimidazole nitrogen, and an oxygen of a water molecule. One of the axial positions is occupied by an apical nitrogen of the Hbida and the other by a chloride anion. The mononuclear octahedral complex 1 mimics the geometry of the key intermediate structure of the catalytic reaction cycle proposed for the FeSODs, which is a distorted octahedral geometry with three histidyl imidazoles, an aspartyl carboxylate, a superoxide anion, and a water molecule. The redox potential of complex 1, $E_{1/2}$ is -0.11V vs. Ag/AgCl (0.12 V vs. NHE), which is slightly lower than those reported for the most FeSODs. The magnetic susceptibility of complex 1 at room temperature is 5.83 $\mu$B which is close to that of the spin only value, 5.92 $\mu$B of high-spin d5 Fe(III).