pH 변화에 따른 중금속 수용액의 반응 메커니즘

송수욱 ( Song Su Ug ),정호진 ( Jeong Ho Jin ) 한국수처리학회 2004 한국수처리학회지 Vol.12 No.1

N/A This study was designed to set up a theoretical mechanism for removal and separation of heavy metal ions from aqueous solutions by analysing reaction between pH and heavy metal ions, and to offer useful data for treatment applications of wastewater containing heavy metals in the future. The obtained results are as follows: Each heavy metal ion has a unique curve between pH and residual heavy metal concentration. When two types of heavy metals are complexed, the reaction rate between OH- and heavy metal ion is more affected by ionization strength rather than competitive reaction. When three types of heavy metals are combined, the ultra-fine particle is formed at about 1-2 lower PH than in the case that independently existed. This is because chemical reaction was caused by complicated reactions of pH of the minimum soluble product, ionization strength, and competitive reaction. The electric field makes ultra-fine particles having a very small amount of charge move more easily than large colloidal particles. Therefore, this study shows that it is possible to improve the efficiency of selective flocculation by electrolysis at PH which forms ultra-fine particles of metal-hydroxides by the application of the results.

2P-200 Aqueous-Phase synthesis of hydroxide nanoplates and hydroxide/Pt and their electrochemical properties

정의영,최형석,유태경 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

We have successfully synthesized transition metal hydroxide (Ni(OH)2, Co(OH)2) nanoplates and transition metal layered double hydroxide nanoplates in an aqueous solution. In addition, we could attach Pt nanoparticles on the hydroxide nanoplates accociated with enhancement for electrochemical catalytic acitivity because of combination transition metal hydroxide and Pt. We could control the ratio of transition metal hydroxide to Pt. We have also measured excellent electrochemical catalytic performance compared to the commercial materials. The synthesized nanomaterials were characterized by using TEM, XRD and XPS. The synthesized nanomaterials have a uniform size and shape.

표면 처리한 Sea sand 를 이용한 Se(4) 제거 : Zeta potential 을 통한 Fe(3) 간의 반응 메카니즘 연구 Zeta potential approach to depict the binding between Fe(3) and Sea sand

박상원,강혜정 한국환경과학회 1999 한국환경과학회지 Vol.8 No.2

Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions. However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals. The process was successful in removing some anions such as SeO_3(-Ⅱ) over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH. Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution) The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

Effect of Waste Lime on Bioavailability and Chemical Speciation of Heavy Metals in Rotary Drum Composting of Water Hyacinth

( Jiwan Singh ),( Ajay S. Kalamdhad ),( Yoon-young Chang ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-

The bioavailability and speciation of heavy metals (Cu, Pb, Cd and Cr) assist an important role in the toxicity of heavy metals in the compost applied for soil conditioning. The study was carried out on bioavailability and speciation of heavy metals in the composting of water hyacinth in rotary drum for 20 days. The exchangeable (F1), carbonate (F2), reducible (F3) and oxidizable (F4) fractions of Cu were decreased in the control and all calcium hydroxide addition compost. Reduction of F1 (88.6%), F2 (76.7%) and F3 (89.4%) fractions (percentage of total fraction) was observed in lime treatment 2. F1 and F2 fractions of Cd, Cr and Pb were reduced, and F5 fraction was increased in lime treatments as compared to the control. Present study concluded that, the optimum amount of waste lime was greatly effective of reduction of water solubility, plant availability, and most boilable fractions (exchangeable and carbonate fractions) of selected heavy metals. The effect of waste lime is highly recommended for immobilization of heavy metals for water hyacinth composting in rotary drum.

Neodymium doped mixed metal oxide derived from CoAl-layered double hydroxide: Considerable enhancement in visible light photocatalytic activity

Fatemeh Khodam,Hamid Reza Amani-Ghadim,Soheil Aber,Ali Reza Amani-Ghadim,Iraj Ahadzadeh 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.68 No.-

Herein, the Neodymium ion (Nd3+) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

수열합성된 나노구조 니켈/니켈 수산화물의 상과 형태 및 슈퍼커패시터 적용

엄승용,정진주,김도형 한국물리학회 2021 새물리 Vol.71 No.6

Urchin-like nanostructured nickel/nickel hydroxides (NNHO) were successfully synthesized by using the hydrothermal method, and the phase and the morphology of the nanostructured nickel/nickel hydroxide were controlled by using different synthesis temperatures. The diameter of the nanostructured NNHO synthesized at a relatively high temperature wes bigger than that of the samples synthesized at low temperature, which could be explained by using Ostwald ripening. The phase of the as-synthesized nanostructure was composed of crystalline metallic nickel on the inside and amorphous nickel hydroxide on the surface. To compare the electrochemical properties, the as-synthesized samples are converted to nickel oxide (NO) by annealing at different temperatures. The as-synthesized NNHO showed the highest specific capacitance, as well as easy electrolyte accessibility, because NNHO had not only an easily accessible nanostructure but also the synergistic effect of crystalline nickel and amorphous nickel hydroxide. The present work can contribute to the synthesis of nanostructured NNHO and to the applications of supercapacitors using heterostructure materials. 성게 모양의 나노구조 니켈/니켈 수산화물(NNHO)을 수열합성법으로 합성하였다. 나노구조 NNHO의상과 형태는 합성 온도와 합성 후 열처리 온도에 의해 조절되었다. 상대적으로 고온에서 합성된 나노구조NNHO의 직경은 저온에서 합성된 샘플보다 직경이 크고, 이는 오스트발트 숙성 (Ostwald ripening)에의해 설명된다. 합성된 나노구조 NNHO의 상은 내부의 결정성 금속 니켈과 표면의 비정질 니켈 수산화물로구성된다. 전기화학적 특성을 비교하기 위해, 합성된 NNHO를 열처리하여 니켈 산화물(NO)로 상전이시켰다. 순환전압전류법 및 정전류 충방전 측정 결과, 합성된 NNHO가 NO에 비해서 더 높은 전기용량과쉬운 전해질 접근성을 보였으며, 이것은 NNHO가 쉽게 접근 가능한 나노구조를 가질 뿐만 아니라 결정질니켈과 비결정질 니켈 수산화물의 시너지 효과 (synergistic effect) 에 의한 것이다. 이 연구는 나노구조 NNHO의 합성과 이종 구조 물질을 활용한 슈퍼커패시터 응용 연구에 기여할 수 있을 것으로 기대된다.

소성된 Mg-Al Layered Double Hydroxide에 의한 비소(V)의 흡착

서영진,강윤주,김준형,박만,최정 한국토양비료학회 2008 한국토양비료학회지 Vol.41 No.6

Special concern has been given to the elevated arsenic content in soils because of its high mobility and toxicity. Layered double hydroxide (LDH) which has a high anionic exchange capacity is another potential anion adsorbent for toxic anions such as arsenic, chromate and selenium etc. The uptake of arsenate from aqueous solutions by the calcined Mg-Al LDH has been investigated. The sorption capacity was about 530 mmol/kg. Sorption isotherm was defined as L-type in which arsenate was removed by LDH through anion uptake reaction. Arsenate sorption by the calcined Mg-Al LDH was occurred by reconstruction of LDH's framework. Competitive adsorption revealed that Mg-Al LDH had higher selectivity for arsenate than for sulfate. These results strongly suggest that calcined Mg-Al LDH has a promising potential for efficient removal of toxic metal oxides like arsenates from aqueous environments.

Effects of metal hydroxide-treated photoanode on the performance of hybrid solar cells

Kim, C.,Kim, J.T.,Kim, H.,Park, S.H.,Son, K.C.,Han, Y.S. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.4

This work reports on the preparation of modified TiO<SUB>2</SUB> electrodes, which could be applied to the photoanodes of dye-sensitized solar cells (DSSCs). TiO<SUB>2</SUB> layers were formed on fluorine-doped tin oxide glasses via doctor-blade method followed by heat treatment. Then, the various metal hydroxides were individually incorporated onto the TiO<SUB>2</SUB> layers via simple dip coating process to give modified TiO<SUB>2</SUB> electrodes to DSSCs. When the surface-treated electrodes were employed, photovoltaic efficiencies of DSSCs were improved by ca. 16% compared to those of the cell fabricated with a bare TiO<SUB>2</SUB> electrode.

Cobalt-iron layered double hydroxide incorporated MOF-derived cobalt phosphide electrodes for efficient overall water splitting in alkaline media

최교훈,백운철,임승만,박정태 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Herein, we incorporated cobalt-iron layered double hydroxide with metal-organic framework derived cobalt phosphide via electrodeposition on carbon cloth. The synthesized CoP@CoFe hierarchical heterostructures exhibited not only possessing high surface area due to the MOF nature, also showed OER, and HER responsive without using any binder on carbon cloth substrate. The prepared electrode was applied to overall water splitting in 1 M KOH, and the overpotentials to reach current density of 10 mA cm^-2 were 270, 172 mV, respectively. The CoP@CoFe hierarchical heterostructures show excellent electrocatalytic activities toward both OER and HER in an alkaline media, attributed to the synergistic effect such as reduced series resistance and increased catalytic active site. Moreover, the catalytic activity was not degraded even after a long operation of more than 50 h.

Side reaction in the hydrogen and carbothermal reductions of BaO and BaCO3: The role of an infinitesimal amount of water

오주현,박지훈,강미정,정성철,Takeuchi Ichiro,정정현,이승훈 한국물리학회 2022 Current Applied Physics Vol.34 No.-

Alkaline earth (AE) metals are irreplaceable ingredients in the synthesis of AE metal-based antiperovskite oxides, and it can be achieved by a chemical reduction of a stable AE metal compound. In this study, hydrogen and carbothermal reduction of BaO and BaCO3 were attempted, and we here report an undesirable side reaction creating barium hydroxide (Ba(OH)2) as the product of the reaction with the small amount of water in ultra-high purity inert gas used in the reduction processes. Such side reaction pathways and products are hardly identifiable in a high-temperature reaction; yet, systematic investigations on phase evolutions using X-ray diffraction, IR spectroscopy, and thermogravimetric analysis enabled the detection of Ba(OH)2⋅xH2O. Unintentional creation of alkaline earth metal oxides in intermediate and subsequent hydration even under a negligible amount of H2O may lead to an unexpected loss of alkaline earth metal element and, consequently, its deficiency in a desired final product.