Yeoil Yoon

Carbonic anhydrase immobilized on encapsulated magnetic nanoparticles for CO2 sequestration.

Bovine carbonic anhydrase (BCA) was covalently immobilized onto OAPS (octa(aminophenyl)silsesquioxane)-functionalized Fe(3)O(4)/SiO(2) nanoparticles by using glutaraldehyde as a spacer. The Fe(3)O(4) nanoparticles were coated with SiO(2), onto which was grafted OAPS, and the product was characterized using SEM, TEM, XRD, IR, X-ray photoelectron spectroscopy (XPS), and magnetometer analysis. The enzymatic activities of the free and Fe(3)O(4)/SiO(2)/OAPS-conjugated BCA (Fe-CA) were investigated by hydrolyzing p-nitrophenylacetate (p-NPA), and hydration and sequestration of CO(2) to CaCO(3). The CO(2) conversion efficiency and reusability of the Fe-CA were studied before and after washing the recovered Fe-CA by applying a magnetic field and quantifying the unreacted Ca(2+) ions by using ion chromatography. After 30 cycles, the Fe-CA displayed strong activity, and the CO(2) capture efficiency was 26-fold higher than that of the free enzyme. Storage stability studies suggested that Fe-CA retained nearly 82 % of its activity after 30 days. Nucleation of the precipitated CaCO(3) was monitored by using polarized light microscopy, which revealed the formation of two phases, calcite and valerite, at pH 10 upon addition of serine. The magnetic nanobiocatalyst was shown to be an excellent reusable catalyst for the sequestration of CO(2).

CO2 Absorption and Sequestration as Various Polymorphs of CaCO3 Using Sterically Hindered Amine

One aspect of the attempt to restrain global warming is the reduction of the levels of atmospheric CO2 produced by fossil fuel power systems. This study attempted to develop a method that reduces CO2 emissions by investigating the absorption of CO2 into sterically hindered amine 2-amino-2-methyl-1-propanol (AMP), the acceleration of the absorption rate by using the enzyme carbonic anhydrase (CA), and the conversion of the absorption product to stable carbonates. CO2 absorbed by AMP is converted via a zwitterion mechanism to bicarbonate species; the presence of these anions was confirmed with (1)H and (13)C NMR spectral analysis. The catalytic efficiency (kcat/Km), CO2 absorption capacities, and enthalpy changes (ΔHabs) of aqueous AMP in the presence or absence of CA were found to be 2.61 × 10(6) or 1.35 × 10(2) M(-1) s(-1), 0.97 or 0.96 mol/mol, and -69 or -67 kJ/mol, respectively. The carbonation of AMP-absorbed CO2 was performed by using various Ca(2+) sources, viz., CaCl2 (CAC), Ca(OOCCH3)2 (CAA), and Ca(OOCCH2CH3)2 (CAP), to obtain various polymorphs of CaCO3. The yields of CaCO3 from the Ca(2+) sources were found in the order CAP > CAA > CAC as a result of the effects of the corresponding anions. CAC produces pure rhombohedral calcite, and CAA and CAP produce the unusual phase transformation of calcite to spherical vaterite crystals. Thus, AMP in combination with CAA and CAP can be used as a CO2 absorbent and buffering agent for the sequestration of CO2 in porous CaCO3.

Degradation Characteristics of Aqueous MEA Solution by Corrosion Products and Absorption Conditions

>> The absorbent loss due to degradation in CO2 capture process using aqueous alkanol amine solution has adverse effect on the economics of overall process. The degradation causes absorbent loss, equipment corrosion, foaming, adhesive material producing and viscosity increase in operation. In this study, the degradation characteristics of CO2 capture process using MEA (monoehtanolamine) under various conditions such as O2 partial pressure, CO2 loading and absorbent temperature. The effects of iron, which generated from the equipment corrosion, on absorbent degradation were studied using Fe2SO4 containing MEA solution. The produced gases were analyzed by FT-IR(Fourier Transform Infrared Spectrophotometer) and the specifically measured NH3 concentration was used as a degradation degree of aqueous MEA solution. The experiments showed that the higher CO2 loadings (α), O2 fraction (yO2) and reaction temperature enhanced the more degradation of aqueous MEA solution. Comparing other operation parameters, the reaction temperature most affected on the degradation. Therefore, it could be concluded that the above parameters affects on degradation should be considered for the selections of CO2 absorbent and operating conditions.

Simulation on CO 2 capture process using an Aqueous MEA solution

The capture technology using an aqueous amine solution is studied widely now. The entire process consists of an absorber to remove carbon dioxide selectively and a regenerator to regenerate absorbent and acquire pure carbon dioxide. Because there are the complicated design variables that affect performance of the process, it needs optimization and analysis through modeling to make a commercially reliable process. In this study, the decomposition method was proposed to consider convergence problem and sensitivity analysis was executed for the carbon dioxide capture process variables. Non-equilibrium model was used in the simulation to get more realistic results and we designed optimized process with more than 95% purity and 90% recovery.

CO 2 decomposition characteristics of Ba-ferrite powder

Abstract The objective of this study is development of carbon recycle technology which convert carbon dioxide captured from flue gas to carbon monoxide or carbon and reuse in industrial fields. Since carbon dioxide is very stable and difficult to decompose, metal oxide was used as activation agent for the decomposition of carbon dioxide at low temperature. Metal oxides which convert CO 2 to CO or carbon were prepared using Ba-ferrite by solid and hydrothermal synthesis. TPR/TPO and TGA were used in this study. The results of TPR by H2 and TPO by CO 2 showed that Ba-ferrite powders synthesized by hydrothermal method were better than those by solid method. TGA showed contrary results that reduction of Ba-ferrite powders synthesized using solid method by H 2 was 21.96 wt%, oxidation by CO 2 was 21.24 wt% and 96.72 wt% of CO 2 decomposition efficiency showing excellent oxidation-reduction characteristics at 500℃. Key Words : Carbon dioxide, Decomposition, Reduction, Ferrite, Barium 본 논문은 지식경제부의 에너지· 자원기술개발사업의 연구비 지원(2008CCD27P010000)으로 수행되었습니다.