Electrocatalytic Reduction of Hydrogen Peroxide on Silver Nanoparticles Stabilized by Amine Grafted Mesoporous SBA-15

Mari Vinoba,정순관,Margandan Bhagiyalakshmi,Muthukaruppan Alagar 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

Mesoporous SBA-15 was synthesized using tetraethylorthosilicate (TEOS) as the silica source and Pluronic (P123) as the structure-directing agent. The defective Si-OH groups present in SBA-15 were successively grafted with 3-chloropropyltrimethoxysilane (CPTMS) followed by tris-(2-aminoethyl) amine (TAEA) and/or tetraethylenepentamine (TEPA) for effective immobilization of silver nanoparticles. Grafting of TAEA and/or TEPA amine and immobilization of silver nanoparticles inside the channels of SBA-15 was verified by XRD, TEM, IR and BET techniques. The silver nanoparticles immobilized on TAEA and /or TEPA grafted SBA-15 was subjected for electrocatalytic reduction of hydrogen peroxide (H2O2). The TEPA stabilized silver nanoparticles show higher efficiency for reduction of H2O2 than that of TAEA,due to higher number of secondary amine groups present in TEPA. The amperometric analysis indicated that both the Ag/SBA-15/TAEA and Ag/SBA-15/TEPA modified electrodes required lower over-potential and hence possess high sensitivity towards the detection of H2O2. The reduction peak currents were linearly related to hydrogen peroxide concentration in the range between 3 × 10‒4 M and 2.5 × 10‒3 M with correlation coefficient of 0.997 and detection limit was 3 × 10‒4 M.

Harvesting CaCO₃ Polymorphs from In Situ CO₂ Capture Process

Vinoba, Mari,Bhagiyalakshmi, Margandan,Choi, Song Yi,Park, Ki Tae,Kim, Hak Joo,Jeong, Soon Kwan American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.31

<P>The in situ sequestration of CO<SUB>2</SUB> using alkanolamine and organometallic calcium (OMC) offers an ecofriendly method for synthesizing a diverse range of calcite, vaterite, and aragonite polymorphs of CaCO<SUB>3</SUB>. Aqueous <I>N</I>-methyldiethanolamine (MDEA) has high CO<SUB>2</SUB> loading capacity with low regeneration energy, but rate of CO<SUB>2</SUB> absorption was found to be slow. The driving force for the binding between CO<SUB>2</SUB> and MDEA could be enhanced by the presence of bovine carbonic anhydrase (bCA). The absorbed CO<SUB>2</SUB> was converted to stable carbonates through the addition of an OMC. The bCA enzyme both accelerated the CO<SUB>2</SUB> absorption and mineralization in the amine–CO<SUB>2</SUB>–OMC system and improved the catalytic efficiency to 1.07 × 10<SUP>4</SUP> M<SUP>–1</SUP> s<SUP>–1</SUP>. The enthalpy of in situ mineralization, the mechanism underlying the CO<SUB>2</SUB> absorption process, and the formation of an aggregated composition of CaCO<SUB>3</SUB> were examined using calorimetric, NMR, and X-ray diffraction techniques, respectively. The crystal formation depended crucially on the mineralization process involving the anions of the OMC precursors. The CaO-based sorbents derived from the CaCO<SUB>3</SUB> polymorphs shows good CO<SUB>2</SUB> capture capacity on combustion process, and the consecutive re-formation–regeneration cycles of the CaO sorbents followed the trend aragonite > vaterite > calcite. Hence, the MDEA–OMC–bCA system offers a promising method for transitioning between CaCO<SUB>3</SUB> polymorphs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-31/jp503448y/production/images/medium/jp-2014-03448y_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp503448y'>ACS Electronic Supporting Info</A></P>

Immobilization of carbonic anhydrase-gold nanoparticle on mesoporous silica: Its nanobiocatalytic activity for hydrolysis of p-nitrophenyl acetate

( Mari Vinoba ),김대훈,임경수,정순관,( Muthukaruppan Alagar ) 한국공업화학회 2010 한국공업화학회 연구논문 초록집 Vol.2010 No.1

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

Vinoba, Mari,Bhagiyalakshmi, Margandan,Grace, Andrews Nirmala,Chu, Dae Hyun,Nam, Sung Chan,Yoon, Yeoil,Yoon, Sung Ho,Jeong, Soon Kwan American Chemical Society 2013 Langmuir Vol.29 No.50

<P>One aspect of the attempt to restrain global warming is the reduction of the levels of atmospheric CO<SUB>2</SUB> produced by fossil fuel power systems. This study attempted to develop a method that reduces CO<SUB>2</SUB> emissions by investigating the absorption of CO<SUB>2</SUB> 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. CO<SUB>2</SUB> absorbed by AMP is converted via a zwitterion mechanism to bicarbonate species; the presence of these anions was confirmed with <SUP>1</SUP>H and <SUP>13</SUP>C NMR spectral analysis. The catalytic efficiency (<I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB>), CO<SUB>2</SUB> absorption capacities, and enthalpy changes (Δ<I>H</I><SUB>abs</SUB>) of aqueous AMP in the presence or absence of CA were found to be 2.61 × 10<SUP>6</SUP> or 1.35 × 10<SUP>2</SUP> M<SUP>–1</SUP> s<SUP>–1</SUP>, 0.97 or 0.96 mol/mol, and −69 or −67 kJ/mol, respectively. The carbonation of AMP-absorbed CO<SUB>2</SUB> was performed by using various Ca<SUP>2+</SUP> sources, viz., CaCl<SUB>2</SUB> (CAC), Ca(OOCCH<SUB>3</SUB>)<SUB>2</SUB> (CAA), and Ca(OOCCH<SUB>2</SUB>CH<SUB>3</SUB>)<SUB>2</SUB> (CAP), to obtain various polymorphs of CaCO<SUB>3</SUB>. The yields of CaCO<SUB>3</SUB> from the Ca<SUP>2+</SUP> 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 CO<SUB>2</SUB> absorbent and buffering agent for the sequestration of CO<SUB>2</SUB> in porous CaCO<SUB>3</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-50/la403671y/production/images/medium/la-2013-03671y_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la403671y'>ACS Electronic Supporting Info</A></P>

In-situ sequestration of CO₂ using MDEA-CA System in post-combustion processes

( Mari Vinoba ),( Marpandan Bhagiyalakshmi ),( A. Nirmala Grace ),추대현,최송이,윤여일,정순관 한국공업화학회 2013 한국공업화학회 연구논문 초록집 Vol.2013 No.1

Carbonic Anhydrase Promotes the Absorption Rate of CO₂ in Post-Combustion Processes

Vinoba, Mari,Bhagiyalakshmi, Margandan,Grace, Andrews Nirmala,Kim, Dae Hoon,Yoon, Yeoil,Nam, Sung Chan,Baek, Il Hyun,Jeong, Soon Kwan American Chemical Society 2013 The journal of physical chemistry. B, Condensed ma Vol.117 No.18

<P>The rate of carbon dioxide (CO<SUB>2</SUB>) absorption by monoethanol amine (MEA), diethanol amine (DEA), <I>N</I>-methyl-2,2′-iminodiethanol (MDEA), and 2-amino-2-methyl 1-propanol (AMP) solutions was found to be enhanced by the addition of bovine carbonic anhydrase (CA), has been investigated using a vapor–liquid equilibrium (VLE) device. The enthalpy (−Δ<I>H</I><SUB>abs</SUB>) of CO<SUB>2</SUB> absorption and the absorption capacities of aqueous amines were measured in the presence and/or absence of CA enzyme via differential reaction calorimeter (DRC). The reaction temperature (Δ<I>T</I>) under adiabatic conditions was determined based on the DRC analysis. Bicarbonate and carbamate species formation mechanisms were elucidated by <SUP>1</SUP>H and <SUP>13</SUP>C NMR spectral analysis. The overall CO<SUB>2</SUB> absorption rate (flux) and rate constant (<I>k</I><SUB>app</SUB>) followed the order MEA > DEA > AMP > MDEA in the absence or presence of CA. Hydration of CO<SUB>2</SUB> by MDEA in the presence of CA directly produced bicarbonate, whereas AMP produced unstable carbamate intermediate, then underwent hydrolytic reaction and converted to bicarbonate. The MDEA > AMP > DEA > MEA reverse ordering of the enhanced CO<SUB>2</SUB> flux and <I>k</I><SUB>app</SUB> in the presence of CA was due to bicarbonate formation by the tertiary and sterically hindered amines. Thus, CA increased the rate of CO<SUB>2</SUB> absorption by MDEA by a factor of 3 relative to the rate of absorption by MDEA alone. The thermal effects suggested that CA yielded a higher activity at 40 °C.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2013/jpcbfk.2013.117.issue-18/jp401622c/production/images/medium/jp-2013-01622c_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp401622c'>ACS Electronic Supporting Info</A></P>

Immobilization of Human Carbonic Anhydrase on Gold Nanoparticles Assembled onto Amine/Thiol-Functionalized Mesoporous SBA-15 for Biomimetic Sequestration of CO₂

Vinoba, Mari,Lim, Kyoung Soo,Lee, Si Hyun,Jeong, Soon Kwan,Alagar, Muthukaruppan American Chemical Society 2011 Langmuir Vol.27 No.10

<P>A biocatalyst was synthesized by immobilizing human carbonic anhydrase onto gold nanoparticles assembled over amine/thiol-functionalized mesoporous SBA-15. The physicochemical properties of the functionalized mesoporous SBA-15 were obtained by XRD, BET, FE SEM, HR TEM, EDS, and zeta potential analysis. The biocatalytic performance was studied for <I>para</I>-nitrophenyl acetate (p-NPA) hydrolysis. The kinetic parameters <I>K</I><SUB>m</SUB> were found to be 22.35 and 27.75 mM, and <I>K</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB> values were 1514.09 and 1612.25 M<SUP>−1</SUP> s<SUP>−1</SUP> for HCA immobilized on gold nanoparticles assembled on amine/thiol-functionalized mesoporous SBA-15 (HCA/Au/APTES/SBA-15 and HCA/Au/MPTES/SBA-15), respectively. These HCA/Au/APTES/SBA-15 and HCA/Au/MPTES/SBA-15 were investigated for biocatalytic hydration of CO<SUB>2</SUB> and its precipitation as CaCO<SUB>3</SUB>. The amount of CaCO<SUB>3</SUB> precipitated over HCA/Au/MPTES/SBA-15 was nearly the same as that precipitated over free HCA. Storage stability and reusability studies suggested that HCA/Au/MPTES/SBA-15 retained its activity even after 20 days storage at 25 °C and 20 recycling runs. The present results demonstrate that HCA/Au/MPTES/SBA-15 and HCA/Au/APTES/SBA-15 are highly efficient potential nanobiocatalysts for industrial-scale CO<SUB>2</SUB> sequestration.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2011/langd5.2011.27.issue-10/la105029h/production/images/medium/la-2010-05029h_0011.gif'></P>

Facile CO₂ sequestration into CaCO₃ using alkonalamines

( Mari Vinoba ),( M. Bhagiyalakshmi ),( A. Nirmala Grace ),추대현,최송이,윤여일,정순관 한국공업화학회 2013 한국공업화학회 연구논문 초록집 Vol.2013 No.-

Electrocatalytic Reduction of Hydrogen Peroxide on Silver Nanoparticles Stabilized by Amine Grafted Mesoporous SBA-15

Vinoba, Mari,Jeong, Soon-Kwan,Bhagiyalakshmi, Margandan,Alagar, Muthukaruppan Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

Mesoporous SBA-15 was synthesized using tetraethylorthosilicate (TEOS) as the silica source and Pluronic (P123) as the structure-directing agent. The defective Si-OH groups present in SBA-15 were successively grafted with 3-chloropropyltrimethoxysilane (CPTMS) followed by tris-(2-aminoethyl) amine (TAEA) and/or tetraethylenepentamine (TEPA) for effective immobilization of silver nanoparticles. Grafting of TAEA and/or TEPA amine and immobilization of silver nanoparticles inside the channels of SBA-15 was verified by XRD, TEM, IR and BET techniques. The silver nanoparticles immobilized on TAEA and /or TEPA grafted SBA-15 was subjected for electrocatalytic reduction of hydrogen peroxide ($H_2O_2$). The TEPA stabilized silver nanoparticles show higher efficiency for reduction of $H_2O_2$ than that of TAEA, due to higher number of secondary amine groups present in TEPA. The amperometric analysis indicated that both the Ag/SBA-15/TAEA and Ag/SBA-15/TEPA modified electrodes required lower over-potential and hence possess high sensitivity towards the detection of $H_2O_2$. The reduction peak currents were linearly related to hydrogen peroxide concentration in the range between $3{\times}10^{-4}\;M$ and $2.5{\times}10^{-3}\;M$ with correlation coefficient of 0.997 and detection limit was $3{\times}10^{-4}\;M$.

Capture and Sequestration of CO₂ by Human Carbonic Anhydrase Covalently Immobilized onto Amine-Functionalized SBA-15

Vinoba, Mari,Bhagiyalakshmi, Margandan,Jeong, Soon Kwan,Yoon, Yeo II,Nam, Sung Chan American Chemical Society 2011 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.115 No.41

<P>Human carbonic anhydrase (HCA) was immobilized onto mesoporous SBA-15 surfaces that had been covalently functionalized using one of three amine compounds, namely, tris(2-aminoethyl)amine (TAEA), tetraethylenepentamine (TEPA), and octa(aminophenyl)silsesquioxane (OAPS). Amine functionalization over SBA-15 was characterized by XRD, FE-SEM, BET analysis, and <SUP>29</SUP>Si and <SUP>13</SUP>C CP MAS NMR spectroscopy. HCA immobilization was verified by FT-IR spectroscopy. The catalytic activity toward hydrolysis of <I>p</I>-nitrophenylacetate (<I>p</I>-NPA) was calculated for free and immobilized HCA. The <I>k</I><SUB>cat</SUB> values for HCA/TEPA/SBA-15, HCA/TAEA/SBA-15, and HCA/OAPS/SBA-15 were found to be 7182, 7368, and 7569 M<SUP>–1</SUP> s<SUP>–1</SUP>, respectively. The activities of immobilized HCA were retained even after long-term storage, exposure to high temperatures, and reuse for 40 cycles. For comparison, CO<SUB>2</SUB> hydration and sequestration were measured in the presence of both free and immobilized HCA. Importantly, the CO<SUB>2</SUB> conversion efficiency was calculated using the ion chromatography method. The CO<SUB>2</SUB> capture efficiency of immobilized HCA was 36 times higher than that of free HCA, and 75% of the initial enzymatic activity was retained through 40 cycles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2011/jpccck.2011.115.issue-41/jp204661v/production/images/medium/jp-2011-04661v_0007.gif'></P>