@article { ISI:000253339800027, title = {Sn-119 magic angle spinning NMR of nanocrystalline SnO2}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {8}, number = {1}, year = {2008}, month = {JAN}, pages = {321-328}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA}, abstract = {

Nanocrystalline SnO2 samples of different grain sizes, prepared by inert gas condensation technique (IGCT) and chemical precipitation method and conforming to the tetragonal phase, have been studied by variable speed (3-10 kHz) Sn-119 MAS NMR at 11.74 Tesla field. Sn-119 solid-state NMR results show that the IGCT prepared samples have good crystallinity and phase purity compared to the samples prepared by the chemical method. The determination of Sn-119 chemical shielding parameters (delta(iso), Delta delta and eta) from slow MAS spectra shows that the Sn-119 isotropic chemical shift (delta(iso)) is strongly influenced at smaller grain sizes, attributable to the change in the O2- local symmetry for the surface Sn-119 ions at smaller grain sizes. The observed line widths in MAS spectra are significantly larger than the life-time broadening due to spin-lattice (T-1) and spin-spin (T,) relaxation. The Sn-119 MAS NMR spectra are thus inhomogeneously broadened by a distribution of isotropic chemical shifts, the line broadening increasing with decrease in grain size.

}, keywords = {Hydrolysis, IGCT, MAS NMR, nanocrystalline SnO2}, issn = {1533-4880}, doi = {10.1166/jnn.2008.015}, author = {Sabarinathan, V. and Chandran, C. Vinod and Ramasamy, S. and Ganapathy, Subramanian} } @article { ISI:000280972500010, title = {Enzymatic hydrolysis and ethanol production using xyloglucanase and debaromyces hansenii from tamarind kernel powder: galactoxyloglucan predominant hemicellulose}, journal = {Journal of Biotechnology}, volume = {148}, number = {4}, year = {2010}, month = {AUG}, pages = {233-239}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The hydrolysis and ethanol production from tamarind kernel powder (TKP), a rich source of galactoxyloglucan (GXG) was investigated for the first time using xyloglucanase and thermotolerant Debaromyces hansenii. The acid hydrolysis of TKP with 2N H(2)SO(4) at 120 degrees C for 30 min yielded an overall saccharification of 94\% based on the total available carbohydrate content and further fermentation at 40 degrees C with thermotolerant D hansenii produced an ethanol yield of 0.35 g/g. A maximum hydrolysis of 55 and 78\% for GXG was obtained in 48 h at 50 degrees C using Thermomonospora xyloglucanase (TXy) and accellerase (TM) 1000, respectively. The synergistic effect of beta-galactosidase and xyloglucanase was demonstrated by the exogenous addition of beta-galactosidase to TXy which improved the overall hydrolysis of GXG by 30\%. The rate of hydrolysis of GXG with TXy and accellerase was increased by 15-20\% in the presence of chemical surfactants (tween 80 and toluene) or protein additive (BSA). The fermentation of enzymatic hydrolysates of GXG by TXy and accellerase with free cells at 40 degrees C produced an ethanol yield of 0.39 and 0.41 g/g whereas with immobilized cells produced 0.45 and 0.43 g/g, respectively, with a theoretical conversion efficiencies of 78-88\%. The immobilized yeast cells were reused six times at 40 degrees C with 100\% fermentation efficiency. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Ethanol, Galactoxyloglucan, Hydrolysis, Tamarind kernel powder, Thermotolerant yeast, Xyloglucanase}, issn = {0168-1656}, doi = {10.1016/j.jbiotec.2010.06.004}, author = {Menon, Vishnu and Prakash, Gyan and Rao, Mala} } @article { ISI:000293288500001, title = {Biodiesel production from vegetable oils and animal fat over solid acid double-metal cyanide catalysts}, journal = {Catalysis Surveys from Asia}, volume = {15}, number = {3}, year = {2011}, month = {SEP}, pages = {145-160}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Biodiesel comprises of fatty acid alkyl esters prepared from vegetable oils or animal fat by esterification/transesterification with short-chain alcohols (methanol or ethanol, for example). It is a biodegradable renewable fuel. Its production is growing exponentially due to greater concerns about environmental protection and depletion of fossil fuel resources. Further, its production from non-edible oils and animal fat is more desirable than from edible oils due to lower cost of non-edible feedstocks and elimination of food verses fuel issues. Solid acid catalysts are ideal for conversion of such low-grade oils to biodiesel. Biodiesel from non-edible oils can be produced by two methods: (1) simultaneous esterification of fatty acids and transesterification of fatty acid glycerides and (2) hydrolysis of glycerides followed by esterification. This account reports the catalytic performance of solid, Fe-Zn double-metal cyanide (DMC) complexes and other acid catalysts in these transformations for biodiesel production. The factors influencing the catalytic performance of the solid acid catalysts in biodiesel production are discussed.

}, keywords = {Biodiesel, Double-metal cyanide, Esterification, Hydrolysis, solid acid catalysts, transesterification}, issn = {1571-1013}, doi = {10.1007/s10563-010-9108-2}, author = {Srinivas, Darbha and Satyarthi, Jitendra K.} } @article { ISI:000287428900016, title = {Bioethanol production from renewable polymer lichenan using lichenase from an alkalothermophilic thermomonospora sp and thermotolerant yeast}, journal = {Fuel Processing Technology}, volume = {92}, number = {3}, year = {2011}, month = {MAR}, pages = {401-406}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Biomass feedstocks available decentrally will be more commodious for localized biorefinery approach than the exhaustive large scale and centralized plants driven by cost intensive technology. Lichen is present in a wide range of habitats in a distributed manner. A maximum hydrolysis of 73\%-76\% for lichenan from Cetraria islandica, Usnea barbata and Parmelia sp. were obtained in 24 h using lichenase from an alkalothermophilic Thermomonospora sp. wherein the hydrolysis was 100\% with commercial enzyme Accellerase (TM) 1000. The synergistic role of beta-glucosidase in lichenan hydrolysis was demonstrated by the exogenous addition of beta-glucosidase to Thermomonospora lichenase which resulted in complete hydrolysis. The hydrolysates of lichenan obtained using Accellerase or a cocktail of Thermomonospora lichenase and beta-glucosidase when fermented with free cells of Saccharomyces at 40 degrees C produced an ethanol yield of 0.45 g/g-0.48 g/g with theoretical conversion efficiencies of 93\%-96\%. The Ca-alginate immobilized yeast cells were reused eight times at 40 degrees C with 100\% fermentation efficiency. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Ethanol, Hydrolysis, Lichenan, Lichenase, Synergism, Thermotolerant yeast}, issn = {0378-3820}, doi = {10.1016/j.fuproc.2010.10.001}, author = {Menon, Vishnu and Divate, Rupesh and Rao, Mala} } @article { ISI:000319545800013, title = {Approach towards biocatalytic valorisation of barley beta-glucan for bioethanol production using 1,3-1,4 beta-glucanase and thermotolerant yeast}, journal = {International Biodeterioration \& Biodegradation}, volume = {82}, year = {2013}, month = {AUG}, pages = {81-86}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

The exploitation of renewable resource containing polymers other than cellulose and hemicellulose are critically important for the feasibility of biofuel production. The potential of 1,3-1,4 glucan 4-gluconohydrolyase mediated saccharification of barley beta-glucan (BG) was investigated for ethanol production using thermotolerant Saccharomyces sp. A maximum hydrolysis of 71\% was obtained in 24 h using in-house produced 1,3-1,4 beta-glucanase from an alkalothermophilic Thermomonospora sp. whereas the hydrolysis was 100\% with Accellerase (TM) 1000. The synergistic effect of beta-glucosidase and 1,3-1,4 beta-glucanase was demonstrated by the exogenous addition of beta-glucosidase to Thermomonospora 1,3-1,4 beta-glucanase which resulted in complete hydrolysis of BG. The hydrolysates of BG obtained using Accellerase or a cocktail of Thermomonospora 1,3-1,4 beta-glucanase and beta-glucosidase when fermented with free cells of Saccharomyces at 40 degrees C produced an ethanol yield of 0.44 g g(-1) and 0.46 g g(-1) respectively and when fermented with immobilized cells produced a yield of 0.49 g g(-1). The Ca-alginate immobilized yeast cells were reused nine times at 40 degrees C with 100\% fermentation efficiency. The economics of barley-to-fuel ethanol program will ameliorate if in addition to barley starch, beta-glucan is also utilized. (c) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {1, 3-1, 4 Glucan 4-gluconohydrolyase, Barley beta-glucan, Ethanol, Hydrolysis, Synergism, Thermotolerant yeast}, issn = {0964-8305}, doi = {10.1016/j.ibiod.2013.03.002}, author = {Divate, Rupesh and Menon, Vishnu and Rao, Mala} } @article { ISI:000338748400051, title = {One-pot synthesis of 5-hydroxymethylfurfural by cellulose hydrolysis over highly active bimodal micro/mesoporous H-ZSM-5 catalyst}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {2}, number = {7}, year = {2014}, month = {JUL}, pages = {1928-1932}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Direct synthesis of 5-hydroxymethylfurfural (5-HMF), a useful renewable biofuel and biochemical, was systematically studied by hydrolysis of microcrystalline cellulose over Bimodal-HZ-5 zeolite. Bimodal-HZ-5 zeolite obtained by post-synthesis modification of H-ZSM-5 with desilication was found to be a potential heterogeneous catalyst with 67\% cellulose conversion and 46\% yield of 5-HMF. Bimodal-HZ-5 was observed to be reusable for four cycles, without any loss in activity. The detailed optimization of process parameters and catalyst reusability are also presented. The present study opens a new avenue for the renewable one-pot synthesis of 5-HMF, a valuable product.

}, keywords = {5-Hydroxymethylfurfural, Biomodal-HZ-5, glucose, Hydrolysis, Microcrystalline cellulose}, issn = {2168-0485}, doi = {10.1021/sc500270z}, author = {Nandiwale, Kakasaheb Y. and Galande, Nitish D. and Thakur, Pratika and Sawant, Sanjay D. and Zambre, Vishal P. and Bokade, Vijay V.} } @article { ISI:000380943900048, title = {Proton play in the formation of low molecular weight chitosan (LWCS) by hydrolyzing chitosan with a carbon based solid acid}, journal = {Carbohydrate Polymers}, volume = {151}, year = {2016}, month = {OCT}, pages = {417-425}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Low molecular weight chitosan (LWCS) constitute a special class of value added chemicals that are primarily obtained from crustacean shells, which are the main water pollutants from crabs and shrimp processing centers. Unlike chitin and chitosan, LWCS possess improved solubility in water and aqueous solutions, making them widely applicable in numerous fields ranging from drug delivery to waste water treatment. Among the methods employed for their production, chemical breakdown by strong liquid acids has yielded good success. However, this method is met with severe concerns arising from the harsh nature of liquid acids, which may corrode the reactors for commercial synthesis, and their limited reusability. The physical methods like ultrasound and microwave are energy intensive in nature, while the enzymatic methods are expensive and offers limited scope for reuse. We have attempted to overcome these problems by employing carbon based solid acid (CSA) for hydrolyzing chitosan to LWCS. CSA can be easily produced using activated carbon, a cost-effective and easily available raw material. Reactions were carried out between chitosan and CSA in a hydrothermal glass reactor and the products, separated by cold centrifugation, were purified and dried. The dried products were characterized for their molecular weight and solubility. Results indicated more than ten-fold decrease in the molecular weight of chitosan and the product exhibited water solubility. The CSA could be used upto four times, without regeneration, to give a consistent quality product. The aqueous solution of resulting LWCS exhibited a pH of 6.03 +/- 0.11, as against the acidic pH range of solutions of commercially available LWCS, indicating its suitability for biomedical applications. Our investigation facilitates a {\textquoteleft}green approach{\textquoteright} that may be employed for commercial production of value added chemicals from waste products of marine industry. (C) 2016 Elsevier Ltd. All rights reserved.

}, keywords = {Carbon based solid acid, Chitosan, green synthesis, Hydrolysis, Low molecular weight chitosan}, issn = {0144-8617}, doi = {10.1016/j.carbpol.2016.05.082}, author = {Krishnan, R. Akhil and Deshmukh, Pranjal and Agarwal, Siddharth and Purohit, Poorvi and Dhoble, Deepa Arun and Waske, Prashant and Khandekar, Dileep and Jain, Ratnesh and Dandekar, Prajakta} } @article {44014, title = {Influence of carbon based supports on selectivity behavior of diols and propanol in Ru catalyzed glycerol hydrogenolysis}, journal = {Applied Catalysis B: Environmental}, volume = {204}, year = {2017}, month = {MAY}, chapter = {134-146}, abstract = {

Activated carbon (AC) and three graphite materials were studied as supports for Ru catalyzed glycerol hydrogenolysis to propanediols and 1-propanol. Structural characteristics of AC and graphite materials were found to greatly affect the reducibility and particle size of supported Ru and hence, the activity and product distribution in glycerol hydrogenolysis. XRD of graphite materials showed distinctly (002) plane having highly organized layered structure and the peak intensity decreased in the order of Ru/KS150 \> Ru/HSAG100 \> Ru/KS6 due to decrease in the graphite sheet thickness. In Raman, the intense D band in HSAG100 compared to that in KS6 and KS150 samples indicated its highly amorphous nature or mixed carbon hybridization. Glycerol conversion for Ru on AC was higher than that on graphite and among different graphites, it showed a descending activity order of Ru/KS6 \> Ru/HSAG100 \> Ru/KS150. The product distribution for AC and HSAG100 supported Ru was similar, giving 1-propanol (45\%) alongwith 1,2-propanediol (1,2-PDO) (37\%) and 1,3-propanediol (1,3-PDO) (9{\textendash}11\%). For graphite supports, availability of Ru although bigger in size (4{\textendash}5 nm), would be higher on the surface than in case of AC which formed deep hydrogenolysis products like 1-, 2- propanol, ethanol etc.

}, keywords = {activated carbon, Amorphous carbon, catalysis, Glycerol, Glycerol conversions, Glycerol hydrogenolysis, graphite composites, Graphite supports, Hydrogenolysis, Hydrolysis, layered structures, Particle size, Product distributions, Propanediols, Propanol, Selectivity behavior, Structural characteristics, Structural effect, Structural effects}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2016.11.032}, author = {Mane, Rasika B. and Patil, S. and Shirai, Masayuki and Rayalu, Sadhana S. and Rode, Chandrashekhar V.} } @article {46677, title = {Understanding the role of solvent properties on reaction kinetics for synthesis of silica nanoparticles}, journal = {Chemical Engineering Journal}, volume = {398}, year = {2020}, month = {OCT}, pages = {125427}, type = {Article}, abstract = {

The effect of various alcoholic solvents and their compositions on the size of silica particles synthesized through hydrolysis and condensation of tetraethyl orthosilicate (TEOS) is studied. The alcohols used are: Methanol, ethanol, propanol, i-propanol, butanol, pentanol, hexanol, octanol, decanol and do-decanol. Ethanol was used as a co-solvent with the higher molecular weight alcohols. Silica particles of size between 100 nm and 2 mu m were obtained by changing solvent composition. Concentrations of total soluble silica and silicic acid were measured and used for exploring the kinetics of hydrolysis and condensation reactions. Polarity, steric hindrance and viscosity of solvent were found to have a strong influence on the rate constants and size of silica nanoparticles. An attempt is made to correlate both final particle size and rate constants with dielectric constant, Wiener index and viscosity of the solvent.

}, keywords = {condensation, Hydrolysis, kinetics, silica particles, Solvents, Stober process}, issn = {1385-8947}, doi = {10.1016/j.cej.2020.125427}, author = {Bari, Atul H. and Jundale, Rajashri B. and Kulkarni, Amol. A.} } @article {47992, title = {Recent developments in the applications of biomass-derived sulfonated carbonaceous solid acid catalysts}, journal = {Helvetica Chimica Acta}, volume = {105}, year = {2022}, month = {AUG}, pages = {e202200032}, type = {Review}, abstract = {

Recently, carbon-based materials are gaining a lot of attraction. It is considered as an emerging area of research and has gained significant importance as an efficient catalyst/material in various fields. Biomass is abundantly available, cheap and a renewable carbon resource. Sulfonated carbonaceous solid acid catalyst can be derived by sulfonation of various sources of biomass such as sugars, lignin, fruit waste, agro-waste, bio-char, etc. Sulfonated carbonaceous solid acid catalysts can be used as a substitute to liquid acids. These catalysts possess a stable carbon skeleton and are insoluble in almost all organic solvents as well as under acidic/basic conditions. This review covers details about biomass-derived sulfonated carbonaceous solid acid catalysts and its catalytic activities in many important transformations such as hydrolysis of cellulose, synthesis of biodiesel, synthesis of various important chemicals and for various organic transformations.

}, keywords = {Biodiesel, Biomass, cellulose, Hydrolysis, sulfonated carbonaceous solid acid catalyst}, issn = {0018-019X}, doi = {10.1002/hlca.202200032}, author = {Kirdant, Swapnali P. and Tamboli, Asma T. Biradar and Jadhav, Vrushali H.} } @article {48095, title = {Use of isoperibolic reaction calorimeter for the study of reaction kinetics of acetic anhydride hydrolysis reaction: effect of acetic anhydride and water ratio}, journal = {Chemical and Process Engineering-Inzynieria Chemiczna I Procesowa}, volume = {43}, year = {2022}, month = {DEC}, pages = {255-264}, type = {Article; Proceedings Paper}, abstract = {

Reaction kinetics of acetic anhydride hydrolysis reaction is being studied at a fixed reaction temperature and ambient pressure using an isoperibolic reaction calorimeter. Temperature versus time data along with heat and mass balance is used to determine the kinetics parameters i.e. activation energy and Arrhenius coefficient. It has been studied with the varying volumetric ratio of acetic anhydride and water; and kinetics parameters were compared and plotted for each ratio. Such a study has not been done previously to determine the kinetics dependency on varying the acetic anhydride water ratio. As the acetic anhydride hydrolysis reaction is exothermic in nature, the present study will help to decide the safe and suitable operating conditions such as concentration and temperature for conducting this reaction at plant scale. The kinetic data presented can be used further for the mathematical modeling and simulation of such exothermic hydrolysis reactions.

}, keywords = {acetic anhydride, Hydrolysis, kinetics, reaction calorimeter, Water}, issn = {0208-6425}, doi = {10.24425/cpe.2022.140829}, author = {Kumar, Rajendra and Tiwari, Anurag Kumar} }