Journal Articles
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Item Technical aspects of biodiesel and its oxidation stability(2009) Kapilan, N.; Ashok Babu, T.P.; Reddy, R.P.Biodiesel is a clean burning alternative renewable fuel made from natural renewable sources. It is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, which conform to ASTM specifications for use in diesel engines. Biodiesel present a very promising alternative fuel to diesel oil and properties of this oil offer the advantage of immediate substitution in existing diesel engines with little or no modifications at all. But one of the major technical problems associated with the biodiesel is its susceptibility to oxidation, which can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. This is due to the unsaturated fatty acid chains and the presence of the double bond in the molecule, which produce a high level of reactivity with the oxygen, especially when it placed in contact with air. The oxidation of fatty acid chains is a complex process that proceeds by a variety of mechanisms. The various other factors influence the oxidation process of biodiesel includes light, temperature, extraneous materials, peroxides, size of the surface area between biodiesel and air. One of the methods of improving biodiesel oxidative stability includes the deliberate addition of antioxidants or modification of the fatty ester profile. This article discusses the technical aspects of biodiesel and its oxidation stability.Item Progress in Electrochemical Trifluoromethylation Reactions(Wiley-VCH Verlag, 2020) Bhaskaran, R.P.; Babu, B.P.The importance of fluorinated organic molecules in drugs and pharmaceuticals led to the development of several synthetic methods for introducing fluorine into bioactive molecules and trifluoromethylation is one of the key approaches for the same. Electrochemical organic synthesis has emerged as one of the most sustainable, green synthetic strategies in recent years and new developments in electroorganic synthesis also focus on electrochemical trifluoromethylation of organic compounds. A considerable number of reports have appeared in recent literature and this review surveys all the recent developments in electrochemical trifluoromethylation reactions. This highly sustainable trifluoromethylating protocol will emerge further soon and pave the way for more energy-efficient and green protocols. (Figure presented.). © 2020 Wiley-VCH GmbHItem Molybdenum based mixed oxide containing Mo0.65V 0.25W0.10 was investigated for the partial oxidation of methanol. The structural property and catalytic activity of the mixed oxide catalyst was studied by surface area (BET), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). The thermal activation of the catalyst resulted increase in the conversion of methanol and the selectivity to formaldehyde. The thermal activation of the MoVW mixed oxide in nitrogen atmospheres induces partial crystallization of a Mo5O14-type oxide at 813 K. The SEM images of the thermally activated catalyst show needle like particles. These particles were agglomerates of platelet-like crystallites of a few hundreds of nanometers in size. SEM and EDX techniques show that the mixed oxide is characterized by an inhomogeneous elemental distribution on the length scale of a few microns. XRD of the thermally activated catalyst showed a nanocrystalline material identified as a mixture of Mo5O 14, MoO3 and MoO2-type MoVW oxides. The catalytic activity of the MoVW mixed oxide show a good conversion of methanol and selectivity to formaldehyde. © 2005 Springer Science+Business Media, Inc.(Partial oxidation of methanol to formaldehyde on molybdenum based mixed oxide catalyst) Badekai Ramachandra, B.; Choi, J.-S.; Choo, K.-Y.; Sung, J.-S.; Song, S.-D.; Kim, T.-H.2005Item Thermal stability and high-temperature wear of Ti-TiN and TiN-CrN nanomultilayer coatings under self-mated conditions(Elsevier Ltd, 2007) Srinivasan, D.; Kulkarni, Trupti.G.; Anand, K.Ti-TiN and TiN-CrN nanomultilayers were thermally stable retaining uniform and sharp layer interfaces up to 24 h at 773 K, without any oxidation or phase transformation accompanying each individual layer. Decreasing the multilayer spacing resulted in an increase in the hardness in both cases. The coating hardness was found to be independent of the substrate type, when applied on HS718, Ti64 and HCHCr substrates. In scratch testing, the multilayers displayed a better resistance to the onset of failure, as compared to the monolayer TiN. The substrate plasticity played an important role in determining the coating failure mode. Self-mated wear tests revealed the CrN-TiN system to exhibit the best wear behaviour, both at room temperature and at 773 K. The Ti-TiN coatings are more accommodative with all three substrates, as compared to TiN-CrN and TiN. © 2006 Elsevier Ltd. All rights reserved.Item Biological treatment of toxic petroleum spent caustic in fluidized bed bioreactor using immobilized cells of thiobacillus RAI01(2008) Potumarthi, R.; Mugeraya, G.; Jetty, A.In the present studies, newly isolated Thiobacillus sp was used for the treatment of synthetic spent sulfide caustic in a laboratory-scale fluidized bed bioreactor. The sulfide oxidation was tested using Ca-alginate immobilized Thiobacillus sp. Initially, response surface methodology was applied for the optimization of four parameters to check the sulfide oxidation efficiency in batch mode. Further, reactor was operated in continuous mode for 51 days at different sulfide loading rates and retention times to test the sulfide oxidation and sulfate and thiosulfate formation. Sulfide conversions in the range of 90-98% were obtained at almost all sulfide loading rates and hydraulic retention times. However, increased loading rates resulted in lower sulfide oxidation capacity. All the experiments were conducted at constant pH of around 6 and temperature of 30?±?5 °C. © 2008 Humana Press.Item Biological sulfide oxidation using autotrophic Thiobacillus sp.: Evaluation of different immobilization methods and bioreactors(2009) Ravichandra, P.; Gopal, M.; Jetty, A.Aims: Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied. Methods and Results: Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl2 concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations. Conclusions: The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage. Significance and Impact of the Study: Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation. © 2009 The Society for Applied Microbiology.Item An optimization study on microwave irradiated, decomposition of phenol in the presence of H2O2(2009) Prasannakumar, B.R.; Iyyaswami, I.; Murugesan, T.Background: Removal of phenol from industrial waste waters involves basic techniques namely extraction, biodegradation, photocatalytic degradation, etc. Among the available processes, the oxidation of phenols using H2O2 is a suitable alternative because of low cost and high oxidizing power. The application of an oxidation process for the decomposition of stable organic compounds in waste water leads to the total degradation of the compounds rather than transferring from one form to another. Since oxidation using Fenton's reagent ismore dependent on pH, in this present work it was proposed to use H2O2 coupled with microwave irradiation. The effects of initial phenol concentration, microwave power and the irradiation time on the amount of decomposition were studied. Results: In the present work experiments were conducted to estimate the percentage degradation of phenol for different initial concentrations of phenol (100, 200, 300, 400 and 500 mg L-1), microwave power input (180, 360, 540, 720 and 900 W) for different irradiation times. The kinetics of the degradation process were examined through experimental data and the decomposition rate follows first-order kinetics. Response surface methodology (RSM) was employed to optimize the design parameters for the present process. The interaction effect between the variables and the effect of interaction on to the responses (percentage decomposition of phenol) of the process was analysed and discussed in detail. The optimum values for the design parameters of the process were evaluated (initial phenol concentration 300 mg L-1, microwave power output 668 W, and microwave irradiation time 60 s, giving phenol degradation 82.39%) through RSM by differential approximation, and were confirmed by experiment. Conclusion: The decomposition of phenol was carried out using H2O2 coupled with microwave irradiation for different initial phenol concentrations, microwave power input and irradiation times. The phenol degradation process follows first-order kinetics. Optimization of the process was carried out through RSM by forming a design matrix using CCD. The optimized conditions were validated using experiments. The information is of value for the scale up of the oxidation process for the removal of phenol from wastewater. © 2008 Society of Chemical Industry.Item 6-[3-(4-Fluorophenyl)-1H-pyrazol-4-yl]-3-[(2-naphthyloxy)methyl][1,2,4]triazolo[3,4-b][1,3,4]thiadiazole as a potent antioxidant and an anticancer agent induces growth inhibition followed by apoptosis in HepG2 cells(2010) Dhanya, D.; Isloor, A.M.; Shetty, P.; Satyamoorthy, K.; Bharath Prasad, A.S.In this paper we have investigated the in vitro antioxidant property of two triazolo-thiadiazoles, 6-[3-(4-fluorophenyl)-1H-pyrazol-4-yl]-3-[(2-naphthyloxy)methyl][1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (FPNT) and 6-[3-(4-chlororophenyl)-1H-pyrazol-4-yl]-3-[(phenyloxy)methyl][1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (CPPT) by spectrophotometric DPPH and ABTS radical scavenging methods as well as by lipid peroxide assay. The anticancer activity along with possible mechanism of action of triazolo-thiadiazoles in Hep G2 cells was explored using MTT assay, [3H] thymidine assay, flow cytometry and chromatin condensation studies. Both FPNT and CPPT exhibited a dose dependent cytotoxic effect on hepatocellular carcinoma cell line, HepG2. The IC50 value was very low for both the compounds when compared to standard drug, doxorubicin. Incorporation of [3H] thymidine in conjunction with cell cycle analysis suggested that FPNT inhibited the growth of HepG2 cells. Flow cytometric studies revealed more percentage of cells in sub-G1 phase, indicating apoptosis, which was further confirmed through chromatin condensation studies by Hoechst staining. FPNT was found to be a potent antioxidant when compared to the standard in DPPH, ABTS radical scavenging assays and lipid peroxidation studies. © 2010 .Item Degradation of paracetamol in aqueous solution by Fenton Oxidation and photo-Fenton Oxidation processes using iron from Laterite soil as catalyst(2011) Manu, B.; MahamoodFor the treatment of paracetamol in water, the photo-Fenton Oxidation process and Classic Fenton oxidation process have been demonstrated and found effective. An iron catalyst extracted from lateritic soil is used to exhibit the degradation and mineralization of paracetamol. Paracetamol reduction and chemical oxygen demand (COD) removal are measured as the objective functions to be maximized. The experimental conditions of the degradation of paracetamol are optimized by Fenton process. the optimum conditions observed for 10 mg/L initial paracetamol concentration are influent pH 3, initial H 2O 2 dosage 30 mg/L, [paracetamol]/[H 2O 2] ratio 1:3 (w/w) and [H 2O 2] / [Laterite iron] ratio 30:0.75 (w/w). At the optimum conditions, for 10 mg/L of initial paracetamol concentration, 76% paracetamol reduction and 69% COD removal by Fenton oxidation and 79% paracetamol reduction and 77% COD removal by UV-C Fenton process are observed in 120 minutes reaction time. At the above optimum conditions, HPLC analysis has demonstrated 100% removal of paracetamol for Fenton oxidation process in 240 minutes and for UV-C photo- Fenton process in 120 minutes. The methods are effective and they may be used in the paracetamol industry. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.Item Enhanced degradation of paracetamol by UV-C supported photo-Fenton process over Fenton oxidation(2011) Manu, B.; Mahamood, S.For the treatment of paracetamol in water, the UV-C Fenton oxidation process and classic Fenton oxidation have been found to be the most effective. Paracetamol reduction and chemical oxygen demand (COD) removal are measured as the objective functions to be maximized. The experimental conditions of the degradation of paracetamol are optimized by the Fenton process. Influent pH 3, initial H 2O 2 dosage 60 mg/L, [H 2O 2]/[Fe 2+] ratio 60 : 1 are the optimum conditions observed for 20 mg/L initial paracetamol concentration. At the optimum conditions, for 20 mg/L of initial paracetamol concentration, 82% paracetamol reduction and 68% COD removal by Fenton oxidation, and 91% paracetamol reduction and 82% COD removal by UV-C Fenton process are observed in a 120 min reaction time. By HPLC analysis, 100% removal of paracetamol is observed at the above optimum conditions for the Fenton process in 240 min and for the UV-C photo-Fenton process in 120 min. The methods are effective and they may be used in the paracetamol industry. © IWA Publishing 2011.