02291nas a2200253   4500008004100000022001400041245009200055210006900147260010600216300001400322490000700336520136000343653001901703653000801722653001301730653002601743653002501769100002401794700002301818700002201841700002701863700002901890856011801919       2007                        eng d  a0009-250900aModeling of bubble column slurry reactor for reductive alkylation of p-phenylenediamine0 aModeling of bubble column slurry reactor for reductive alkylatio  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcDEC  a7290-73040 v623 a<p>A bubble column slurry reactor (BCSR) model has been developed for the reductive alkylation of p-phenylenediamine (PPDA) with methyl ethyl ketone (MEK) to N, N'-di-secondary-alkyl-p-phenylenediamine (Di-amine). This particular reaction system is commercially relevant and involves a combination of parallel and consecutive reactions comprising equilibrium non-catalytic (homogeneous) and catalytic (heterogeneous) steps. The proposed model is based on the `mixing cell approach'. In this work the mixing cell approach has been extended by including a liquid backflow stream from all but the bottommost mixing cell. The model incorporates the contributions of gas-liquid and liquid-solid mass transfer, heat effects, and complex multistep reaction kinetics. CFD model is used to estimate the extent of backflow among mixing cells and its dependence on operating parameters. The effect of gas and liquid velocities, catalyst loading, inlet PPDA concentration, and temperature on the conversion, selectivity, global rate of hydrogenation, and temperature rise is discussed. The comparison of the current approach with the traditional mixing cell model is discussed. The BCSR model presented here will be useful to provide guidelines for designing and improving overall performance of bubble column reactors. (C) 2007 Elsevier Ltd. All rights reserved.</p>10abubble columns10aCFD10akinetics10aMathematical modeling10aReductive alkylation1 aChaudhari, Amit, S.1 aRampure, Mohan, R.1 aRanade, Vivek, V.1 aJaganathan, Rengaswamy1 aChaudhari, Raghunath, V.  uhttp://library.ncl.res.in/content/modeling-bubble-column-slurry-reactor-reductive-alkylation-p-phenylenediamine-002646nas a2200265   4500008004100000022001400041245012000055210006900175260000900244300001200253490000800265520177000273653001502043653001702058653001302075653001402088653002502102100001602127700002402143700002102167700002202188700002202210700002502232856012302257       2019                        eng d  a0301-479700aHydrodynamic cavitation using vortex diode: an efficient approach for elimination of pathogenic bacteria from water0 aHydrodynamic cavitation using vortex diode an efficient approach  cJUL   a210-2190 v2423 a<p>The present study successfully demonstrates greener methodology of hydrodynamic cavitation using rotational flows for disinfection of water. Disinfection of two model microbial strains-gram-negative (Escherichia colt) and gram-positive (Staphylococcus aureus) using vortex diode was evaluated. The removal efficacy was quantified for two different cavitation reactors. Practically complete elimination of E. coli was achieved (99%) after 1 h of cavitation at a pressure drop of only 0.5 bar. However, elimination of S. aureus using vortex diode was observed to be lower in comparison to the removal of E. coli and only 60% disinfection could be achieved under similar conditions, which can be subsequently enhanced up to 98% by increasing pressure drop. The results were compared with another cavitating device that employs linear flow for cavitation, orifice. The reactor geometry has significant impact on the disinfection process and orifice was found to require significantly higher pressure drop (10 bar) conditions for disinfection and for eliminating grain-positive bacteria with high efficiency. A plausible mechanism for disinfection was proposed to elucidate the role of cavitation in cell destruction leading to death of cells through the rupture of cell wall, oxidative damage and possible DNA denaturation. Also, a cavitation model using per pass disinfection was developed that can provide meaningful physical description of the disinfection process as against the conventional first order reaction rate model. This study would provide meaningful insight into cavitation process based on hydrodynamic cavitation for the destruction of both gram-negative and gram-positive bacteria from various water sources, including industrial wastewaters.</p>
10aCavitation10aDisinfection10akinetics10apollution10aWastewater treatment1 aJain, Pooja1 aBhandari, Vinay, M.1 aBalapure, Kshama1 aJena, Jyotsnarani1 aRanade, Vivek, V.1 aKilledar, Deepak, J.  uhttp://library.ncl.res.in/content/hydrodynamic-cavitation-using-vortex-diode-efficient-approach-elimination-pathogenic