The Experts below are selected from a list of 44202 Experts worldwide ranked by ideXlab platform
Sue Ellen Costa Bottrel - One of the best experts on this subject based on the ideXlab platform.
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ozonation and peroxone oxidation of ethylenethiourea in water Operational Parameter optimization and by product identification
Environmental Science and Pollution Research, 2015Co-Authors: Sue Ellen Costa Bottrel, Camila C Amorim, V Ramos, G Romao, Monica Maria Diniz LeaoAbstract:The objective of this work was to study the degradation and mineralization of ethylenethiourea (ETU) in water by ozonation at different pH values and in the presence of hydrogen peroxide. Degradation experiments were performed using an initial ETU concentration of 50 ppm for 180 min with a gas flux of 0.25 dm3 min−1 and an O3 production rate of 12.1 mg min−1. Degradation of by-products was monitored by direct injection electrospray ionization mass spectrometry (ESI-MS), ETU concentration was determined by HPLC-UV, and its mineralization was detected by total organic carbon (TOC) analysis. Optimum degradation of ETU in water was observed at pH = 11, whereas at pH = 3, the degradation of ETU was slowest, indicating that the reaction occurred through different mechanisms. The additional effects of hydroxyl radicals formed at the highest pH can be used to explain the results obtained in this study. Peroxone experiments were carried out in the presence of 400 and 800 mg L−1 H2O2; the degradation of ETU was faster at 400 mg L−1 H2O2. This was attributed to the scavenging effect of the excess H2O2. ETU treatment by ozonation produced several by-products of degradation such as ethylene urea and 2-imidazoline.
David J Robichaud - One of the best experts on this subject based on the ideXlab platform.
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catalyst residence time distributions in riser reactors for catalytic fast pyrolysis part 2 pilot scale simulations and Operational Parameter study
ACS Sustainable Chemistry & Engineering, 2017Co-Authors: Thomas D Foust, Jack L Ziegler, Sreekanth Pannala, Peter N Ciesielski, Mark R Nimlos, David J RobichaudAbstract:Using the validated simulation model developed in part one of this study for biomass catalytic fast pyrolysis (CFP), we assess the functional utility of using this validated model to assist in the development of CFP processes in fluidized catalytic cracking (FCC) reactors to a commercially viable state. Specifically, we examine the effects of mass flow rates, boundary conditions (BCs), pyrolysis vapor molecular weight variation, and the impact of the chemical cracking kinetics on the catalyst residence times. The factors that had the largest impact on the catalyst residence time included the feed stock molecular weight and the degree of chemical cracking as controlled by the catalyst activity. Because FCC reactors have primarily been developed and utilized for petroleum cracking, we perform a comparison analysis of CFP with petroleum and show that the operating regimes are fundamentally different.
Nicolaus Dahmen - One of the best experts on this subject based on the ideXlab platform.
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moisture content as a design and Operational Parameter for fast pyrolysis
Journal of Analytical and Applied Pyrolysis, 2019Co-Authors: Frederico Gomes Fonseca, Axel Funke, A Niebel, Ana Paula Soares Dias, Nicolaus DahmenAbstract:Abstract Fast pyrolysis trials of wheat straw were performed in a pilot plant featuring a screw reactor and two stage condensation system. Trials differed in the moisture content of the used biomass (1.2%, 9.2%, and 23.6%) and the sweeping gas flowrate. Higher moisture feedstock seems to lead to higher bio-oil production but the largest organic liquid yield occurred at intermediate feedstock moistures. Increasing the sweeping gas flow rate at the system leads to a higher liquid yield richer in organics. Based on these results it is concluded that the highest organic liquid yield is not observed for dry feedstock because the missing water vapour leads to longer hot vapour residence time, favouring secondary gas phase cracking reactions. Information and yields obtained at the pilot were scaled up to industrial scale (500 kg h−1 of feedstock) and used to construct an Aspen Plus® model that can be used to estimate heat availability in different parts of the system as well as simulate a dryer that would employ available internal process heat. This model was used to investigate the impact of using moister feedstock in the process. Enough heat is available for drying moist feedstock by using flue gas of the heat carrier loop in a different manner as in the current design.
J L Garciamorales - One of the best experts on this subject based on the ideXlab platform.
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new approach for integral treatment of ofmsw comparative analysis of its methane performance versus a conventional continuously stirred tank reactor
Chemical Engineering Journal, 2013Co-Authors: Nunez F Fernandez, L A Fdezguelfo, Perez M Garcia, J L GarciamoralesAbstract:Abstract The overall objective of this study was to compare the methane performance between a new four-stage scheme to degrade OFMSW as source of substrate versus a conventional methanogenic continuously stirred tank reactor (CSTR) operated at its optimum hydraulic retention times (HRTs). The new approach proposed is based on a methanogenic up-flow anaerobic filters (UFAFs) reactor as biomethanization technology. To develop this comparative, in this study was necessary to determine experimentally the HRT in which maximum methane production was reached (optimum HRT) using UFAF technology. Bio-hydrogen effluents resulting of the dark fermentation of OFMSW coming from a full-scale mechanical–biological treatment plant was used as feedstock. To determine the optimum HRT, a sequential decreasing of this Operational Parameter from 7.5 to 1.5 days was established. The results obtained indicate that the maximum specific methane yield, 0.26 and 0.28 LCH 4 /g COD r respectively, were obtained at 3 days HRT in mesophilic (35 °C) and thermophilic (55 °C) regime of temperature. Finally, the comparative analysis showed that the methane production of the new scheme based on methanogenic–thermophilic UFAF reactor is approximately 4 times higher than methanogenic–thermophilic CSTR (2.00 versus 0.48 LCH 4 /L/d respectively) and, in addition, higher methane percentage on biogas is reached (75.9% versus 70.6% respectively).
Manuel I. Peña-cruz - One of the best experts on this subject based on the ideXlab platform.
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Modified sol-gel/hydrothermal method for the synthesis of microsized TiO2 and iron-doped TiO2, its characterization and solar photocatalytic activity for an azo dye degradation
Journal of Photochemistry and Photobiology A-chemistry, 2018Co-Authors: S. Velázquez-martínez, Susana Silva Martinez, Carlos A. Pineda-arellano, A.e. Jiménez-gonzález, Iván Salgado-tránsito, Ariadna A. Morales-pérez, Manuel I. Peña-cruzAbstract:Abstract TiO2 and iron-doped TiO2 microsized powder is prepared by sol–gel method combined with hydrothermal treatment as an alternative to obtain high specific area under controlled conditions. Synthesis Parameters such as temperature of hydrothermal treatment (125 °C–210 °C), calcination temperature (500 °C–900 °C), and calcination time (1 h–9 h) along with Operational Parameter as solution pH (3, 7 and 9) in the solar photocatalytic reaction are assessed. TiO2 and iron-doped TiO2 micro powders are characterized by XRD studies, FE-SEM, specific area BET and photocatalytic activity by basic orange 2 (BO2) mineralization under solar irradiation. Results showed that ultrafine anatase microspheres are generated by sol-gel/hydrothermal treatment. Iron-doped TiO2, prepared by consecutive steps such as sol-gel/hydrothermal treatment at 200 °C, washed with ethanol, followed by calcination at 600 °C and dried with a rotary evaporator, showed the highest discoloration and mineralization of BO2. Outstanding performance is observed when compared with commercial TiO2 (Hombikat).