Hazards from chemical reactions and flammable materials in batch reactor operations

1997 ◽  
pp. 253-288 ◽  
Author(s):  
R. Rogers
Keyword(s):  
Chemical Reactions ◽  
Batch Reactor

scholarly journals Stochastic modeling of microstructure of homopolymers and copolymers in batch reactor

2020 ◽  
Vol 9 (2) ◽  
pp. e04921930
Author(s):  
Matheus Dias Carvalho ◽  
Jorge David Alguiar Beliido ◽  
Antonio Marcos de Oliveira Siqueira ◽  
Júlio Cesar Costa Campos
Keyword(s):  
Stochastic Modeling ◽  
Chemical Reactions ◽  
Batch Reactor ◽  
Polymer Chains ◽  
Stochastic Methods ◽  
Batch Reactors ◽  
Straight Chain ◽  
Reaction Conditions ◽  
C Language ◽  
Methyl Styrene

Find the microstructure of the product generated in a reaction of polymerization is desirable from a material science standpoint, due to the association between the microstructure and the physical properties. For the science of this fact, this paper aims to use stochastic modeling to obtain the microstructure and key information from a set of polymer chains generated during a reaction. From this data, the present article contributes to the minimization of experimental expenses, besides the saving of time, since no experiments are necessary to discover the characteristics of the polymer obtained under certain reaction conditions. This information cannot be found by other usual methodologies for modeling chemical reactions, such as the deterministic form. Also, from a given desired structure, the initial concentration and temperature conditions for forming that product can be obtained. This study was conducted based on Monte Carlo stochastic methods, by which we seek to replicate the randomness present in chemical reactions. The algorithm created in C ++ language determines the variation of the number of molecules of each species with time, besides the chemical composition, the sequence of mere and size of the generated chains. This approach applies to straight-chain homopolymerizations and copolymerizations. In this paper, we studied the polymerization in styrene batch reactors to form polystyrene, in addition to the copolymerization of styrene with alpha-methyl styrene. These simulations were characterized by forming chains with small blocks of monomers.

Phosphorus removal from nightsoil with sequencing batch reactor (SBR)

1997 ◽  
Vol 36 (12) ◽  
pp. 55-60 ◽  
Author(s):  
S. W. Oa ◽  
E. Choi
Keyword(s):  
Chemical Reactions ◽  
Phosphorus Removal ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Chemical Precipitation ◽  
Phosphorus Release ◽  
Biological Nutrient Removal ◽  
Biological Phosphorus Removal ◽  
P Fractionation ◽  
Biological Phosphorus

Phosphorus removal characteristics are rather complicated in a highly nitrogenous waste like nightsoil under treatment with SBR (sequencing batch reactor). It was found that the increased pH due to denitrification in anaerobic period stimulated chemical precipitation of phosphorus as struvite and hydroxyapatite, and the depressed pH due to nitrification in the aerobic period dissolved the previously formed precipitates. Phosphate accumulating organisms (PAO) worked as in the ordinary BNR (biological nutrient removal) systems regardless of the chemical reactions, but the chemical reactions masked the biological phosphorus release and uptake reactions. About 36% of phosphorus applied was removed biologically in polyphosphate granules. P-fractionation of sludges confirmed this phenomenon. Biological phosphorus removal could be increased with the increased anaerobic period. The morphological types of phosphorus precipitates were examined by SEM in combination with x-ray diffraction.

Removal of Phenol from Water: A Comparison of Energization Methods

2005 ◽  
Vol 8 (2) ◽  
Author(s):  
Lukas R. Grabowski ◽  
Eddie M. van Veldhuizen ◽  
Wijnand R. Rutgers
Keyword(s):  
Energy Efficiency ◽  
Thin Layer ◽  
Chemical Reactions ◽  
Ozone Concentration ◽  
Batch Reactor ◽  
Phenol Degradation ◽  
Volume Ratio ◽  
Phenol Removal ◽  
Initial Testing ◽  
Fe Ions

AbstractDirect electrical energization methods for removal of persistent substances from water are under investigation in the framework of the ytriD-project. The emphasis of the first stage of the project is the energy efficiency. A comparison is made between a batch reactor with a thin layer of water and an aerosol reactor. The method of energization is mainly the application of fast pulses. In case of the batch reactor it is compared with DC. The ozone concentration is determined as an indicator for the efficiency of the chemical reactions, the yield is 4 g/kWh for the DC batch reactor, 50 g/kWh for the pulsed batch reactor and 50-100 g/kWh for the aerosol reactor. For initial testing phenol degradation is determined. 50% of the initial 0.1 mM is reached in 8 min in the pulsed batch reactor and less than 30 s in the aerosol reactor. The phenol removal speeds up by a factor 3 upon the addition of Fe-ions. Matlab simulations confirm that the surface-to-volume ratio is an important parameter for the speed of phenol degradation.

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

Gum Arabic in Chemical Reactions

1883 ◽  
Vol 15 (366supp) ◽  
pp. 5844-5844
Author(s):  
MM. Jules Lefort ◽  
P. Thibault
Keyword(s):  
Chemical Reactions ◽  
Gum Arabic
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