Filtration typical conditions

The Vinyloop process is based on the selective dissolution of PVC used in composites applications like cable insulation, flooring, tarpaulins, blisters, etc. After removal of insoluble parts like metals, rubber or other polymers, the PVC is reprecipitated with all additives by introduction of a non-solvent component whieh will form with the seleetive solvent an azeotropie mixture. By using typical conditions, the process is able to reeover a pure PVC eompound powder ready for use without any additional treatment like melt filtration or a new pelletisation (speeific characteristics of the powder are average diameter of 400 microns and bulk density above 600 kg/ eub.m). All the solvents used are eompletely reeyeled and reused. PVC compounds recovered in the Vinyloop process can be reused in a closed-loop recycling scheme... 

HPLC allows a quantitative determination with relatively simple extractions. In many cases, extraction only involves a heating of the commodity with water, followed by filtration and injection onto an HPLC column. In the determination of caffeine, theobromine, and theophylline in cocoa, coffee, or tea, as well as in other foods, there is scarcely a month that passes without a new paper on this assay. Kreiser and Martin provide typical conditions for analysis.28 In their studies, samples were extracted in boiling water and filtered prior to injection onto the HPLC column. The HPLC conditions used a Bondapak reversed phase column and a mobile phase of water methanol acetic acid (74 25 1) with detection at 280 nm. This method is accurate, precise, and conserves time. It has also been adopted by the AOAC as an official method for the determination of theobromine and caffeine in cocoa beans and chocolate products.29... 

The final filtration step is not meant to remove significant amounts of particles or to reduce turbidity. For economic reasons, there should not be many particles left from the first filtration step when entering into the second (final) filtration step. Only if this condition is maintained the costs for the secondary filtration can be kept low. Also, the filtration should only remove microorganisms, and not retain other useful components of beer, i.e., those proteins that have a role in foam formation and stability. On the other hand, bacteria, which should be separated from beer during final filtration, typically have sizes down to 0.5 p,m. This small difference in size between the desirable ingredients and those particles that should be removed, such as bacteria, shows that the selection of the filtration technique and media needs to be done very carefully. 

Under typical conditions of 290°C spinning temperature, the molten viscosity is ca 200-2000 Pacs (2000-20,000 P) depending on average molecular weight. This is extremely viscous—similar to hot asphalt. The pump must provide a pressure of 10-20 MPa ( 100-200 bar) to force the flow through the pack, which contains filtration media (eg, a sand bed) to remove any particles larger than a few micrometers. 

Preparation. The most common method for the preparation of pyridine iV-oxide is through the oxidation of pyridine with m-CPBA. Typical conditions are as follows (eq 17) to a solution of pyridine (1 equiv) in chloroform (2M) was added 70% m-CPBA portionwise (1 equiv) at 0 °C. The reaction mixture was then stirred at room temperature for 12 h and then diluted with CHCI3. Next K2CO3 (4 equiv) was added, and the resulting slurry was stirred for 10 min. The solid was separated by filtration, dried over Na2S04, and concentrated under reduced pressure to give the title compound in 86-90% yield. 

Mlcrofiltra.tlon, Various membrane filters have been used to remove viral agents from fluids. In some cases, membranes which have pores larger than the viral particle can be used if the filtration is conducted under conditions which allow for the adsorption of the viral particle to the membrane matrix. These are typically single-pass systems having pore sizes of 0.10—0.22 lm. Under situations which allow optimum adsorption, between 10—10 particles of poHovims (28—30 nm) were removed (34—36). The formation of a cake layer enhanced removal (35). The titer reduction when using 0.10—0.22 p.m membrane filters declined under conditions which minimized adsorption. By removal standards, these filters remove vimses at a rate on the low end of the desired titer reduction and the removal efficiency varies with differences in fluid chemistry and surface chemistry of viral agents (26). 

A typical flow diagram for pentaerythritol production is shown in Figure 2. The main concern in mixing is to avoid loss of temperature control in this exothermic reaction, which can lead to excessive by-product formation and/or reduced yields of pentaerythritol (55,58,59). The reaction time depends on the reaction temperature and may vary from about 0.5 to 4 h at final temperatures of about 65 and 35°C, respectively. The reactor product, neutralized with acetic or formic acid, is then stripped of excess formaldehyde and water to produce a highly concentrated solution of pentaerythritol reaction products. This is then cooled under carefully controlled crystallization conditions so that the crystals can be readily separated from the Hquors by subsequent filtration. 

Two main categories of the wet process exist, depending on whether the calcium sulfate is precipitated as the dihydrate or the hemihydrate. Operation at 70—80°C and 30% P20 in the Hquid phase results in the precipitation of CaSO 2 filterable form 80—90°C and 40% P20 provide a filterable CaSO O.5H2O. Operation outside these conditions generally results in poor filtration rates. A typical analysis of wet-process acid is given in Table 4. For more detailed discussion of the wet-process acid, see Fertilizers. 

Filtration experiments are typically conducted in pilot scale equipment and generally tests are conducted either at constant pressure or constant rate to determine axo, as well as s and Rf, for a given sludge and filter medium. Such tests provide empirical information that will enable the time required tor the pressure drop to reach the desired level for a specified set of operating conditions to be determined. In the initial stages of filtration, the filter medium has no cake. Furthermore, Ap is not zero, but has a value that is a function of the resistance of the medium for a given flowrate. This initial condition can be stated as ... 

Typically, an acetanilide (1 mol. equiv.) was treated with the Vilsmeier reagent generated from POCI3 (7 mol. equiv.) and V,V-dimethylformamide (DMF, 2.5 mol. equiv.) at 75 °C for 4 - 20 h. The reaction products were readily obtained by filtration after pouring the reaction mixture onto ice-water minor reaction products were isolated after basification of the filtrate. A variety of acetanilides were studied under these optimised reaction conditions and some significant observations were noted. Activated acetanilides 3 [e.g. R = 4-Me (70%), 4-OMe (56%)] reacted faster and in better yield to give quinolines 4 than other strongly deactivated systems 3 [e.g. R = 4-Br (23%), 4-Cl (2%), 4-NO2 (0%)] — in these cases, formamidines 5 and acrylamides 6 were the major reaction products. 

A typical UF pilot plant has been used in this study. Examples of application for these membranes can be found in the literature [40, 58]. The UF unit woks in deadend mode (2.5 m h ) and it can be operated in filtration, backwash and chemically enhanced backwash (CEB) modes as described in the literature for similar UF systems [40]. The specifications of the hollow fiber UF modules and the operating conditions are summarized in Table 5. 

The ICl-CaC03 procedure required a filtration to remove insoluble, inorganic by-products prior to biphasic extraction. In an effort to develop a homogeneous process for the iodination step, a pH control protocol was later implemented in the manufacturing process. The pH-controlled iodination was run in a single phase in a MeOH-water system by simultaneous addition of the aqueous IC1 solution and 1M NaOH. Citric acid was added to increase the buffer capacity to the optimal pH (5-5.5) for robust operation. Under these conditions, the iodoaniline 28 was typically obtained in >99 A% with <1% of diiodoaniline 32. Residual... 

One of the cornerstones of combinatorial synthesis has been the development of solid-phase organic synthesis (SPOS) based on the original Merrifield method for peptide preparation [19]. Because transformations on insoluble polymer supports should enable chemical reactions to be driven to completion and enable simple product purification by filtration, combinatorial chemistry has been primarily performed by SPOS [19-23], Nonetheless, solid-phase synthesis has several shortcomings, because of the nature of heterogeneous reaction conditions. Nonlinear kinetic behavior, slow reaction, solvation problems, and degradation of the polymer support, because of the long reactions, are some of the problems typically experienced in SPOS. It is, therefore, not surprising that the first applications of microwave-assisted solid-phase synthesis were reported as early 1992 [24],... 

A laboratory where the measurement takes place must be free from odor and is typically air-conditioned with air filtration. The odor sample is placed in an olfactometer that basically is a device for dilution of the sample. Typically, the meter has two outlet ports diluted odorous air flows from one, and clean odor-free air flows from the other. In dynamic olfactometry, panel members assess the two ports of the olfactometer. The assessors indicate from which of the ports the diluted sample is flowing. The measurement starts with a dilution that is large enough to make the odor concentration beyond the panelists threshold. This concentration is normally increased by a factor of two in each successive presentation. Only when the correct port is chosen and the assessor is certain that the choice is correct and not just a guess, is the response considered a true value. 

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