Gas filtration

Five sterilization processes are described in the USP steam, dry-heat, filtration, gas, and ionizing radiation. All are commonly used for parenteral products, except gas and ionizing radiation, which are widely used for devices and surgical materials. To assist in the selection of the sterilization method, certain basic information and data must be gathered. This includes determining... 

Langmuir-Blodgett films may have value in many applied areas of traditional interest to the industrial chemist, such as adhesion, encapsulation, and catalysis. The permeability characteristics of monolayer assemblies may also find application as synthetic membranes for ultrafine filtration, gas separation, and reverse osmosis. For example, Albrecht et al. (44) proved the eflSciency of polymeric diacetylene monolayers on semipermeable supports in reducing the flow of CH4. One interesting possibility lies in using LB monolayers as lubricants in magnetic tape technology. Unpublished reports have indicated that frictional coeflScients can be reduced markedly when the tape is coated with a few monolayers. In applications such as those listed previously, difiSculties may well be encountered with the mechanical stability of the films. To date, relatively little research has been carried out in this area. 

In studies of tar cracking using a separate catalyst bed, two types of tar sources are applied, one directly drawn from a biomass gasifier and the other from model compounds. According to VTTs work [12], the tar consists mainly of highly stable compounds such as benzene (60-70 wt %), naphthalene (10-20 wt %), and other polyaromatic hydrocarbons (10-20 wt %), which can amount to 15-20 g of tar/Nm in biomass gasification. So, benzene and naphthalene were used in this work as tar model compounds with a fixed concentration of 15 g/Nm (4300 ppm) for benzene and 5 g/Nm (875 ppm) for naphthalene, respectively. The gas composition used was 50 vol % N2, 12 vol % CO, 10 vol % H2, 11 vol % CO2, 12 vol % H2O, 5 vol % CH4, 4300 ppm benzene (or 875 ppm naphthalene), which is a typical composition of the product gas from a biomass fluidised bed gasifier operated with air. The reaction tests were performed under three filtration gas velocities 2.5, 4 and 6 cm/s. All experimental points were monitored for at least 60 min after the reaction reached an apparent steady state at the selected operation condition. 

Fig. 5 shows the benzene conversion as a function of the reaction temperature and gas velocity with a 1 wt % nickel-modified filter disc. As a reference, the benzene conversions using a blank disc (no catalyst inside) in the same conditions are displayed in the figure. It was found that full conversion of benzene was obtained at typical filtration gas velocities (2.5 and 4 cm/s) and in a temperature range from 750°C to 900°C. Even at a higher filtration velocity such as 6 cm/s, a complete conversion is still reached above 800 °C. 

Apparently, the nickel-activated filter disc displayed an excellent catalytic performance for the decomposition of either benzene or naphthalene as tar model compound in the simulated biomass gasification gas at a typical filtration gas velocity when the reaction temperature was in the rai e of800-900 °C. 

Sterilisation Autoclave Sterile products Saturated steam Hot air Dry heat Radiation Ethylene oxide Hydrogen peroxide Plasma Membrane filtration Gas sterilisation... 

Biochemical engineering is a subspecialty of chemical engineering. Chemical engineering began in 1901 when George E. Davis, its British pioneer, mathematically described all the physical operations commonly used in chemical plants (distillation, evaporation, filtration, gas absorption, and heat transfer) in his landmark book, A Handbook of Chemical Engineering. 

Tubular shapes for blood vessels and nerve regenerations Three-dimensional scaffolds for bone and cartilage regenerations Liquid filtration Gas filtration Molecular filtration Thermal sensor Piezoelectric sensor Biochemical sensor Fluorescence optical chemical sensor Skin cleansing Skin healing... 

B. Miller, 1. Tyomkin, J.A. Wehner, Quantifying the porous structure of fabrics for filtration applications, in R.R. Raber (Ed.), Proceedings of a symposium held in Philadelphia, Pennsylvania, USA, Fluid filtration gas, vol. 1, ASTM Special Technical Publication 975, 1986, pp. 97—109. 

Occasionally the membrane is seen attached to cells in suspension culture (Fig. 5.1.2B). This membrane is associated with a variety of unusual structures containing phenolic residues and tannin. The role of these membranes or skins in osmotic phenomena, filtration, gas exchanges, lectin and enzyme partitioning, and energy transduction at or on surfaces is unknown. Lectins are associated usually with juvenile tissues, such as embryos and seeds, rather than with mature tissues (19, 20). However, lectins that bind manganese and zinc have been isolated from the bark of Robinia pseudoacacia (68). 

Process monitoring requires techniques that are selective and sensitive while providing rapid feedback. Several types of detectors can offer a rapid response but are limited by relatively poor selectivity, sensitivity, and versatility. The combination of FIA-based systems with sample pretreatment and/or separation techniques can overcome these limitations. Several sample pretreatment techniques such as dialysis, filtration, gas diffusion, derivatization, and ion exchange have already been successfully applied to FIA systems (Karlberg and Kuban, 2000). 

Porous glass membranes (PGMs) are used for many applications, especially in membrane separation processes such as micro- and ultra-filtration,gas separation, demulsification medium and membrane emulsification, gas-liquid contacting process and gas dispersion process. ... 

Filtration. In filtration, suspended solid particles in a liquid or gas are removed by passing the mixture through a porous medium that retains the particles and passes the fluid. The solid can be retained on the surface of the filter medium, which is cake, filtration, or captured within the filter medium, which is depth filtration. The filter medium can be arranged in many ways. 

The oxime is freely soluble in water and in most organic liquids. Recrystallise the crude dry product from a minimum of 60-80 petrol or (less suitably) cyclohexane for this purpose first determine approximately, by means of a small-scale test-tube experiment, the minimum proportion of the hot solvent required to dissolve the oxime from about 0-5 g. of the crude material. Then place the bulk of the crude product in a small (100 ml.) round-bottomed or conical flask fitted with a reflux water-condenser, add the required amount of the solvent and boil the mixture on a water-bath. Then turn out the gas, and quickly filter the hot mixture through a fluted filter-paper into a conical flask the sodium chloride remains on the filter, whilst the filtrate on cooling in ice-water deposits the acetoxime as colourless crystals. These, when filtered anddried (either by pressing between drying-paper or by placing in an atmospheric desiccator) have m.p. 60 . Acetoxime sublimes rather readily when exposed to the air, and rapidly when warmed or when placed in a vacuum. Hence the necessity for an atmospheric desiccator for drying purposes. 

Formamide. Commercial formamide may contain excess of formic acid. It is purified by passing ammonia gas into the mixture until a slight alkaline reaction is obtained. The ammonium formate thus formed is precipitated by the addition of acetone the filtrate, after drying over anhydrous magnesium sulphate, is distilled under reduced pressure. Pure formamide has b.p. IO571I mm. 

In a 500 ml. Pyrex round-bottomed flask, provided with a reflux condenser, place a mixture of 40 g. of freshly-distUled phenylhydrazine (Section IV.89) and 14 g. of urea (previously dried for 3 hours at 100°). Immerse the flask in an oil bath at 155°. After about 10 minutes the urea commences to dissolve accompanied by foaming due to evolution of ammonia the gas evolution slackens after about 1 hour. Remove the flask from the oil bath after 135 minutes, allow it to cool for 3 minutes, and then add 250 ml. of rectified spirit to the hot golden-yellow oil some diphenylcarbazide will crystallise out. Heat under reflux for about 15 minutes to dissolve the diphenylcarbazide, filter through a hot water funnel or a pre-heated Buchner fuimel, and cool the alcoholic solution rapidly in a bath of ice and salt. After 30 minutes, filter the white crystals at the pump, drain well, and wash twice with a little ether. Dry upon filter paper in the air. The yield of diphenylcarbazide, m.p. 171 °, is 34 g. A further 7 g. may be obtained by concentrating the filtrate under reduced pressure. The compound may be recrystallised from alcohol or from glacial acetic acid. 

---