Filter fibrous materials

The predominant cellulose ester fiber is cellulose acetate, a partially acetylated cellulose, also called acetate or secondary acetate. It is widely used in textiles because of its attractive economics, bright color, styling versatiUty, and other favorable aesthetic properties. However, its largest commercial appHcation is as the fibrous material in cigarette filters, where its smoke removal properties and contribution to taste make it the standard for the cigarette industry. Cellulose triacetate fiber, also known as primary cellulose acetate, is an almost completely acetylated cellulose. Although it has fiber properties that are different, and in many ways better than cellulose acetate, it is of lower commercial significance primarily because of environmental considerations in fiber preparation. 

Expression Dewaterings of Fibrous Materials. Fibrous materials are frequently dewatered in belt-filter, screw, disk, and roU presses and in batch pot and cage presses. Table 1 Hsts appHcations of screw, roU, and pot presses. Screw and high pressure belt presses are continuous and have replaced batch pot and cage presses in most appHcations. Traditionally, however, batch presses have been used for squee2ing cocoa butter from cocoa beans, which require pressures up to 41 MPa (6000 psi) (39). A description of many types of batch presses is included in Reference 40. 

The turbo-tray dryer can handle materials from thick slurries [1 million (N s)/m (100,000 cP) and over] to fine powders. It is not suitable for fibrous materials which mat or for doughy or tacky materials. Thin slurries can often be handled by recycle of dry product. Filter-press cakes are granulated before feeding. Thixotropic materials are red directly from a rotary filter by scoring the cake as it leaves the drum. Pastes can be extruded onto the top shelf and subjected to a hot blast of air to make them firm and free-ffowing after one revolution. 

Dry filters are normally a finer-weave fabric or fibrous material and will separate smaller particles than viscous filters, typically down to 0.5 pm. They may be thrown away or washed when dirty, depending upon type. 

Preparation of Soluble Sample for Decarboxylation. The photolyzed fabric swatch was placed in 20 ml of distilled DMAc at 100°C for 5 minutes. The DMAc solution was filtered to remove any insoluble fibrous material from the decarboxylation flask (a round 30 ml two-neck Pyrex flask with a protruded bottom well) and dried in vacuo with the temperature kept below 50°C leaving a residual film on one side of the flask. 

The GPC instrumentation and GPC procedures used here are the same as described earlier (I) but with slight alterations. The Kroeger HAK-1 pads furnished with the pressure filter were replaced by Millipore 5-/x Mitex membranes to reduce changes in solution concentrations arising from adsorption of the solute on the fibrous material of the pad. When retention of eluted fractions was desired, two shallow aluminum pans filled with tetrahydrofuran (THF) were placed in the syphon box, and then the door was closed and latched. The saturation of the enclosed air space by THF vapor minimized evaporation of the solution during drop formation, drop fall, and retention of fraction in the syphon. The possibility of diluting the sample solution when charging the sample loop was... 

The kraft lignin fractions thus obtained are heterogeneous with regard to their chemical properties (see Sect. 3.3.4 for analytical data). When the black liquor contains fibrous materials, it is filtered through a Whatman No. 2 paper prior to the acidification step. 

There are a variety of different depth filter and membrane filter materials used within the pharmaceutical processes. Depth filter are fibrous materials for example, polypropylene, borosilicate, or glassfibre fleeces (Fig. 3). Borosilicate and glassfibre materials are highly adsorptive and commonly used to remove colloidal substances, like iron oxide from water or colloidal haze from sugar solutions. 

Non-woven media in the form of felts and compressed cellulose pulps, are used for clarification by depth filtration. Unless carefully prepared, they have the disadvantage of losing fibrous material from the downstream side of the filter. The application of sheet media has been discussed earlier. High wet strength is conferred on paper sheets by resin impregnation. An alternative technique employs asbestos fibers supported in a cellulose framework. 

The main features of purification filters based on ion exdiange fibrous materials are high sorption capacity and purification degree, low aerodynamic resistance, and efficient regeneration. As studies have shown [4 ], at a gas,flow rate of 0.1 m/s in a dense layer of a non-woven material, the length of a working layer is 2 mm which makes it possible to use filtering cloths of 10—20 mm thickness. The area of the filter is 20 m per 1 m of operation volume which corresponds to specific output, 7 10 m /h of purified air. The aerodynamic resistance of filters in this case does not exceed 20 Pa. 

Since the ACFs are fibrous materials that can be easily molded and woven, filters can be designed that do not have the setding and channeling problems of the conventional granular and powder ACs [1]. Due to their low hydrodynamic resistance, they can be used as thin cloths for the treatment of high flow of gases, very useful for control of gas-phase pollution [2]. 

As an alternative to foams, fibrous materials in the form of tissues or filters may be used as structured catalysts [53,62-65]. Of particular interest for MSRs are sintered metal fibers (SMFs) [64,65]. These materials have open and homogeneous structures with porosities of 70-90% and high thermal conductivities, which ensure homogeneous temperatures in the catalytic bed. SMF materials consist of thin metallic fibers of 10-20 pm diameter. The small fiber diameters ensure high external fluid-solid mass transfer [66]. The fibers can be covered with a homogeneous layer of zeolitic material [66] or a washcoat, which can be impregnated with an active material [67,68]. Luther et al. [67] integrated the SMF catalyst in a... 

FiberCatalysts As an alternative to foams, fibrous materials in the form of tissues or filters may be used as structured catalysts [43-50]. The characteristic properties of fibrous materials as catalyst supports are compared with catalyst pellets and monoliths in Table 11.2. 

Fibrous materials found in bottled wines are usually cellulosic in nature, originating from the filter pad matrix or from case lint that may find itself in bottles prior to filling. 

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