Suspension in Water

Starch slurry make-down systems are designed to prepare a uniform suspension, using batch or continuous systems. In modem paper mills, automated batch or continuous systems are used. Water content and bulk density will affect the flow of dry starch.90 In the batch slurry system, weighed increments of starch are drawn from the silo and periodically added to a measured quantity of water in the make-up tank. The suspension is screened and automatically pumped to a larger storage tank on demand by a level transmitter. Continuous make-down of starch slurry is accomplished by simultaneously feeding starch and water at controlled rates into the slurry make-down tank. The dry starch is metered with a volumetric screw feeder. The slurry is screened before dispersion by batch or continuous cooking. 

In calculating starch and water quantities, adjustments need to be made for the water content of starch, which ranges from 10% to 12% for com starch to 15-18% for potato starch. Starch solids in the slurry may fluctuate if the delivered product is not uniform. The bulk density of the starch will vary depending on the method of drying. Flash dried starch has a bulk density of about 608 kg/m3, while belt dried starch has a bulk density of about 672 kg/m3. 

All starch systems have to be designed to prevent settling of starch granules, which have a density of about 1.5 g/cm3. Piping has to be sized to maintain a velocity of at least 45cm/s and must be equipped for self-draining, particularly in vertical sections.91 In case of a power loss exceeding 30 minutes all slurry pipes should be flushed and drained. An air lance will be required for resuspension of settled starch. 

When starch is added to cold water (below 29°C, 85°F), only negligible swelling will occur. However, the suspension volume expands, since the insoluble starch replaces water. Addition of starch to water at a concentration of 10% will increase the volume by 13%. The maximum in suspension solids is 40-45%. Various methods are used to determine the solids content of the starch slurry aerometer,92 density cells, densitometer, attenuation of vibration (Dynatrol) or a radiation-type density meter. Concentrated starch slurries have high viscosity and shear thickening (dilatent) rheology. Settling of starch from the slurry produces densely packed sediments that are difficult to disperse. 

Modified starches tend to swell more after contact with water due to a weakened granular structure. Their suspensions have higher viscosity, lower maximum suspension solids and a slower settling rate. Suspension solids and viscosity are also affected by mechanical starch damage during drying. 

---

Sprays are the most common means of insecticide appHcation and generally involve the use of water as the principal carrier, although volatile oils sometimes are used. With the older inorganic insecticides, suspensions in water were used at dilutions of 0.1 ndash 0.2%. The development of the more effective organic insecticides has allowed the widespread use of concentrate sprays in which the toxicant is contained at 10 ndash 98% and the amount of carrier to be appHed is enormously reduced. The use of concentrate or ultralow volume sprays has brought about a revolution in spray equipment away... 

At high neutralization levels with alkaH metal ions, many ionomers spontaneously form coUoidal suspensions in water when stirred vigorously at 100—150°C under pressure. Depending on soHds content and acid level, the dispersions range in viscosity from water-like to paste-like. These provide convenient methods for applying thin coatings of ionomers to paper and other substrates. 

Hot Hthopone leaving the calciner has to be cooled quickly to prevent the oxidation of ZnS to ZnO. Rapid cooling is accompHshed by its suspension in water that might contain a small amount of sulfuric acid to remove any traces of undesirable 2inc oxide. The suspension is then wet milled, filtered off, and dried to the commercial product. 

Guanine is obtained fiom various fish including menhaden, herring, and alewives. To prepare the colorant, scales are scraped from the fish, levigated, and washed with water, and then made into one or more commercial forms, depending on the intended use. Typically, guanine is suppHed as a paste or suspension in water, castor oil, or nitrocellulose. Guanine is not a colorant in the strict sense but instead is used to produce iridescence in a product. 

Rheopectic behavior is the opposite of thixotropy. Shear stress increases with time at constant shear rate. Rheopeclic behavior has been obsei ved in bentonite sols, vanadium pentoxide sols, and gypsum suspensions in water (Bauer and Colhns, ibid.) as well as in some... 

Ion-exchange resins swell in water to an extent which depends on the amount of crosslinking in the polymer, so that columns should be prepared from the wet material by adding it as a suspension in water to a tube already partially filled with water. (This also avoids trapping air bubbles.) The exchange capacity of a resin is commonly expressed as mg equiv./mL of wet resin. This quantity is pH-dependent for weak-acid or weak-base resins but is constant at about 0.6-2 for most strong-acid or strong-base types. 

The operating cycle of a belt vacuum filter consists of filtration, washing and dewatering stages. The solids suspension in water is separated under the following set of conditions ... 

Stable solids suspensions in water- The mechanisms involved in keeping solids suspended in water,... 

The light yellow solid which separated was collected by filtration the filtrate was reserved for treatment as described below. Suspension in water of the solid, which weighed 12 grams, and acidification of the mixture with dilute hydrochloric acid produced a gum which soon crystallized. Recrystallizatiori of this solid from ethanol gave 10.2 grams (30%) of 2-di-phenylacetyl-1,3-indandione as a light yellow crystalline solid, which melted at 146 -147°C. 

Most conventional chemical and petrochemical plants do not process many, if any, non-Newtonian fluids. However, polymers, grease, hea y oils, cellulose compounds, paints, fine chalk suspensions in water, some asphalts, and other materials do exhibit one type or another of the characteristics of non-Newtonians, classified as ... 

The great merit of starch is that it is inexpensive. It possesses the following disadvantages (1) insolubility in cold water (2) instability of suspensions in water (3) it gives a water-insoluble complex with iodine, the formation of which precludes the addition of the indicator early in the titration (for this reason, in titrations of iodine, the starch solution should not be added until just prior to the end point when the colour begins to fade) and (4) there is sometimes a drift end point, which is marked when the solutions are dilute. 

Farooqi, S. I. and Richardson, J. F. Trans. I. Chem. E. 58 (1980) 116. Rheological behaviour of kaolin suspensions in water and water-glycerol mixtures. 

Biological indicators (Bis) for use in thermal, chemical or radiation sterilization processes consist of standardized bacterial spore preparations which are usually in the form either of suspensions in water or culture medium or of spores dried on paper, aluminium or plastic carriers. As with chentical indicators, they are usually placed in dummy packs located at strategic sites in the sterilizer. Alternatively, for gaseous sterihzation these may also be placed within a tubular hehx (Line-Pickerill) device. After the sterilization process, the aqueous suspensions or spores on carriers are aseptically transferred to an appropriate nutrient medium which is then incubated and periodically examined for signs of growth. Spores of Bacillus stearothermophilus in sealed ampoules of cultrrre medium are used for steam sterilization morritoring, and these may be incubated directly at 55°C this eliminates the need for an aseptic transfer. 

The carbon produced in the flame reaction, and which is subsequently removed as carbon suspension in water, amounts to 1.5 per cent by weight of the fuel oil feedstock charge. Some H2S present in the crude gas is removed by contact with the quench water. 

The metal hydroxide is often produced as a suspension in water. 

A similar technique has been applied to the generation of monodisperse suspensions in water. This type of method was first used in medical field and then widely used to spray monodisperse solid particles such as polystyrene latex particles. Aerosols of solutes have also been produced by atomizing solutions of salt, sugar or methylene blue dye dissolved in water. In practical operations, a low concentration of solid particles in a solvent is recommended in order to avoid possible agglomeration of suspensions in the solvent. 

Once the pulp fibres have been refined to the necessary degree, they are then formed into a sheet of paper on the paper machine. The paper formation process itself is essentially a fast filtration process and involves the delivery of a dilute fibre suspension in water on to a woven endless plastic wire belt, through which it drains to form a wet fibre network. The Fourdrinier paper machine is the most well-established system for forming the wet web, but there are now many variations of this basic principle. A schematic diagram of the Fourdrinier formation process is shown in Figure 5.15. 

Presentation Swollen beads 60 to 140 pm in diameter, available as a 4% suspension in water,... 

Presentation Prepared from agarose by reaction with 2, 3-dibromopropan-l-ol in strongly alkaline enviroment. It occurs as swollen beads 60 to 140 pm in diameter and is available as a 4% suspension in water. 

Scrivens WA, Tour JM, Creek KE, Pirisi L (1994) Synthesis of C-14-labeled C-60, its suspension in water, and its uptake by human keratinocytes. J Am Chem Soc 116 4517 1518. 

Scrivens WA, Tour, J, Creek, K, Pirisi, L (1994) Synthesis of 14C-labeled C60, its suspensions in water. Preparation and Characterization. J.American Chemical Society 116, 4517—4518. 

In a test on a centrifuge all particles of a mineral of density 2800 kg/m3 and of size 5 xm, equivalent spherical diameter, were separated from suspension in water fed at a volumetric throughput rate of 0.25 m3/s. Calculate the value of the capacity factor E. 

---