Colloidal Solids

The chemical treatment methods reduce dispersability property, of drilling fluids through the increase of size of cuttings which improves separation and prevents the buildup of colloidal solids in the mud. These methods include ionic inhibition, cuttings encapsulation, oil phase inhibition (with oil-base muds), and flocculation. The mechanical solids removal methods are based on the principles presented in Table 4-55. 

Sol-gel is one of the most useful techniques for preparation of inorganic membranes with fine pores in the nanometer range (1-5 nm). The sol is a stable suspension of colloidal solid particles within soft uniform solution. The gel was obtained by hydrolysis with open reflux in 24 hours at 85-90 °C. The advantage of sol-gel technology is the ability to produce... 

Westesen and Siekmann [11] used suspensions of colloidal solid lipid particles as well as lyophilizates as delivery systems for the parenteral administration of the drug for its particle morphology determination. 

Larger particles of grit and dust settle relatively fast, but colloidal solids can require weeks for complete sedimentation (i.e. colloid breaking) to occur completely. Such sedimentation occurs when microscopic colloid particles approach, touch and stay together because of an attractive interaction, and thereby form larger particles, and sink under the influence of gravity. We call this process aggregation. 

Colloidal particles, foams used to collect and separate, 12 22 Colloidal powders, 23 55-56 Colloidal silica, 22 380, 382, 384 applications of, 22 394 modification of, 22 393-394 preparation of, 22 392-393 properties of, 22 391-392 purification of, 22 393 Colloidal silica gels, 23 60 Colloidal solids, 7 293-294 Colloidal stability, 7 286-291 10 116 22 55 Colloidal stabilizers, in polychloroprene latex compounding, 19 857 Colloid mills, 8 702 10 127 Colloids, 7 271-303 23 54. See also Polymer colloids analysis, 7 296 applications, 7 292-296 conducting, 7 524... 

Fig. 3.1 shows that many suspended and colloidal solids encountered in waters sediments and soils have a surface charge and that this charge may be strongly affected by pH. 

Table 10 gives the characteristics of hquid waste arising in liver and beef extract production from a biological production pharmaceutical plant [18]. These wastes can be very high in BOD, COD, TS, colloidal solids, toxicity, color, and odor. The BOD/COD ratio of the... 

Carbon also is produced and used in other forms namely, activated carbon, carbon black, and coke, that have many commercial applications. Structurally they are amorphous forms of carbon belonging to the graphites. Activated carbon or activated charcoal has a highly porous honeycomb-like internal structure and adsorbs many gases, vapors, and colloidal solids over its very large internal surface area. Some of its major applications include purification of water and air, air analysis, waste treatment, removal of subur dioxide from stack gases, and decolorization of sugar. 

Bunjes H., Koch and Westesen K., Effect of particle size on colloidal solid... 

The CHEMIC process is effective in removing cadminm, mercnry, lead, iron uranium, strontium, cesium, and cobalt. The process also removes other inorganic and organic materials present as suspended or colloidal solids. 

Another, and on the face of it, rather different example, is the coprecipitation of solid solution compounds, such as CulnSi and CulnSei—semiconductors of particular interest due mainly to their applicability for photovoltaic cells. It was shown, by X-ray diffraction, that the precipitate resulting from reaction between H2S and an aqueous solution containing both Cu" and In " ions was, at least in part (depending on the concentrations of the cations), single-phase CulnSi [3]. Two factors were found to be necessary for this compound formation (1) the presence of sulphide on the surface of the initially precipitated colloidal solid metal sulphide and (2) one of the cations being acidic and the other basic. The monovalent Cu cation is relatively basic, while the trivalent In cation is relatively acidic. It is not clear what the physical reason is for this latter requirement. A difference in practice between acidic and basic cations is that, in an aqueous solution of both cations, the acidic cation is more likely to be in the form of some hydroxy species (not to be confused with hydrated cations), while the basic cation is more likely to exist as the free cation. 

It was previously mentioned that PDADMAC (Cat-Floe) was the first commercial flocculant approved for potable water [26]. Since then, PDADMAC has been continuously used for coagulation/flocculation both in potable water and waste water treatment. A good example of the performance of PDADMAC in the coagulation of colloidal solids is the reduction of turbidity in fresh water of 150 mg L 1 of Ca(OH)2. A reduction of 82% in turbidity is observed with the addition of only 2 mg L 1 of branched PDADMAC [217]. In addition, PDADMAC and copolymers of DADMAC are reported to be effective in the removal of hard-to-elimi-nate impurities in the water treatment industry. Emulsified impurities from streams of a petroleum refinery waste water and an automotive oily effluent water have been removed by the use of water soluble copolymers consisting essentially of DADMAC and small amounts of anionic acrylic monomers [89]. 

Aluminum sulfate, A12(S04)3, is commonly added to water to remove fine colloidal solids. Suggest a reaction of this salt with water to produce a substance that will remove colloidal solids from water. 

Although colloids may be undesirable components in industrial systems, particularly as waste or by-products and, in nature, in the forms of fog and mist, they are desirable in many technologically important processes such as mineral beneficiation and the preparation of ceramics, polymers, composite materials, paper, foods, textiles, photographic materials, drugs, cosmetics, and detergents. The remainder of this chapter specifies some applications for colloidal solids, liquids, and gases and illustrates how colloids can affect many technologically important systems. 

These pigments are manufactured by treating ferrous sulfate (FeS04) solutions (sometimes in the presence of ammonium sulfate) with sodium ferrocyanide, giving a white ferrous ferrocyanide, which is then oxidized to ferric ferrocyanide, Fe4[Fe(CN)6], or to Fe(NH4)[Tc(CN)6 by different reagents such as potassium chlorate, bleaching powder, and potassium dichromate. The colloidal pigment is washed and allowed to settle to enhance separation, since filtration of the colloidal solid is difficult. 

Fermentation is typically conducted in dilute suspension culture. The low concentration in such systems limits reaction efficiency, and the presence of particulate and colloidal solids poses problems for product recovery and purification. By circulating the fermentation broth through an ultrafiltration system, it is possible to recover product continuously as they are generated while minimizing loss of enzyme or cells and keeping product concentration in the bioreactor below the self-inhibition level for the biocatalyst. This process is referred to as perfusion. As the ultrafiltration unit is part of the production process, the entire system is often considered a membrane reactor. 

Other colloidal solids than NaX(s) and other electrolytes than NaCl may be present in the soil suspension, but they are assumed not to interfere with the performance of the electrode pair. The development of electrical potential at the sodium electrode is a somewhat complicated process that includes the creation... 

Emulsion polymerization was successfully employed for the preparation of nano-scale MIPs by synthesizing core-shell latexes with an imprinted shell. The use of a template with surfactant properties led to enhanced surface imprinting. Magnetic cores were synthesized to render MIPs which could be manipulated by magnetic fields in suspension, thereby facilitating the separation of the colloidal solid phase from the suspending solution. 

Ion exchange is normally defined by a distribution coefficient or by a selectivity coefficient more than by an equilibrium exchange constant (see below). These coefficients relate the amount of the exchanged ions that stay in the colloidal solid matrix to that in the aqueous phase. In this context, a simplified example of an ion exchange reaction (e.g., H+ for K+) is... 

Lubricating greases are oils which have been thickened to a semi-fluid consistency by dispersing in them a colloidal solid. They therefore differ in several respects from other semi-fluid materials such as heavy petroleum oil, bitumen, petrolatum (petroleum wax) or low-molecular-weight polymers. One of the most important of these differences is that under certain circumstances they may separate into their two main constituents, thickener and base fluid. Another important... 

Figure 19.2 Self-similarity analysis for nanotextured silver surfaces prepared in different ways. The root mean square roughness inferred from atomic force microscopy is plotted versus measurement area. The various surfaces are 100 nm thick evaporated silver films (solid squares, red line)-, 5.2 nm thick evaporated silver films (open circles, green line) nanoparticle films assembled from colloid attachment to self-assembled monolayers (solid circles, blue line) films from deliberate precipitation of silver colloid (solid up-triangles, black line) Tollens reaction films (open down-triangles, orange line). Lines with slopes H = 1.0 and H = l.S representing two-dimensional and 1.5 dimensional surfaces respectively are...

Simulated wastes containing suspended and colloidal solids... 

Most undergraduate students of aqueous geochemistry are told that polynuclear aqueous complexes can largely be ignored because they form only from concentrated metal solutions that are rare at the Earth s surface. However, these polynuclear complexes can serve as models for more-complicated surface structures and are the precursors to nanometric and colloidal solids and solutes. There are many reasons why polynuclear complexes should be foremost in the minds of geochemists, and particularly those geochemists who are interested in molecular information and reaction pathways ... 

---