Read onlinepdf 546 kb go to volume 12, issue get ealerts. Flocculation process where a solute comes out of solution in the form of flocs or flakes. Origins of depletion flocculation the first experimental observation of depletion flocculation was reported by traube 2, whilst investigating the creaming of natural rubber in the presence of water soluble polymers. Frustratingly, if we add a little too much polymer, we can destabilize the system via a nonintuitive effect called depletion flocculation. The minimum fibril concentration for flocculation is two orders of magnitude higher for the short. Coagulation, flocculation and clarification of drinking water. Stability against demixing, rheology and microstructure of emulsions that were. Droplet flocculation caused the spectral reflectance and l.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The material is derived from articles chris white wrote for brew your own magazine many years ago. Review the documents for the research phase of the frame engineering design model. Sep 14, 2017 example problem for designing a flocculation basin. Suppression of depletion flocculation in oilinwater emulsions. Depletion stabilization and depletion flocculation suppression of depletion flocculation in oilinwater emulsions. Yeast is responsible for turning sweet wort into what we call beer. The creaming data for emulsions containing excess added ionic surfactant i. Depletion flocculation of polystyrene latices by watersoluble polymers. Depletion flocculation of aqueous, electrosterically.
This can take place spontaneously or may be brought about by adding clarifying agents. Sep 15, 2002 read depletion flocculation of latex dispersion in ionic micellar systems, journal of colloid and interface science on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. There follows, during the flocculation step,an increase in the size of the particlespresent in the water phase resulting in the formation of flocs. Depletion flocculation of latex dispersion in ionic.
A number of factors that affect selective fkjccu1ation of fines have been identified and the effect of e of parameters on p behavior has been explained with the help of a few case studies. Words such as pitching, attenuation, and flocculation take on special meaning to brewers. Coagulation and flocculation in water and wastewater treatment provides a comprehensive account of coagulation and flocculation techniques and technologies in a single volume covering theoretical principles to practical applications thoroughly revised and updated since the 1st edition it has. But depletion flocculation is a very significant effect in realworld formulations, so its worth. Depletion flocculation in colloidal dispersions science. Feb 09, 2016 this feature is not available right now. This knowledge will provide a basis for understanding the needs of the. Depletion forces and flocculation with surfactants, polymers and particles synergistic effects. Further, the ability of the thickener to depletion flocculate latexes as a function of surfactant and electrolyte is explored. Depletion forces and flocculation with surfactants, polymers. Suspended particles vary in source, charge, particle size, shape, and density. These data correlate well with the depletion flocculation predicted for the lower concentration and the depletion stabilization predicted for the higher dextran concentration.
Depletion flocculation, induced in dispersions of hydrophobic silica particles in. The influence of droplet flocculation on the optical properties of 1 and 10 wt% oil. Elsevier depletion flocculation in colloidal dispersions paul jenkinsa, martin snowden b, alan wark research institute, university of south australia, warrendi road, the levels sa 5095, australia bschool of chemical and life sciences, university of greenwich, woolwich, london se18 6pf, uk abstract advances in colloid and advances in colloid and interface science interface 68 1996 5796. The stokes equation was applicable provided the average droplet diameter was less than. Flocculation, in the field of chemistry, is a process in which colloids come out of suspension in the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. Yeast consume the sugar in wort, and turn that sugar into co2, alcohol, and flavor compounds. The extent of asphaltene flocculation changes with fluid composition, temperature and pressure. Depletion flocculation of nonaqueous dispersions containing. In the flocculated system, there is no formation of. Download this article pdf format article references. The magical art of yeast coming together, dropping to the bottom of a fermentor, is called flocculation. Pitching is adding yeast to wort to start fermentation.
An example of such a synergistic effect is shown in fig. Coagulationflocculation process for produced water. Polymer thickeners can induce good dispersion, bridging, or depletion flocculation of latexes depending on the polymer structure and concentration. The aggregation of small particles into larger particles. Depletion flocculation in dispersions of stericallystabilised particles. For precipitated asphaltenes, flocculation is also affected by the shear environment. All species are assumed to interact as simple hard spheres, meaning that the depletion force profile between the. These data correlate well with the depletion flocculation predicted for the lower concentration and the depletion. Depletion flocculation practical solubility science. A creaming study of weakly flocculated and depletion. Flocculation was induced by addition of sds micelles to the aqueous phase of emulsions to increase the depletion attraction between droplets. Flocculation by depletion and bridging was induced by addition of the polysaccharide carboxymethylcellulose cmc to emulsions that were stabilised by lactoglobulin lg at ph 6. Influence of flocculation on optical properties of.
Well, most of us are, and we have two models here to add to the difficulties. Flocculation in oilinwater emulsions using fibrillar. Selective flocculation of fines columbia university. Depletion forces and flocculation with surfactants. Pdf suppression of depletion flocculation in oilin.
Enhancement of ostwald ripening by depletion flocculation. Depletion flocculation modelled in prof steven abbotts practical solubility science apps. A new way to treat the waste water 105 2sulfoethyl methacrylate is of limited commercial value owing to the hydrolytic instability of the ester linkage. Runkana langmuir center for colloids and interfaces, columbiauniwrsity, new york. Coagulation and flocculation process fundamentals 1 coagulation and flocculation. Mar 31, 2016 flocculation is the agglomeration of destabilized particles into a large size particles known as flocs by slow mixing which can be effectively removed by sedimentation or flotation. To get a feel for the effect, play with the radius of the particles, the radius radius of gyration of the polymer, its concentration and mwt.
Experimental critical flocculation concentrations cfc are compared to values expected based on molecular volume and potential energy calculations. The flocculation behavior of coal, quartz and clay was studied by measuring the turbidity of the supernatant liquid after one hour of settling. Subsequently, various authors 3,4 described the aggregation of red blood cells using hydrophilic polymers. The results are consistent with the bridging theory. Subsequently, various authors 3,4 described the aggregation. Negatively charged vesicles containing aot and phospholipids, in the absence and presence of additional reducing agent. Flocculation definition, to form into flocculent masses. Depletion flocculation has also been observed in systems where surfactants are used in place of polymers as the flocculant species. Steric stabilisation and flocculation by polymers polymer. At low polymer concentrations, depletionflocculated emulsion gels may separate serum.
This volume details the thermodynamics and kinetics of the adsorption of surfactants and polymers on solids, as well as coagulation and flocculation mechanisms demonstrating the applicability of the newest theoretical approaches on practical systemswritten by over 15 international experts in the field, coagulation and flocculation. The effect of addition of free polymer to sterically stabilised dispersions, i. Depletion flocculation induced by synergistic effects of nanoparticles and polymers. Attenuation is the percentage of sugars yeast consume during fermentation. Example problem for designing a flocculation basin. To the best of the authors knowledge, this is the first time the behavior of mfc in the rheometer gap was characterized by this realtime imaging method. Engelhardt application development manager drinking water hach company photo by author the intent of this paper is to provide cursory information about coagulation, flocculation and clarification. Invaluble for water scientists, engineers and students of this field, coagulation and flocculation in water and wastewater treatment is a convenient reference handbook in the form of numerous examples and appended information. Flocculation is a process in chemistry wherein colloids are extracted from suspensions which then take the form of flake or floc.
Coagulationflocculation process for produced water treatment. The theory of flocculation 3 adsorbed even though the net charge of the particle is of the same sign as the polymer. The amount of chemical you use is an important consideration for a green engineer. Pdf depletion flocculation in colloidal dispersions. Depletion flocculation of polystyrene latices by watersoluble. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually dissolved in a solution. Coagulation and flocculation in water and wastewater treatment provides a comprehensive account of coagulation and flocculation techniques and technologies in a single volume covering theoretical principles to practical applications. A depletion force is an effective attractive force that arises between large colloidal particles that are suspended in a dilute solution of depletants, which are smaller solutes that are preferentially excluded from the vicinity of the large particles. The aim of this study was to develop a onestep synthesis of gold nanotriangles nts in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified nts. If the surface has a negative charge, positive ions will be attracted to it, forming a bound layer of positive ions.
Various sizes of particles in raw water particle diameter mm type settling velocity 10 pebble 0. Coagulation and flocculation in water and wastewater. Though often used interchangeably with coagulation, it is in fact a distinct process that. This followed by description of the methods that can be applied for studying steric. Flocculation free download as powerpoint presentation. Flocculation or floculation is a significant process widely utilized in water treatment operations, including purification of drinking water, sewage water treatment, storm water treatment and treatment of various other industrial wastewater streams. Ramavandi, 2014 ramavandi, 2014evaluated the coagulation potential of fcefecl3inducedcrudeextract obtained. Depletion flocculation in colloidal dispersions sciencedirect. Coagulation and flocculation are used to separate the suspended solids portion from the water. Depletion flocculation of latex dispersion in ionic micellar.
At d at all these dextran concentrations, the erythrocytes are coated with considerable amounts of dextran. But depletion flocculation is a very significant effect in realworld formulations, so its worth trying to understand what is going on so you can avoid the problem. Coagulation, flocculation and clarification of drinking water terry l. Figure 14 is a plot of turbidity and adsorption density against equilibrium concentration. Department of environmental science and technology shivaji university, kolhapur maharashtra kulkarni g. Flocculants, with their very high molecular weights long monomer chain and their charge content, fix the destabilized particles and aggregates along the polymer chain. It can be downloaded for ibooks, for kindle and as pdf. Oct 23, 2017 flocculation is a process in chemistry wherein colloids are extracted from suspensions which then take the form of flake or floc. Flocculation,flocculation process,uses of flocculation process. The turbidity of the supernatant liquid decreases until a minimum is reached and tends to rise thereafter. A basic statisticalmechanical calculation of the force is presented and some di. The minimum required fibril concentration for flocculation was determined experimentally for fibril lengths of about 3 and 0. From my course ees 3030, water treatment systems, in the department of environmental engineering and earth sciences at clemson university. Coagulation flocculation chemistry physical sciences.
Depletion flocculation and depletion stabilization of erythrocytes. Steric stabilisation and flocculation by polymers polymer journal. The journal of physical chemistry b 20, 117 51, 1660216609. Groundwater and surface water contain both dissolved and suspended particles. Brewing terms attenuation and flocculation are defined and explained in this section. If theyre added to stormwater along with some positive ions, the soil particles will bind onto these anionic polymer molecules and form the ionic bridges shown in figure 2. Effects of a nonadsorbing polymer on colloid stability. Influence of flocculation on optical properties of emulsions. The flocculation behavior of anionic and cationic latex dispersions induced by addition of ionic surfactants with different polarities sds and cetyltrimethylammonium bromide ctab have been evaluated by rheological measurements. Both theories account well for the depletion flocculation observed when the added free polymer is of the same type as the attached polymer, that is, in this case. Department of environmental science and technology shivaji university, kolhapur maharashtra kore v. Depletion flocculation practical solubility science prof steven. Pdf the destabilisation of colloidal dispersions by free. However, when the associative interactions are destroyed, depletion flocculation of the latex can result.
However, anionic polymers, which carry a negative charge, are not toxic. In the context of heavy oil, asphaltenes are known to flocculate at the molecular level before precipitation and in the precipitated state. Surfactant and electrolyte effects on latex depletion. Pdf depletion flocculation in colloidal dispersions researchgate. At all these dextran concentrations, the erythrocytes are coated with considerable amounts of dextran. An approximate theory of depletion stabilization and depletion flocculation i. Since the area of positive charge will only be small, it is likely that the polymer molecules are attached by the ends, and not along any length of the chain. Coagulation flocculation free download as powerpoint presentation.
The creaming of weakly flocculated and depletion flocculated oilinwater emulsions was investigated and the data compared with theory. Depletion flocculation practical solubility science prof. Water treatment plant waste sludge disposal is dealt with in considerable detail, in an appendix devoted to this subject. Depletion flocculation and depletion stabilization of. One of the earliest reports of depletion forces that lead to particle coagulation is that of bondy, who observed the separation or creaming. Depletion stabilization and depletion flocculation sciencedirect. Serum separation and structure of depletion and bridging. Rheology of microfibrillated cellulose mfc water suspensions was characterized with a rotational rheometer, augmented with optical coherence tomography oct.
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