Coagulation/precipitation

The reverse of coagulation in which a coagulated precipitate reverts to smaller particles. 

The basic unit operations/processes required for treating the acid pickling wastewater are (a) neutralization with NaOH and/or lime to increase the pH and (b) physicochemical methods, such as chemical coagulation, precipitation, clarification (sedimentation or DAF), and filtration to remove BOD5, COD, and iron. 

Adachi A., M. Kamide, R. Kawafume, N. Miki, and T. Kobuyashi (1990). Removal-efficiency of anionic and nonionic surfactants from chemical wastewater by a treatment plant using activated carbon adsorption and coagulation precipitation processes. Environmental Technology 11 133-141. 

Chemical Family a group of elements that share similar chemical properties and share the same column in the periodic table, for example, halogens, alkali earth Chirality condition that describes the handedness of a molecule or whether a molecule exists in forms that can be superimposed on each other Chlorofluorocarbons also called CFCs, compounds consisting of chorine, fluorine, and carbon that are responsible for stratospheric ozone destruction Coagulation precipitation or separation from a dispersed state Coefficient of Thermal Expansion measure of the rate at which a substance will expand when heated... 

Small Quantities. Wear nitrile rubber gloves, laboratory coat, and eye protection. Work in the fume hood. Dissolve the compound in a minimum of 6 M hydrochloric acid (add concentrated acid to an equal volume of cold water). Filter and treat the filtrate with a slight excess of 6 M ammonium hydroxide (add 42 mL of concentrated ammonium hydroxide to 58 mL of cold water, about pH 8 to pHydrion paper). Boil and allow the coagulated precipitate to settle for about 12 hours. Filter and dry. Recycle, return to supplier, or send for disposal in a secure landfill.6 7... 

Chemical treatment coagulation/precipitation/flocculation, neutralization Biological treatment aerobic suspended growth processes, fixed film processes, aerated lagoons, anaerobic treatment processes... 

Coagulation-Precipitation The nature of an industrial wastewater is often such that conventional physical treatment methods will not provide an adequate level of treatment. Particularly, ordinary settling or flotation processes will not remove ultrafine colloidal particles and metal ions. In these instances, natural stabilizing forces (such as electrostatic repulsion and physical separation) predominate over the natural aggregating forces and mechanisms, namely, van der Waals forces and Brownian motion, which tend to cause particle contact. Therefore, to adequately treat such particles in industrial wastewaters, coagulation-precipitation may be warranted. 

Zn(OH)2 suspension. Preparation and purification from Fe, Mn, and other metals dissolve 2 g of zine nitrate in 50 ml of water, add 5 mg of La (in the form of the nitrate solution), some H2O2 solution, and ammonia in exeess. Filter off the coagulated precipitate, evaporate off the excess of ammonia from the filtrate, and acidify the solution slightly with HCl. Preeipitate Zn(OH)2 by adding dilute NaOH solution until the pH is 8-9. Filter off the precipitate and wash it with water until Cf ions are no longer present in the washings. Mix the precipitate with 100 ml of water. ... 

Before the addition of Zn(OH)2, adjust the solution to pH 2-3 with dilute NaOH solution. After the Zn(OH)2 is added, heat the solution for about 15 min at 70°C, filter off the coagulated precipitate, and wash it with hot water. 

In the case when the depth of potential minimum is smaller than several kT, the coagulation (i.e., the combination of two particles) becomes thermodynamically unfavorable even at low height of the potential barrier (Chapter VII, 1), and the stability of colloidal system towards coagulation is of thermodynamic nature. This is confirmed by observed peptization of coagulated precipitates upon washing out the excess of coagulating electrolyte and by stabilization of sols by specifically adsorbed ions. 

Soluble MnOj was first detected in the oxidation of organic compounds by Mn04 using UV-VIS spectrophotometry (19). Laboratory synthesis is easily achieved using the method of Perez-Benito et al (12) by the stoichiometric reaction of permanganate with thiosulfate (eq. 1). A solution of 1 mM is stable to coagulation/precipitation and remained... 

DestabiUzes contaminants to cause aggregation or adsorption on coagulant precipitates or membrane surfaces... 

Polymeric flocculants and coagulants Precipitates (gypsum, hydroxides, jarosites) Bacteria, fungi, and algae... 

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