Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from a release of the gas. The word effervescence is derived from the Latin verb fervere (to boil), preceded by the adverb ex. It has the same linguistic root as the word fermentation, a complex biochemical reaction leading to, among other things, the production of carbon dioxide and to the subsequent liberation of CO2 gas from a solution when it becomes supersaturated with respect to this gas. The making of beer, wine, or champagne by fermentation is thus accompanied by effervescence of CO2 from the barrel where the process occurs.
Effervescence can also be observed when opening a bottle of champagne, beer or carbonated beverages such as soft drinks. The visible bubbles are produced by the escape from solution of the dissolved gas (which itself is not visible while dissolved in the liquid).
In the laboratory, a common example of effervescence is seen if hydrochloric acid is added to a block of limestone. If a few pieces of marble or an antacid tablet are put in hydrochloric acid in a test tube fitted with a bung, effervescence of carbon dioxide can be witnessed.
- CaCO3 + 2 HCl → CaCl2 + H2O + CO2
- H2CO3 → H2O + CO2
In simple terms, it is the result of the chemical reaction occurring in the liquid which produces a gaseous product.
|Look up effervescence in Wiktionary, the free dictionary.|
|Look up effervescence in Wiktionary, the free dictionary.|
Granulation was a vital unit operation in the production of pharmaceutical oral dosage forms. Changing regulatory compliances that was directed towards enhancement of product quality came up with process validation of each unit operation, increasing product output, decreasing product throughput time, reducing labour and energy cost; had revolutionized the GT, since its introduction, thereby resulting in development of novel granulation technologies. Each and every GT had its own limitations vis-à-vis possesses superiority over other.
Granulation method was selected not only on the basis of individual properties of the ingredients like their flow property, compressibility, eject-ability, and disintegrate-ability but also on the basis of compliance of the regulatory requirement for the product and employed technologies. Pharmaceutical industry was very conservative with respect to application of new applications and new technologies associated with their required regulatory compliances with respect to the reproducibility of the process. Depth knowledge in the GT was essential to adopt proper granulation process during development stage of product to get a targeted granulation and final product parameters. Present review was aimed to give an outline on technicality of GT while emphasis was put on to provide information related to advanced GT so that a suitable GT can be adopted for granulating a material. In this respect databases were extensively searched to gather data that were presented as a handy reference and the presented data will help scientists engaged in developing an efficient GT for the product in hand.
Granulation: Granulation was a particle design process that involves gathering of small particles into large masses in which the original particles can still be identified. Granulation was done for improving flow and compression characteristics, improving content uniformity, reducing segregation, facilitating metering or volumetric dispensing, controlling/manipulating release rate, eliminating generation of excessive amounts of fine particles thereby increasing bulk density of the product, decreasing dust generation thereby reducing employee exposure to the product, and resulting in improvement of yield and productivity, reduced down time, and so on. Mechanisms of particle-particle interactions during Granulation: Mechanism of particle-particle interactions to be studied appropriately to select an efficient GT as this will provide an insight for the granule formation mechanism, an essential parameter for predicting not only energy requirement for the formation of granules but also its stability. Independent of the process employed, five discrete bonding mechanisms at the point of particle–particle interactions had been recognised that were enlisted as below:
1. Solid bridges: chemical reaction and/or sintering/heat hardening associated solid bridges were formed due to dissolution during granulation with subsequent solvent removal in the drying phase.
2. Immobile liquids: addition of speciality binder(s) solution in granulating solvent that softens, deforms, and adhere to particles, then hardens during drying.
3. Mobile liquids: liquid bridges, at higher fluid levels, which occupy void spaces thereby bonds particles.
4. Intermolecular and long-range forces: van der Waals forces, electrostatic forces results in bonding of the particles.
5. Mechanical interlocking: fracture and deformation due to pressure that results in shape related bonding or intertwining of long fibrous particles.
Granulation Technology: GT comprises the art and science for process and production of granules. All over the world granulation was done either by wet-granulation or by dry-granulation process. Technological breakthrough in the area of GT, over a period of time, as an urge to improve commercial output, had leaded to evolution of diverse newer and novel GT like moisture activated dry granulation (MADG), thermal adhesion granulation (TAG), pneumatic dry granulation (PDG), melt/thermoplastic granulation (MTG), fluidized bed granulation, freeze granulation (FG), foam binder granulation (FBG), steam granulation (SG), and so on. Prerequisites of an Ideal Granulation Technology:
1. Must have potentiality to improve reproducibility in the product performance,
2. Must decrease variability in the process performance,
3. Must have potentiality to minimize post-approval process changes,
4. Must have potentiality to decrease cost and time, and
5. Should produce spherical granules with controlled size distribution, specific granule voidage (i.e., intragranular porosity), specific bulk density, good flowability and compact-ability, suitable structural stability and physical strength.
Classification of Granulation Technologies: Basing upon the type of processing, that had been involved, GT can be classified as follows:
1. Conventional methods (i) Dry granulation (ii) Wet granulation (a) High-shear wet granulation (b) Low-shear wet granulation
2. Novel/advanced methods (i) Moisture activated dry granulation (ii) Thermal adhesion granulation (iii) Pneumatic dry granulation (iv) Melt/thermoplastic granulation (v) Fluidized bed granulation (vi) Extrusion-spheronization granulation (vii) Spray drying granulation (viii) Freeze granulation (ix) Foam binder granulation (x) Steam granulation
Technical breakthrough in the granulation field will came with latest technology. Depth knowledge was essential to adopt proper granulation process to get targeted granulation and final product parameters. While application of newer technique by the pharmaceutical and other industries will be a function of their inherent conservatism and regulatory controls.
- G. Liger-Belair et al., "Study of Effervescence in a Glass of Champagne: Frequencies of Bubble Formation, Growth Rates, and Velocities of Rising Bubbles", Am. J. Enol. Vitic. 50:3 (1999) 317–323
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