Thursday, March 10, 2011

Use of detergent in Manufacturing.

Use of detergent in Manufacturing.
Substance that aids in the removal of dirt. Detergents act mainly on the oily films that trap dirt particles. The detergent molecules have a hydrocarbon portion, soluble in oil, and an ionic portion, soluble in water. The detergent acts as an emulsifier, i.e., by bridging the water and oil phases, it breaks the oil into tiny droplets suspended in water. The disruption of the oil film allows the dirt particles to become solubilized. Soap, the sodium salt of long-chain fatty acids, is a good detergent although it has some disadvantages, e.g., it forms insoluble compounds with certain salts found in hard water thus diminishing its effectiveness, and in acid solutions, frequently used in industry, it is decomposed (thus precipitating the free fatty acid of the soap). Synthetic detergents were produced experimentally in France before the middle of the 19th cent. and were further developed in Germany during World War I. However, not until the 1930s were chemical processes developed that made production in quantity feasible in any country. Synthetic detergents were first developed for commercial use in the 1950s. Detergents are classified as anionic, or negatively charged, e.g., soaps; cationic, or positively charged, e.g., tetra alkyl ammonium chloride, used as fabric softeners; nonionic, e.g., certain esters made from oil, used as degreasing agents in industry; and zwitterionic, containing both positive and negative ions on the same molecule. Detergents are incorporated in such products as dry-cleaning solutions, toothpastes, antiseptics, and solutions for removing poison sprays from vegetables and fruit. Laundry detergent preparations may contain substances called builders, which enhance cleansing; however, phosphate-containing builders have been found to contribute to eutrophication of waterways and their use has been banned in many areas. Detergents that can be decomposed by microorganisms are termed biodegradable. Detergents are important chemicals used for enhanced petroleum recovery.

Types of detergent-
Soda Ash
Sodium Hydroxide
Magnesium Oxide
Potassium Chloride
Ammonium Bisulphate
Gel L.C. Seal (Fibers)
Potassium Hydroxide
Gel Nut Plug (Walnut Shell)
Gel Cal graded calcium carbonate


Desizing agent-
Desizing is the process of removing the size material from the warp yarns in woven fabrics.

Desizing processes-
Desizing, irrespective of what the desizing agent is, involves impregnation of the fabric with the desizing agent, allowing the desizing agent to degrade or solubilise the size material, and finally to wash out the degradation products. The major desizing processes are:
Enzymatic desizing of starches on cotton fabrics
Oxidative desizing
Acid desizing
Removal of water-soluble sizes

Enzymatic desizing-
Enzymatic desizing is the classical desizing process of degrading starch size on cotton fabrics using enzymes. Enzymes are complex organic, soluble bio-catalysts, formed by living organisms, that catalyze chemical reaction in biological processes. Enzymes are quite specific in their action on a particular substance. A small quantity of enzyme is able to decompose a large quantity of the substance it acts upon. Enzymes are usually named by the kind of substance degraded in the reaction it catalyzes.
Amylases are the enzymes that hydrolyses and reduce the molecular weight of amylose and amylopectin molecules in starch, rendering it water soluble enough to be washed off the fabric.
Effective enzymatic desizing require strict control of pH, temperature, water hardness, electrolyte addition and choice of surfactant.
 Oxidative desizing-
In oxidative desizing, the risk of damage to the cellulose fiber is very high, and its use for desizing is increasingly rare. Oxidative desizing uses potassium or sodium persulfate or sodium bromite as an oxidizing agent.

 Acid desizing-
Cold solutions of dilute sulphuric or hydrochloric acids are used to hydrolyze the starch, however, this has the disadvantage of also affecting the cellulose fiber in cotton fabrics.

Removal of water-soluble sizes-
Fabrics containing water soluble sizes can be desized by washing using hot water, perhaps containing wetting agents (surfactants) and a mild alkali. The water replaces the size on the outer surface of the fiber, and absorbs within the fiber to remove any fabric residue.

Soda ash:-
Soda ash is a versatile product that can be produced inexpensively and used for a number of different applications. Here are some basic facts about soda ash, and how the compound is used throughout the world every day.
More properly known as sodium carbonate, soda ash is a sodium salt of carbonic acid. Carrying an official registration as Na2CO3, soda ash normally comes into being as a crystallized heptahydrate that can be formed into a white powdery substance, known as a monohydrate. Soda ash can be manufactured from the ashes of a number of different types of plants, as well as created from the processing of ordinary table salt. The ability to manufacture soda ash in bulk ensures that the many goods produced with the compound will be available to us for many years to come.

Caustic Acid-
Sodium hydroxide (NaOH), also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 1998 was approximately 45 million tonnes.[citation needed] Sodium hydroxide is a common base in chemical laboratories.
Pure sodium hydroxide is a white solid; available in pellets, flakes, granules and as a 50% saturated solution. It is hygroscopic and readily absorbs water from the air, so it should be stored in an airtight container. It is very soluble in water with liberation of heat. It also dissolves in ethanol and methanol, though it exhibits lower solubility in these solvents than does potassium hydroxide. Molten sodium hydroxide is also a strong base, but the high temperature required limits applications. It is insoluble in ether and other non-polar solvents. A sodium hydroxide solution will leave a yellow stain on fabric and paper.

Enzyme-
Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.
Like all catalysts, enzymes work by lowering the activation energy (Ea‡) for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions. A few RNA molecules called ribozymes also catalyze reactions, with an important example being some parts of the ribosome. Synthetic molecules called artificial enzymes also display enzyme-like catalysis.
Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Activity is also affected by temperature, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins, making the meat easier to chew).