For a very long time soaps, alkaline salts, and bleach were mainly used to treat the different linen by most laundries. However, as time passed the co
Bada Laundry: Evolution and Trends of
Laundry Washing Chemicals
For a very long time soaps, alkaline salts, and bleach were mainly used to treat the different linen by most laundries. However, as time passed the compositions have evolved as per the requirement in the treatment of various linen.
Let us understand the evolution of the composition of chemicals used in laundry.
When I was young I remember that bathing time was like torture and the soap seemed like a weapon attacking me.
The basic raw material for making soap are a Sodium (or Potassium) salt of various higher fatty acids (It has a very good cleaning power, due to its property of emulsifying oily soil) and fats/oils.,
Its drawbacks are that the soap can split heavy soil causing acid soap and this can settle on fabrics/linen/garments and wash items can become gray.
With a hardness of more than 60ppm, soap can form lime soap, which can also settle on fabric to make it yellowish or grayish. It is necessary to know the particular range of washing temperature. If the wash temperature is higher or lower than required, it may be insoluble and can disturb quality. Moreover, pure soap has pH=10.0.
To protect the soap, add alkaline salts. These salts need to have pH>10.5. The water must have TDS up to 250-300 pp and hardness up to 60-70 ppm and no more. The alkali added to protect the soap can turn linen yellowish or grayish if added in excess and acidic soap could be formed if alkalis are added less than required.
The oldest references to literature in the Babylonian civilization from 2200 BC soap formulation consisted of water, alkali and cassia oil. Industrial production of soap remained basically the same until 1916. Due to the shortage of fats for making soap at the time of World War II, the first synthetic detergent was developed by Germany.
Soaps have advantages over synthetic detergents regarding soil re-deposition and maintaining whiteness, as it acts as a water softener. The need for anti-re-deposition agents began with the introduction of multi component laundry detergents based on synthetic surfactants.
Sixty years ago, it was discovered that chemicals can change the molecular structure of water with the introduction of the very first laundry detergent. It was understood by then that lowering the surface tension was required for better cleaning and this was achieved by chemical surfactants.
The surfactants used in early synthetic detergent were prepared by reacting to benzene with propylene tetramer to form alkyl aryl group, which was then sulfonated. These materials are so called hard alkyl benzene sulphonates and are non-biodegradable. Over time they accumulate in the environment to an extent that the foaming resulted in sewage water treatment plants and waterways.
In the mid of 1970s, the introduction of ion exchange materials and zeolites as detergent builders led to gradual moment away from phosphate technology. Importantly, this was achieved without compromising performance and consumer value. The move to nil phosphate builder systems increased the complexity of powdered detergents. Today nil phosphate powder contains zeolite and silicates for hardness control. Polycaroxylate polymers for soil suspension, citric acid for soil peptization and dispersion as well as pH control and carbonate for calcium control and buffering.
Chemical Energy in Detergents:
A). Surfactants: Synthetic Surfactants decrease the surface tension of water.
B). Alkaline builders: Builders decrease water hardness and enhance surfactant's ability
C). Water softening chemicals
D). Borax: A mineral that boosts cleaning.
E). Electrolytes as performance enhancers.
F). Anti-re-deposition agents-keep loosened dirt from reattaching to clean fabric.
G). Fillers: Anti-foaming agents or corrosion inhibitors.
H). Bleaches: Helps detergents remove soils and stains.
Detergents are better than soap with respect to stability and to get quality. Detergents have successfully replaced soaps for laundering. Detergents perform well in a wide range of water hardness levels. Quantity of detergent to be added while washing depends on a number of factors like the type of garment/linen/fabric to be washed, the soil condition of cloth, construction/composition/dies used, stitching threads, padding, and water quality. These are the ways to find the right quantity out.
The following factors/chemicals are required for detergent Formulation:
Powders are mild, and especially suited for lightly soiled items and baby clothes
A). Builders: These give alkalinity, decrease water hardness, enhances
surfactant’s ability. One needs to adjust these 3 factors DS/PH/Hardness
and also soil/dye/fabric and temperature, to have quality.
B). Electrolytes: Used to increase soil detachment from
C). Surfactants: Decrease surface tension helps emulsification and aid
D). Suspenders: To suspend dispersed and deflocculating of soil, so as not
to allow settling on linen/clothes.
E). Sodium Carbonate or Bicarbonate agents: Neutralizes acidity and
Maintains pH level.
F). Heavy anti-re-depositing agents: Keeps loosened dirt from reattaching to
G). Enzymes: For protein-based stains, Oxidizing bleaches -Either
incorporated or separate.
H). Fillers: Anti-foaming agents or corrosion inhibitors.
Anti-bacterial or anti-microbial chemicals
The liquid form of disinfectants is generally used in laundry additives. It is a good idea to use disinfectant as it kills germs in the laundry. Clothes get contaminated by sewage waste, like flood soiled clothes, and disinfectants should be used. Liquid chlorine bleach is the most accessible, least expensive and easiest to use disinfectant.
Normally disinfectants are not included in the wash cycle because the disinfectant factors may be present in water, detergent, from the dryer or while drying in sunshine.
Use of Bleach in Laundry:
Bleach helps detergents to remove soils and stains from laundry and it is the most popularly used laundry aid.
By the process of oxidation, laundry bleach converts soil into more soluble, dispersible, and colorless particles, which can be removed by the detergent and carried away in the wash water.
There are two types of bleach (Oxidizing agents)
1. Oxygen Bleach and
2. Chlorine Bleach (Sodium Hypochlorite)
These two bleaches are never used together as it loses its property.
Oxygen bleach is suitable for all types of clothes and is available both in powder and liquid form.
Hydrogen peroxide generated by the reaction of this bleach with the soil and other organic material, either de-colorizes or breaks them up.
Hydrogen peroxide does not have disinfection properties as in the sodium hydro chlorite, but hydrogen peroxide provides very gentle action on clothes.
Use of hot water accelerates bleaching rates, and in low-temperature exposure time must be increased substantially.
The procedure of using Oxygen Bleach:
Oxygen bleach is suitable for all fabrics, it is available in both liquid and powder form. The hydrogen peroxide created by this bleach reacts with the soil and organic material in the wash load to decolorize or break them up.
Oxygen bleach provides a very gentle bleaching action compared to sodium hypochlorite used in chlorine bleach, but it does not disinfect.
Add oxygen bleach to water before adding clothes to wash. Before adding colored fabric for washing, first test the fabric for colorfastness.
Color removers available in the market have the capability to remove most of the colors, but some color prints cannot be removed. Color removers help whiten the gloomy colors, to remove brown rust stains washed in water containing iron and manganese.
Bluing the liquid should be diluted with water prior to adding it to the washer before washing or in the final rinse. The blue traces in the wash will enhance the white and light-colored items, making them appear white and bright.
Booster enables detergent to work more efficiently. Boosters are generally used and are effective in hard water. They are available in powder and liquid form and are used in the wash along with the detergent as per the recommended amount. Liquid boosters are sometimes used in spotting, such as removing the stains before washing (pre-treating).
Disinfectants contain germicides and are used to kill germs in the laundry. To sanitize clothes, add two tablespoons of liquid chlorine bleach per wash load. Liquid chlorine bleach is accessible, economical, and easy to use.
The powdered product contains enzymes, builders, surfactants, bluing agents, fluorescent brighteners and possibly oxygen bleach. Enzymes pre-soaks are used for soaking the laundry prior to washing to remove tough stains and soils like egg, blood, grass, etc. They are sometimes used as boosters in the wash.
Chemicals for Dry-Cleaning:
As water is not used in this process it is called s dry cleaning. When clothes are taken to dry cleaner for laundry. It is inspected for the stains. these stains are identified and pre-treated before being taken to the wash using spotting chemicals. After that, the clothes are taken to wash in solvent (perchloroethylene) in a front-loaded washing machine.
The clothes are dried in a dryer in a similar fashion as we do at home. Post-drying the washed clothes are taken to post spotting, to check for any remaining stains on the clothes. A combination of chemicals, steam and air pressure is used to remove the remaining stains, if any, on the spotting table. Finally, the clothes are ironed and folded and wrapped in the plastic to protect from dirt, and then it is dispatched.
Tetrachloroethylene or perchloroethylene:
This is the main solvent used in dry cleaning. It is not just a chemical but it is a chemical solvent. It is also termed PERC in the laundry industry. This solvent rapidly evaporates into the air, has a strong, sweet smell, and is also used in a variety of applications like stripping paint, printing ink, automotive cleaners, etc.
The chemical composition of this solvent is a combination of two elements of carbon and four elements of chlorine. It is colorless, non-flammable and toxic in nature. This product is heavily used by industrial companies.
Let us see some more chemicals used in dry cleaning:
This chemical is more environmentally friendly and sometimes more effective than PERC. One of the chemicals in this family is dipropylene glycol tertiary butyl ether may become a substitute or replacement for PERC. It has a higher flash point and level of solvency better than PERC and other glycol solvents that are commercially used in laundry including dry cleaning.
They require a longer cleaning cycle as they are less aggressive than PERC. They are combustible but do not really represent a high degree of fire or explosion risk under normal and proper use. An example of this type of solvent is Exxon Mobil’s DF-2000 and Ecosolv, produced by Chevron Phillips.
This type of chemical is gentler for clothes than PERC. This is more environmentally friendly and does not cause any color loss. It is comparably more expensive. This chemical solvent is not used often in the dry cleaning process. It is also called decamethylcyclopentasiloxane or D5.
Liquid Carbon Dioxide:
Consumer report magazine has declared the use of this solvent as better than the conventional method (PERC). However, the dry cleaning and laundry industry has described it as having a low cleaning ability.
With the turn of the century or mid of the last decade, a liquid system of detergents was introduced. The system has advantages over powder detergents in terms of solubility, time of dosage adjusted and executed with precision and addition of chemicals precise and exact.
Hence, the high-end laundries are switching over to the liquid system.
Additions and precautions are necessary for a liquid system of detergents to succeed:
a. Machinery must be compatible with liquid dosing so that both systems that is machine programmer and liquid dosing of the system can be adjusted together for exact chemical addition at the correct time.
b. Pumps and tubes must be maintained.
c. Containers for liquid chemicals must be checked for levels.
d. Alarms for low level/no or less pumping.
Ozone has been studied for wet cleaning with good results. However, it needs to be constantly monitored, concentrations in the atmosphere due to some minute leakage checked and all parts of machines to be compatible with it.
Trials with ozone have been successful with very good results in hospital laundry. Ozone wash should and will be extremely useful for the healthcare industry, for disinfecting, even sterilizing linen and uniforms, and also linen even from OT.
Extensive trials need to be taken in health-care Laundry, Though!