Laundry detergent

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The two forms of laundry detergent: powder and liquid

Liquid laundry detergents in a Chinese supermarket, April 2020 Laundry detergents.jpg
Liquid laundry detergents in a Chinese supermarket, April 2020

Laundry detergent is a type of detergent (cleaning agent) used for cleaning dirty laundry (clothes). Laundry detergent is manufactured in powder (washing powder) and liquid form.

Contents

While powdered and liquid detergents hold roughly equal share of the worldwide laundry detergent market in terms of value, powdered detergents are sold twice as much compared to liquids in terms of volume. [1]

History

FEWA, an early laundry detergent from Germany FEWA Feinwaschmittel Logo.svg
FEWA, an early laundry detergent from Germany

From ancient times, chemical additives were used to facilitate the mechanical washing of textile fibers with water. The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in ancient Babylon. [2]

German chemical companies developed an alkyl sulfate surfactant in 1917, in response to shortages of soap ingredients during the Allied Blockade of Germany during World War I. [1] [3] In the 1930s, commercially viable routes to fatty alcohols were developed, and these new materials were converted to their sulfate esters, key ingredients in the commercially important German brand FEWA, produced by BASF, and Dreft, the U.S. brand produced by Procter & Gamble. Such detergents were mainly used in industry until after World War II. By then, new developments and the later conversion of aviation fuel plants to produce tetrapropylene, used in household detergents production, caused a fast growth of domestic use in the late 1940s. [3]

Soils

Washing laundry involves removing mixed soils from fiber surfaces. From a chemical viewpoint, soils can be grouped into:

Soils difficult to remove are pigments and dyes, fats, resins, tar, waxes, and denatured protein. [4]

Components

Laundry detergents may contain builders (50% by weight, approximately), surfactants (15%), bleach (7%), enzymes (2%), soil antideposition agents, foam regulators, corrosion inhibitors, optical brighteners, dye transfer inhibitors, fragrances, dyes, fillers and formulation aids. [4]

Builders

Builders (also called chelating or sequestering agents) are water softeners. Most domestic water supplies contain some dissolved minerals, especially in hard water areas. The metal cations present in these dissolved minerals, particularly calcium and magnesium ions, can react with surfactants to form soap scum which is much less effective for cleaning and can precipitate onto both fabric and washing machine components. Builders remove mineral ions responsible for hard water through precipitation, chelation, or ion exchange. In addition, they help remove soil by dispersion.

The earliest builders were sodium carbonate (washing soda) and sodium silicate (waterglass). In the 1930s phosphates (sodium phosphates) and polyphosphates (sodium hexametaphosphate) were introduced, continuing with the introduction of phosphonates (HEDP, ATMP, EDTMP). While these phosphorus-based agents are generally non-toxic they are now known to cause nutrient pollution, which can have serious environmental consequences. As such they have been banned in many countries, leading to the development of phosphorus-free agents, such as polycarboxylates (EDTA, NTA), citrates (trisodium citrate), silicates (sodium silicate), gluconic acid and polyacrylic acid; or ion exchange agents like zeolites.

Alkali builders may also enhance performance by changing the pH of the wash. Hydrophilic fibers like cotton will naturally have a negative surface charge in water, whereas synthetic fibers are comparatively neutral. The negative charge is further increased by the adsorption of anionic surfactants. With increasing pH, soil and fibers become more negatively charged, resulting in increased mutual repulsion. The optimum pH range for good detergency is 9–10.5. [5] Alkalis may also enhance wash performance via the saponification of fats.

Builder and surfactant work synergistically to achieve soil removal, and the washing effect of the builder may exceed that of the surfactant. With hydrophilic fibers like cotton, wool, polyamide and polyacrylonitrile, sodium triphosphate removes soil more effectively than a surfactant alone. It is expected that when washing hydrophobic fibers like polyesters and polyolefins, the effectiveness of the surfactant surpasses that of the builder, however this is not the case. [6]

Surfactants

Anionic surfactants: branched alkylbenzenesulfonate, linear alkylbenzenesulfonate, and a soap. Detergents.png
Anionic surfactants: branched alkylbenzenesulfonate, linear alkylbenzenesulfonate, and a soap.

Surfactants are responsible for most of the cleaning performance in laundry detergent. They provide this by absorption and emulsification of soil into the water and also by reducing the water's surface tension to improve wetting.

Laundry detergents contain mostly anionic and non-ionic surfactants. Cationic surfactants are normally incompatible with anionic detergents and have poor cleaning efficiency; they are employed only for certain special effects, as fabric softeners, antistatic agents, and biocides. Zwitterionic surfactants are rarely employed in laundry detergents mainly for cost reasons. Most detergents use a combination of various surfactants to balance their performance.

Until the 1950s, soap was the predominant surfactant in laundry detergents. By the end of the 1950s so-called "synthetic detergents" (syndets) like branched alkylbenzene sulfonates had largely replaced soap in developed countries. [7] [8] Due to their poor biodegradability these branched alkylbenzenesulfonates were replaced with linear alkylbenzenesulfonates (LAS) in the mid-1960s. Since the 1980s, alkyl sulfates such as SDS have found increasing application at the expense of LAS.

Since the 1970s, nonionic surfactants like alcohol ethoxylates have acquired a higher share in laundry detergents. In the 1990s, glucamides appeared as co-surfactants, and alkyl polyglycosides have been used in specialty detergents for fine fabrics. [4]

Bleaches

Despite the name, modern laundry bleaches do not include household bleach (sodium hypochlorite). Laundry bleaches are typically stable adducts of hydrogen peroxide, such as sodium perborate and sodium percarbonate; these are inactive as solids but will release hydrogen peroxide upon exposure to water. The main targets of bleaches are oxidisible organic stains, which are usually of vegetable origin (e.g. chlorophyll, anthocyanin dyes, tannins, humic acids, and carotenoid pigments). Hydrogen peroxide is insufficiently active as a bleach at temperature below 60 °C (140 °F), which traditionally made hot washes the norm. The development of bleach activators in the 1970s and 1980s allowed for cooler washing temperatures to be effective. These compounds, such as tetraacetylethylenediamine (TAED), react with hydrogen peroxide to produce peracetic acid, which is an even more effective bleach, particularly at lower temperatures. [4]

Enzymes

The use of enzymes for laundry was introduced in 1913 by Otto Rohm. The first preparation was a pancreatic extract obtained from slaughtered animals, which was unstable against alkali and bleach. Only in the latter part of the century with the availability of thermally robust bacterial enzymes did this technology become mainstream.

Enzymes are required to degrade stubborn stains composed of proteins (e.g., milk, cocoa, blood, egg yolk, grass), fats (e.g., chocolate, fats, oils), starch (e.g., flour and potato stains), and cellulose (damaged cotton fibrils, vegetable and fruit stains). Each type of stain requires a different type of enzyme: proteases (savinase) for proteins, lipases for greases, α-amylases for carbohydrates, and cellulases for cellulose.

Other ingredients

Many other ingredients are added depending on the expected circumstances of use. Such additives modify the foaming properties of the product by either stabilizing or counteracting foam. Other ingredients increase or decrease the viscosity of the solution, or solubilize other ingredients. Corrosion inhibitors counteract damage to washing equipment. Dye transfer inhibitors prevent dyes from one article from coloring other items, these are generally polar water-soluble polymers such as polyvinylpyrrolidone, to which the dyes preferentially bind. Antiredeposition agents such as carboxymethyl cellulose are used to prevent fine soil particles from reattaching to the product being cleaned. [4] Commercial or industrial laundries may make use of a laundry sour during the final rinse cycle to neutralise any remaining alkali surfactants and remove acid-sensitive stains.

A number of ingredients affect aesthetic properties of the item to be cleaned or the detergent itself before or during use. These agents include optical brighteners, fabric softeners, and colorants. A variety of perfumes are also components of modern detergents, provided that they are compatible with the other components and do not affect the color of the cleaned item. The perfumes are typically a mixture of many compounds, common classes include terpene alcohols (citronellol, geraniol, linalool, nerol) and their esters (linalyl acetate), aromatic aldehydes (helional, hexyl cinnamaldehyde, lilial) and synthetic musks (galaxolide).

Market

Worldwide, while liquid and powdered detergents hold roughly equal market share in terms of value, powdered laundry detergent is more widely used. In 2018, sales of powdered detergent measured 14 million metric tons, double that of liquids. While liquid detergent is widely used in many Western countries, powdered detergent is popular in Africa, India, China, Latin America, and other emerging markets. Powders also hold significant market share in eastern Europe and in some western European countries due to their advantage over liquids in whitening clothes. According to Desmet Ballestra, designer and builder of chemical plants and detergent-making equipment, powdered detergents have a 30–35% market share in western Europe. According to Lubrizol, the powdered detergent market is growing by 2 percent annually. [1]

Environmental concerns

Phosphates in detergent became an environmental concern in the 1950s and the subject of bans in later years. [9] Phosphates make laundry cleaner but also cause eutrophication, particularly with poor wastewater treatment. [10]

A 2013 academic study of fragranced laundry products found "more than 25 VOCs emitted from dryer vents, with the highest concentrations of acetaldehyde, acetone, and ethanol. Seven of these VOCs are classified as hazardous air pollutants (HAPs) and two as carcinogenic HAPs (acetaldehyde and benzene)". [11]

The EEC Directive 73/404/EEC stipulates an average biodegradability of at least 90% for all types of surfactants used in detergents. The phosphate content of detergents is regulated in many countries, e.g., Austria, Germany, Italy, the Netherlands, Norway, Sweden, Switzerland, United States, Canada, and Japan.

See also

Related Research Articles

<span class="mw-page-title-main">Detergent</span> Surfactants with cleansing properties

A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more soluble in hard water, because the polar sulfonate is less likely than the polar carboxylate to bind to calcium and other ions found in hard water.

<span class="mw-page-title-main">Surfactant</span> Substance that lowers the surface tension between a liquid and another material

Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word "surfactant" is a blend of surface-active agent, coined c. 1950. As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt.

<span class="mw-page-title-main">Trisodium phosphate</span> Chemical compound

Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution. TSP is used as a cleaning agent, builder, lubricant, food additive, stain remover, and degreaser.

<span class="mw-page-title-main">Persil</span> German brand of laundry detergent

Persil is a German brand of laundry detergent manufactured and marketed by Henkel around the world except in the United Kingdom, Ireland, France, Latin America, China, Australia and New Zealand, where it is manufactured and marketed by Unilever. Persil was introduced in 1907 by Henkel. It was the first commercially available laundry detergent that combined bleach with the detergent. The name was derived from two of its original ingredients, sodium perborate and sodium silicate.

A fabric softener or fabric conditioner is a conditioner that is applied to laundry after it has been washed in a washing machine. A similar, more dilute preparation meant to be applied to dry fabric is known as a wrinkle releaser.

Sodium perborate is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na+]2[B2O4(OH)4]2−. Its name is sometimes abbreviated as PBS.

<span class="mw-page-title-main">Tetraacetylethylenediamine</span> Chemical compound

Tetraacetylethylenediamine, commonly abbreviated as TAED, is an organic compound with the formula (CH3C(O))2NCH2CH2N(C(O)CH3)2. This white solid is commonly used as a bleach activator in laundry detergents and for paper pulp. It is produced by acetylation of ethylenediamine.

<span class="mw-page-title-main">Dishwashing liquid</span> Detergent used for cleaning dishes

Dishwashing liquid, also known as dishwashing soap, dish detergent, and dish soap is a detergent used to assist in dishwashing. It is usually a highly-foaming mixture of surfactants with low skin irritation, and is primarily used for hand washing of glasses, plates, cutlery, and cooking utensils in a sink or bowl. In addition to its primary use, dishwashing liquid also has various informal applications, such as for creating bubbles, clothes washing and cleaning oil-affected birds.

<span class="mw-page-title-main">Bleach</span> Chemicals used to whiten or disinfect

Bleach is the generic name for any chemical product that is used industrially or domestically to remove colour (whitening) from fabric or fiber or to disinfect after cleaning. It often refers specifically to a dilute solution of sodium hypochlorite, also called "liquid bleach".

<span class="mw-page-title-main">Cleaning agent</span> Substance used to remove dirt or other contaminants

Cleaning agents or hard-surface cleaners are substances used to remove dirt, including dust, stains, foul odors, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing offensive odor, and avoiding the spread of dirt and contaminants to oneself and others. Some cleaning agents can kill bacteria and clean at the same time. Others, called degreasers, contain organic solvents to help dissolve oils and fats.

Stain removal is the process of removing a mark or spot left by one substance on a specific surface like a fabric. A solvent or detergent is generally used to conduct stain removal and many of these are available over the counter.

A soap substitute is a natural or synthetic cleaning product used in place of soap or other detergents, typically to reduce environmental impact or health harms or provide other benefits.

Wet Processing Engineering is one of the major streams in Textile Engineering or Textile manufacturing which refers to the engineering of textile chemical processes and associated applied science. The other three streams in textile engineering are yarn engineering, fabric engineering, and apparel engineering. The processes of this stream are involved or carried out in an aqueous stage. Hence, it is called a wet process which usually covers pre-treatment, dyeing, printing, and finishing.

Wastewater comes out of the laundry process with additional energy (heat), lint, soil, dyes, finishing agents, and other chemicals from detergents. Some laundry wastewater goes directly into the environment, due to the flaws of water infrastructure. The majority goes to sewage treatment plants before flowing into the environment. Some chemicals remain in the water after treatment, which may contaminate the water system. Some have argued they can be toxic to wildlife, or can lead to eutrophication.

<span class="mw-page-title-main">Bleach activator</span>

Bleach activators are compounds that allow a lower washing temperature than would be required otherwise to achieve the full activity of bleaching agents in the wash liquor. Bleaching agents, usually peroxides, are usually sufficiently active only at 60 °C and up. With bleach activators, this activity can be achieved at lower temperatures. Bleach activators are included in some laundry detergent powders, some laundry additive powders, and a few laundry additive pods. They are not included in any liquid laundry detergents. Bleach activators react with hydrogen peroxide in aqueous solution to form peroxy acids. Peroxy acids are more active bleaches than hydrogen peroxide at lower temperatures (<60 °C), but are too unstable to be stored in their active form, and hence must be generated in situ.

<span class="mw-page-title-main">Dishwasher detergent</span> Type of detergent specifically used to wash dishes in a dishwasher

Dishwasher detergent is a detergent made for washing dishes in a dishwasher. Dishwasher detergent is different from dishwashing liquid made to wash dishes by hand.

Phosphates in detergent refers to the use of phosphates as an ingredient in a detergent product. The advantage of using phosphates in a consumer laundry detergent or dishwashing detergent is that they make detergents more efficient by chelating calcium and magnesium ions. The disadvantage of using phosphates is that they remain in wastewater and eventually make their way to a natural body of water. While phosphates are low toxicity, they instead cause nutrient pollution and feed the algae. This leads to eutrophication and harmful algal bloom.

<span class="mw-page-title-main">Detergent enzymes</span> Biological enzymes that are used as laundry detergents

Detergent enzymes are biological enzymes that are used with detergents. They catalyze the reaction between stains and the water solution, thus aiding stain removal and improving efficiency. Laundry detergent enzymes are the largest application of industrial enzymes.

<span class="mw-page-title-main">Fabric treatment</span>

Fabric treatments are processes that make fabric softer, or water resistant, or enhance dye penetration after they are woven. Fabric treatments get applied when the textile itself cannot add other properties. Treatments include, scrim, foam lamination, fabric protector or stain repellent, anti microbial and flame retardant.

References

  1. 1 2 3 McCoy, Michael (27 January 2019). "Almost extinct in the US, powdered laundry detergents thrive elsewhere in the world". Chemical & Engineering News. American Chemical Society. Archived from the original on 13 December 2019. Retrieved 13 December 2019.
  2. ↑ Willcox, Michael (2000). "Soap". In Hilda Butler (ed.). Poucher's Perfumes, Cosmetics and Soaps (10th ed.). Dordrecht: Kluwer Academic Publishers. p. 453. ISBN   978-0-7514-0479-1. Archived from the original on 20 August 2016. The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BCE in ancient Babylon.
  3. 1 2 Spriggs, John (July 1975), An economical of the development of substitutes with some illustrative examples and implications for the beef industry (PDF), Staff paper series, University of Minnesota, pp. 34–37, retrieved 9 May 2008
  4. 1 2 3 4 5 Eduard Smulders; et al. (2007), "Laundry Detergents", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, pp. 1–184, doi:10.1002/14356007.a08_315.pub2, ISBN   978-3527306732
  5. ↑ Yangxin Yu; Jin Zhao; Andrew E. Bayly (2008), "Development of Surfactants and Builders in Detergent Formulations", Chinese Journal of Chemical Engineering, 16 (4): 517–527, doi:10.1016/S1004-9541(08)60115-9
  6. ↑ Rubingh, D. (23 October 1990). Cationic Surfactants: Physical Chemistry. CRC Press. p. 475. ISBN   978-0-8247-8357-0.
  7. ↑ SNELL, FOSTER DEE (January 1959). "Syndets and Soaps". Industrial & Engineering Chemistry. 51 (1): 42A–46A. doi:10.1021/i650589a727.
  8. ↑ Dee, Foster; Snell, Cornelia T. (August 1958). "50th ANNIVERSARY FEATURE—Fifty Years of Detergent Progress". Industrial & Engineering Chemistry. 50 (8): 48A–51A. doi:10.1021/ie50584a005.
  9. ↑ Knud-Hansen, Chris (February 1994). "HISTORICAL PERSPECTIVE OF THE PHOSPHATE DETERGENT CONFLICT". www.colorado.edu. CONFLICT RESEARCH CONSORTIUM. Archived from the original on 28 May 2010. Retrieved 21 March 2017.
  10. ↑ Kogawa, Ana Carolina; Cernic, Beatriz Gamberini; do Couto, Leandro Giovanni Domingos; Salgado, Hérida Regina Nunes (February 2017). "Synthetic detergents: 100 years of history". Saudi Pharmaceutical Journal. 25 (6): 934–938. doi:10.1016/j.jsps.2017.02.006. PMC   5605839 . PMID   28951681.
  11. ↑ Anne C. Steinemann, "Chemical Emissions from Residential Dryer Vents During Use of Fragranced Laundry Products", Air Quality, Atmosphere and Health, March 2013, Vol. 6, Issue 1, pp. 151–156.
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