Chemistry and Cleanliness
Chemistry plays a crucial role in cleanliness through soaps and detergents that this paper seeks to determine. In inferring this role, the paper considers the chemistry of soap and detergents. The results are that chemical engineering is vital in cleanliness.
Keywords: surfactant, soap, detergent, saponification, micelles
Soap and detergent evaluation and analysis
The process of manufacture of surfactants is highly dependent on whether it is soap or detergent. According to Woollatt (1985), soaps are manufactured from natural products while detergents are synthetic. Soaps are manufactured through a process of saponification of fats and oils to produce glycerine and metal soap. Glycerine is then removed leaving only a portion of it. Removal of glycerine is through the addition of lye, a solution of brine. An electrolytic process is then used resulting into spent lye and crude soap. Afterward, removal of spent dye is done, and the soap is dried and mixed with other additives. These steps outline the batch process of saponification. The process of saponification is as illustrated below;
The active species in soaps and detergents is the surfactant, also referred to as micelles. Surfactant refers to an ionic part comprising of two parts. The first part involves the polar head that is a carboxylate group while the other end is a linear non-polar tail, which is a hydrocarbon group. According to Amrita.olabs.co.in, (2013), the ionic nature of the head makes it water soluble while the tail is insoluble in water. The non-polar end of the soap is oil soluble. In the presence of dirt, the hydrocarbon part dissolves in the oil or grease while the head remains dissolved in water. Several micelles tails dissolve in the oil or dirt and remain attracted to the water causing dispensing of the dirt into the water through lowering of the surface tension of the water (Presto & Preston, 1948). Surface tension lowering allows water to incorporate the oil molecules (dirt) present in the cloth, consequently cleaning it. The figure below indicates the working mechanism of micelles.
Source: amrita.olabs.co.in, (2013)
Soap, detergents and the processes of their production have evolved from craftsperson’s act into a science of chemical engineering. The evolution of soaps, detergents and the processes of making them have changed due to the dynamic nature of the market that has necessitated for high-quality products. Consequently, soaps and detergents have evolved from cleaning products to contain other materials that enhance their properties. For instance, according to Rieger and Rhein (1997), soaps are currently comprising of materials such as moisteners, emollients and emulsifiers that are intended to improve their quality. The inclusion of these materials has necessitated change in the finishing step of soap production.
Moreover, recent saponification processes have been developed to replace the traditional batch process. These processes employ countercurrent washing columns, centrifuge mode of separation in the final step and saponification reactors with in-line jets that are of high energy and are continuous (Rieger & Rhein, 1997). Moreover, recent technologies in soap production have utilized enzymatic action for different water conditions such as properase enzyme for cold water (McCoy, 2000).
Most solvents used in cleaning and the textile industry for similar purposes have been halogenated hydrocarbons and petroleum distillates. The choice of solvent requires an understanding of the chemical nature of the solvent and the solute (Gani et al., 2006). Often the solubility of the dirt is the first consideration that most people make. However, there also exists other crucial chemical factors for consideration in the selection of a suitable solvent. Such factors include the solvent’s penetrative ability into the dirt, surface tension and the textile (Timar-Balazsy & Eastop, 1998). Moreover, it is prudent to consider the solvent retention in the textile.
Surface tension includes various aspects of the chemical nature of the solvent. For instance, Timar-Balazsy and Eastop (1998) argue that it involves the chemical’s polarity and the bonding types. The former property affects the latter and determines the extent of polarization. On the other hand, the degree of polarization of the solvent molecules determines its surface tension. Solvents whose polarity is minimal have a surface tension that is low and can penetrate textile in the absence of surfactants.
Knowledge of the textile chemical nature is also crucial in choosing solvents. Solvents may be polar or less polar (Friedman & Wolf, 1996). Polar solvents cause swelling in hydrophilic textiles. On the other hand, less polar solvents do not cause swelling of the textiles. Solvent retention in the textile results from bond formation. Some solvents form bonds with their solutes. For instance, organic solvents form secondary bonds with cellulose-based fibers.
Chemical bonds is also a crucial factor in solvent selection due to its effects on evaporation rate. The evaporation rate is slower in cases when the solvent forms secondary bonds with textile. Timar-Balazsy and Eastop (1998) argue that the evaporation rate is also affected by other factors such as relative humidity, vaporization pressure, vapor pressure and fiber type. The pH of the solvent is also crucial to consider due to its effects on surfactants effectiveness while cleaning (Tharir, 2012).
The analysis and the evaluation of household cleaners in the removal of common stains can be achieved by considering their use. Per this factor, household cleaners can be grouped as general cleaners, disinfectants, bathroom cleaners, glass cleaners and glass cleaners (Davis et al., 1992). Moreover, spot removers, scouring cleansers, carpet and toilet bowl cleaners are also categories of household cleaners according to product use.
According to Davis et al. (1992), general purpose cleaners are multipurpose and can remove various stains. Bathroom cleaners are specifically for the removal of stains found in showers and tubs. For instance, they are used in removing mildew stain in bathrooms. Glass cleaners remove stains on glasses while scouring cleansers are for removing stains that require application of abrasiveness. Spot removers are used in removing spots except bleachers while carpet cleaners are used for stains that cannot be removed by dry cleaning. Some of these household cleaners have an antimicrobial activity to remove common and bacteria stains.
Stain removal can be through various processes. However, the type of stain remover used depends on the stains being removed (Myers & John Wiley & Sons, 2006). Choice of detergent depends on properties such as size, solubility and polarity of the stain. Various stain removers use different methods to achieve their purposes such as by use of enzymatic action or chemical action. Chemical action involves such as bleaching through the use of oxidizers, use of bases and acids, surfactants or phosphates. Oxidizing agents are used for bleaching through redox reaction that breaks the double bond in chromophores resulting in colourlessness of the textile (American Cleaning Institute, 2015). Acid and base cleaners are used for stains of similar pH value. Phosphates are used for blood stains, which they remove through displacement reactions.
The chemical action limitation of soaps depends on the water type. The effectiveness of soap is dependent on whether the water is hard or soft. Hardness of water lowers the effectiveness of soap in cleaning. On the other hand, the chemical action of detergent cannot be correctly revealed by its composition. Determination of detergency is through the consideration of reflectance.
American Cleaning Institute (2015). Soaps & Detergents: Products & Ingredients. Retrieved on June 19, 2015 from http://www.cleaninginstitute.org/clean_living/soaps__detergents_products__ingredients_3.aspx
amrita.olabs.co.in, (2013). Cleaning Capacity of Soap with Hard and Soft Water. Retrieved 19 June 2015, from amrita.olabs.co.in/?sub=73&brch=3&sim=120&cnt=1
Anonymous. Soaps, Detergents and Cleaning. Retrieved on June 19, 2015 from http://science.csustan.edu/nhuy/chem1002/soapexp.htm
Davis, G. A., Dickey, P., Duxbury, D., Griffith, B., Oakley, B., & Cornell, K. (1992). Household cleaners: environmental evaluation and proposed standards for general purpose household cleaners. Prepared for Green Seal, Inc. Center for Clean Products and Clean Technologies.
Friedman, M., & Wolf, R. (1996). Chemistry of soaps and detergents: various types of commercial products and their ingredients. Clinics in dermatology,14(1), 7-13.
Gani, R., Jiménez-González, C., ten Kate, A., Crafts, P. A., Jones, M., Powell, L., & Cordiner, J. L. (2006). A modern approach to solvent selection.Chemical Engineering, 113(3), 30-43.
McCoy, M. (2000). Soaps and detergents. Chemical & Engineering News, 24, 37-52.
Myers, D., & John Wiley & Sons (Firma comercial). (2006). Surfactant science and technology. Hoboken, New Jersey: J. Wiley.
Presto, W. C., & Preston, W. (1948). Some correlating principles of detergent action. The Journal of Physical Chemistry, 52(1), 84-97.
Rieger, M., & Rhein, L. D. (Eds.). (1997). Surfactants in cosmetics (Vol. 68). CRC Press.
Tharir, M. M. (2012). Soaps and Detergents [Presentation slides]. Retrieved on June 19, 2015 from http://www.slideshare.net/muhammedthahir129/soap-and-detergents-15243636
Tímár-Balázsy, Á., & Eastop, D. (1998). Chemical principles of textile conservation. Routledge.
Woollatt, E. (1985). The manufacture of soaps, other detergents, and glycerine. Ellis Horwood.