Detergency soil types

Solid Soil Type and Size. Different soHd soils differ greatly in ease of removal and redeposition behavior. These differences can be traced to particle size and soil—substrate bonding. The effect of particle size variation on detergency has been studied with soil removal and redeposition techniques. 

The I I cleaning procedures as a whole, compared with household laundering, are characterized by huge variations in the composition of the soils, types of surface to which they adhere, cleaning time available, etc. The optimum choice of enzyme type and dosage level normally has to be established through a cooperation between the customer (end user), manufacturer of the detergent, and enzyme producer. 

Figure 2 shows isodets at high temperature, high hardness, and high concentration giving a different optimum than at the lower conditions of Figure 1. Foam and detergency profiles on different soil types with different wash temperatures can be found in the literature(4-10).

Several methods have been described to evaluate the ability of different shampoos or detergents to clean soil from the hair [11,13,16-24], Most of these methods have been developed to evaluate the removal of lipid soil from the hair [13,16,18,19]. Some of these methods are soil-specihc [18] or are more sensitive with specihc soil types [13,21], whereas others work for most soils [20]. 

All the enzymes considered so far aim at solubilizing the soils by degrading their main constituents. Cellulase, the last detergent enzyme type introduced on the market, plays quite differently and delivers other diverse benefits fabric softening, color brightening, antipilling, soil-release properties, and antiredeposition [31]. These benefits are the result of the removal of microfibrils from the surfaces of cotton fibers [5]. The efifects are cumulative and increase considerably with the number of wash cycles performed [2]. 

Any correlation between the detergent power of a surfactant and its chemical structure will be complicated by the existence of a wide variety of soil types that may have vastly different interactions with a given surfactant type. It is important, therefore, to specify the exact nature of the system when trying to make any general statements concerning such correlations. 

One-step clean-and-shine products have become popular in the household market. These products are appHed to the floor with a sponge mop and their detergent action removes and suspends soil, which coUects on the mop and is removed when the mop is rinsed with water. The formulation, which remains on the floor, dries to a poHsh film. An earlier product of this type was dispensed from an aerosol as a foam. Formulas as of this writing (ca 1995) are appHed as Hquids (29,30). In one product, the dried film obtained from the formulation is soluble in the formulation, which includes low molecular weight, high acid polymers and a fairly large amount of ammonia (31). Repeated use does not contribute to a buildup of poHsh. 

Although it is impossible to Hst all the practical detersive systems that might be encountered, a large proportion fall in a small number of classes. This classification disregards surfactant stmcture and type of substrate (fibrous or hard surface) and is restricted to a consideration of the soil present on the substrate, the mechanical action employed, the bath ratio, and the detergent used. Some of the more commonly encountered detersive systems are classified on this basis in Table 1. 

Alkaline cleaners are available which allow the separation of excess oily soil from the cleaner. These formulations involve the use of surfactants that are good detergents but poor emulsifiers. Agitation of the bath during the work shift causes a temporary emulsification, which keeps the soil in suspension. After a prolonged period of inactivity (usually overnight), the oily soils float to the surface where they are skimmed off. This method is quite effective with mineral oil-type soils but is less so with fatty oils. 

Surfactants. By definition every detergent product contains one or more types of surfactants. Basically, every surfactant is an organic compound consisting of two parts (I) a hydrophobic portion, normally including a long hydrocarbon chain, and (2) a hydrophilic portion, which renders the entire compound sufficiently soluble or dispersible in water or other polar solvent to serve its intended use. Together, these combined hydrophobic and hydrophilic moieties render the compound surface-active—able to concentrate at the interface between a surfactant solution and another phase, such as air. soil, and textile substrate to be cleaned. 

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