Hand dishwashing detergent is a cleaning agent, used to wash dishes, cutlery and glasses which can then be reused. When used again, dishes are therefore brilliantly clean. The most important ingredients in dishwashing detergents enabling easy washing are surfactants, which can be ionic, non-ionic and amphoteric. Their function is to reduce the surface tension of water, which increases wettability of the dirt and improves the cleaning effect. This ability is due to the polar and non-polar parts of the molecule. Water is a polar molecule, while dirt, which is difficult to remove, is mostly fat, a non-polar molecule. In principle, fat and water do not mix. With its polar and non-polar part, the surfactant allows water and fat to mix.
In our study, we examined SLES (sodium lauryl ether sulfate), which is one of commonly used surfactants in detergents. An interesting property of SLES is that, when adding sodium chloride, it can be used to regulate the viscosity of detergent.
In the experimental part of the presented thesis, the results showed that viscosity increases with the addition of salt, while at some point it reaches its maximum. If the salt concentration continues to increase, viscosity starts to decrease, and at higher concentrations of salt it reaches very low values, which is not desirable in case of detergents. Higher viscosity ensures greater stability of hand dishwashing detergents, which consequently results in a better cleaning effect and lower detergent consumption.
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