Gunvor Karlsson

Environmentally benign nonionic surfactant systems for use in highly alkaline media

The increasing use of surfactants has put more and more emphasis on environmental requirements for the chemicals used. It is also important to follow the whole lifetime of the products and to offer possibilities for efficient wastewater treatment. Good cleaning of oily soil from hard surfaces and efficient separation of the oily soil from the wastewater within the same surfactant system is a challenge. In this article a system is described which, by using the specific cloud-point profile that can be achieved when mixing alkyl ethoxylates with alkyl glucosides, offers a possibility to meet that challenge. Alkyl ethoxylates are known to be good wetting agents, emulsifiers and cleaning agents. They are, however, usually not soluble in concentrated electrolytes and/or alkali, which may be needed in the practical use with different water qualities, etc. The more recently developed nonionic surfactant named alkyl glucoside, which has a polyhydroxyl functionality as its hydrophilic part arising from natural sources such as carbohydrates, offers better solubility as well as strong surface activity. When combining these two categories of surfactants good solubility in, for instance, alkali, is achieved and a special concentration-dependent cloud-point curve results. This phenomenon can be used both to fine-tune the cleaning and wetting efficiency and to stimulate the separation of the emulsified oil from the wastewater.