Green synthesis of surfactants for removing grude-oil films off water surface

Abstract

As traditional sources of raw materials and energy like petroleum, coal, gas, etc. are gradually depleted, more and more attention is attracted by alternative and renewable ones to which, among the firsts, natural lipids of vegetable and animal origin belong. As is known, natural oils and fats mainly consist of triglycerides of higher monocarboxylic acids. These triglycerides being ecologically clean esters by nature are very convenient initial products for carrying out “green” syntheses. Taking the above-mentioned into consideration investigations have been performed in order to synthesize novel nonionic surfactants by direct interaction of triglycerides of olive, corn, sunflower, flax-seed, soybean and other vegetable oils as well as of beef, mutton, goat, pork fats, cod-liver and seal oils with such ethanolamines as mono-, di- and triethanolamine (TEA). The resulting products being respectively monoethylolamides, diethylolamides and triethanolamine esters, according to stalagmometric measurements, exhibit efficient surfactant properties greatly reducing surface tension at the kerosene-water interface from 46.0–46.5 down to 1–2 mN/m under room conditions. These surfactants have an applied importance as they have a capability to remove thin crude oil films off the water surface, water having a very wide range of mineralization (distilled, fresh, sea and stratal waters). In soft waters under the action of these surfactants thin crude-oil films are mainly transformed into a spot, i.e. they behave as crude oil collectors. In hard waters the mentioned surfactants usually disperse ecologically dangerous crude-oil films eliminating their hazard to marine inhabitants since such films disordering gas (for example, oxygen and carbon dioxide) and energy (mainly of sunlight origin) exchange at the water-air interface disturb an ecological balance. They also demonstrate high inhibitor properties against corrosion of steel. Phosphate- and ethanolaminophosphate derivatives of the mentioned mono- and diethylolamides as well as TEA esters of natural higher monocarboxylic acids fractions have also been synthesized which pertain to efficient anionic surfactants. According to laboratory tests, they also possess strong capabilities to collect or disperse thin crude-oil films from the surface of water having various degrees of mineral salts contents. The obtained chemicals are of great practical interest, first of all, for the Caspian Sea region which is very rich in crude oil reserves.