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Cleaning oily water

Many processes produce oily water, including marine, oil exploration and drilling and power plants. Water containing oil is usually a combination of free mineral oil, which is relatively easy to separate, and stable emulsions. Stabilized emulsions are often the result of particle pollutants that collect on the surfaces of the oil droplets in the water, or by surface-active molecules that prevent the oil droplets from coalescing. Lucent Oil’s products for cleaning oily water are designed to break up the oil emulsions through destabilization with a combination of coagulation and flocculation of the oil droplets.

The photo below illustrates the result when the two chemical products WC-40A and WC-45F are used on water that is thoroughly contaminated by oil. In the test tube on the right is the cleaned water after the water phase has been decanted from the test tube in the middle.

The products’ mechanisms

Lucent Oil’s products for cleaning oily water are two-component systems and they are active through a broad range of temperatures – from cold to hot water.

WC-40A is a compound of uncharged polymers in an alkaline environment. When it is combined with the oily water, the oil droplets are destabilized because the polluting particles and/or other surface-active substances are loosened from the droplets, and this facilitates the coalescence of the oil droplets.

WC-45F consists of a coagulant (metal salt) that interferes with the repelling forces that exist between droplets of oil. There is also a strong cationic polymer that flocculates the oil droplets in order to speed up the oil separation.

Stearate collector

Metal salts of stearatic acid, including sodium and calcium stearates, are commonly found in so-called dry drawing compounds, which are lubricants for, among other uses, wire and pipe manufacturing. After the rolling process, the residual stearate lubricant is removed by washing with hot water or with hot water containing a surface-active degreasing agent. In order to achieve the best possible results from the washing, and at the same time avoid the need to dispose of large quantities of stearate-contaminated wash water, it is important that the soluble metal stearates be removed from the wash-water baths. Once this is done, the wash water can be re-circulated.

By adding a stearate collector to the stearate-contaminated wash water, the solubility of the metal stearates is reduced, see photo below. As a result, the insoluble stearates coagulate and become easier to separate, either through centrifugal separation or by filtration through paper filters.

Emulsion destabilizer

When water-based degreasers are used for industrial degreasing there occurs an enrichment of the cooling liquids, most often oil emulsions, that have been used with the metal manufacturing. As the level of this enrichment increases in the oil emulsions there is a decrease in the ability to function as a degreasing in the manufacturing process.

Lucent Oil’s emulsion destablizer consists of thermo-sensitive polymers and surface-active contaminates that break-up the oil emulsions that are stabilized by negative, neutral and positive charged emulsifiers. Once freed, the oil can be separated using oil-skimmers, lamella or high-speed separators and then the cleaned degreasing fluids can be re-circulated.

Last Updated on Thursday, 04 November 2010 11:21