Glycerin purification by MEGA electrodialysis

What is glycerin used for

Glycerol has a wide range of applications. It is mainly used in the food, cosmetic and pharmaceutical industries. It is suitable as a sweetener for diabetics and as a substitute for sugar in food (it is 60 % sweeter than sucrose and does not feed the bacteria that form plaque and cause dental cavities). It is also used in meat and cheese production for surface treatment, as a solvent in alcoholic and non-alcoholic beverages, confectionery, bakery, and sausage products. As a food additive, glycerol is designated E422.

In the cosmetics industry as in a diluted state, it is used to treat the skin in cosmetic products, especially as an ingredient in moisturizing creams and soaps, or as a humectant in toothpastes.

Glycerol is used in medical, pharmaceutical, and personal care products, often as a smoothness enhancer, lubricant, and moisturiser. Glycerin is mildly antimicrobial and antiviral. As a result, it is widely used in wound care products, including glycerin-based hydrogel sheets for treating burns and other wounds.

It is also used in the manufacture of plastics, resin mixtures, detergents, lubricants, and adhesives. In combination with ethylene glycol, it is a component of antifreeze refrigerants.

Why purify glycerol

High purity glycerol has a wide range of applications in various industries such as pharmaceutical, cosmetics, and food production. The crude glycerin produced from biodiesel contains 20 to 30 % of impurities from oils, fats and substances added during glycerol production. For further use, it is necessary to achieve a concentration of 95,5 to 99 % by purification.

The impurities in crude glycerol create a significant challenge to convert it into a value-added product and it is, therefore, important to purify it.

Crude glycerin from biodiesel production can be purified by membrane processes followed by distillation, with adequate pretreatment.

Benefits of using MEGA electrodialysis to purify glycerine

In order to provide a more cost-effective and flexible process for purifying crude glycerin from biodiesel production, MEGA and its subsidiary MemBrain developed new highly efficient electrodialysis applications to remove impurities from this biodiesel by-product.

The main benefits are:

• proven technology for glycerol desalination,
• recovery more than 99 %,
• fair purchasing cost,
• lower energy costs,
• adjustable recovery ratio,
• low maintenance costs,
• automatic operation,
• no large quantities of a hazardous by-product with the need of specialized liquidation.

Applications of glycerine purified by MEGA electrodialysis

MEGA electrodialysis technology is necessary for the following producers, who use glycerin for further products:

• cosmetics producers,
• oral care products manufacturers,
• food producers,
• tobacco processing plants,
• pharmaceuticals and drugs producers,
• other application with specific glycerine purity demand.

Electrodialysis in the glycerin purification process

Electrodialysis is an electrochemical separation process in which ions from the treated liquid are transferred through ion-exchange membranes from one solution (feed/diluate) to another solution (brine/concentrate) under the influence of DC voltage. Charged components are attracted to the cathode or anode and collected in the concentrate stream. Product - organic non-ionic compounds - are retained in a diluate stream.

Salts such as inorganic salts, weak organic acids, and inorganic acids are transported from diluate to concentrate. Glycerol is retained in diluate loop (high recovery).

Thus, the undesirable by-products of chemical pretreatment can be easily removed.