Introduction
Glycerine, also called glycerol, is a simple polyol – C3H5(OH)3. With three hydroxyl groups, this trihydric alcohol is highly water-soluble. It’s obtained as a by-product of processes like the saponification of oils and fats (to manufacture soap) and the transesterification reaction (used to producebiodiesel).
Why should you care about this compound? Well, because it’s an incredibly versatile substance with many industrial and commercial applications. It is used in pharmaceutical manufacturing as a solvent and sweetening agent, in cosmetics production as an emollient, humectant and lubricant, in commercial food production as a sweetener, humectant and preservative, and in other industries for the manufacturing of plasticisers and antifreeze.
Perhaps more importantly, using glycerine in diverse industries is a step towards greater sustainability. As a by-product produced in many industrial processes, glycerine could be treated as waste and disposed of, leading to a waste management problem. When it’s redirected towards industries where it is highly valuable, glycerine becomes part of acircular economy. Instead of waste, it becomes a resource. It creates value rather than causing harm to people and the planet.
From a commercial standpoint, glycerine is also vital because it generates additional revenue sources, enhancing the profitability as well as sustainability of your business.
That’s where crude glycerine refining comes in.
Why do we need the crude glycerine refining process?
The crude glycerine refining process turns crude glycerine, derived from transesterification or saponification, into refined glycerine.
Refined glycerine is a purified version of crude glycerine. It meets the quality criteria needed for it to be used as an ingredient in the pharmaceutical, food, cosmetic, and other industries. The crude glycerine refining process lends this essential ingredient a neutral odour and colour, making it more appealing to consumers. It also eliminates the physical and chemical impurities that would negatively impact its performance.
Before we get into the details of the refining process of crude glycerine, let’s examine the quality standards that a crude glycerine refinery must adhere to to ensure the quality and safety of its products.
Quality standards for crude glycerine refining.
In different parts of the world and in different industries, crude glycerine refining must meet different standards. So, depending on the region in which your crude glycerine refinery is located, you will have to research the relevant standards and regulations. You’ll have to do the same for your specific industry, i.e. pharmaceutical manufacturing, food production, etc.
Nonetheless, globally, there are some widely accepted standards that you should be familiar with. Even if not relevant to your area of operations, they offer a blueprint for the gold standard in global crude glycerine refining.
For starters, there is the USP, or the United States Pharmacopoeia; another is the BP or the British Pharmacopoeia. The USP/BP Grade applies to personal care and pharmaceutical products. This grade ensures that refined glycerine is pharma-grade, i.e. it doesn’t contain any contaminants that could harm human health.
If you’re refining crude glycerine for use in the food processing industry, you should be familiar with standards laid down by food regulatory authorities in your region. Typically, this is the FDA or the Food and Drug Administration of your country.
In regions where kosher or halal certifications are mandated for food and pharmaceutical products, your crude glycerine refining operations must conform to the appropriate requirements.
The crude glycerine refining process.
As we’ve discussed at the start of this post, crude glycerine is produced when the triglycerides in oils and/or fats are broken down into glycerine and fatty acids.
Triglycerides + H20 (high-pressure hydrolysis) --> fatty acids + glycerine
Glycerine may also be produced via the transesterification reaction.
Triglycerides + alcohol --> fatty acid alkyl esters + glycerine
The crude glycerine produced in these reactions is then subjected to a refining process to make it suitable for use in other industries.
Step 1: Pretreatment and Filtration. The initial filtration of crude glycerine involves the removal of solid impurities. This can be achieved using a filter press or any other mechanical filtration device. This step sets the stage for the subsequent chemical refining stages, ensuring their effectiveness and efficiency.
Step 2: Neutralisation or acidulation. The neutralisation or acidulation process of crude glycerine refining involves adding hydrochloric acid or sulphuric acid to neutralise the free fatty acids (FFAs) present in it. Pure glycerine gets separated from fatty acids and salts, reducing its acidity and enhancing its stability.
Fatty acids + acid --> glycerine + free fatty acids
Step 3: Vacuum distillation. Arguably the most critical step in the crude glycerine refining process, vacuum distillation involves heating glycerine under reduced pressure. The low pressure reduces the boiling point of glycerine, enabling it to evaporate at a lower temperature. This step separates glycerine from volatile impurities like water and methanol, all while preventing thermal degradation and preserving the glycerine’s functionality and quality. The glycerol-rich fraction is collected for further processing, while the distillate of lower-boiling impurities is removed.
Step 4: Deodorisation. After distillation of the crude glycerine, in the deodorisation step, distilled glycerine is treated with live steam to remove the unpleasant odours. The result? Refined glycerine with a neutral odour, suitable for cosmetic, pharmaceutical and food applications.
Step 5: Bleaching. The final step in glycerine refining is treatment with activated carbon, clay or other bleaching agents to improve the product’s colour as per the market requirement and remove contaminants that negatively impact the glycerine’s appearance and quality.
The market for refined glycerine.
Glycerine production and refining have their own set of challenges. For starters, since the feedstock is an agricultural product, feedstock availability and costs can fluctuate, consequently affecting production costs as well. Maintaining consistent quality, managing wastewater disposal, optimising energy use, and compliance with evolving regulatory requirements also pose challenges.
Despite these challenges, the global demand for refined glycerine has grown significantly in recent years. This is particularly so in the personal care and cosmetics industries. Given that it is an industrial by-product which has been converted into a valuable resource, glycerine production is also important from a sustainability perspective, helping businesses meet their ESG goals.
At Kumar, we have eight decades of experience in oilseeds processing, with our expertise spanning food, feed, fuel, and all the other products that are produced within these value chains. If you’re looking to set up a crude glycerine refinery, reach out to us today.
