It used to be, biodiesel producers were not that concerned about the quality of the glycerin they produced. But these days the by-product of the biodiesel process is getting more attention in the quality level and where it will be marketed. This article from Biodiesel Magazine outlines some of the aspects of glycerin quality and offers three examples of how the Next Generation Scientists for Biodiesel scientists are producing glycerin.
There are many grades of glycerin beyond crude, including technical- and pharmaceutical-grade (USP). USP Glycerin is 99 percent minimum with very tight limits on a multitude of potential contaminants, [Darol Brown, president of Portland, Ore.-based Sego International Inc.] says, and each shipment of USP requires a certificate of analysis. The applications for USP glycerin are endless. It’s used in an almost unlimited number of products. USP-grade glycerin is found in pharmaceuticals, food materials, nutraceuticals, cosmetics and personal care items. Some are less known applications, such as its use on raisins to keep them chewy, or as a cleanser for dairy cow udders to ward off infection.
There really is no set specification for crude glycerin, Brown says. “But each potential buyer has his own limits,” he explains. “Crude sellers must supply a lab test showing the assay of glycerin, the amount of methanol, ash, salts, and water and, in some cases, the amount of fatty acids. In general, unless you have changed the raw materials used, the plant will produce a consistent product and, if you know the producer, you can have some surety that the product will not vary, although most still require the test results to come with the shipment.” Some of the more common applications for crude glycerin include propylene glycol (anti-freeze), dust control and use an animal feed ingredient. “Crude glycerin is a cheap source of carbon and can be used in place of corn, grains or molasses in cattle feed, but it’s the lowest price and gives the least return to the producer,” Brown says. “Dust control is a major user of crude glycerin, but it is formulated with many other additives and is a rather cheap net back to the producer of the glycerin.” Brown says other applications are somewhat small and dependent on low-cost product.
The article goes on to look at the research Karthik Gopalakrishnan from Clemson University, Derek Pickett at the University of Kansas, and Michael Morgan from Utah State University are doing on glycerin.