Crystal Clear
September 20, 2009
The sparkling clarity of a diamond, the smoothness of a rich chocolate bar, the creamy texture of ice cream, and the speed at which an acetaminophen pain reliever dissolves in the body all depends on crystal size and shape distribution (CSD). Dr. Priscilla Hill, an associate chemical engineering (ChE) professor, is conducting research that studies the shape and size of crystals. Hill chose the research specialty of particle technology and crystallization because how and why crystals break into certain sizes and shapes isn’t thoroughly understood by scientific experts.
“It’s important because when consuming a solid drug, there are crystals in the tablet. How fast that dissolves and gets in the bloodstream depends a lot on the crystal size,” explained Hill. “This is something that pharmaceutical companies and the Federal Drug Administration monitor closely when making medicines. If the shape and size of the crystals are not correct, a person could overdose or not get enough of the medicine.”
Hill’s two research assistants are using crystallization, cooling a chemical until a desired chemical solidifies, as a purification technique to form crystals in the lab. They then study how crystals break into different shapes and sizes by examining the process in a special stirred-tank.
“Crystal shape affects the flow-ability of foods and consumer products. How well ingredients pour in a manufacturing type environment affects that company’s profitability. If they break into an undesirable shape it not only affects the quality of the product, but it can cause plant operating problems, such as clogging pipes and filters,” offered Sheena Reeves, a graduate ChE student.
To date Reeves and ChE undergraduate student Stephen Castellane have examined the crystallization and breakage of sodium chloride, used in food products; ammonium sulfate, used in fertilizer; pentaerythritol, used in coatings and plastics; and acetaminophen, used in pain relievers. In addition, Reeves has studied using crystallization to purify linolenic acid, an Omega 3 fatty acid used in vitamin additives.
“Crystal size has a significant effect on ignitability,” said Castellane. “Experts believe the huge sugar refinery fire and explosion in Georgia happened because the small crystal size made sugar easier to ignite and explode.”
As a result of Hill’s research, scientists and industry experts will have a crystal-clear technique for producing consistent crystal sizes and shapes that influence the effectiveness, safety and quality of a variety of products consumers depend on every day.
For more information about the research being conducted at the Swalm School of Chemical Engineering at Mississippi State, contact department head Dr. Mark White.