ECBC’s Chemical Biological Radiological (CBR) Filtration Branch developed a material based on zirconium hydroxide as a filtration adsorbent that was also discovered to react with and neutralize chemical agent molecules.

“This discovery led to collaboration with the Decontamination Sciences Branch where we optimized the surface chemistry of the material for a broad range of agents,” said Greg Peterson of the CBR Filtration Branch. Working with Defense Threat Reduction Agency’s Joint Science and Technology Office, the research team developed a new concept of operations for decontamination. In order to be able to apply it to combat vehicles, the Decontamination Sciences Branch researchers had to develop the decontamination solution to be sprayable and able to stick to both horizontal and vertical vehicle surfaces.

“One of the challenges of the formulation effort was to find a suitable carrier liquid to deliver the zirconium hydroxide material; a carrier that would be readily available in the field,” said Matt Shue, branch chief of ECBC’s Decontamination Sciences Branch. “That led us to options including water and kerosene in the form of JP8 aviation fuel. These are better options than other low flashpoint solvents that would be extremely flammable.”

The next step was to find just the right combination of components including kerosene and water combined with the zirconium hydroxide. The team had to maximize its effectiveness on a number of different military vehicle surfaces, and also to maximize the types of chemical agents it could effectively decontaminate.

Software Saves Time, Cuts Costs

Using the traditional method of painstakingly trying every possible combination of kerosene and water plus two variations of the zirconium hydroxide, the team would have had to evaluate at least 5,100 separate samples. This would take many months and cost more money than the research effort could support. The solution they came up with was to use a state-of-the art experimental design software program that builds a customized, highly efficient experimental design. Using it for their research, the team found that as few as 300 samples could generate the information required to get the answers they needed.

“The software package we used is called JMP® 12 by the SAS Institute,” said Jay Davies, an ECBC research physicist and member of the research team. “It has been used very successfully by semiconductor manufacturers to optimize their chips, engineering firms to improve their industrial processes, and pharmaceutical companies to perform clinical trials more efficiently.”

When faced with their complex experimental scenario, developing a decontaminant formulation for use with multiple chemical agents on multiple surfaces, Davies’ applied the software’s advanced, proprietorial algorithm. The algorithm alters the experimental design to fit the problem rather than forcing the researcher to alter the problem to fit an “off-the-shelf” design. This enables the researchers to maximize the information obtained from a much smaller number of experimental samples.

“The custom experimental design is highly efficient because it is really a series of experiments compressed together into a super compact form where each sample is simultaneously providing information to answer many research questions in contrast to the traditional method where each sample can only provide information for a single research question,” said Davies.

“For example, it includes experiments to measure the effectiveness of the zirconium hydroxide, kerosene, and water mixture at first a high amount of water then a low amount of water, then the same thing is repeated for kerosene,” said Davies. “When we inputted the results into the software for analysis, it generated a statistical prediction curve going from the lowest amount of water we tried to the highest amount of water. It did the same for kerosene, so the software, in effect, filled in everything in the middle for both water and kerosene showing us how effectively the mixture would decontaminate chemical agent at every point along the curve.”

That substituted for a long, painstaking series of experiments in which the team members would have to first gradually increase the amount of water, then kerosene to see how well each gradation of change worked as a decontaminant.

Dizzying Combinations of Variables

Arriving at an efficient experimental design was essential to the research team. Not only would they have had to test each of these gradations of both water and kerosene, but they would have had to do the entire experimental series with two types of decontamination powder, type-B powder and type-C powder.

Another complication is that they needed to see how the decontamination formulations work against each of three types of chemical agents they were concerned with; VX nerve agent, soman, and mustard agent. Additionally, the team wanted to determine which one of these many possible formulations would best work on all three chemical agents. Then there was the additional experimental variables of the amount of time each of the three types of agents sat on each of four types of vehicle surfaces, whether the exposed surface was oriented vertically or horizontally, and the amount of time each of the decontamination formulations was applied to the contaminated part of the surface.

The number of combinations to be tested quickly becomes dizzying. But it doesn’t stop there. The researchers had to account for the interaction effects of all these possible combinations of water and kerosene in type-B and type-C powder. At certain ratios, the water-kerosene combination could actually interfere with each other in either type-B or type-C powder, or both, reducing its effectiveness as a decontaminant.

“In the end, the software enabled us to perform a workable experimental design that would find the best formulation of water, kerosene and the variant of decon powder, B or C, for each one of the three chemical agents we tested, plus the best formulation for a three-in-one agent decontamination solution,” said Joseph Myers, an ECBC chemist and member of the research team. “And, we got to this result with only a small fraction of the effort that would have been required without this software.”

As the decontamination formula makes its way through the acquisition process, the team of ECBC researchers will study the effect of adding green, black, or tan pigments to change the color of the decontaminant to maintain the vehicles’ camouflage. The goal, said Shue, “is to continue maturing this technology and continuously increase its value to Soldiers”.