Stirred from within: Micromotors mix for more effective oxidative degradation of chemical weapons

Oct 31, 2013
Stirred from within: Micromotors mix for more effective oxidative degradation of chemical weapons

(Phys.org) —Rapidly and efficiently converting chemical weapons into nontoxic products in remote areas is one of the most difficult tasks in the disposal of weapons of mass destruction. In the journal Angewandte Chemie, a team from the University of California, San Diego has now described how self-propelled micromotors can accelerate the oxidative neutralization of nerve agents by intensively mixing the remediation solution.

Environmentally friendly processes that use hydrogen peroxide and an activator (e.g. sodium bicarbonate) to degrade like sarin, VX, soman, and mustard gas have recently replaced earlier chlorine-based methods. However, they generally require high concentrations of peroxide, long reaction times, and intensive mechanical mixing—which can be extremely problematic in the elimination of stocks of chemical weapons in remote regions or enemy camps.

A team headed by Joseph Wang has now developed a novel strategy based on mixing of the remediation solution with self-propelled micromotors. The motors are tiny conical tubes made from a bilayer with a polymer on the outside and platinum on the inside. In this process, hydrogen peroxide acts as both the oxidizing agent for the chemical weapons and fuel for the micromotors. As the is catalytically decomposed on the inner platinum surface, oxygen are formed. The bubbles exit the tubes at their rear (wider) end, pushing them through the liquid. The movement of the motors through the liquid combined with the gas bubbles provides for efficient mixing of the remediation solution. This significantly increases both the turnover and the speed of the decontamination reaction without requiring high concentrations of peroxide.

Wang's team was able to demonstrate the efficiency of their new method by breaking down a variety of organophosphate pesticides with chemical structures similar to those of organophosphate . In a demonstration reaction, 1.5 million micromotors in a volume of about 15 mL achieved mixing comparable to a magnetic stirrer at 200 revolutions per minute.

The concept of mixing through the movement of self-propelled micromotors is not limited to the neutralization of chemical weapons. It could also be used to accelerate chemical reactions in general. This could be useful in applications like microreactors, where mechanical is often difficult.

Explore further: Newly discovered mechanism propels micromotors

More information: Wang, J. Micromotor-Based High-Yielding Fast Oxidative Detoxification of Chemical Threats, Angewandte Chemie International Edition. dx.doi.org/10.1002/anie.201308072

Related Stories

Newly discovered mechanism propels micromotors

Oct 15, 2013

Scientists studying the behavior of platinum particles immersed in hydrogen peroxide may have discovered a new way to propel microscopic machines. The new mechanism is described in The Journal of Chemical Ph ...

Explainer: What are chemical weapons?

May 24, 2013

There was chaos on the streets of Halajba in March 1988. In this corner of Iraq, at the time Iraqi Kurdistan, people had suddenly started experiencing cold-like symptoms – tight chest and nasal congestion. ...

Mapping the chemistry needed for life at Europa

Apr 05, 2013

(Phys.org) —A new paper led by a NASA researcher shows that hydrogen peroxide is abundant across much of the surface of Jupiter's moon Europa. The authors argue that if the peroxide on the surface of Europa ...

Recommended for you

A new approach to creating organic zeolites

Jul 24, 2014

Yushan Yan, Distinguished Professor of Engineering at the University of Delaware, is known worldwide for using nanomaterials to solve problems in energy engineering, environmental sustainability and electronics.

A tree may have the answers to renewable energy

Jul 23, 2014

Through an energy conversion process that mimics that of a tree, a University of Wisconsin-Madison materials scientist is making strides in renewable energy technologies for producing hydrogen.

User comments : 0