Protecting the world from homemade explosives
Researchers from Victoria University have developed an innovative new approach for rapid screening of peroxide-based ‘homemade’ improvised explosive devices (IEDs).
IEDs sow the seeds of death and destruction, and the terrorists and criminals that create them seek to spread fear, destabilise governments and divide society.
IEDs based on explosives such as nitroglycerin, TNT, military Semtex and C4, and fertilizer-derived nitrates are relatively difficult to make at home. The starting ingredients are hard to obtain, and the chemical synthesis isn’t easy to perform. A certain level of training or expertise is needed to work with these materials. However, a new generation of explosives – organic peroxide explosives (OPEs) – have placed the potential for massive destruction into the hands of those with ill intent who previously did not have the access to the materials or chemical expertise needed to create IEDs.
Peroxides are chemicals that contain a peroxy functional group in which two oxygen atoms are linked together by a single covalent bond (-O-O-). Peroxides are good bleaching agents, have wonderful antiseptic and disinfectant properties and are excellent solvents. In fact, you probably have peroxide products in your home in the form of hair dyes, hydrogen peroxide, nail polish remover, cosmetics and toothpaste.
What makes OPEs so dangerous? OPEs contain very unstable peroxy groups that are highly reactive. Easily exploding with heat or friction, their destructive power rivals that of military grade materials. It is surprisingly easy to make a ‘homemade’ OPE bomb. Starting materials can be easily purchased in large amounts in convenience and grocery stores because the ingredients are used in our everyday lives. A person doesn’t need to be a chemist or have specialized training to convert these innocent products into explosive devices.
Several global incidents demonstrate the increasing use of OPE-based IEDs to terrorize people going about their daily lives: football stadiums and theatres (Paris 2015), airports (Brussels 2016), concert venues (Manchester 2017), and churches and hotels (Sri Lanka in 2019 and Indonesia in 2018 and 2021)). While not exhaustive, this list illustrates the invasion of IEDs into the places where we work, relax and worship.
Current screening technologies identify trace amounts of commonly used explosives in the air. However, these devices fail to distinguish OPEs (real positives) from other peroxides (false positives). Unfortunately, fast screening of OPE-based IEDs presents a real challenge for airport and venue security, first responders and military personnel.
Our inability to rapidly and clearly discern harmless from harmful peroxides demands an alternative rapid screening system. The detection device must be portable, fast, and easily used by both soldiers or civilians at airports, transportation hubs, and high-profile events like concerts and sporting occasions.
Dr Chowdhury Kamrul Hasan and Dr Parvez Mahbub of Victoria University’s Institute for Sustainable Industries & Liveable Cities have developed a microfluidic system employing acid hydrolysis or photolysis to ‘break’ down peroxides. OPE degradation pathways differ from that of commonplace hydrogen peroxide. Initial testing shows that their screening system can detect these differences and clearly differentiate OPEs from hydrogen peroxide. With the ability to analyse swabs within 12 seconds, their system provides the critical speed needed in real-life screening situations.
However, it is not enough to demonstrate that the chemistry works. Researchers must prove how it works before their new detection method can be adopted and replace older technology. Drs Hasan and Mahbub teamed up with ANFF-Vic and the Melbourne Centre for Nanofabrication (MCN) to uncover the chemical mechanism for how the system reactions proceed (e.g., identification of chemical intermediates).
With the chemistry firmly established, future work will focus on fabricating a microfluidic prototype and performing a comparative study against the conventional screening system. Hasan and Mahbub, in collaboration with ANFF and the Defence Science and Technology Group (DSTG), plan to demonstrate the effectiveness of their prototype device in actual field conditions with human volunteers, hopefully leading eventually to a way to further protect our day-to-day lives.
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