Sustainable processes for the decontamination of chemical warfare agents

Despite the signature of the Chemical Weapons Convention (CWC) by almost all the countries in the world (only North Korea, Egypt and South Sudan have not signed the CWC; Israel having signed but not ratified it), a frightening resurgence of chemical weapons has recently appeared in the course of various conflicts (sarin attack at Khan Cheikhoun in Syria in April 2017), or terrorist attacks (assassination of Kim Jong-nam in Kuala Lumpur in February 2017, attack in the Tokyo subway in 1995). The CWC outlaws the large-scale production of chemical weapons, but the world's stockpiles of old chemical weapons also remain large; the question of their destruction and the development of safer methods is therefore a current challenge. While most of the Western countries that are signatories to the CWC have set up secure destruction sites in recent years, the Syrian case has raised new issues. Indeed, given the internal conflict situation and the refusal of many states to accept the Syrian weapons stockpile for destruction on their territory (1,033 t of mustard gas and 300 t of sarin and VX officially), decontamination finally took place at sea, for 2 years, on board the "Cape Ray", an American ship equipped with a chemical treatment platform, the "Field Deployable Hydrolysis System" (FDHS). Unfortunately, the effluents resulting from this treatment are colossal (several tens of liters of water/liter of agent treated) and must be reprocessed at a cost sometimes higher than the neutralization of the toxic agent. France, for its part, has around 300 tonnes of stored chemical weapons dating back to the First World War. The SECOIA program (Site d'Élimination des Chargements d'Objets Identifiés Anciens) was initiated with this in mind: the destruction method used is based on automated destruction by explosion in an armored enclosure, after which the waste is recovered, packaged and processed. The operational efficiency of this process for fossil shells is the safest because it is automated, and it will take several decades to destroy current stocks. The discovery of a further 10 to 20 tonnes each year exacerbates the problem, as not all chemical weapons discovered are eligible for SECOIA, which only accepts intact devices (with no toxic leaks). The staff of the French Civil Protection and Crisis Management Agency (DGSCGC) must then carry out neutralization treatment depending on the type of toxic agent. It is therefore essential to have effective and sustainable methods for the efficient neutralization of chemical warfare agents in different conditions and locations. This article describes the latest advances in the neutralization of toxic molecules present in chemical weapons. This involves the use of recent (2000-2018) methods from the academic world (catalysis, continuous flow reactor) to save quantities of reagents and/or facilitate...