Reactive decontamination of toxic chemicals within porous media

Following a chemical weapons attack, it is crucial for both public health and the environment that the toxic chemical agent is properly cleaned up. One particular issue is when the agent has contaminated porous materials, such as brick or concrete; in such cases, decontamination is typically achieved by reacting the agent with a cleanser, which neutralises it in a chemical reaction. The agent and cleanser fluids are usually immiscible, so that the chemical reaction occurs only at fluid--fluid interfaces within the pores of the porous medium. While it is relatively straightforward to write down a model that describes the interplay of the agent and cleanser on the scale of the pores, it is computationally expensive to solve such a model over realistic spill sizes. In this talk we present homogenised models for the reactive decontamination of porous media, which are computationally efficient to simulate while still taking the pore-scale behaviour into account. Solutions of these homogenised models show how differences in the initial distribution of agent affect both the decontamination time and the amount of cleanser required to fully decontaminate the porous material.