The researchers used water and an ultrasonic extraction process, followed by gas chromatography-mass spectrometry to quantify the amount of cocaine in more than 230 bills collected in 17 cities.

Scientists at reykjavik want to bypass the slow process of CO2 absorption into water and the risks it poses by mixing the gas with water before injecting it underground.

The key component in the process is a catalyst -- cobalt metal, phosphate and an electrode, placed in water -- that produces oxygen gas from water, while another catalyst produces hydrogen gas.