During the past years different systems have been developed in order to remove metal-ions from water based systems. The most used systems are based on solid phase functionalization or modification of the scavenger material and require several steps for the surface functionalization in order to remove metals from waste water. Moreover, the waste water purification set-up requires several parts such as flow regulators, columns and filters. Here we propose a one-pot approach to prepare metallic-core carbon-shell particles. Plastic granulate (a mix of polypropylene, polyethylene and polystyrene) was mixed with cobalt oxide nano-powder and processed in a Barbender mixer. The resulting composite material was carbonized at 700°C under an inert atmosphere. The resulting magnetic particles coated with active carbon can be used to remove metal ions from waste water simply by mixing particles in the water to be purified. Afterwards the particles are removed simply by using a magnet. The successful removal of the metal-ions from the waste water is controlled by measuring electrical conductivity.