Using hydrogel-biochar composites for enhanced cadmium removal from aqueous media

Mining activities and metallurgical processes often introduce considerable amounts of heavy metals to the surrounding environment; especially the nearby water bodies as well as groundwater system.1 High concentrations of most heavy metals are highly toxic to living organisms including humans. Moreover, many heavy metals can accumulate in organisms (i.e., bioaccumulation) and be consumed by other organisms along the food chain.2 among the common heavy metals, cadmium (Cd), which is mostly sourced from zinc refinery, has the highest toxicity to most organisms.3 Inhalation of high levels of Cd in a short period of time can lead to acute flu-like symptoms and lung damages, while long-term exposure to Cd can result in serious kidney, bone and lung diseases.4 In addition, cadmium and its compounds are also known to be carcinogenic.5 Therefore, removing heavy metals, particularly Cd from the contaminated aquatic environment has long been an important challenge.