A group of scientists from Beijing, China have discovered a simple method for removal of the poison arsenic from contaminated water using cigarette ash. Arsenic can arrive in drinking water from both natural and anthropogenic sources. It is widely dispersed as a constituent in over 200 minerals throughout the Earth’s crust and can contaminate surface waters when mixing with arsenic-rich geothermal fluids. Bangladesh, West Bengal and regions of China are most affected by endemic contamination with serious consequences to human health. Mining related activities are the most common human cause of arsenic contamination. The mining process mobilizes arsenic, which is released from minerals through a variety of bio-geochemical reactions. Coal burning, arsenic in pesticides and wood preserving arsenicals contribute to contamination in many areas from Australia to Europe to North America.
A favoured method for murder in the Middle Ages and Renaissance, arsenic can lead to a quick death. Constant exposure to lower levels of arsenic in drinking water leads to chronic arsenic poisoning. The poison interferes with many, many key biochemical processes in the body. The molecule inhibits an enzyme which helps the cell produce energy and disrupting this process leads to cell death. Also, it disrupts signals in the body controlling heart and brain function by blocking membrane channels. There are many physical symptoms starting with headaches, confusion and drowsiness. More acute poisoning leads to diarrhoea, vomiting, blood in urine and cramping. All very unpleasant.
Sophisticated treatment methods to remove arsenic from water have been developed however the areas most severely affected by contaminated waters lack the equipment and technical ability to carry them out. Li and colleagues’ new one-step method binds aluminium oxide to cigarette ash. Cigarette ash is a porous medium, which allows easy complex formation.
Amazingly this substance can absorb the arsenate, producing clean drinking water once filtered to separate the water and ash. They tested the product in ground water and found it removed more that 96 percent of the arsenic, reducing its levels to below that set by the World Health Organization. The team also showed that the aluminium oxide and ash mixture could be used at least six times before there was any significant decrease in absorption capacity. Reducing arsenate using a reusable complex from recycled ash!