14 DAY TRIAL // Researchers at Rice University in Houston have discovered that magnetite, a common mineral containing iron oxides, could offer a simple and inexpensive method for cleaning potable water out of harmful arsenic levels, when crashed into a powder of tiny crystals.
High arsenic levels in water supplies are found in China and Southeast Asia, but also in parts of Latin America, Africa and the US. Tens of millions of poor farmers are exposed this way to harmful doses of arsenic, which provokes cancer, heart diseases and hypertension. In the US, the accepted limits of arsenic in municipal waters have been lowered from 50 parts per billion to 10.
The research team found that magnetite crystals smaller than 40 nm wide were much more sensitive to low-strength magnetic fields than larger magnetite particles. Magnetite crystals 12 nm wide binded up to 100 times more arsenic than iron crystals currently used in water filters, yet they can be easily put out from the water using cheap magnets widely used as computer components. A well water could be cleaned of arsenic by simply tossing a small amount of magnetite powder into a well pot and removing the magnetite with a magnet, after consuming the arsenic. "This should come out costing one to two cents a day for a family of four in the developing world," said Mason B. Tomson, professor of engineering.
This method also produces a small amount of residue: in one year, the residue from a well would fill a cooking pot. Technology based on magnetite crystal filters is already in designed to collect contaminants and particles in centralized water systems, replacing magnets. Other minerals implying nanotechnology already used in such systems include zirconium, aluminum, and manganese compounds.
This magnetite using technology is going to be tested on the field in Brownsville, Texas, and India. Other technologies to be designed for removing arsenic imply clay filters and plants that suck arsenic from the ground. "All of the arsenic removal systems so far require filtration of some sort," said Alexander van Geen, a scientist at Columbia University's Lamont-Doherty Earth Observatory. Such systems need proper maintenance and are vulnerable to microbial contamination. Another simpler solution would be drilling deeper wells that reach uncontaminated water tables.