Arsenic contamination of drinking water is an issue that affects millions of people in both developing and industrialized regions. Arsenic is a toxic element that can cause arsenicosis and certain types of cancers, making its remediation an area of great concern amongst environmental agencies around the globe. There are a number of technologies that remove arsenic from drinking water such as ion exchange, reverse osmosis and membrane filtration, but these methods can be costly, particularly in developing nations. Due to cost, adsorption has been the most widely used means of tremoving arsenic from drinking water. In this method, arsenic is bound to iron oxide particles such as hematite or goethite mineral particles.
Using these particles for arsenic remediation has some drawbacks in simple fixed column systems. Iron hydroxides have low mechanical resistance, so they have been functionalized by attaching iron oxide nanoparticles to activated charcoal to improve their filtration efficiency in aqueous solution. Attaching the iron oxides nanoparticles to activated carbon allows for an increased surface area, resulting in better adsorption of arsenic with less total mass of iron oxide nanoparticles.
Research is currently focusing on the best ways to functionalize activated carbpon with iron oxides to produce better, cheaper arsenic filtration medium. One method in particular is showing considerable promise. Activated carbon is modified with Iron (III) Chloride(FeCl3) solution through forced hydrolysis. Small carbon granulars of approximately 100-150 micrometers in size are mixed with reagent grade FeCl3 solution in a sealed container at 25 degrees celsius for 24 hours to allow the solution to saturate the pores in the carbon. The particles are then heated in a furnace to force thermal hydrolysis of the iron oxide and anchor the particles to the carbon surface. After thermal hydrolysis, the activated carbon is rinsed with distilled water to remove any remaining unattached iron oxide crystals.
The resultant material is activated carbon with functionalized iron oxide nanocrystals for use in fixed column water filtration. The filter medium is also reuseable. RInsing the activated charcoal with other non-toxic chemicals will recharge the filters for re-use, allowing for the controlled disposal of the arsenic and the reuse of the filters.
Advancements in incorporating iron oxide nanoparticles into activated carbon filter medium has the potential for use in purification of groundwater resources as well as the cost effective remediation of brownfields and chemically contaminated sites. This will lead to improved environmental and human health, particularly in communities in less developed regions.