Lead contamination is a huge problem in many parts of the world. From mining operations to industrial waste, it can leech into the ground water and soil, causing neurological disseases in animals and humans. Emily Dellwig of Kansas has developed a method of removing lead from soils using some squashed oranges and a battery.
Well, ok, it’s a little more complicated than that, but the principle is quite simple. Lead, while not magnetic, possesses ions that will migrate towards a a negative charge. The trouble is, getting lead soluble enough to actually move through the ground and actually be able to extract it, is difficult. That’s where the oranges come in. The citric acid “enhances electroosmosis of the ions in the soil as well as makes the lead compounds more soluble.” This means that it is easier for them to travel to the anode.
Surrounding the anode itself is a mass of liquified orange peel, pulp, and juice, mixed with calcium hydroxide; otherwise known as Saponified Orange Waste (SOW) Gel. This gel, in addition to helping with the migration process due to its acidic nature, provides a surface that the lead ions can deposit themselves on. This allows them to be removed from the soil when the SOW gel is pulled out. Using only water in this process, it was shown to remove only 75% of the lead whereas with the oranges, an average rate of 93.8% lead extraction was achieved.
Since conventional lead extraction and clean up from the natural environment is extremely expensive, this process makes a lot of sense. It is organically based, requires very little equipment, and would also provide cash-strapped orange farmers with an extra revenue source for unsuitable fruits and the remains once the juice has been extracted. Emily says that the next step would be to look at the effectiveness of pure ascorbic acid as a solubility and migration aid, and also to investigate methods of removing the lead from the organic matter once it is removed from the soil, thereby allowing the lead to be recycled and reused.
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