Thursday, June 23, 2016

Cleaning the environment: It’s the pits - Syrian researchers use date stones to suck up toxic materials

TO DISCOVER how to use a waste material to clean up hazardous chemicals is a notable achievement. To do so while working in a war zone is doubly impressive. But that, with a little help from some foreign friends, is just what Abdulsamie Hanano of Syria’s Atomic Energy Commission, in Damascus, has done. Over the past four years Dr Hanano, who works in the commission’s molecular-biology department, and his colleagues have developed a way to use the stones (or pits) of dates, a waste product of the fruit-packing industry, to clean up dioxins, a particularly nasty and persistent type of organic pollutant that can lead to reproductive and developmental problems, damage the immune system, and even cause cancer. Dioxins are produced mainly as a by-product of industrial processes.
Dr Hanano lit on date stones for this task for three reasons. One was that they are rich in oils of a sort that have an affinity for dioxins. The second was that, though they are not unique in this oil-richness, unlike other oil-rich seeds (olives, rape, sesame and so on) they have no commercial value. The third was that, despite lacking commercial value, they are abundant.
It was not the oil per se that Dr Hanano wanted, though. Rather, he intended to extract in one piece the droplets into which this oil is packaged within a stone. Besides oil, these droplets contain special proteins that help to hold them together. And each droplet is surrounded by a membrane composed of a substance called a phospholipid which, unlike oil, is attractive to water. This means that when the droplets are shaken up with water, they form a stable emulsion.
To gather the droplets, Dr Hanano and his colleagues first softened up their date stones by soaking them in water for two weeks. That done, they ground them up and centrifuged the result. This process separated the droplets from the rest of the gunk as a creamy emulsion. It was then a question of testing the emulsion’s ability to extract dioxins from water. As the group report in Frontiers in Plant Science, it did this well. The droplets’ phospholipid membranes proved no barrier to the passage of dioxins, which accumulated satisfactorily in the oil. One of Dr Hanano’s collaborators, Denis Murphy of the University of South Wales, in Britain, describes the droplets as acting like little magnets for dioxins. “Within a minute,” he says, “virtually all the dioxins are sucked out of a solution. It is very fast.”
In particular, the droplets absorbed 2,3,7,8-tetrachlorodibenzo-p-dioxin, an extremely toxic herbicide that was one of the constituents of Agent Orange, used to destroy vegetation by American forces during the Vietnam war. And, once the dioxins are inside the droplets, their affinity for the oil is such that they never leave. Disposing of them is just a matter of scooping up the droplets (which will eventually rise to the top of any water containing them) and destroying them safely in, say, a furnace.

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