I’ve just stumbled upon a great article on the BBC website. The article can be found here:


The article is about a group of plants that have evolved to take up toxic metal ions into their systems. The metals in question are nickel and zinc and usually, these ions would be toxic to plants, even in relatively small concentrations. Plants that have this ability are referred to as hyperaccumulators.

One tree in particular, the rare Pycnandra acuminate produces a latex that is blue-green in colour because it contains up to 25% nickel ions.

The big question is why? What advantage does this give to the tree? Well, nickel ions are not only toxic to plants, but they are also toxic to animals and it is believed the tree has evolved this special latex to defend against insects.

It is hoped that these plants and other hyperaccumulators can be used to clean up soil that has been contaminated by metal ions from man’s misuse of the environment. The process is called phytomining and it involves using hyperaccumulators to not only clean up toxic soils but also to serve as a way of recycling metals. In theory, metals recovered from toxic soils could be recovered and recycled simply by gently burning away the hyperaccumualtors, leaving the metal ions behind. These ions could then be reused.

This brings me on to the IA / EE. Could a project be developed that looks at precipitating, for example, nickel ions of a known concentration from a solution? What percentage of the nickel ions could be recovered?

I’m thinking along the lines of taking a known volume of 0500 mol dm-3 solution of Ni2+ (this would allow the moles of Ni2+ to be calculated). Then, adding a known amount of 1.00 mol dm-3 NaOH to it to produce [Ni(OH)2] which is an insoluble precipitate.

The precipitate could be dried and weighed to constant mass. It should be possible to determine the moles of insoluble nickel ions in the precipitate and hence the moles of Ni2+ ions in the solution. It would be good to compare how many moles of Ni we precipitated compared with the moles of Ni2+ originally used. Are you able to account for any differences or do the results of the experiment tally closely?

What do you think? It’s over to you now. It would be great to read your posts and ideas below.

Image Credit

André Karwath aka Aka, via Wikimedia Commons (CC BY-SA 2.5)