Iodine extraction from Sea Weed?

[Caustic]

I have read a post somewhere that said that iodine can be extracted from seaweed. How much iodine is present in seaweed and what kinds of seaweed has the highest yield? Living in southern california there is plenty of Kelp and sea grass off the coast and i am very interested in the potential for iodine extraction from these plants. If anybody has any info and even a procedure for the extraction i would greatly appreciate it.

 

ps. if there is another source of cheap iodine that anyone knows of please share. thanks.

[budullewraagh]

haha, funny you say that. i used to live in cape cod and my family still travels there often (we have a house there). last time my parents went (i had to stay home studying) they brought me back a bucketful of seaweed. im so proud of them for that.

 

first off, iodine is by no means cheap. it is very, very expensive as crystals and even iodide salts are quite pricy.

 

a quote from a site with information about the amount of iodine in seawater and seaweed:

Seawater contains 0.05 ppm (parts per million) iodine which means that there are approximately 76 billion pounds of iodine in the world’s oceans. Iodine was first discovered in seaweed. Dried seaweeds, particularly those of the Liminaria family, contain as much as 0.45% iodine.

 

not so good. if i have, say a kilo of seaweed, i end up with 4.5g of iodine.

still, it's definately worth it beacuse iodine is that cool.

 

if you want to extract it, here's what ya do:

 

-burn seaweed to ashes

-acidify ashes with an acid. DO NOT USE A HALIDE ACID. if you use a halide acid, by the end of your experiment you will oxidize the halide and end up with [math]Cl_2[/math] if you use hydrochloric, for example sulfuric works best, as oxidation will give you a fun to use by-product and will not ruin the experiment by neutralizing the acidity of your solution

-mix a little, to make sure all the salts dissolve. then filter a few times with coffee filters to get rid of all those burned organics

-add a strong oxidizing agent. i highly recommend hydrogen peroxide. it should be relatively highly conced solution. to conc hydrogen peroxide just freeze the water off and pour out your conc peroxide. a word to the wise: dont mess with conc hydrogen peroxide as it will oxidize your flesh away, and will explode on contact with metals and organics depending on the concentration. when you add the peroxide, add it slowly because you probably will form peroxy acids, which are bloody insane. if you do it with sulfuric acid, you will make peroxymonosulfuric acid, aka pirahna bath. it will rip straight through your flesh, and explodes if the peroxide is added too quickly. dont mess with it. try using a lower concentration of sulfuric (30%?) and a high concentration of peroxide.

 

when you add the peroxide you should get halogens. do this in a well-ventilated area because chlorine gas is no fun to breathe in too much of. you'll end up with a good bunch of chlorine, some bromine and a bit of iodine. the iodine sublimes readily so be prepared to capture it as well as the bromine in vessels that can handle a bit of pressure. store in a cool area.

[boris_73]

ok generally i do not do anything from totse.com but this method does work it is basically the same as what bud said

 

Ok, lets see an easy experiment supposing you want to prepare the Iodine first. You will need:

 

 

Bunsen burner and asbestos square (or a hot plate)

Tripod and tin lid

Beaker, 250 ml

Separating funnel 100ml

Evaporating dish

Hydrogen peroxide 20 volume

Tetrachloromethane or dichloromethane

Distilled water

1M solution of Sulphuric acid

Supply of ribbon seaweed(Laminaria) - that you can obtain a a biological supply store or from the sea shore

 

 

Procedure

 

(You must work at a fume cupboard)

 

 

Collect and dry about a dozen 50cm lenghts of the seaweed and heat them strongly on a tin recipient until they are reduced to ash; probably it will reduce a quite small quantity, about a spoonful.

Add to the ash 20 ml of distilled water in a beaker, and heat the suspension until it boils.

Filter the suspension

Acidify the filtered with Sulphuric acid solution

Add then the hydrogen peroxide solution. You will observe the formation of a brown colour due the iodine liberation from the iodine ions present.

Transfer the mixture to a separating funnel

Extract the Iodine with tetrachloro methane or other solvent. The result is an organic solution of iodine.

In order to obtain crystals , the solvent may be allowed to evaporate at room temperature, by placing it in an evaporating dish in a fume cupboard. It will result crystals of iodine or rather gray-black brilliant flakes.

[budullewraagh]

ah, good idea with the solvent.

 

ok so i would imagine that the chlorinated organic solvent and the peroxymonosulfuric/sulfuric would separate. my only reservation is the possibility of the chlorine in the organic solvent being oxidized by the peroxide. organic peroxides are really, really scary,

 

got any other ideas for non-chlorinated solvents that readily turn to vapor?

 

EDIT: why did i just mention the possibility of acetone????? (before the edit) acetone peroxide anyone? ACK!

[boris_73]

could you use an extraction fan instead of a fume cuboard because i have one of those in my kitchen its just a thought but its basically the same concept except of course not having a cuboard

[budullewraagh]

i'd just do it outside. i dont like the thought of chlorinated organic gases floating about in my house

[boris_73]

how much do hot plate's cost because i wouldnt mind getting one and where do you get them from the best thing i have to an heat source which i could use out side is a gas burner those used in camping so you could put a frying pan on there

[budullewraagh]

if it's like a cooking hot plate then im thinking $75-150

 

if it's for chem, i've seen them between $150 and 400, and as much as $2,000

[boris_73]

bloody hell up to £1114 i think thats a little expensive for a hot plate what do you use

[budullewraagh]

i use a stove burner

 

im considering buying a cheap hotplate, however, but that may be difficult because i want to take some college classes next summer and my parents wont pay for it because i am only going to be a senior in high school after that summer...so i may not have enough money

[boris_73]

yes money is the problem here as well i have spent most of mine on glassware, driving lessons, etc and soon its all going to go on elements if i buy some mercury or francium, i need a job

[Skye]

Electric frying pans can make pretty reasonable alternatives. Ask around at second hand shops, you could get lucky.

[boris_73]

what are electrical frying pans i dont think we have them in england

[boris_73]

ive looked on the internet and i am pretty sure they dont sell them in england ive never seen them before

[Skye]

They are a frying pan that plugs into a wall socket and have a built in electrical heating element. They might have another name in england (griddle or skillet maybe) but I'm sure you'd have something like it.

[boris_73]

ill have a look around what temperature can they go up to if is quite high then great idea

[budullewraagh]

funny how they dont have electric frying pans in england but they sell nitric acid to lower soil pH

[boris_73]

they might sell electric frying pans in england its just that ive never heard of them

[Shoushou]

Well, I liked the Idea so much, but I have things to ask about:

1)What's a fume cupboard ( a place/a tool?) & why should I work at it?

2)What's the separating funnel? & what's is used for? & why should i transfer the mixture of H2O2,H2SO4 & the organic iodine solution to a separating funnel?

I need a clear explanation for the proceding questions, so I may have a complete background of this experiment...

[Caustic]

after performing the process once, can the H2SO4 / H2O2 be reused? or do you need to start with a fresh batch every time? H2SO4 isnt cheap, even if you get it from car batteries, the batteries are expensive unless you get lucky and find some cheap used ones. and H2O2 is expensive too. Im trying to find a way to make a good amount of iodine crystals inexpensively.

[boris_73]

no the sulphuric acid or hydrogen peroxide can not be used again and yes you do need a fresh batch but you should be able to get a decent amount of iodine from the seaweed procedure and this method is really for where it is hard to get hold of iodine

[Dapthar]

... that may be difficult because i want to take some college classes next summer and my parents wont pay for it because ...

[tangent] Unless your parents are barely getting by (in the financial sense), they would seem to think that their money is better spent on ventures besides that of furthering your academic knowledge. The inevitable question that arises is, what are they spending it on in lieu of advancing your education? I suggest you ask them. [/tangent]

[boris_73]

i think he is on about his parents wont pay for a hot plate not his college classes the hot plate has nothing to do with hs education at school

[budullewraagh]

actually youre both wrong:\

 

i am a junior in high school now. after this school year, in the summer, i intend to go to college to take classes. i intend to go back to high school after next summer in order to finish my high school education. i intend to go to college after high school and then graduate school. my parents are willing and able to pay for my collegiate and graduate studies, but are not willing to pay for college classes next summer. as a result, i must pay for them. they are going to be expensive, so i will need to save my money. thus, i most likely will not be buying a good hotplate anytime soon

[boris_73]

well why do you need to go to college in the summer im sure they teach you everything you need to know at high school, and you will save alot of money