How are you desorbing your metals?

Dear Colleague Tom,

This is my question, how can I desorb the heavy metals?

Have a very good day

Thanks

Ahmed

Ah, ok. Easiest way is often to acid wash - most metals will dissolve in acidic solution and then precipitate out again as you raise the pH. Try and avoid nitric acid though, otherwise you run the risk of digesting your biomass, depending on what it is. If you used acidic conditions for adsorption in the first place you can try solvent exchange methods similar to SPE extraction. Generally try and reverse the conditions that made it adsorb in the first place.

This is on phenols, rather than metals, but has a good section on adsorbing followed by desorbing onto biomass: http://pubs.acs.org/doi/ipdf/10.1021/sc4001675

If I add acid to the biomass, it will hydrolyse as the acid medium act as polymerisation of  cellulose and hemicellulose ?

what about leaching it in hot water so the adsorption bonds between the biomass and the heavy metals may be broken

Yes, biomolecules will get hydrolyzed in acid medium. Anyway your interest is in estimation of heavy metals.

Moreover heavy metals may be in bound form sometimes and acidic conditions are required for the release of heavy metals.

If you need the biomass back afterwards, that will make things trickier, yes. What conditions did you use to adsorb the metals onto your biomass in the first place?

just in deionized water, I added the biomass to the wastewater that contain the heavy metals 

Heated water is probably a good place to start then, yes. Perhaps use a gentle chelating acid, such as citric acid, if no success at first.

OK thanks

Difficult to recover biomass after harsh acid treatment. Biomass will undergo hydrolysis.

thanks