Hot to separate water solvable graphene quantum dots from Sulfuric acid (H2SO4) solution?

Method 1:

I used 0.22 um corning PES filter membrane to filter water soluble GQDs, followed by freeze drying of this filter solution, again do the 0.22 um filtration. This obtained solution having highly conc. Solution of GQDs. In each filtration your removing most of salts fomed in Neutralization as well as the particles size above 0.22 um size. Followed, by dialysis of this obtained filter solution with 1000 or 2000 Da dialysis bags, u can get pure GQDs size less than 10 nm.

Method 2:

If you want to get the all GQDs. then add DMSO or DMF solvents to this water soluble GQDs (2:1 v/v ratio, DMF: water GQDs), you will get white precipate of GQDs with salts (sodium sulphate, if you add NaOH for Neutralization). You can just do either decantation or precipitation then collect semi solid/powered GQDs solution. Then add acetone/isopropanol/ethanol which have low boiling points solvents (need to select GQD insoluble solvents) to remove DMF and water content in this wet product. Repeat this step 3 times and remove all the impurities. After, one day you can get powered GQDs.

By using 0.22 um filter membrane and freeze drying of solution, you can remove most of the sodium sulphate salts and unreacted impurities.

By using DMSO/DMF solvents, you can get white precipate (sodium salts) and black ppt (GQDs).

Method 3:

You can also try column or flash chromatography with water and Acetonitrile (80:30) as a solvents ratio, to purify this GQDs.

Parveen Kumar

From your question it seems you didn't neutralized your GQDs solution before Dialysis. IF so then you should make it neutral (pH=7), as the dialysis may degrade in acidic medium.

Also roughly 1000 Da refers to 1.3 to 1.5 nm pore size. thus certainly you will loose GQDs smaller then these, so its bit better if you use 500 Da.

Why sometimes after KOH activation of carbon, there is no carbon remaining?

what is the simplest definition of ion exchange capacity

what is the simplest definition of ion exchange capacity

Physics: Why do we describe light by referring to its wavelength, but microwaves and radar pulses by referring to their frequency?

Chlorinated organic formation in odor control scrubbers using hypochlorite?

What solvent can I used for Paal Knorr reaction between 6-amino hexanoic acid and 2.5 hexanedione?

How the parameters (such as Mw, Chemical bonds, polymer bland and so on) affect the mechanic property of polymer (such as storage, loss modulus) ?

Why are the velocities so high in my Boussinesq approximation Fluent simulation?

Why almost every element would be metallized in sufficiently high pressure and low temperature?

Discrete Phase model (DPM) particle break-up has particle size limits during particle tracking?

How Relativistic effects is one reason for lanthanide contraction?