I am removing the Pb(II) from wastewater using copper nanoparticles. I have done FITIR and XRD analysis after the adsorption of Pb and there is clear change in the peaks in both FTIR and XRD.
In XRD 2 theta at 32.9 degree indicates formation of Pb-OH. Whereas the typical peaks of Cu2O diminished. What reaction could possibly has occurred? I am unable to conclude. Kindly guide me.
Also there's clear difference in the peaks some have shifted and doublet turned to single.
I will be grateful for your help.
Noor Ul Ain
2Cu2O +4H2O +O2= 2Cu (OH)2 slowly, oxygen in water
Pb2+ - 2e =Pb4+
Cu2+ +2e = Cu
I would suggest
Cu2O + Pb(2+) + H2O --->2Cu+ + Pb(OH)2 (my recollection is that Pb(OH)2 is less soluble than Cu2O/CuOH)
2Cu+ + 1/2O2 + H2O ---> 2Cu(2+) + 2OH- ---> Cu(2+) + Cu(OH)2 (oxygen in water does play a role)
Emanuel Cooper
Thanks for your assistance . I have used the nanocomposite membrane containing cu2o nanoparticles. Are you suggesting Pb(II) transformed to Pb(OH)2 by reacting to Cu2O nanoparticles and then Cu2O released as Cu or Cu(OH)
Emanuel Cooper
If you do not want to give a recommendation, then you must mark the name of the person who gave the correct answer. Otherwise, your answer looks like a schoolchild cheating.
Noor Ul Ain
Yes that's what I was suggesting, although I suspect I was wrong - Cu2O may not be more basic than Pb(OH)2 (from handbook data). I agree with Yuri Mirgorod that oxidation of Cu2O to Cu(OH)2 is probably part of the mechanism, but I don't think Pb(4+) is involved.
However, respectable scientists have published in this area without a detailed mechanism explanation, just talking about adsorption of Pb(2+) (see DOI : http://dx.doi.org/10.13005/ojc/350615, DOI : http://dx.doi.org/10.13005/ojc/350615), so I'm not embarrassed not to have a good theory...
One possibility that's worth a look is adsorption of Pb(2+) on the copper oxide facilitated by carbonate. Your Cu2O probably has some Cu(OH)2 on the surface, and if it's not very fresh and/or kept under nitrogen a Cu(OH)2 surface will react with CO2 and form some carbonate or basic carbonate (e.g. malachite). Since PbCO3 is significantly less soluble than CuCO3 (pKsp ~13 versus ~10 for CuCO3), it makes sense that you'd have an "ion exchange" on the surface with Pb(2+) replacing Cu(2+). This is consistent with the fact that exchange of Pb is more efficient than of Ni and Cd (see the first DOI ref. above).