Does anybody know the reasons for the little increase in the adsorption capacity of Hg(II) and Cd(II) ions after modification, but for the large increase in the adsorption capacity of As (III) ions?
my data (adsorption capacity) are:
before modification:238.09(Cd) -212.766(Hg) -74.074(As)
after modification: 285.70(Cd) -227.273(Hg) -131.579(As)
Hi Dear
@Guy Lanza
yes, I modified graphene oxide with 3-aminopyrazole in the chemical process.
Mobina -
I’m not an expert but the adsorption differences that you note are probably regulated by ion exchange between positively charged metals/metalloids and negatively charged surfaces, and diffusion of metals/metalloids into the surface layer. One possible explanation could be that trivalent As has a higher degree of electronegativity than the divalents you tested and your treatment with 3-aminopyrazole apparently is more effective for trivalents. Of course adsorption is a function of pH (Langmuir isotherm model) and I assume that you carefully controlled for pH and that your values reflect measurements taken at the same pH.
I hope this helps.
You need to gve exact details about your "modification"
do you use a rducing agent, edta,etc
Thank you Guy, I do the experiments for each metal at optimum pH of the solution. Also, these values of capacity adsorption were for Langmuir isotherm study.
I think it could be described by HSAB theory. but I couldn't explain it because I don't know it correctly
Hi Mobina
It has noting to do with HSAB theory.
it is sulphur in your Thionyl chloride that binds to arsenite
Arsenic III has high affinity for S groups followed by mercury and then Cd,
there is no reason why an amino group in 3-aminopyrazole will have nay affinity for arsenite
According to HSAB theory hard arsenic will not combine with soft sulphur, but it does
my modification way was as follows:
1-GO modified with SOCl2-->(GO-Cl)
2-GO-Cl modified with 3-aminopyrazole -->(GO-f)
is it possible that Sulphur exist in GO-f?
could you send me references for your idea that sulphur prefers to adsorbed As ions?
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