i have an adsorbent consist of cellulose and treated with Hcl. After adsorption of cr, cd, and cu in it, i have done XPS of the adsorbent separately for each metal. Basically it should show C, O , Cl and adsorbed heavy metal in XPS image. As metal has been adsorbed efficiently and adsorption is good. But i have found only C and O in the Xps image. Please suggest, where is the error or any other technique?
Cellulose forms complexes with heavy metal ions. The long cellulose chains form globules perhaps. Metal ions are hidden inside the globules, like iron in hemin in gemoglabin. Cellulose еlements are on the surface of the globule. XPS defines the elements only at a depth of 3-10 nm. You need to use EPR, NMR.
Best regards.
You may try ICP-MS to detect even very low level of metal ions. SEM with EDX may also help. It has deeper penetration. X--ray fluorescence may be also helpful, although less sensitive. After digesting the organic component atom absorption spectrometry may also be used.
Hi Renu,
Have you a XPS PATTERN of adsorbent before adsorption? May be, you can then compare them! So, XPS defines the chemical composition of the surface of a material to a depth of up to 10 nm.
Best regards
Only the top 5 - 10 atomic layers are seen by ESCA/XPS. I assume you've confirmed the bulk composition contains your heavy metals. XPS invariably shows that the top layers are rich in oxygen, that any elements present are in a high oxidation state, and that carbon is invariably present due to CO2 in the atmosphere. Indeed the 285 eV peak of carbon is invariably used to gauge the oxidation state of other material present. Are your heavy metals deeper in the matrix? Is so then argon ion etching may begin to reveal them and get down to the bulk composition. Note that in any multicomponent system in air the surface and the bulk compositions cannot ever be the same.
I am agree with Safia's view, you can check XPS prior and after adsorption.
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