I am studying the removal of Cr (VI) from an aqueous solution by following the adsorption mechanism using Fe3O4NPs/activated carbon nanocomposite. I adjusted the pH range from acidic to basic. I observed good adsorption occurred in acidic medium and graph line fall continuously in the neutral region, it was expected but it gradually rises in the basic medium. As this behavior has not been observed in the literature that adsorption for Cr (VI) also rises in basic medium. If any experience/insights related to the problem please throw some light.
Hi.
Probably a dumb question, but are you sure the Cr 6 is adsorbing at acid pH? Don't forget that it is a powerful oxidising agent in acidic conditions. I've seen time and time again students trying out new adsorbants and getting exited only to conclude that in fact Cr 6+ was just reduced to Cr 3+.
Cheers!
Hi
I donot know you use which kind of characterization for Cr (VI).
But .in higher pH the concenteration Cr(Iii) increaing and this kind of Cr has lower intraction with your composite
This behaviour could be explained in case of Cr(III) not Cr(VI).
Normally at basic pH, a decrease in the adsorption of chromium in basic medium will be observed. I think you have to measure the final pH, because when you put an adsorbent in contact with a pollutant and you adjust the pH, the final pH will be different from the initial pH.
Thanks to all of you for your insights and experience on this question. Mojgan Zendehdel I have attached the image. It shows an increase in removal %age as I increased pH to value 10. I think it might be possible owing to the charge on the adsorbent surface.
Moreover, is this right that Cr(III) exists as Cr (III) cationic species in acidic media and Cr (III) anionic species in basic media?