Harbottle AM, Hira SM, Josowicz M, Janata J. Lewis Acid Based Sorption of Trace Amounts of RuCl3 by Polyaniline.
LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016;
32:8315-8321. [PMID:
27479848 DOI:
10.1021/acs.langmuir.6b02237]
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Abstract
A sorption process of RuCl3 in phosphate buffer by polyaniline (PANI) powder chemically synthesized from phosphoric acid was spectrophotometrically monitored as a function of time. It was determined that the sorption process follows the Langmuir and Freundlich isotherms, and their constants were evaluated. It was determined that chemisorption was the rate-controlling step. By conducting detailed studies, we assigned the chemisorption to Lewis acid based interactions of the sorbent electron pair localized at the benzenoid amine (-NH2) and quinoid imine (═NH) groups, with the sorbate, RuCl3, as the electron acceptor. The stability of the interaction over a period of ∼1 week showed that the presence of the Ru(III) in the PANI matrix reverses its state from emeraldine base to emeraldine salt, resulting in a change of conductivity. The partial electron donor based charge transfer is a slow process as compared to the sorption process involving Brønsted acid doping.
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