In this article, we report the efficacy of ultrasonication in understanding the adsorption mechanism involving the interaction between tetraoctylammonium bromide (ionic liquid), Amberlite XAD 4 (synthetic polymer) and dichromate anion. The ionic liquid impregnated polymeric adsorbent was prepared by ultrasonication in hexane medium and showed good selectivity in adsorbing carcinogenic chromium(VI) with a high Langmuir adsorption capacity of 196.1 mg g(-1). The acoustic cavitation and the subsequent interactions such as ion-pair, cation-pi, electrostatic, van der Waals and hydrophobic hydration play a pivotal role in the adsorption process. The interesting aspect to take cognizance is that the mechanism visualizes an appealing cation-pi interaction between the tetraoctylammonium cation and the polymeric matrix followed by the effective electrostatic affinity of dichromate anion with the ionic liquid. The adsorption thermodynamics reflects an enthalpically encouraging host-guest interaction along with a decrease in the entropy. The experimental data correlates well with the pseudo second order kinetics. The greener aspect in the procedure is emphasized in the regeneration of the adsorbent using ascorbic acid as the reducing agent for Cr(VI) and the procedure was validated in electroplating and tannery effluent samples. (C) 2013 Elsevier B.V. All rights reserved.