Bis-pyridinium dibromides modified organo-bentonite for the removal of aniline from wastewater: A positive role of π-π polar interaction

Aniline removal is of great importance for water treatment, and adsorption is an efficient treatment method. Hexamethylene bis-pyridinium dibromide modified bentonite (HEMBP-B) was firstly prepared and characterized by XRD, FT-IR, BET, SEM, TEM and TG-DTG analysis. Adsorptive experiments of aniline on the organo-bentonite were carried out using batch method as a function of the length of linking carbon chain (n), concentration of HEMBP (C), contact time (t), temperature (T) and pH. The optimal conditions for aniline removal on HEMBP-B were as follows: n of 5 or 6, C of 1.0 CEC, t of 120 min, T of 298 K, and natural pH of 6.6. The pi-pi polar interaction existed between the aromatic rings of aniline and HEMBP has successfully explained the main adsorption mechanism. The equilibrium data of aniline removal on HEMBP-B followed Freundlich and D-R isothermal models precisely, which indicated a less favorable and physical process of aniline adsorption. The kinetic data could be best described by the pseudo-second-order model. Besides, the thermodynamic study revealed that aniline adsorption on HEMBP-B was non-spontaneous, exothermic and physical. (C) 2013 Elsevier B.V. All rights reserved.