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

Abstract 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 π–π 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.