Batch and column tests study on coexistence of TNT and aniline enhancing their Transports in Chinese loess

Abstract

Abstract Batch adsorption and column tests were conducted to explore characteristics of transports of TNT and aniline and their interactions in saturated Chinese loess sampled from Xi’an, China. Batch tests show that the performances of TNT and aniline adsorptions on Chinese loess are not same when they exist alone. When they coexist, their adsorptions inhibit each other and their inhibitions potentials were different. TNT inhibition on aniline adsorption is in linear and increases with TNT concentration increasing, while aniline inhibition on TNT adsorption also depends on its concentration but in two stages, where the inhibition is few when aniline concentration is lower than 5 mg/L, and then also gets linear increasing with aniline concentration increasing over 5 mg/L. Even though, the inhibition of aniline on TNT adsorption is generally greater than that of TNT on aniline adsorption. Column tests show that, compared with the transport behavior when they exist alone, theier coexistence can promote each other to transport in the saturated loess, importantly, aniline promotes more obviously TNT transport than TNT promotes aniline transport. Kinetics, isotherms and thermodynamics studies indicat that, TNT adsorption is primarily through the surface adsorption while aniline adsorption is mainly via electrostatic adsorption and inner pore diffusion adsorption as well as surface adsorption. There is a certain competitive relationship in their adsorptions on Chinese loess because they have same adsorption sites, meanwhile, they have different adsorption sites, especially, electrostatic force is greater than surface force, when they coexist. So, these inhibitions on adsorption are conducive to the existences of TNT and aniline in the water solution rather than being fixed on Chinese loess, thus enhancing their transports in the saturated loess and aniline has a great effect on TNT migration, while TNT has a small effect on aniline transport, indicating their coexistence can increase the risk of deep soil and even groundwater pollution.