Adsorption of aniline from aqueous solutions onto a nanoporous material adsorbent: isotherms, kinetics, and mass transfer mechanisms

Abstract

MCM-48, which is particulate and nanoporous, was formulated to actively remove aniline (AN) (i.e., benzenamine) from wastewater. MCM-48 was characterized by several methods. It was found that the MCM-48 was highly active in adsorbing aniline from wastewater. The Langmuir, Freundlich, and Temkin isotherms were employed to evaluate the adsorption equilibrium. At 100 and 94 mg g−1, the maximum theoretical and experimental absorption of aniline, respectively, fit with a Type I Langmuir isotherm. The Langmuir model was optimal in comparison to the Freundlich model for the adsorption of AN onto the mesoporous material MCM-48. The results of these kinetics adsorption models were investigated using model kinetics that employed both pseudo-first- and pseudo-second-order models as well as models utilized intraparticle diffusion. The kinetics adsorption models demonstrated that the absorption was rapid and most closely agreed with the pseudo-first-order model. The kinetic studies and the adsorption isotherms revealed the presence of both physical adsorption and chemisorption. The potential adsorption mechanisms include the following: (1) hydrogen bonding, (2) π-π interactions, (3) electrostatic interaction, and (4) hydrophobic interactions. The solution's pH, ionic strength, and ambient temperature also played essential roles in the adsorption. HIGHLIGHTS The mesoporous silica MCM-48 was very successful to remove aniline.; A maximum aniline adsorption 94 mg/g was achieved on MCM48 adsorbent.; MCM-48 was found very active for the removal of aniline compounds from wastewater.; Aniline adsorption mechanism is a chemisorption and physical adsorption process.; The MCM-48 was regenerated and reused efficiently in a batch adsorption.;

Keywords

• benzenamine
• kinetics adsorption
• mass transfer
• mechanism adsorption
• mesoporous material
• wastewater treatment