Effective adsorption of chloroanilines from aqueous solution by m-phenylenediamine modified hyper-cross-linked resin: Kinetic, equilibrium, and thermodynamic studies

Herein m-phenylenediamine was employed as the introduced polar groups reagent to prepare a novel amino-modified hyper-cross-linked resin (MPDAMR) by two successive Friedel–Crafts reactions. The adsorption capacities of MPDAMR for two chloroanilines in aqueous solution were compared with two commercial resins (macroporous resin XAD-4 and hyper-cross-linked resin NDA150) and its precursor (post-cross-linked resin, PCLR). MPDAMR possessed high BET surface area (1040.7 m2/g), abundant micropores, and plentiful amino groups. The adsorption efficiencies of 4-chloroaniline (4-CA) and 2,4-dichloroaniline (2,4-DCA) by MPDAMR were 78.7% and 97.8%, respectively, which were much higher than that of XAD-4, NDA150, and PCLR. The excellent adsorption capacity of MPDAMR for chloroanilines was attributed to its high surface area, abundant micropores, primary amine driven enhanced polarity, and π–π stacking interactions. Pseudo first-order kinetics equation and Freundlich equation were capable of explaining the adsorption process of chloroanilines onto MPDAMR. Both the intraparticle diffusion and film diffusion were rate-controlling steps. The thermodynamics results attested that the adsorption of chloroanilines was a spontaneous exothermic process. The saturated adsorption capacities of MPDAMR for 4-CA and 2,4-DCA were 213.8 mg/g and 278.4 mg/g dry resin, respectively. Additionally, MPDAMR had good regenerated adsorption capacity after five adsorption-desorption cycles. Thus, MPDAMR was a potential adsorbent used to remove chloroaniline compounds from industrial effluent.