Aniline modified hypercrosslinked polystyrene resins and their adsorption equilibriums, kinetics and dynamics towards salicylic acid from aqueous solutions

A series of aniline modified hypercrosslinked polystyrene resins named as HJ-Y0, HJ-Y2, HJ-Y4, HJ-Y8 and HJ-Y12 were synthesized from macroporous crosslinked chloromethylated polystyrene by adding different quantity of aniline in the Friedel-Crafts reaction and these resins were evaluated for adsorption of salicylic acid from aqueous solutions. The structure characterization indicated that Brunauer-Emmett-Teller (BET) surface area and pore volume decreased with increment of the added quantity of aniline whereas the nitrogen content increased, which implied these resins processed different adsorption selectivity towards difference aromacit compounds. HJ-Y4 possessed the largest uptakes towards salicylic acid, the Freundlich model was more suitable for fitting the equilibrium data and the isosteric enthalpies decreased with increasing of the fractional loading due to the surface energy heterogeneity. The pseudo second-order rate equation was more appropriate for characterizing the kinetic data and the adsorption process might be concerned with a chemical reaction. The breakthrough capacity (C/C0 = 0.05) of salicylic acid on HJ-Y4 resin column was measured to be 50.24 mg/mL wet resin and the resin column could be regenerated completely by a mixture desorption reagent containing 0.01 mol/L of NaOH (w/v) and 40% of ethanol (v/v) and the resins exhibited good reusability.