Assessment on the removal of dimethyl phthalate from aqueous phase using a hydrophilic hyper-cross-linked polymer resin NDA-702

A hydrophilic hyper-cross-linked polymer resin (NDA-702) was synthesized, and the adsorption performance of dimethyl phthalate (DMP) on NDA-702 was compared with that on the commercial hydrophobic macroporous resin (Amberlite XAD-4) and granular activated carbon (AC-750). The kinetic adsorption of DMP onto NDA-702 and AC-750 is limited mainly by intraparticle diffusion and obeys the pseudo-second-order rate model, while the uptake on XAD-4 is limited mainly by film diffusion and follows the pseudo-first-order rate model. All the associated adsorption isotherms are well described by the Freundlich equation, and the larger uptake and stronger affinity of NDA-702 than AC-750 and XAD-4 probably result from the microporous structure, phenyl rings, and polar groups on NDA-702 polymer matrix. An interesting observation is that in the aqueous phase all the adsorbents spontaneously adsorb DMP driven mainly by enthalpy change, but the hydrophilic nature of NDA-702 and AC-750 surfaces results in less entropy change compared to hydrophobic XAD-4. Dynamic adsorption studies show that the high breakthrough and the total adsorption capacities of NDA-702 are 388 and 559 mg per gram dry resin at 313 K. Nearly 100% regeneration efficiency for the resin was achieved by methanol at 313 K.