In the current work, poly(4-vinylpyridine) (P4VP) was grafted on a macroporous polystyrene resin via free-radical polymerization by using the pendent vinyl group. The grafting conditions such as swelling agent, initiator concentration, reaction temperature, and amount of 4-vinylpyridine (4VP) monomer were optimized, and three resins with different 4VP monomer amounts (SC-1, SC-2, and SC-3) were chosen as adsorbents. P4VP-grafted resins were characterized by scanning electron microscopy, N2 sorption/desorption isotherms, Fourier transform infrared, and X-ray photoelectron spectroscopy. The sorption properties of 2-naphthalenesulfonic acid (NSA) on three resins were comparatively investigated. The experimental data revealed that the sorption process on three resins fitted well with the pseudo-second-order kinetics equation, and the equilibrium isotherms were in good agreement with the Langmuir model. The NSA sorption onto resins was an endothermic and spontaneous process, and SC-3 loaded with NSA can be efficiently regenerated by NaOH and ethanol mixed solution after sorption. The maximum sorption capacities of three resins indicated that P4VP-grafted resins possess good sorption ability toward NSA.
Two novel weakly basic anion exchange resins BNH and BN2 bearing two different functional groups was fabricated via the two-step amination of chloromethylated polystyrene-divinylbenzene beads with dibutylamine and dimethylamine. The adsorption properties of BNH and BN2 for the 2-naphthalenesulfonic acid (NSA) removal from wastewater were compared with two synthesized monofunctional anion exchange resins BN0 and BN6 (derived from dimethylamine and dibutylamine, respectively). The experimental data revealed that the adsorption process on the four resins fitted well with the pseudo-second-order kinetics equation and the equilibrium isotherms were in good agreement with the Langmuir model. Thermodynamic analyses illustrated that 2-naphthalenesulfonic acid adsorption onto resins was an endothermic and spontaneous process. Importantly, BN2 still displayed relatively high adsorption capacity in the existence of Na2SO4, indicative of an excellent selectivity for 2-naphthalenesulfonic acid over sulfate than other resins. The obtained results elucidate that BN2 could have potential industrial application in effluent disposal fields because of its superior selectivity, acceptable kinetics, and desorption capability.