Functionalized Hypercrosslinked High Internal Phase Emulsion Materials Based on 4-Vinylbenzyl Chloride for Anionic Dye Adsorption.

Synthesis and characterization of porous polymeric monoliths as high-performance adsorbents for the removal of Acid Blue 113 dye from aqueous solutions is reported. High internal phase emulsion (HIPE) polymerization process was employed for the synthesis of polymeric-HIPEs (polyHIPEs) using 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) as co-monomers. To optimize their adsorption properties by inducing micro/meso porosity and introducing cationic functionalities, the polyHIPEs were post-modified via a two-step procedure. The first step involves the Friedel-Crafts hypercrosslinking reaction using FeCl3 as a catalyst, leading to high-surface-area materials, followed by cationic modification of residual chloromethyl groups with triethylamine to incorporate positively charged ammonium functionalities. The prepared polyHIPEs were characterized by Attenuated Total Reflectance-Fourier-Transform Infrared (ATR-FTIR), X-ray Photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller surface area analysis (BET), and Scanning Electron Microscopy (SEM). BET analysis verified the huge surface area enhancement from 10.1 to 614.5 m2 g-1 due to hypercrosslinking. The modified cationic adsorbent showed higher adsorption capacity (280.1 mg g-1) compared to the non-functionalized analogue (110 mg g-1) for anionic dye Acid Blue 113. Adsorption followed pseudo-second-order kinetics, suggesting chemisorption as the dominant mechanism. The adsorption mechanism was investigated via XPS, revealing that electrostatic interactions along with hydrogen bonding and π-π interactions are major contributors to this process.