Micro-mesoporous divinyl benzene-based polymer for ultrafast, effective and selective removal of cationic dyes

Poly(divinyl benzene-co-maleic anhydride) (PDVB-MAH) with hierarchically micro-mesoporous structure was fabricated by a facile sol-gel method, which was used as an adsorbent for the removal of cationic dyes including methylene blue (MB), rhodamine B (RhB), methyl violet (MV) and malachite green (MG) from wastewater. The resulting PDVB-MAH possessed micro-mesoporous structure with the surface area of 209 m(2) g(-1), which could facilitate the mass transfer process. The effects of pH (2-10), adsorbent dosage (0.2-2.0 g L-1), contact time, salt concentrations (0.1-0.6 mol L-1), initial concentrations (50-600 mg L-1) of dyes and temperature (298, 308 and 318 K) on the adsorption performance were investigated. The selective adsorption for cationic dyes was rapid and quantitative where removal efficiencies of 100% were obtained for MB and RhB within 5 and 15 min, respectively. The adsorption capacities of PDVB-MAH were 315.9 mg g(-1) and 420.4 mg g(-1) for MB and RhB, respectively. The adsorption behaviors on MB and RhB were accordance with the pseudo-second-order model and Sips model. The estimated thermodynamic parameters indicated the adsorption process was spontaneous and exothermic. Furthermore, the synergistic effect of pi-pi stacking interaction and electrostatic attraction was confirmed with the help of FTIR spectroscopy and DFT method. These results demonstrated that the PDVB-MAH could be a potential polymeric adsorbent with efficient dye removal from colored wastewater.