Sulfonic acid-functionalized polymers by O-alkylation of carboxylated PIM-1 for adsorption of Cu2+ from water

The prototypical polymer of intrinsic microporosity PIM-1 was acid hydrolysed to introduce carboxylic acid functionality (cPIM-1), and then further decorated with stronger cation exchange side groups by O-alkylation with 1,3-propanesultone (PS) and 1,4-butanesultone (BS). The PIM-1 and modified polymers were characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopy, thermogravimetric analysis and elemental analysis. Average molar mass of PIM-1 was determined by multi-detector gel permeation chromatography. For adsorption of Cu(II) from aqueous solution, the kinetics was analysed using pseudo-first order and pseudo-second order kinetic models, and isotherm data were fitted to a Langmuir model. The adsorbents cPIM-1, PS-cPIM-1 and BS-cPIM-1 showed the ability to chelate Cu(II) from aqueous media. The cPIM-1 exhibits reasonable adsorption capacity, q m = 17 mg g -1 , with high Cu(II) uptake rate constant, k 2 = 0.06 g mg -1 min -1 . Alkylsulfonic acid PIM-1 exhibits a significant improvement in the uptake capacity with q m = 39 and 43 mg g -1 for PS-cPIM-1 and BS-cPIM-1, respectively. PS-cPIM-1 and BS-cPIM-1 both showed k 2 values of 0.02 g mg -1 min -1 . The polymers show promise for future applications in treating real-world waste or process effluents.