Efficiency of polyurethane elastomer containing sulfonated groups as chain extender in removing Malachite green

A novel type of polyurethane elastomer (PUE) containing nanocomposites of sodium alginate thiacalix[4]arene macrocycles including sodium alginate-thiacalix[4]arene and sodium alginate-tetra-sulfonated thaiacalix[4]arene (SA-TSTCA) was prepared. The key role of these nanocomposites merged into polyurethane elastomers is to function as chain extenders. To provide profound insight into the structural, thermal, mechanical, morphological and hydrophilic properties of the samples, several techniques were employed, namely Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Also the results were compared with the results of polyurethane elastomer based on glycerol (Gly) as chain extender. The results showed that the samples extended with nanocomposites as chain extender have better thermal and mechanical properties and between them the PUE containing SA-TSTCA showed higher thermal and mechanical properties. Furthermore, these elastomers have been used as adsorbent for removal of Malachite green (MG) for investigation of the effect of sulfonated groups introduced on the chain extender. The results revealed that SA-TSTCA-based polyurethane elastomer nanocomposite could well adsorb Malachite green from aqueous media by a batch adsorption method. The pseudo-first-order and pseudo-second-order kinetic models were employed to provide an in-depth study of the adsorption capacity of MG, suggesting that its adsorption onto PUE/SA-TSTCA elastomer was in accordance with pseudo-second-order kinetic process. A possible mechanism of adsorption was suggested where π–π stacking interactions, H-bonding interaction and electrostatic attraction controlled the MG adsorption.