Sponge shape semi-interpenetrating polymeric networks based on PDMS/CS/PVA/GEN to capture an azo dye

We have demonstrated the feasibility of obtaining semi-interpenetrating polymeric networks containing PDMS and hybrid hydrogels CS/PVA/GEN produced as sponges. They were intended to capture acid blue 113 (AB113), which was dissolved in water at concentrations of 10, 5, and 2.5 ppm with a pH of 5.8. The chemical stability of the sponges was proved after reusability cycles of AB113 capturing; FT-IR analysis did not reveal any chemical changes or degradation in the sponges after their use as a removal device. Using PDMS in the CS/PVA/GEN blend enhances the sponges’ mechanical response, exhibiting an elastic modulus of 21\(-\)26.7 kPa in the dry state and 15–16 kPa in the hydrated state, respectively. The sponges were able to capture AB113 up to 3 cycles of reuse. The possible mechanisms of AB113 capture include electrostatic attractions, hydrogen bonding (dipole–dipole and Yoshida H-bonding), n-\(\pi\) stacking, and \(\pi\)-\(\pi\) interactions. In the first cycle of capture, the sponges showed capture percentages ranging 76 ± 11% , 79 ± 2%, and 90 ± 1%; however, for the third cycle of capture, their efficiency decreased to 20 ± 3%, 22 ± 1%, and 34 ± 3%, for concentrations of 10, 5, and 2.5 ppm, respectively. Lower concentrations of AB113 implied better removal capacity of the sponges. Our results demonstrated that sponges can potentially remove contaminants such as organic dyes from water. These findings open the possibility of using them to capture other pollutants, such as heavy metals or pesticides that have chemical affinity to the chemical structure of the semi-interpenetrating polymeric network-based PDMS/CS/PVA/GEN sponges.

Graphical abstract