An eco-friendly supramolecular hydrogel based-on [NaP5W30O110]14− as a giant inorganic cluster crosslinker: Green synthesis, characterization, and study of thermal and mechanical properties.

This study is a new sight to the application of Preyssler heteropolyacid with the formula of [NaP 5 W 30 O 110 14− as a green and nontoxic inorganic crosslinker to prepare a supramolecular hydrogel using chitosan and polyvinyl alcohol. This novel Preyssler/chitosan/polyvinyl alcohol hydrogel was designed using a multicomponent synthesis method and characterized by multiple techniques including infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), force atomic microscopy (AFM), contact angle measurement, mechanical tests and thermogravimetric analysis (TGA). TGA was conducted to measure the weight loss of the synthesized hydrogel at a heating rate of 10 °C min−1 in the nitrogen atmosphere. It is evident that Preyssler is acting as a crosslinker which has high thermal degradation or high thermal stability. The FTIR of the synthesized hydrogel reveals no chemical changes during crosslinking. The resultant surface showed excellent hydrophilic ability and had a water contact angle (CA) of 19.8 ± 4. Results of the SEM revealed that the surface of the hydrogel film is homogeneous and continuous. The sample had a low elongation at break (1.84 ± 2.38%), due to strong hydrogen bonding interactions between the Preyssler, chitosan, and PVA. The performance of the synthesized hydrogel using Preyssler's anion was compared with chitosan/polyvinyl alcohol. In all cases, the maximum improvement was observed by using the Preyssler heteropolyacid. To expand the potential application of the synthesized hydrogel in water treatment, the removal of methyl orange and red pigment as common azo dye pollutants in the environment was selected as a test reaction to estimate the potential application of the synthesized hydrogel and found to be excellent. • This study is a new sight to the application of Preyssler heteropolyacid as crosslinker. • Preyssler/chitosan/polyvinyl alcohol hydrogel was synthesized and fully characterized. • A green and nontoxic inorganic crosslinker used to prepare supramolecular hydrogel. • The process as a green technology does not require harmful and corrosive crosslinkers. • The synthesized hydrogel is a good candidate to remove azo dyes from color wastewaters. [ABSTRACT FROM AUTHOR]