Synthesis and characterization of semi-interpenetrating polymer network hydrogel based on polyacrylic acid/polyallylamine and its application in wastewater remediation

This study was an attempt to synthesize novel semi-IPN Hydrogels of Poly(acrylic acid) (PAAc)-Poly(allylamine) (PAlAm) and PAAc-poly(allylamine hydrochloride) (PAH) with different molar ratio of components. The influence of pH, time, temperature and salinity of water, as well as cross-linker amount, were also investigated. The synthesized PAAc/PAlAm and PAAc/PAH hydrogels were characterized using Fourier Transform Infrared Spectroscopy. The swelling behavior of the semi-IPN hydrogels revealed that the maximum swelling ratio was obtained for the sample SAPH1 with a PAAc/PAH ratio of 1/0.25 and for the sample SAP3 with a PAAc/PAlAm ratio of 1/1. Moreover, for the PAAc/PAH system, the maximum swelling degree was observed in alkaline pH, while for PAAc/PAlAm system, the maximum swelling was shown in pH = 7. The swelling study of the hydrogels in the aqueous solution of NaCl showed that increasing the salt concentration caused the limitation of water absorption. It was also shown that the increase in temperature of the swelling process led to an enhancement of the swelling ratio in distilled water. According to the results, the optimum amount of cross-linker was found for achieving the maximum swelling degree. UV–Vis spectroscopy was employed to determine the dynamic change of the 4-nitrophenol concentration. The results revealed the complete absorption of the 4-nitrophenol pollutant. This suggests that the prepared semi-IPN hydrogel is an appropriate system for treating the wastewater. Graphical abstract