Facile preparation of poly(acrylic acid–acrylamide) hydrogels by frontal polymerization and their use in removal of cationic dyes from aqueous solution

Frontal polymerization (FP) was used as a new facile technique for the preparation of poly(acrylic acid–acrylamide) (PAA) hydrogels obtained from acrylic acid (AAc) and acrylamide (AM) in the presence of N,N′-methylenebisacrylamide (MBA) as a crosslinker. The dependence of the front velocity and front temperature on the factors such as the ratio of AAc and AM, the content of MBA and initiator was investigated. The microstructure, dynamic swelling, morphology and cationic dyes removal of PAA hydrogels prepared via FP were studied by FTIR spectrum, FE-SEM and swelling measurements. The results showed that PAA hydrogels prepared via FP exhibited good swelling and adsorption capacity toward cationic dyes and the adsorption capacity of may reach 4.12 and 11.23 mg/g in crystal violet (CV) and basic magenta (BM) solution after 72 h, respectively.

Graphical abstractVisual images of the propagation front of the PAA hydrogel. Cationic dyes (CV (a) and BM (b)) adsorption capacity of PAA hydrogels prepared by FP.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FP is an alternative fast method for synthesis of ionic hydrogels used in wastewater treatment. ► The frontal velocity and cross-linking density determine the properties of hydrogels. ► Cationic dye adsorption was strongly affected by the frontal velocity of hydrogels.