Rapid and effective absorption of dye molecules from their low-concentrated water solutions by organically cross-linked polyacrylamide-hexagonal boron nitride nanocomposite and polyacrylamide hydrogels

Abstract

Dye-laden wastewater from textile industries significantly impacts the environment and, eventually, human health. It is, therefore, necessary to treat wastewater effluent from textile industries before it is discharged into water sources. Herein, we report the potential of organically cross-linked polyacrylamide-based nanocomposite hydrogels to rapidly and effectively absorb different dye molecules (methylene blue (MB), phenol red (PR), and methyl orange (MO)) from their respective low-concentrated water solutions. The polyacrylamide-hexagonal boron nitride nanocomposite hydrogel (PAM/hBN) was prepared by reacting PAM molecules with organic cross-linkers such as N, N’ methylene bisacrylamide (MBS) in the presence of hBN at high temperatures (150 °C; 8 h.). The FT-IR results revealed the successful formation of the PAM/hBN nanocomposite hydrogels. The differential scanning calorimetric (DSC) results also complement the nanocomposite formation as the melting temperature of PAM/hBN nanocomposite is comparatively higher than that of the neat-PAM hydrogel. The SEM showed that the PAM/hBN nanocomposite has macroporous morphology (average pore size of 2 μm) while neat-PAM hydrogel exhibited dense structures. The equilibrium absorption of PAM/hBN nanocomposite hydrogels is as high as 13.5 mg/g, while the equilibrium is reached within 10 min. The porous morphology of the nanocomposite hydrogels promotes the mass transfer process and leads to the rapid absorption of dye molecules from low-concentrated water solutions.