Layered double hydroxide/polyacrylamide nanocomposite hydrogels: Green preparation, rheology and application in methyl orange removal from aqueous solution

Layered double hydroxide (LDH)/polyacrylamide (PAM) nanocomposite (NC) hydrogels were successfully prepared utilizing Co/Al-LDH nanosheet as inorganic crosslinker, acrylamide as monomer via in-situ free radical polymerization at room temperature in water. The Co/Al-LDH used here is freshly prepared Co/Al-LDH solution with a Tyndall phenomenon, which avoids the exfoliation and dispersion process of LDH using toxic organic solvent or modifiers. The hydrogel formation mechanism can be ascribed to the coordination and hydrogen bonding interactions between hydroxyl groups on LDH nanosheet and amide groups on acrylamide. The effect of LDH content on viscoelastic properties were studied by rheology measurement. The removal of methyl orange as a probe dye by Co/Al-LDH/PAM NC hydrogel accords with Langmuir adsorption isotherm and pseudo-second-order equation. (C) 2019 Elsevier B.V. All rights reserved.