Fabricating polymeric hydrogel membranes embedded with amine- and copper- modified nanostructures for RG 19 removal

We aim to develop new types of adsorbents for Reactive Green 19 (RG 19) removal studies by combining nanoparticles and polymeric hydrogel membranes (PHMs). Poly (2-hydroxyethyl methacrylate) [p(HEMA)]-based PHMs embedded with modified nanoparticles are synthesised for the first time ever, and their performance are investigated vis-a-vis Reactive Green 19 (RG 19) removal from aqueous solution. First, p(HEMA) nanoparticles are synthesised by surfactant-free emulsion polymerisation. Next, the nanoparticles are modified with amine and copper (Cu) to increase the number of dye-binding active sites. The PHMs containing modified and unmodified nanoparticles, respectively, are synthesised by photopolymerisation. The PHMs are characterised with attenuated total reflectance Fourier transform infrared spectrometry, scanning electron microscopy/energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy, contact angle, and swelling capacity analyses. RG 19 is removed from aqueous solution under different parameters, such as pH, initial dye concentration, and contact time. The maximum RG 19 adsorption capacities over a 2-h period are 816.0, 648.0, and 194.1 mg/g (pH = 7.0; temp = 298.0 K; dye concentration = 15,000 mg/L) for the PHMs containing amine-modified, Cu-modified, and unmodified nanoparticles, respectively. We observe that the adsorption process occurs over two steps. The kinetic model is compatible with the pseudo-second-order kinetic model. The RG 19 adsorption capacities of the PHMs do not considerably decrease during six adsorption − desorption cycles. In turn, the PHMs embedded with amine- and Cu-modified nanoparticles, respectively, might be an economical alternative to adsorbents with high adsorption capacity in the context of RG 19 removal studies. Graphical abstract