Removal of Pollutants by Ferrihydrite Nanoparticles Combined with Brij L4 Self-Assembled Nanostructures

Abstract

Release of contaminants such as pharmaceuticals, dyes, pesticides, and industrial wastes due to anthropogenic activities is a threat to human health and the environment. Self-assembled nanostructures of nonionic surfactants are highly efficient in removing organic and inorganic pollutants from various environmental media. Here, we present an evaluation of the pollutant-removal efficiency of Brij L4 nonionic surfactant as a function of the surfactant concentration and self-assembled structures. In addition, small-angle X-ray scattering (SAXS) and rheology were employed to investigate interactions between the Brij L4 isotropic micellar phase and lyotropic liquid crystals and ferrihydrite nanoparticles (Fh NPs). Ferrihydrite nanoparticles in the micellar phase destabilized lyotropic liquid crystals at low surfactant concentrations, while remaining stable in lyotropic phases at high concentrations. Maximum pollutant-removal efficiency (22%) was obtained using a self-assembled nanostructure of pure Brij L4 at 1 wt %. However, Fh NPs are nanoporous and strongly interact with negatively charged organic matter, enhancing the pollutant-removal efficiency of 10 wt % Brij L4. We constructed binary and pseudo-binary phase diagrams at 25 °C of the surfactant in water and in the presence of ferrihydrite nanoparticles, respectively. The Brij L4/water binary phase diagram identified rod-shaped structures at 10 wt % of surfactant. The results of this study identify effective strategies for formulating highly efficient pollutant-removal systems using nanotechnology.