No abstract

Photocatalytic degradation of organic pollutants is an efficient, energy-saving, renewable technology. MIL-101(Fe) is an effective photocatalyst; however, its degradation efficiency for dye molecules is reduced by its hydrophobicity and sedimentation in aqueous solutions. In this study, MIL-101(Fe)/cellulose-nanocrystal (CNC) hybrid nanoparticles (MCs) with high photocatalytic activity were prepared by in situ growth. Owing to their unique amphiphilicity and interfacial adsorption, the MC-stabilised Pickering emulsions exhibited uniform particle size and stability. The MCs were uniformly adsorbed at the oil–water interface of the emulsion and dispersed in the water phase through a three-dimensional (3D) network with clusters. This facilitated complete contact of the MCs with pollutants, thereby significantly increasing the photocatalytic efficiency. The tuneable wettability of MIL-101(Fe) induced by CNCs considerably affected the stabilisation and photocatalytic degradation performance. At 0.5 wt% CNC, the MCs had a three-phase contact angle of 92°, resulting in the highest photocatalytic degradation rate and emulsion stability of the samples studied herein. An emulsion with a constant emulsification index of 100% was obtained at 0.4 wt% MCs and an oil-phase volume fraction of ~ 0.2. The MC-stabilised emulsion system exhibited high photocatalytic degradation efficiency for Rhodamine B. Moreover, the MCs could be recycled several times while ensuring a degradation efficiency within an acceptable range. Herein we introduce a new approach for improving and fabricating green, sustainable photocatalysts for degradation of organic pollutants in aqueous systems.

Compared with traditional surfactant-stabilised emulsions, Pickering emulsions, stabilised by clay nanoparticles, have the advantages of strong interface stability, strong versatility, and low toxicity. Moreover, they have excellent application potential in the fields of food and medicine. In this study, a food-grade Pickering emulsion stabiliser was prepared by physically adsorbing the cationic surfactant ethyl lauroyl arginate (LAE) on the surface of nano-montmorillonite (NMMT). Different LAE/NMMT combinations were assessed for their capacity to stabilise an oil-in-water emulsion at a low solid concentration (0.5%, w/v). The controllability of the droplet diameter and stability of the Pickering emulsions can be realised by changing the content of LAE. Scanning electron microscopy (SEM), and laser confocal microscopy (CLSM) confirmed the successful preparation of sunflower oil Pickering emulsion droplets stabilised by LAE/NMMT (0.0075%/1%). Additionally, the LAE/NMMT studied in this work could be used as a highly effective antibacterial surfactant with inorganic nanoparticles to efficiently stabilise Pickering emulsions, thus expanding the potential of preparing edible Pickering emulsion formulae.