TiO2-alginate composite aerogels as novel oil/water separation and wastewater remediation filters

Developing effective and "green" approaches to handle aquatic pollution problems is currently one of the most important research subjects of environmental remediation. In this paper, an environmentally friendly, low cost, self-cleaning, highly stable and multifunctional TiO2 enhanced Sodium alginate composite (SAT) aerogel for oil water separation is developed via a simple combined ionic cross-linking and freeze drying method. The morphological, structural and surface chemical properties of the as-prepared SAT aerogels is characterized by scanning electric microscopy (SEM), X-ray diffraction (XRD), Flourier transformation infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The characterizations demonstrate that the SAT aerogel is of three-dimensional porous microstructure with uniformly dispersed TiO2 nanoparticles (NPs) on alginate matrix. The hydrophilic alginate matrix combined with this unique morphostructure will ensure the SAT aerogels with underwater oleophobicity and subsequent excellent oil/water separation efficiency (up to 99.7%). Moreover, the firmly attached TiO2 NPs can also endow the aerogel with better UV-aging resistance, photoinduced self-cleaning and environmental remediation performance. The SAT aerogel exhibits better oil/water separation reusability (at least 60 cycles) compared to SA aerogel and excellent photocatalytic performance for methyl orange (MO) degradation (> 85% after 6 times repeated use). The "green" facile fabrication process, excellent oil/water separation, photoinduced self-cleaning and reusable performances make the SAT aerogel promising for practical application in aquatic environments. This work may open up new avenues for designing versatile aerogel for wastewater remediation.