Photo‐regenerable liquid crystalline polymers for the adsorption of organic pollutants

The increasing presence of organic pollutants such as herbicides and pesticides in water, soil and air requires efficient strategies for their removal and degradation in a reliable and environmentally sound manner. This work focuses on adsorbent materials for water remediation, also addressing pollutant degradation, a critical aspect allowing adsorbent re-use. A photo-regenerable adsorbent based on a liquid crystal network (LCN) is proposed, consisting of a highly ordered nanoporous material obtained through the polymerization of reactive mesogenic monomers. The addition of titanium dioxide nanoparticles in the LCN matrix as photocatalyst opens to its photoregeneration, allowing degradation of the pollutants and further cycles of adsorption. The LCN-TiO2 composite was optimized using methylene blue (MB) as a model and then tested for a real pollutant. The adsorber proved its efficiency with a maximum pollutant uptake of 86 wt% and total photoregeneration achieved by irradiation with an ultraviolet source. The best tradeoff of adsorption capacity and photoregeneration efficacy was found for samples loaded with only 1 wt% of TiO2 nanoparticles. This composite also exhibited a high pollutant adsorption capacity and fast and complete photo-regeneration toward the herbicide Diquat, opening the way for a new versatile strategy for water remediation from emerging organic pollutants.