A defect-rich layered double hydroxide nanofiber filter with solar-driven regeneration for wastewater treatment

The need for environmental technology treatment of contaminants of emerging concerns (CECs) is increasing as CECs lead to detrimental effects on human health and ecosystems. Herein, defect-rich layered double hydroxide (LDH) structured into a fibrous filter with a facile solar-driven regeneration function was fabricated for efficiently removing adsorbed CECs in wastewater. The physical and chemical interactions between the LDH filter and CECs are revealed. It is demonstrated that the introduction of unsaturated Cu^δ+ sites (δ < 2) and creating oxygen vacancies represents an effective way for improving adsorbing activity of the defect-rich LDH host layer. Also, the nanofiber-particle friction coefficient of the hierarchical LDH filter affects the filtration efficiency as revealed by 3D modelling. The LDH filter is capable of filtrating sixteen types of CECs and shows the capability of photocatalytic degradation of adsorbed CECs, thus enabling filter regeneration. This work thus presents a new perspective into bottom-up design of adsorbent materials: from molecular interactions to shaping adsorbents into microscopic nanofibers and assembling these into macroscopic 3D adsorbent filters.