Hierarchical Micro/Nanofiber Composite Architectures for Multifunctional Remediation

Abstract

Hierarchical micro/nanofiber composite architectures are increasingly being used as a versatile platform for tackling complex environmental remediation requirements. These materials have both functional and structural properties that are tunable at several different scales for synergistic improvements in adsorption capacity, catalytic activity, selectivity, and regeneration performance. For example, the hierarchical membranes and sorbents discussed in this chapter have contaminant removal efficiencies ranging from 88-99% for pharmaceutical micropollutants and dyes up to 100% for targeted heavy metal ions within minutes to hours of contact time. The results illustrate the quantitative performance gains that motivate this design strategy. This chapter summarizes innovations in the design, development, and application of hierarchical fiber-based composites with multiple functionalities for remediation of organic contaminants, heavy metals, pathogenic microorganisms, and oil-water mixtures. Fiber strategies that combine high surface area and high mechanical strength achieved at the nanometer scale provide tailored porosity, controlled wettability, and efficient mass transfer. Electrospinning, co-assembly, surface functionalization, and hybridization of nanomaterials and metal-organic frameworks and their catalytic domains to achieve the best structure-property-performance relations are discussed. These design principles allow a single hierarchical architecture that combines adsorption, catalysis, and size-exclusion functions and is directly applicable to emerging applications such as reactive membranes, smart filters, and fully integrated water- and air-purification systems. Finally, several major issues, such as long-term stable performance, fouling resistance, and sustainable production, are described, and future opportunities for new remediation technologies with even higher efficiency and lower environmental impact are proposed.