Nanomaterials for Sustainable Water Remediation

Abstract

Ever increasing industrialization leads to a rise in contaminated water resources due to the release of pollutants, such as organic dyes, into aquatic environments. Adsorption process, which involves the transfer of undesirable chemicals from a fluid phase to the surface of a solid adsorbent with high binding affinity and capacity, has become a leading separation technique for point-of-use water applications. Due to their high surface area, nanomaterials, such as carbon nanotubes or graphene, have the ability to uptake larger amounts of molecules before reaching saturation than conventional adsorbents like biochar. However, nanomaterials have the tendency to aggregate, hindering their adsorption properties and causing detrimental pressure drops in continuous flow systems. To avoid this, carbon nanomaterials can be dispersed using surfactants and deposited into porous templates. In this research, we propose using lignin in tandem with a double-acoustic irradiation system as a sustainable surfactant and hardwoods as renewable supports for nanosorbents to prevent material agglomeration and facilitate fast water transport. Hardwoods exhibit a unique mesoporous structure, comprising partially aligned, hollow channels (vessels), connected together through perforation plates with micrometer-sized pores, enabling continuous conduction of fluids along the wood channels. Here, we prepared sustainable water filters by decorating the hardwood template with aqueous solutions of alkali lignin and graphene nanoplatelets using a vacuum assisted impregnation method for the removal of methylene blue from aqueous solutions. Results showed that complete removal of methylene blue was achieved within a broad range of concentrations even at high flow rates, providing great opportunities for environmental remediation and separation applications.