Design Approaches, Functionalization, and Environmental and Analytical Applications of Magnetic Halloysite Nanotubes: A Review

Abstract

Researchers have long been committed to developing alternative, low-cost nanomaterials that have comparable capacity to carbon nanotubes. Halloysite nanotubes (HNTs) are naturally hollow, multi-walled, tubular structures that have high porosity, enlarged volumes and surface areas, and hydroxyl groups ready for modification. In addition, HNTs are non-toxic, biocompatible, inexpensive, abundant in nature, and easy to obtain. Magnetic nanocomposites have aroused widespread attention for their diverse potential applications in analytical fields and so magnetic halloysite nanotubes (MHNTs) have emerged as outstanding magnetic nano-adsorbent materials. Owing to their superparamagnetism, selective adsorption ability, and easy separation and surface modification, these captivating nanomaterials excel at extracting and enriching various analytes from environmental, biological, and food samples. The current review article gives an insight into recent advances in the design, functionalization, characterization, and application of MHNTs as magnetic, solid-phase extraction sorbents for separation of antibiotics, pesticides, proteins, carcinogens such as polycyclic aromatic hydrocarbons (PAHs), dyes, radioactive ions, and heavy-metal ions in complex matrices.

Halloysite-Based Magnetic Nanostructures for Diverse Applications: A Review

“…Molecular imprinting involves the formation of a template-monomer complex, followed by polymerization and subsequent removal of the template molecule, leaving behind cavities or “imprints” in the polymer that are complementary in shape and functionality to the target molecule. It has gained significant attention due to the potential applications of molecularly imprinted polymers (MIPs) in various areas, such as chemical sensing, separation, catalysis, drug delivery, and biomimetic systems. , …”

“…It has gained significant attention due to the potential applications of molecularly imprinted polymers (MIPs) in various areas, such as chemical sensing, separation, catalysis, drug delivery, and biomimetic systems. 166,167 As an improvement, the same group reported another nanostructure for the selective recognition of TCP, in which Fe 3 O 4 -HNT was prepared via a polyol-medium solvothermal method, where magnetic HNTs were modified with 3-(methacryloyloxy)propyl trimethoxysilane followed by immobilization of vinyl groups. Finally, methacrylic acid (MAA) and Nisopropyl acrylamide (NIPAM) were used as functional monomer units to synthesize a temperature-responsive and magnetic molecularly imprinted polymers (t-MMIPs) system (Scheme 41).…”