Adsorption of methylene blue by a high-efficiency adsorbent (polydopamine microspheres): Kinetics, isotherm, thermodynamics and mechanism analysis

Halloysite is an alumosilicate tubular clay with a diameter of 50 nm, an inner lumen of 15 nm and a length of 600-900 nm. It is a natural biocompatible nanomaterial available in thousands of tons at low price, which makes it a good candidate for nanoarchitectural composites. The inner lumen of halloysite may be adjusted by etching to 20-30% of the tube volume and loading with functional agents (antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins) allowing for formulations with sustained release tuned by the tube end-stoppers for hours and days. Clogging the tube ends in polymeric composites allows further extension of the release time. Thus, antioxidant-loaded halloysite doped into rubber enhances anti-aging properties for at least 12 months. The addition of 3-5 wt% of halloysite increases the strength of polymeric materials, and the possibility of the tube's orientation promises a gradient of properties. Halloysite nanotubes are a promising mesoporous media for catalytic nanoparticles that may be seeded on the tube surface or synthesized exclusively in the lumens, providing enhanced catalytic properties, especially at high temperatures. In vitro and in vivo studies on biological cells and worms indicate the safety of halloysite, and tests for efficient adsorption of mycotoxins in animals' stomachs are also carried out.

Halloysite Clay Nanotubes for Loading and Sustained Release of Functional Compounds.

Recent advance in research on halloysite nanotubes-polymer nanocomposite

Properties and applications of halloysite nanotubes: recent research advances and future prospects

Dyes adsorption using clay and modified clay: A review

Study on the adsorption of Neutral Red from aqueous solution onto halloysite nanotubes.

Halloysite clay tubes have 50 nm diameter and chemically different inner and outer walls (inner surface of aluminum oxide and outer surface of silica). Due to this different chemistry, the selective etching of alumina from inside the tube was realized, while preserving their external diameter (lumen diameter changed from 15 to 25 nm). This increases 2-3 times the tube lumen capacity for loading and further sustained release of active chemical agents such as metals, corrosion inhibitors, and drugs. In particular, halloysite loading efficiency for the benzotriazole increased 4 times by selective etching of 60% alumina within the tubes' lumens. Specific surface area of the tubes increased over 6 times, from 40 to 250 m(2)/g, upon acid treatment.

Enlargement of Halloysite Clay Nanotube Lumen by Selective Etching of Aluminum Oxide

NiCoP nanowire@NiCo-layered double hydroxides nanosheet heterostructure for flexible asymmetric supercapacitors

Halloysite nanotubule clay for efficient water purification.

Preparation of highly ordered cubic NaA zeolite from halloysite mineral for adsorption of ammonium ions.

Yafei Zhao

Papers

Study on the adsorption of Neutral Red from aqueous solution onto halloysite nanotubes.

Enlargement of Halloysite Clay Nanotube Lumen by Selective Etching of Aluminum Oxide

NiCoP nanowire@NiCo-layered double hydroxides nanosheet heterostructure for flexible asymmetric supercapacitors

Halloysite nanotubule clay for efficient water purification.

Preparation of highly ordered cubic NaA zeolite from halloysite mineral for adsorption of ammonium ions.