Novel composite nanomaterials based on magnetic molecularly imprinted polymers for selective extraction and determination of rutin in fruit juice

In this work, with the attempt to further improve the selectivity, magnetism and loading proportion of existing adsorbents, a novel composite (MGO/MHNTs@MIPs) was synthesized by electrostatically combining molecularly imprinted polymer based on the surface of magnetic halloysite nanotubes (MHNTs@MIPs) with magnetic graphene oxide (MGO). Then some characterizations were done to prove its successful synthesis. Besides, the bonding experiment showed that it possessed a loading capacity of up to 132 mg·g^-1, and the adsorption behavior of MGO/MHNTs@MIPs was elucidated by Langmuir isotherm model and Pseudo-second order model. By comparing its adsorption capacity to analogues, we concluded that the MGO/MHNTs@MIPs with the MHNTs@MIPs as basic elements exhibited higher selectivity (imprinting factor = 2.25) than that of MGO/MHNTs@NIPs based on MHNTs@NIPs for template rutin. Furthermore, a series of solid phase extraction conditions were optimized, and then the materials were used for the extraction and detection of rutin in fruit juice under the optimal conditions.

Ultrasound-assisted bottom-up synthesis of Ni-graphene hybrid composites and their excellent rhodamine B removal properties

In this paper, a facile one-pot bottom-up approach has been developed for the rapid preparation (≤5 min) of graphene nanostructures and Ni-graphene hybrid composites. Under the aid of ultrasonic irradiation, the graphene nanostructures were prepared via reducing hexachloro-benzene(C₆Cl₆) with sodium (Na) in non-polar organic solvent n-tetradecane (C₁₄H₃₀). On the basis of this route, the Ni-graphene hybrid composites were easily synthesized by adding Ni nanoparticles (NPs) into reaction system. The whole reaction was carried out at low temperature (100-120 °C) and in air atmosphere. Despite the absence of nitrogen protection, the result from surface analysis still shows a relatively high C/O ratio (10:1). The effect of the Ni NPs content and size on the specific surface area (SSA) of the products is also investigated. The synthesized samples exhibit large SSA, which is significantly affected by the Ni NPs content rather than their size. The adsorption performances of the samples are evaluated for the removal of organic dyes such as rhodamine B (RhB) from aqueous solutions. The testing results show great adsorption capacity (q_max = 963.04 mg g^-1), rapid adsorption rate (~99.88%, 2 min), high adsorption efficiency (>99.7%) and good chemical stability in a wide pH range (3-13), high salt tolerance (>80 mg mL^-1), and good recyclability (>99.5%, 20 cycles).

Halloysite nanotubes in analytical sciences and in drug delivery: A review

Halloysite (HNT) is a natural inorganic mineral that has many applications in manufacturing. This review (with 192 references) covers (a) the chemical properties of halloysites, (b) the effects of alkali and acid etching on the loading capacity and the release behavior of halloysites, (c) the use of halloysite nanotubes in analytical sciences and drug delivery, and (d) recent trends in the preparation of magnetic HNTs. Synthetic methods such as co-precipitation, thermal decomposition, and solvothermal method are discussed, with emphasis on optimal magnetization. In the analytical field, recent advancements are summarized in terms of applications of HNT-nanocomposites for extraction and detection of heavy metal ions, dyes, organic pollutants, and biomolecules. The review also covers methods for synthesizing molecularly imprinted polymer-modified HNTs and magnetic HNTs. With respect to drug delivery, the toxicity, techniques for drug loading and the various classes of drug-halloysite nanocomposites are discussed. This review gives a general insight on the utilization of HNT in analytical determination and drug delivery systems which may be useful for researchers to generate new ideas. Graphical abstract Schematic presentation of the structure of halloysite nanotubes, selected examples of modifications and functionalization, and represetative field of applications.

One-step synthesis of SnO2-reduced graphene oxide (SOG) composites for efficient removal of organic dyes from wastewater

In this work, SnO₂ functionalized graphene oxide was shown to possess high adsorption capacities and fast adsorption rates for organic dyes over wide pH ranges. Additionally, the adsorbent could be easily regenerated by washing with ethanol.