Fe3O4-Halloysite Nanotube Composites as Sustainable Adsorbents: Efficiency in Ofloxacin Removal from Polluted Waters and Ecotoxicity

Abstract

The present work aimed at decorating halloysite nanotubes (HNT) with magnetic Fe3O4 nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/Fe3O4) to remove the antibiotic ofloxacin (OFL) from waters. The chemical–physical features of the obtained materials were characterized through the application of diverse techniques (XRPD, FT-IR spectroscopy, SEM, EDS, and TEM microscopy, thermogravimetric analysis, and magnetization measurements), while ecotoxicity was assessed through a standard test on the freshwater organism Daphnia magna. Independently of the synthesis procedure, the magnetic composites were successfully obtained. The Fe3O4 is nanometric (about 10 nm) and the weight percentage is sample-dependent. It decorates the HNT’s surface and also forms aggregates linking the nanotubes in Fe3O4-rich samples. Thermodynamic and kinetic experiments showed different adsorption capacities of OFL, ranging from 23 to 45 mg g−1. The kinetic process occurred within a few minutes, independently of the composite. The capability of the three HNT/Fe3O4 in removing the OFL was confirmed under realistic conditions, when OFL was added to tap, river, and effluent waters at µg L−1 concentration. No acute toxicity of the composites was observed on freshwater organisms. Despite the good results obtained for all the composites, the sample by co-precipitation is the most performant as it: (i) is easily magnetically separated from the media after the use; (ii) does not undergo any degradation after three adsorption cycles; (iii) is synthetized through a low-cost procedure. These features make this material an excellent candidate for removal of OFL from water.

Design of Etched- and Functionalized-Halloysite/Meloxicam Hybrids: A Tool for Enhancing Drug Solubility and Dissolution Rate

“…The siloxane and silanol groups on the outer surface and the aluminol on the inner one infer a negatively and positively charged nature to the two surfaces, respectively [ 27 ]. All these features, combined with the cheapness of halloysite (large number of deposits), non-toxicity, and biocompatibility [ 28 , 29 ], make HNTs suitable for a variety of applications in catalysis, polluted water remediation and environmental depuration, drug carrier and delivery systems, and polymer fillers [ 30 ]. The large number of applications can be further widened by HNT modifications, which aim to make the internal and external surfaces of halloysite nanotubes more reactive and selective and to make the interlayer space accessible to specific molecules.…”

Effect of High-Energy Ball Milling, Capping Agents and Alkalizer on Capacitance of Nanostructured FeOOH Anodes

“…Wet chemical synthesis methods represent an important tool in nanotechnology. Such methods are widely used in the nanotechnology of metals, quantum dots, metal oxides and hydroxides for nanoparticle synthesis from solutions of metal salts [ 21 ]. Such methods offer the advantages of simplicity, affordability, speed and good control of particle size and morphology.…”

Nanoparticles in the Environment and Nanotoxicology

“…This Special Issue aims to provide recent novel research findings of nanoparticles on their determination, detection, and degradation in the environment as well as the toxicity of nanoparticles. This Special Issue provides ten outstanding papers comprising two review articles and eight research articles with a range of original contributions detailing various types of nanoparticles in terms of their toxicity [ 1 , 2 , 3 , 4 , 5 ], removal of antibiotics [ 2 , 6 ], and behavior in natural environments [ 3 , 7 , 8 ].…”

“…The contamination of pharmaceuticals and personal care products (PPCPs) has driven attention due to their intensive usage and widespread into the environment as well as their potential risk to humans and ecosystems [ 10 ]. In this Special Issue, the potential of using nanomaterials to remove PPCPs was reported [ 2 , 6 ]. Capsoni et al [ 2 ] synthesized halloysite nanotubes (HNT) with magnetic Fe 3 O 4 nanoparticles as adsorbents to quantitatively reduce the concentration of antibiotic ofloxacin in tap, river, and effluent waters and further evaluated the acute toxicity with the freshwater organism Daphnia magna .…”

“…In this Special Issue, the potential of using nanomaterials to remove PPCPs was reported [ 2 , 6 ]. Capsoni et al [ 2 ] synthesized halloysite nanotubes (HNT) with magnetic Fe 3 O 4 nanoparticles as adsorbents to quantitatively reduce the concentration of antibiotic ofloxacin in tap, river, and effluent waters and further evaluated the acute toxicity with the freshwater organism Daphnia magna . Sulfamethazine (SMZ), one of the most commonly used antibiotics, was found to experience degradation that could be promoted by graphene oxide (GO) under UV light in a water environment [ 6 ].…”