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This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), size distribution measurements, density measurement by He pycnometry, superconducting quantum interference device (SQUID) magnetometry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), zeta potential measurement, hydrophobicity determination by contact angle, Brunauer–Emmett–Teller surface area analysis (BET technique) and atomic force microscopy (AFM). Batch experiments were performed in function of process parameters such as contact time and initial concentration of Fe3+. The natural palygorskites (Palys) had excellent performance for the removal of Fe3+ from aqueous solutions by adsorption (around 60 mg/g), and the Langmuir is supposedly the best model fitted the experimental data. [ABSTRACT FROM AUTHOR]

ABSTRACT: Water contaminated by oil poses challenges to the management of water resources. Magnetic nanoparticles has been issue of different potential applications including remotion oil from water. Magnetic polystyrene–palygorskite nanocomposites were prepared by a heterogeneous phase polymerization for the removal of organic contaminants from water. The organo‐Fe3O4‐palygorskite nanoparticles were coated with polystyrene, forming water repellent and oil absorbing surfaces to promote the removal of oil from the surfaces of nanocomposites by applying an external magnetic field. X‐ray fluorescence, X‐ray diffraction, scanning electron microscopy, zeta potential and size distribution measurement, surface area determination by BET, density measurement by He pycnometry, carbon grade determination, thermogravimetric analysis, Fourier‐transform infrared spectroscopy, Raman spectroscopy, and evaluation of hydrophobicity by contact angle were used to characterize the nanoparticles. The magnetic nanocomposite obtained showed excellent hydrophobicity, around 78° contact angle. In addition, oil removal capability tests were also performed, according to which the preliminary results indicated removal of approximately 98% of oil in synthetic oily water samples. The oil–water separation using this magnetic nanocomposite provides a promising alternative strategy for water treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46162. [ABSTRACT FROM AUTHOR]

The organophilization of clays to increase interfacial interactions is a typical practice when the objective is its encapsulation with a polymer. This work intend to synthesize and characterize an organo-palygorskite-Fe 3 O 4 , to change the hydrophilicity of the material and investigate its efficiency in the removal of two anionic dyes from aqueous solution with the aim to use this material to treat wastewater contaminated with dyes. The organophilization of modified palygorskite–Fe 3 O 4 was done with a cationic surfactant (cetyl trimethylammonium bromide, CTAB) and the material obtained was characterized by XRF, SEM, XRD, FTIR, Nano Zetasizer, density, BET surface area, TGA/DTA and contact angle measurements. XRF and FTIR confirmed the presence of carbon in the modified palygorskite–Fe 3 O 4 nanoparticles while XRD showed new crystalline phases from CTAB. Furthermore, a positive zeta potential value appeared and an inversion in the nanoparticles' hydrophobicity happened due to the increase of organic carbon content in the organo-palygorskite-Fe 3 O 4 . The adsorbed anionic dye on organo-palygorskite-Fe 3 O 4 may be completely recovered by the action of a magnet, showing an excellent adsorptive property and economical alternative adsorbents to treat dye wastewater. The negative values calculated for the free energies of adsorption indicate that the adsorption of methyl orange and indigo carmine on the active sites of organo-palygorskite-Fe 3 O 4 surface was spontaneous and that the indigo carmine had the best interaction with the magnetic organo clay. [ABSTRACT FROM AUTHOR]

Recently there has been considerable interest in magnetic sorbents materials, which is added excellent capabilities such as sorption and magnetic response to an applied field. Accordingly, palygorskite nanoparticles were covered by magnetite using a co-precipitation technique and characterized by: X-ray fluorescence (XRF), X-ray diffraction (XRD), surface analysing and scanning electron microscopy (SEM) with element analysis and mapping, particle size, pore surface area (BET), density, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and zeta potential. Additionally, magnetic properties were studied by SQUID magnetometer, magnetic force microscopy (MFM) and also using a simple experimental setup. Magnetic nanoparticles produced had average diameters in a nanometric range. The amount of iron present in the nanoparticles increased by six times after the magnetization and a superparamagnetic behavior was exhibited with high saturation magnetization, from 4.0 × 10 −4 Am 2 /kg to about 20 Am 2 /kg. A weight loss was also observed around 277 °C–339 °C by TGA, indicating a structural change from magnetite to maghemite, which confirms the magnetization of palygorskite. Batch adsorption experiments were carried out for the removal of methylene blue cationic dye from aqueous solution using pure and covered by magnetite palygorskite nanoparticles as adsorbents. Furthermore, about 90% of methylene blue was removed within 3 min using magnetized palygorskite. [ABSTRACT FROM AUTHOR]

Highlights: [•] Palygorskite was characterized by chemical analysis, morphology and particle size. [•] Using XRD pattern, it was observed that palygorskite is the main mineral. [•] SEM images show the fibrous aspect of the palygorskite and ribbon-like structures. [•] Palygorskite is positively charged below pH 8 and becomes negatively charged above it. [ABSTRACT FROM AUTHOR]